Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 98
8
Effects on Animals
Animals can be affected directly by oil and gas activi-
ties or indirectly via alterations in habitat or food supplies.
At sea, animals can be affected by noise, particularly sounds
generated by seismic exploration, and by spills of oil and
other contaminants. On land, animals can be affected by
noise associated with seismic exploration, routine industrial
activities, vehicle and aircraft traffic, and disturbance of
dens. In addition, animals can be indirectly affected by
changes in vegetation caused by industrial activities, con-
taminant spills, withdrawal of water from lakes and streams,
and by the availability of anthropogenic food sources. For
obvious reasons, attention has been directed toward animal
species such as whales, seals, fish, bears, caribou, and birds
that have particular economic, esthetic, or cultural value.
Most invertebrates and many smaller vertebrates have not
been studied. A review of the fates and effects of oil in the
sea (NRC 2003) details much recent information.
POPULATION DYNAMICS
Terrestrial animals are mobile as adults. They can move
away from sources of disturbance or find new habitat. De-
clining populations in areas where local extinction is a dan-
ger can be replenished by the immigration of individuals
from other areas. The movements of individual animals,
however, make it difficult to assess the effects of industrial
activities on the North Slope. Data are needed on the behav-
ior of individual animals and on trends over larger areas than
are required, for example, to assess effects of road dust on
plants.
Although many studies have examined the responses of
various species on the North Slope to roads, ground and aerial
traffic, gravel pads, pipelines, and impoundments, it is diffi-
cult to assess the implications of the findings for the long-term
population dynamics of those species. Rarely are data avail-
able with which to compare the quality of the lost or disrupted
habitats with that of remaining, undisturbed habitats. There
98
are only inadequate estimates of the total fraction of high-
quality habitats affected by commercial activities.
To guide its thinking about effects of industrial activi-
ties on animals, the Committee on Cumulative Environmen-
tal Effects of Oil and Gas Activities on Alaska's North Slope
used basic principles and concepts of population ecology.
One process of central importance is habitat selection (Cody
1985~. All animals select habitats for various activities
(breeding, molting, hibernating) using clues associated with
the suitability of habitats for those activities. Because indi-
viduals that make good habitat choices reproduce more suc-
cessfully than those that make poor choices, populations
evolve so that individuals prefer to be in habitats that best
serve their needs. Thus, individual animals select the regions
containing the best, on average, available habitats
(Rosenzweig 1981), and use poorer habitats only when bet-
ter habitats are fully occupied or when the density of indi-
viduals in the better habitats is high enough to lower ex-
pected success below levels attainable in poorer habitats. At
a landscape scale, animals travel to regions that maximize
long-term productivity, although in a particular year, those
regions might not be the best (Griffith et al. 2002~.
Biologists can use habitat selection behavior as an indi-
cator of habitat quality. For example, because some species
of waterfowl travel long distances after completing repro-
duction to molt in particular areas on the North Slope, we
can assume that those are the best available molting areas
and that their loss would force individuals to molt in less
favorable places. Similarly, if caribou typically calve in spe-
cific areas, we can assume that those are the best available
calving areas. Although data might not be available about
the likely suitability of other areas to which individuals
might be displaced it is prudent to assume that alternative
areas are less desirable than the ones currently used.
When patterns of habitat occupancy are constrained by
behavioral dominance or population density, a population is
likely to have "source-sink population dynamics" (Hanski
OCR for page 99
EFFECTS ON ANIMALS
and Gilpin 1997), which result when reproductive rates are
higher than death rates in high-quality habitats. The better
habitats are sources of emigrants that disperse into and oc-
cupy poorer quality habitats (sink habitats), in which death
rates exceed birth rates. Population densities can be quite
high in sink habitats even though persistence of the species
in those habitats depends on a regular supply of immigrants
from source habitats.
An important consequence of source-sink population
dynamics is that a substantial proportion of the population of
a species can be found in sink habitats. Without detailed de-
mographic data, distinguishing between source and sink
habitats can be difficult at best (Pulliam 1988~. Loss of
source habitats could threaten the viability of a population
even though most of the habitat occupied by the species in a
region remains relatively intact. Thus, as activities and struc-
tures associated with oil and gas development expand into
the National Petroleum Reserve-Alaska and into the foot-
hills of the Brooks Range, the result could be an unexpected
decline of species even though total habitat loss might be
modest. In predicting the effects of expanded activity on the
North Slope, the committee attempted to identify those spe-
cies and areas where source-sink population dynamics are
likely to be operating and used the available information to
evaluate the likelihood that source-sink dynamics would oc-
cur. Although all receptors were considered from this point
of view, source-sink dynamics is discussed only for those
that appear to be affected by it.
MARINE MAMMALS
Although primary productivity is low in the freshwater
and marine ecosystems of northern Alaska, it is enough to
support many species of carnivorous vertebrates. The ma-
rine mammal fauna off northern Alaska consists of three
truly arctic species: ringed seal (Phoca hispida), bearded seal
(Erignathus barbatusJ, and polar bear (Ursus maritimus);
and four subarctic species: spotted seal (Phoca largha), wal-
rus (Odobenus rosmarus), beluga whale (Delphinapterus
Lucas), and bowhead whale (Balaena mysticetus) that move
into the area seasonally from the Bering and Chukchi seas
(Ferrero et al. 2000, Frost and Lowry 1984, Lentfer 1988~.
Beluga whales spend most of their time in the Beaufort Sea
in deep offshore waters.
Bowheacl Whales
The bowhead whale is a large up to 18 m (60 ft) long-
baleen whale that once was common in northern circumpo-
lar waters. Massive exploitation by commercial whalers
greatly reduced its numbers to the current five small groups
in the Bering Sea, Okhotsk Sea, Spitzbergen, Davis Strait,
and the Hudson Bay (Shelden and Rugh 1995~.
The Bering Sea stock is found seasonally in the Bering,
Chukchi, and Beaufort seas and in parts of the East Siberian
99
Sea. For many centuries bowhead whales have been impor-
tant nutritionally and culturally to the coastal Native people
of western and northern Alaska (Inupiat), the Chukotka Pen-
insula (Inupiat and Chukchi) of the Russian Far East, and
northwestern Canada (Inuit) (for example, see Krupnik 1987,
Sheehan 1995, Stoker and Krupnik 1993~. This stock was
heavily exploited by commercial whalers beginning in 1848
and ending in about 1914 (Woodby and Botkin 1993~. Be-
fore commercial whaling, the population is estimated to have
been between 14,000 and 26,000 (Breiwick et al.1981) with
estimates of 22,000 animals having been taken (Shelden and
Rugh 1995~. By the end of the commercial whaling period it
is thought that only a few thousand remained.
As a result of the 1993 census effort conducted off Point
Barrow, Alaska, the Bering Strait stock of bowhead whales
is estimated at 8,200 (95% estimation interval from 7,200 to
9,400) (Raftery and Zeh 1998~. The estimated annual rate of
increase from 1978 to 1993 was 3.2% with 95% confidence
interval 1.4% to 5.1%. As described in Chapter 1, accurate
censuses of bowhead whales were accepted only after long
efforts by Alaska Native hunters to correct earlier work.
The Bering Sea stock of bowhead whales spends the
winter (from about late November to about mid-March) in
the Bering Sea primarily at or near the ice edge. In the spring,
most bowheads move north from the vicinity of Saint
Lawrence Island, along the Alaskan coast to Point Barrow,
and then eastward, with most reaching the Canadian part of
the Beaufort Sea by early to mid-June (Shelden and Rugh
1995~. Although many spring migrants move in newly form-
ing open areas (leads) in the ice, bowheads also move
through ice-covered seas (Clark and Ellison 1988, 1989;
Clark et al. 1996), often breaking through ice (to at least 15
cm [6 in.~) to breathe (George et al. 1989~. Most spend the
summer in the Canadian part of the Beaufort Sea. During fall
(late August to mid-October), they migrate westward
through the Alaskan part of the Beaufort Sea, then into the
northern part of the Chukchi Sea, and then south along the
Chukotka coast. Most return to the Bering Sea by mid-
November.
Bowhead whales feed primarily on euphausiids and
copepods about 3-4 cm (Carroll et al. 1987, Lowry 1993,
Lowry and Burns 1980, Lowry and Frost 1984, Lowry et al.
2001~. Bowheads feed throughout the year, at least to some
extent. There are inadequate data to properly evaluate the
importance of the Alaskan portion of the Beaufort Sea as
feeding habitat for bowhead whales, especially during their
fall migration. Because this is the time when they are sus-
ceptible to disturbance by the noise of exploration for oil, the
information is needed for a full assessment of the effects of
noise on bowheads.
It probably takes about two decades for a bowhead to
achieve sexual maturity. Conception likely occurs in late
winter or early spring, and calves are usually born during the
spring migration (Kenney et al. 1981; Koski et al. 1993;
Rugh et al. 1992; Shelden and Rugh 1995; Tarpley et al.
OCR for page 100
100
1983,1999; Tarpley and Hillmann 1999~. Bowheads can live
100 years or more (George et al. 1995, 1999~.
Oil- and Gas-Relatecl Activities and Bowheacl Whales
The activities most likely to affect bowhead whales are
marine seismic exploration, exploratory drilling, ship and air-
craft traffic, discharges into the water, dredging and island con-
struction, and production drilling. To date there have been docu-
mented effects of industrial noise. As was true of early censuses,
the current understanding of the effects of noise on bowheads
was achieved only after long efforts of Alaska Native hunters to
correct early, imperfect studies (Chapter 1~. There have been no
major offshore oil spills on the North Slope.
Marine seismic exploration produces the loudest indus-
trial noise in the bowhead whale habitat. Some seismic sur-
veys are conducted in winter and spring on the sea ice, but
most are done in the summer-autumn open-water period.
Thus, bowheads and seismic boats are in the same areas dur-
ing the westward fall migration. In the nearshore Alaskan
Beaufort Sea, nearly all the fall-migrating bowhead whales
avoided an area within 20 km (12 mi) of an operating vessel,
and deflection of the whales began at up to 35 km (21 mi)
from the vessel (Richardson 1997,1998,1999; NMFS 2002~.
Noise levels received by these whales at 20 km (12 mi) were
117-135 dB (NMFS 2002~.
Disturbance to fall migrating bowhead whales also has
been shown in relation to offshore drilling in the Alaskan
Beaufort Sea. At the 1992 Kuvlum site the approaching fall-
migrating whales began to deflect to the north at a distance
of 32 km (19 mi) east of the drilling platform and bowhead
calling rates peaked at about the same distance (Brewer et al.
1993~. At the 1993 Kuvlum #3 site the whales were nearly
excluded from an area within 20 km (12 mi) of the drilling
platform (Davies 1997, Hall et al. 1994~.
During the 1986 open-water drilling operations at the
Hammerhead site, no whales were detected closer than 9.5
km (6 mi) from the drillship, few were seen closer than 15
km (9 ml), and one whale was observed for 6.8 hours as it
swam in an arc of about 25 km (15 mi) around the drillship
(LGL and Greeneridge 1987~. The zone of avoidance there-
fore seemed to extend 15-25 km (9-15 mi) from the
drillship. Acoustic studies done at the same time provided
received levels of drillship noise that can be related to the
zone of avoidance. At 15 km (9 mi) from the 1986 Corona
site, received sound was generally 105-125 dB (LGL and
Greeneridge 1987~; at 11 km (6 mi) from Hammerhead, re-
ceived sound was generally 105-130 dB.
Estimating Future Accumulation of Effects
In~lustrial Noise
If oil- and gas-related activities continue in the Alaskan
waters of the Beaufort Sea, the major noise will be generated
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
by marine seismic exploration. Other significant noise will
continue to be produced by exploratory and production drill-
ing, island construction, and vessel transit. The probable con-
sequences are diversion of animals from their normal migra-
tory path, possibly into areas of increased ice cover, and less
use of the fall migration corridor as feeding habitat.
If two or more types of disturbance occur at the same
time or in the same general area, the effects could be greater
than those observed from single sources. The greatest diver-
sion would occur if two or more seismic vessels operated
simultaneously with one just offshore of the other.
Such a disturbing influence set across the migratory path
could displace the whales seaward into areas where ice con-
ditions are more dangerous for hunters, prevent some whales
from passing, reduce use of the area as feeding habitat, and
affect the other behavior in the animals.
Spille~l Oil
There are no data on Arctic oil spills and bowheads be-
cause no major oil spill has occurred in the Beaufort Sea.
However, the potential for an oil spill and its likely effects
on bowhead whales are viewed by bowhead-dependent hunt-
ers as the greatest threat to the whale population and to their
cultural relationship with the animal (Ahmaogak 1985,1986,
1989; Albert 1990~. Oil spilled in broken-ice cannot be
cleaned up effectively, and it is expected that whales would
not avoid oil-fouled waters.
Each environmental impact statement (EIS) relating to
industrial activity in the Beaufort Sea contains estimates of
the likelihood of an oil spill. For example, the final EIS for
Beaufort Sea Planning Area Oil and Gas Lease Sale 170
(MMS 1998: IV-A-12) estimated a 46-70% chance of a spill
of 1,000 barrels (bbl) or more. Increasing industrial activity
in the Beaufort Sea, coupled with existing production at the
Endicott and Northstar facilities, would lead to rising prob-
ability of a significant oil spill.
The Exxon Valdez experience shows that cleaning up
spilled oil is difficult, even in ideal conditions in ice-free
waters (Loughlin 1994~. An oil spill would be most difficult
to control during periods of broken ice in the fall when
bowheads migrate through the area. During this period, new
ice is forming, slush ice is often present, ice is in the form of
chunks and pans, and ice formed earlier can move into the
area with the drifting and shifting ice pack. Mechanical re-
covery alone would likely be able to clean up only a small
fraction of oil in broken ice (ADEC 2000~.
An oil spill would pose less risk to bowhead whales if
the whales could detect spilled oil and avoid it. Although
there is no direct evidence about how bowhead whales would
react to oil-fouled waters, Dall's porpoise, harbor porpoise,
killer whales, and grey whales moved through waters con-
taminated by the Exxon Valdez accident (Harvey and
Dahlheim 1994~. Also, fin, humpback, and probably right
whales did not avoid an oil spill off Cape Cod, Massachu-
OCR for page 101
EFFECTS ON ANIMALS
setts (Goodale 1981, cited in BLM 1982~. Bowhead whales
regularly surface in slush ice, and easily break through thin
ice to breathe, so they are unlikely to avoid surfacing in oil-
covered waters. The toxic effects of inhaled oil vapors and
ingested oil on bowhead whales would probably be similar
to those described below for seals and polar bears.
A modest amount of attention has been devoted to study-
ing the likely effects of spilled oil on bowheads (for example,
see Albert 1981b, Hansen 1985 and Beaufort-Sea-related
EISs). One method compares the structure of the various
tissues of the whale that are most likely to contact the oil
with those of better-studied mammals. Related studies of the
bowhead, begun in the late 1970s with examination of sub-
sistence harvested whales and with the collection and ex-
amination of tissues from those whales (Albert 1981a, Kelley
and Laursen 1980), indicated that the skin, the eyes, the ba-
leen, and the lining of the gastrointestinal tract of bowhead
whales are likely to be injured by contact with spilled oil
(Albert 1981b).
101
The Skin
The skin of a bowhead whale is 10-22 mm (0.4-0.9 in.)
thick over much of its body (Haldiman et al. 1981, 1985,
1986~. Although bowheads have the soft, smooth skin typi-
cal of most cetaceans, they also have dozens to hundreds of
roughened areas (1-4 cm [0.4-1.6 in.] diameter) of skin sur-
face (Albert 1981b, Haldiman et al. 1985, Henk and Mullan
1996) the cause of which is not yet known (see Figure 8-1~.
In some of the roughened areas, the epidermal cells between
the epidermal rods have been removed. The exposed epider-
mal rods then appear as tiny hairlike or filamentous projec-
tions. The great increase in exposed surface (microrelief) of
these roughened areas increases the area to which oil can
adhere. In a laboratory experiment, oil adhered, in propor-
tion to the roughness of the skin surface, to formalin-pre-
served bowhead skin exposed to crude oil on water (Haldi-
man et al. 1981~. The roughened areas of skin had large
numbers of diatoms and bacteria, including potential patho-
FIGURE 8-1 Subsistence harvested bowhead whale, on the ice at Barrow. This photo shows a portion of the left side of the head. The
blowhole area is in contact with ice (near knife). A portion of left row of baleen is visible in the upper right of the photo. Note the large
number of lesions (arrows) on the skin surface. These commonly seen eroded areas make the skin surface much rougher than in unaffected
areas. A section of skin with lesions (upper right) was removed from the skin of the upper jaw. Photograph by Thomas Albert.
OCR for page 102
102
yens with varying tissue-destructive enzymes (Shotts et al.
1990~. Thus, it is likely that oil contact would be harmful.
The Eyes
The conjunctival sac associated with the eye is so exten-
sive that an adult human's fingers can pass beneath the eye-
lids and reach approximately two-thirds of the way around
the eye (Albert 1981b, Dubielzig and Aguirre 1981, Haldi-
man et al. 1986~. Thus, a large surface exists for an irritant
(such as spilled oil) to contact sensitive visual structures (Zhu
1996, 1998; Zhu et al. 2000, 2001~.
The Baleen
Bowheads filter prey from the water with their exten-
sive baleen apparatus (Lambertsen et al. 1989~. Many of the
hair-like filaments that form the margin of the baleen plates
break off during feeding and are commonly found in the
stomachs of harvested bowheads. Because the bowhead's
baleen apparatus is so extensive and the filaments on the
margin of each plate are so prominent, the baleen would be
fouled if a whale fed in oiled waters (Albert 1981b, Braith-
waite 1980, Braithwaite et al. 1983~.
A laboratory study (Braithwaite et al.1983) showed that Finclin s
crude oil strongly adhered to isolated bowhead baleen and 9
interfered with filtration efficiency for approximately 30
days. Less of an effect on filtration was found on isolated
baleen of species (fin, set, humpback, gray whale) that have
shorter, stiffer bristles than bowheads (Geraci 1990, Geraci
Baleen attached to jaw of subsistence-harvested bowhead whale.
September 2001. Photograph by David Policansky.
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
and St. Aubin 1982, 1985~. Petroleum also had little direct
effect on isolated baleen from several whale species (St.
Aubin et al. 1984~. A bowhead probably could filter out the
heavier portions of spilled oil, including globules and "tar
balls," and would probably swallow the oily material and the
dislodged oiled baleen filaments along with its prey.
The Stomach
Broken-off baleen bristles swallowed during feeding can
form "tangles" in the stomachs of bowheads (George et al.
1988~. Those dislodged bristles could combine in the stom-
ach with weathered oil components (such as tar balls) to form
a sticky mass (Albert 1981b).
The stomach of the bowhead whale consists of four
chambers, one of which is a narrow channel that connects
two other larger chambers (Tarpley 1985; Tarpley et al.
1983, 1987~. Blockage, leading to gastric obstruction, could
occur in this small, narrow connecting channel, which has
small entrance and exit openings, if a bowhead fed in oil-
fouled waters (Albert 1981b). Ingested oil would also have
toxic effects whose severity would be related to the amount
of oil swallowed.
· Noise from exploratory drilling and marine seis-
mic exploration causes fall-migrating bowhead whales to
divert around noise sources, including drillship operations
and operating seismic vessels, at distances of 15-20 km
(9-12 ml).
· In view of the large zone of near total avoidance
around a single operating seismic vessel, if more than one
such vessel is operating in the Alaskan portion of the Beau-
fort Sea when fall-migrating bowheads are in those waters,
the diversion of migrating whales could be much greater.
· Data needed for an improved assessment of the ef-
fects of seismic noise was delayed for many years due to
overreliance on a study that underestimated such effects, and
because of inadequate consideration given to relevant obser-
vations by subsistence hunters.
· Available data are inadequate regarding the full ef-
fects of industrial noise (seismic noise in particular) on fall-
migrating bowhead whales in the Alaskan portion of the
Beaufort Sea.
· There are inadequate data regarding the importance
of the Alaskan portion of the Beaufort Sea as feeding habitat
for the bowhead whale, especially during the fall migration.
· Harm to marine mammals from contact with spilled
oil (as in the Exxon Valdez experience and other instances)
and specific morphological characteristics of the bowhead
whale (extensive baleen apparatus, eroded areas of skin, ex-
tent of conjunctival sac, narrowness of stomach-connecting
channel) indicate that spilled oil would pose a great potential
threat to those organs in bowhead whales.
OCR for page 103
EFFECTS ON ANIMALS
Recommenclations
· Studies should determine the distance from an oper-
ating seismic vessel (and received noise at that distance) at
which the "average" bowhead whale begins to deflect, be-
gins to change its rate or type of vocalization, reaches the
point of greatest deflection, and returns to the normal migra-
tion path. Studies also should examine the effects of mul-
tiple noise sources in different configurations.
· Studies should determine the extent to which bow-
head whales make use of the Alaskan portion of the Beaufort
Sea as feeding habitat.
· The use of sound to divert whales from a spill site
and prevent them from contacting spilled oil should be
investigated.
Seals and Polar Bears
In Alaska, spotted seals, bearded seals, and walrus spend
most of their time in the Bering and Chukchi seas and gener-
ally use only the westernmost part of the waters off the
Alaska North Slope. Ringed seals and polar bears are com-
mon in waters off the North Slope where oil and gas explo-
ration and development have occurred. The main areas of
concern with regard to effects on those animals from oil and
gas activities are the potential for contamination (reviewed
by Geraci and St. Aubin 1990) and for disturbance caused by
industrial noise in the air and water (reviewed by Richardson
et al. 1995).
The effects of industrial activity on marine mammals in
the North Slope have been difficult to measure. Clearly,
spilled oil can be toxic to marine mammals (Geraci and St.
Aubin 1990, Loughlin 1994, NRC 2003), although there
have been no major spills in the Beaufort Sea, or in any
similar arctic environment, so no field data exist that can be
used to evaluate or predict consequences. Observations and
studies of responses of marine mammals to noise are diffi-
cult to interpret (Richardson et al. 1995~; nevertheless, it is
clear that noise can cause pronounced behavioral reactions
and displacement of some species. However, it has not been
possible to predict the type and magnitude of responses to
the variety of disturbances caused by oil and gas operations,
or, most important, to evaluate the potential effects on popu-
lations. Even if there were no effects on populations of the
affected marine mammal species, displacement of animals
could have important consequences for Alaska Natives seek-
ing to harvest those animals for subsistence.
Hunting and Other Deaths Causecl by Humans
Before the Marine Mammal Protection Act (MMPA)
became law in 1972, active sport hunting for polar bears off
western and northern Alaska reduced that population
(Amstrup et al. 1986~. Since then, marine mammals may be
hunted only for subsistence and handicraft purposes by
Alaska Natives, and there are no federally imposed limits on
103
that hunting unless populations are declared depleted. Since
1988, hunting of polar bears from the southern Beaufort Sea
stock has been controlled by a conservation agreement be-
tween the Inupiat of northern Alaska and Inuvialuit of the
western Canadian Arctic who hunt a shared population
(Nageak et al. l991~; the number of animals taken each year
is well documented. From 1988 to 1995 the average annual
take of 58.8 bears was well below the estimated "potential
biological removal level" of 73 (FWS 1998) and therefore
was considered safe.
Little is known about the number of ringed seals har-
vested, but they are an important subsistence resource to in-
digenous people throughout the Arctic (Smith et al. 1991~.
Alaska Native dependence on, and interest in, hunting ma-
rine mammals is influenced by many factors, including cul-
tural involvement, employment, community wealth, logis-
tics, and ice and weather conditions. The number of animals
killed by hunters can be expected to vary accordingly. How-
ever, current legal restrictions should prevent harm to popu-
lations of these animals if they are properly enforced.
Marine mammals also are killed in other ways. At least
one ringed seal pup has been killed by a bulldozer that was
clearing seismic lines on shore-fast ice of the Beaufort Sea.
A polar bear died on the North Slope apparently after eating
a container of dye used to mark temporary airstrips (Amstrup
et al. 1989~. It is not uncommon for residents to shoot polar
bears in defense of life and property, both in coastal commu-
nities and at industrial facilities. Two polar bears were killed
in this manner along the Beaufort Sea coast in 1990 and
1993, one at the Stinson oil exploration site and the other at
Oliktok Point (S. Schliebe, FWS, personal communication,
2001~. Regulatory agencies and the oil and gas industry have
made serious efforts to minimize interactions with polar
bears, both to increase human safety and to safeguard the
bears (Truest 1993~.
Oil
Laboratory experiments in which three polar bears were
coated with crude oil showed dramatic effects (0ristland et al.
1981~. Oil ingested during grooming caused liver and kidney
damage. One bear died 26 days after oiling and another was
euthanized. Stirling (1990) detailed numerous behavioral char-
acteristics and ecological considerations that suggest that po-
lar bears are especially susceptible to oil contamination. Labo-
ratory experiments also have been done to determine the
effects of oiling on ringed seals (Englehardt et al.1977~. After
24 hr in a pen with oil-covered water, ringed seals' blood and
tissues showed evidence of hydrocarbons that had been incor-
porated through inhalation, and kidney and liver damage. In
another study (Geraci and Smith 1976), three seals died within
71 minutes after oil was put into their pool, presumably be-
cause of a combination of hydrocarbon inhalation and stress.
Data presented by St. Aubin (199Oa) described the various
ways that pinnipeds could be affected by oil, much of it con-
OCR for page 104
104
firmed by studies of effects of the Exxon Valdez oil spill on
harbor seals (Frost et al. 1994a,b; Lowry et al. 1994; NRC
2003; Spraker et al. 1994~. However, as far as is known, nei-
ther ringed seals nor polar bears have been affected by oil
spilled as a result of North Slope industrial activities.
Noise
Most of the effort to describe the effects of noise and
disturbance on marine mammals has been devoted to studies
of bowhead whales. However, pinnipeds also react to a vari-
ety of disturbances, such as noise from aircraft and ocean
vessels (Richardson et al. 1995~. Some studies of the poten-
tial effects of disturbance on shore-fast ice on pupping ringed
seals have been done. Those studies showed that there was
probably some displacement of ringed seals from areas close
to artificial islands in the central Beaufort Sea (Frost and
Lowry 1988), and that there was a higher abandonment rate
of seal breathing holes close to seismic survey lines (Kelly et
al. 1988~. Noise probably affects haulout behavior of pinni-
peds but no quantitative data are available. From data col-
lected in the central Beaufort Sea from 1985 to 1987, Frost
and colleagues (1988) concluded that there were no broad-
scale effects of industrial activity on ringed seals that could
be measured by aerial surveys, but they also noted that there
was little offshore activity during those years. Subsequent
industry-funded monitoring studies for the Northstar and
Liberty projects suggested minor effects on ringed seals from
ice road construction and seismic exploration (Harris et al.
2001, Richardson and Williams 2000~. For most of the year,
polar bears are not very sensitive to noise or other human
disturbances (Amstrup 1993, Richardson et al. 1995~. How-
ever, pregnant females and those with newborn cubs in ma-
ternity dens both on land and on sea ice are sensitive to noise
and vehicular traffic (Amstrup and Gardner 1994~. Seismic
exploration has disturbed a bear in a maternity den (FWS
1986~. Current regulations require industry to avoid polar
bear dens as much as possible (FWS 1995b).
Habitat Changes
Human activities in, on, and adjacent to sea ice can cause
habitat changes that affect marine mammals. In winter,
ringed seals maintain holes in the shore-fast ice, and they
give birth to their pups in lairs under the snow in spring
(Smith and Stirling 1975~. If the thickness of the ice, the
amount and distribution of snow cover, or the timing and
characteristics of breakup change, seal productivity or sur-
vival will be reduced (Furgal et al.1996, Smith and Harwood
2001~. Polar bears can be attracted to artificial structures that
create leads in the ice because the leads increase the area
bears use to hunt ringed seals. Buildings also offer places for
bears to forage for human discards and stimulate their curi-
osity (Stirling 1988a). Not only does this increase the likeli-
hood that bears will encounter contaminants, but it also in-
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
creases the chances they will need to be driven away or killed
to protect human safety. Ice breaking, especially in areas of
shore-fast ice, obviously would result in major changes to
habitat, with likely effects on ringed seals and polar bears.
In waters off the North Slope, ringed seals feed princi-
pally on arctic cod, euphausiids, and amphipods (Lowry et al.
1980~. Those species, along with bowhead whales, copepods,
and seabirds, form a relatively simple pelagic trophic system
with some obvious potential for competitive interactions
(Frost and Lowry 1984~. Ringed seals are the primary prey of
polar bears (Smith 1980, Stirling 1988b). Changes in popula-
tion sizes of any of these species, either natural or caused by
humans, could affect other components of the ecosystem.
For polar bears, mark-recapture studies in the Beaufort
Sea suggest that the population increased considerably be-
tween 1967 and 1998 (Amstrup et al. 2001), probably be-
cause hunting has been limited (Amstrup et al.1986~. Ringed
seals are harder to count. Efforts to develop a program to
monitor ringed seals in the Beaufort Sea region began in
1985-1987 and continued in 1996-1999. Analysis of data
from 1970 to 1987 (Frost et al. 1988) suggested the density
of hauled-out seals fluctuated considerably from a high of
3.5 seals per km2 (9.1 seals per mi2) to a low of 1.1 seals per
km2 (2.6 seals per mid. Results of more recent surveys are
being analyzed (Frost et al. 2002~. Neither assessment pro-
gram is sensitive enough to detect the substantial changes in
population size that would be expected to result from oil and
gas exploration and development and other human activi-
ties. However, because so far the marine waters of the Beau-
fort Sea have seen only limited and sporadic industrial activ-
ity, it is likely that there have been no serious effects or
accumulation of effects on ringed seals or polar bears.
Permitting Inciclental Take
The Marine Mammal Protection Act prohibits the tak-
ing of marine mammals including polar bears and ringed
seals except in specifically permitted circumstances. The
MMPA allows the secretary of commerce to permit indus-
trial operations (including oil and gas exploration and devel-
opment) to take small numbers of marine mammals, pro-
vided that doing so has a negligible effect on the species and
will not reduce the availability of the species for subsistence
use by Alaska Natives. Regulations governing the permits
identify permissible methods, means to minimize harm, and
requirements for monitoring and reporting. The permits have
been used to minimize the effects of on-ice activities on pup-
ping ringed seals, to require planning and personnel training
that minimizes conflicts with polar bears, and to provide
buffer zones around known polar bear maternal den sites.
Potential for Accumulation of Effects
Although the U.S. Fish and Wildlife Service (FWS) has
produced a useful review of current and future threats to
OCR for page 105
EFFECTS ON ANIMALS
polar bears and their habitats (FWS 1995b), no formal pro-
jections have been made of how likely effects on ringed seals
or polar bears from future oil and gas activities are to accu-
mulate with effects of other human activities. For purposes
of making such a projection, the committee's scenario as-
sumes that offshore exploration for oil and gas, and possible
extraction, will occur in the Beaufort Sea from Barrow to
Flaxman Island, and possibly to the Canadian border. Activ-
ity would occur mostly near shore, adjacent to onshore oil
reserves, and development would entail methods and struc-
tures similar to those currently in use (gravel islands or
bottom-founded structures, horizontal drilling, buried pipe-
lines, and an emphasis on working during winter).
Full-scale industrialization of near-shore areas would
most likely result in at least partial displacement of ringed
seals. The frequency with which polar bears come into con-
tact with people and structures is undoubtedly a function of
the amount of activity in their habitats. Even with the best
possible mitigation measures in place, it is certain that some
bears will be harassed or killed. More human activity along
the coast and near shore could reduce the suitability of some
areas for use by donning female bears. This effect is likely to
be greatest east of the Canning River, especially within the
1002 Area of the Arctic National Wildlife Refuge, where the
highest concentration of on-land dens is found (Amstrup
1993, Amstrup and Gardner 1994~. Efforts to identify areas
where polar bears are most likely to den in the eastern part of
the North Slope (Durner et al. 2001), should improve the
ability of regulators and industry to reduce disturbance of
donned bears.
Contact with spilled oil or other contaminants in the
ocean would harm ringed seals and polar bears, and the like-
lihood of spills would increase with increased exploration
and development. Amstrup and colleagues (2000) modeled
the spread of a hypothetical 5,900 bbl (939,000 L, 248,000
gal) oil spill from the Liberty prospect) as it might affect the
seasonal distribution and abundance of polar bears in the
Beaufort Sea. The number of bears potentially affected by
such a spill ranged from O to 25 with summer open-water
conditions and O to 61 with autumn broken-ice conditions.
In its findings permitting the oil and gas industry to take
polar bears in Alaska waters, the FWS stated, "We conclude
that if an oil spill were to occur during the fall or spring
broken-ice periods, a significant impact to polar bears could
occur" (65 Federal Register 16833 [20001~. It seems likely
that an oil spill would affect ringed seals the same way the
Exxon Valdez affected harbor seals (Phoca vitulina) (Frost
et al. 1994a, Lowry et al.1994, Spraker et al.1994), and the
number of animals killed would depend largely on the sea-
son and the size of the spill. Polar bears could be further
affected if they ate oil-contaminated seals (St. Aubin l990b).
Climate change also will affect marine mammals (Tynan
and DeMaster 1997~. Sea ice is important in the life of all
~ The Liberty prospect is not being developed as of late 2002.
105
marine mammals in the arctic and subarctic regions (Fay
1974~. Already, there have been dramatic decreases in the
extent and thickness of sea ice throughout the northern hemi-
sphere, and those trends are expected to continue through
the next century (Vinnikov et al. 1999, Weller 2000~. The
distribution, abundance, and productivity of Alaskan marine
mammal populations will likely be altered by the combined
effects of changes in physical habitats, prey populations, and
interspecies interactions (Lowry 2000~. Warming is likely to
increase the occurrence and residence times of subarctic spe-
cies (spotted seals, walrus, beluga whales, bowhead whales)
in the region.
Negative effects on populations of truly arctic species
(polar bears, ringed seals, and bearded seals) are likely to
result from climate warming. Polar bears and ringed seals
depend on sea ice, and reductions in the extent and persis-
tence of ice in the Beaufort Sea will almost certainly have
negative effects on their populations (FWS 1995b). Climate
change has already affected polar bears in western Hudson
Bay, where bears hunt ringed seals on the sea ice from No-
vember to July and spend the open-water season on shore
where they feed little. In a long-term study, Stirling and col-
leagues (1999) documented decreased body condition and
reproductive performance in bears that correlated with a
trend toward earlier breakup of sea ice in recent years. The
earlier breakup gives bears a shorter feeding season. They
are leaner when they come ashore, and they must fast longer.
Many ringed seals give birth to and care for their pups on
stable shore-fast ice, and changes in the extent and stability
or the timing of breakup of the ice could reduce productivity
(Smith and Harwood 2001~. Because of the close predator-
prey relationship between polar bears and ringed seals, de-
creases in ringed seal abundance can be expected to cause
declines in polar bear populations (Stirling and 0ritsland
1995~.
How these independent factors might combine to influ-
ence populations cannot be predicted with current knowl-
edge. If climate warming and substantial oil spills did not
occur, cumulative effects on ringed seals and polar bears in
the next 25 years would likely be minor and not accumulate.
Currently there are no research plans or studies that spe-
cifically address potential accumulating effects on polar
bears or ringed seals off the North Slope. Unless such stud-
ies are designed, funded, and conducted over long periods
(decades), it will be impossible to verify whether the effects
occur, to measure their magnitude, or to explain their causes.
Finclings
· Industrial activity in marine waters of the Beaufort
Sea has been limited and sporadic and likely has not caused
serious accumulating effects on ringed seals or polar bears.
· Careful mitigation can help to reduce the effects of
North Slope oil and gas development and their accumula-
tion, especially if there is no major oil spill. However, the
OCR for page 106
106
effects of full-scale industrial development of the waters off
the North Slope would accumulate through displacement of
polar bears and ringed seals from their habitats, increased
mortality, and decreased reproductive success.
· A major Beaufort Sea oil spill would have major ef-
fects on polar bears and ringed seals.
· Climate warming at predicted rates in the Beaufort
Sea region is likely to have serious consequences for ringed
seals and polar bears, and those effects will accumulate with
the effects of oil and gas activities in the region.
· Unless studies to address potential accumulation of
effects on North Slope polar bears or ringed seals are de-
signed, funded, and conducted over long periods, it will be
impossible to verify whether such effects occur, to measure
them, or to explain their causes.
CARIBOU
Introduction
The effects of North Slope industrial development on
barren-ground caribou (Rangifer tarandus grant)) herds have
been contentious. Although much research has been con-
ducted on caribou in the region, researchers have disagreed
over the interpretation and relative importance of some data
and how serious data gaps are. The disagreements are espe-
cially significant because caribou are nutritionally and cul-
turally important to North Slope residents and because cari-
bou are widely recognized as important symbols of the state
and well-being of North Slope environments. For these rea-
sons, the committee assembled information on caribou and
evaluated conflicting interpretations of the information about
how oil and gas development might have affected their popu-
lation dynamics. The committee's consensus on effects to
date, and projections of probable future effects, is the prod-
uct of this careful analysis and deliberation.
Assessing the effects of oil and gas development on cari-
bou is not straightforward because many factors other than
oil and gas activities affect the sizes of North Slope caribou
herds weather, vegetation, disease, and predators, for ex-
ample. Therefore, there is no steady baseline against which
to identify and assess disturbance-induced changes. To
evaluate the effects of petroleum development on caribou,
the committee examined changes in distribution and habitat
use, and evaluated the nutritional and reproductive implica-
tions of those changes and how they altered population
dynamics.
Background
Caribou are ubiquitous on the North Slope. Four sepa-
rate herds, ranging nearly 20-fold in size, are recognized on
the basis of distinctly different calving grounds (Skoog 1968,
Figure 8-2~. The extent of seasonal migration varies with
herd size (Bergerud 1979, Fancy et al. 1989, Skoog 1968~.
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
By far the largest is the Western Arctic Herd (WAH), esti-
mated at 460,000 (in 2001~. It calves in the Utukok uplands
south of Barrow and summers throughout the North Slope
and Brooks Range west of the Colville River, including most
of the National Petroleum Reserve-Alaska. Wintering areas
include both the western North Slope and the southern
foothills of the Brooks Range. The annual range of the
Teshekpuk Lake Herd (TLH), numbering 27,000 (in 1999),
lies within the WAH summer range. Calving and summer
ranges are in the coastal zone near Teshekpuk Lake; the win-
ter range typically is confined to the coastal plain and nearby
foothills. Estimated at 123,000 (in 2001), the Porcupine Cari-
bou Herd (PCH) calves on the coastal plain and lower
uplands in northeastern Alaska within the Arctic National
Wildlife Refuge and adjacent Yukon Territory. During the
summer, the PCH ranges throughout much of the eastern
North Slope and Brooks Range; its wintering areas include
the Ogilvie and Richardson mountains in western Canada
and the southern Brooks Range in eastern Alaska. At 27,000
(in 2000), the Central Arctic Herd (CAM) is distributed pri-
marily within state lands between the Colville and Canning
rivers. CAM calving and summer ranges are on the coastal
plain, and the winter range typically extends southward into
the northern foothills of the Brooks Range. During the past
27 years, the size of the PCH has been nearly constant; the
other three herds have increased substantially (Figure 8-3~.
Central Arctic Hercl
For the past 50 or 60 years, all four herds (Figure 8-2)
have been exposed to oil and gas exploration activity, but
only the CAH has been in regular and direct contact with
surface development related to oil production and transport.
Its calving ground and summer range lie within the oil-field
region near Prudhoe Bay; its autumn, winter, and spring
ranges encompass the Dalton Highway (also called the Haul
Road) and the area around the Trans-Alaska Pipeline
(Cameron and Whitten 1979b). The CAH has increased from
around 5,000 animals in the late 1970s to its current (2000)
size of 27,000 (Figure 8-3~.
Parturient females, along with most nonparturient fe-
males and yearlings, arrive on the coastal calving ground in
mid-May (Gavin 1978, Smith et al. 1994~. The exact timing
depends on patterns of snowfall and snowmelt (Cameron et
al. 1992, Gavin 1978~. Most calving occurs within 50 km
(31 mi) of the Beaufort Sea (Whitten and Cameron 1985,
Wolfe 2000~. Virtually all calves are born between late May
and early June (Cameron et al. 1993) within two or three
calving concentration areas (Whitten and Cameron 1985,
Wolfe 2000~. At the landscape level, selection and repeated
use of a calving ground is probably related to both the distri-
bution of predators, which are less abundant on the coastal
plain (Rausch 1953; Reynolds 1979; Shideler and Hechtel
2000; Stephenson 1979; Young et al. 1992, 2002) and the
likelihood of favorable foraging conditions (Griffith et al.
OCR for page 107
EFFECTS ON ANIMALS
107
:~
. ~ ~
FIGURE 8-2 Arctic caribou herds. SOURCE: Alaska Geobotany Center, University of Alaska Fairbanks, 2002.
7 -
.N 6 -
cn
Cad
o 5 -
. _
=4 -
o
AL 3 _
. _
~ 2 -
a~ -
lY 1 -
.~W
fit
it:
-
O- 1 1 1 1 1 1 1 1 1 1 1
1975 1980 1985 1990 1995 2000
Year
-
PCH - 1 78K
WAH - 463K
CAH - 27K
m
TLH - 28K
FIGURE 8-3 Relative post-calving herd sizes (minimum ob-
served = 1.0) of the four Alaska barren-ground caribou herds (PCH,
Porcupine Caribou Herd; WAH, Western Arctic Herd; CAH, Cen-
tral Arctic Herd; TLH, Teshekpuk Lake Herd), 1976-2001. Maxi-
mum observed population size for each herd is noted in the legend.
SOURCE: Griffith et al. 2002.
2002~. Annual shifts in concentrated calving within the over-
all calving ground are driven by spatial changes in the qual-
ity and quantity of new forage, principally sedges (Bishop
and Cameron 1990, Wolfe 2000~. An additional advantage
of coastal calving is proximity to "insect-relief habitat,"
which eliminates the need for extensive travel with a young
calf.
Bulls and the remaining noncalving females and sub-
adults, which stay inland during the calving period, follow
the northward progression of plant growth (Whitten and
Cameron 1979), arriving on the coastal plain in late June
(Cameron and Whitten 1979a, Gavin 1978~. The midsum-
mer diet includes a variety of deciduous plants (Roby 1978;
Trudell and White 1981; White and Trudell 1979, 1980;
White et al. 1975, 1981~.
Insects substantially affect energy balance by reducing
food intake and by increasing energy expenditure. Mosqui-
toes are present from late June through late July (Dau 1986,
Russell 1976, White et al.1975~. On warm, calm days, when
mosquitoes are active, caribou move rapidly to cooler,
windier areas on or near the coast, returning inland to pre-
ferred feeding areas when harassment abates (Cameron and
Whitten 1979a, Cameron et al.1995, Child 1973, Dau 1986,
Roby 1978, White et al. 1975~. These movements appear to
optimize foraging opportunity relative to energy expendi-
ture (Russell 1976, Russell et al. 1993, Walsh et al. 1992,
White et al. 1975~. Oestrid flies (warbles and nose bots)
emerge in mid-July and persist through early August (Dau
1986~. When oestrids are active, caribou stand head-down or
run erratically (Dau 1986, Nixon 1990, Roby 1978~. This
behavior probably reduces larval infestation, but at the ex-
pense of energy balance (Helle and Tarvainen 1984, Murphy
and Curatolo 1987, Russell et al. 1993~.
By autumn, caribou move inland (Cameron and Whitten
1979a), and breeding occurs from late September through
mid-October, while enroute to the winter range. Most of the
OCR for page 108
108
CAH winters in the foothills and mountainous terrain of the
northern Brooks Range, although a few caribou typically
remain on the coastal plain year round (Cameron and
Whitten 1979b, Cameron et al. 1979, White et al. 1975~.
Lichens, which are low in protein, predominate in the winter
and spring diets (Roby 1978~.
Ecological Strategies
During June and July, caribou body energy and nutrient
reserves are low (Chan-McLeod et al. 1999, Gerhart et al.
1996), and parturient and maternal females attempt to maxi-
mize theirintake of high-quality forage (Klein 1970, Kuropat
1984, Kuropat and Bryant 1979, Russell et al. 1993, White
et al.1975~. They replenish body protein reserves mobilized
during late gestation (Gerhart et al. 1996) and attempt to
meet or exceed the metabolic demands of lactation (White et
al. 1975, 1981), which are highest during the first 3 weeks
postpartum (Chan-McLeod et al. 1999, White and Luick
1984~. The benefits of good nutrition include increased
growth rates (Allaye-Chan 1991, White 1992) and survival
of calves (Haukioja and Salovaara 1978~. Good nutrition also
enhances summer weight gain of a female and increases the
probability that she will conceive in autumn (Adams and
Dale 1998; Cameron and Ver Hoef 1994; Cameron et al.
1993, 2000; Dauphine 1976; Eloranta and Nieminen 1986;
Gerhart et al.1997b; Lenvik et al.1988; Reimers 1983; Tho-
mas 1982; Thomas and Kiliaan 1998; White 1983~.
The intake of high quality forage often is reduced by
adverse weather. A late spring snowfall or late snowmelt
decreases forage quality and availability, resulting in lower
birth weights (Adamczewski et al. 1987, Bergerud 1975,
Eloranta and Nieminen 1986, Espmark 1979, Reimers 2002,
Rognmo et al. 1983, Skogland 1984, Varo and Varo 1971)
and delayed parturition (Cameron et al. 1993 Sko~land
1983, 1984), both of which reduce survival of offspring
(Adamczewski et al. 1987, Eloranta and Nieminen 1986,
Haukioja and Salovaara 1978, Rognmo et al.1983, Skogland
1984~. From late June through early August, repeated and
often severe insect harassment reduces the frequency and
duration of both suckling (Thomson 1977) and foraging
bouts (Helle et al. 1992, Morschel and Klein 1997, Murphy
1988, Murphy and Curatolo 1987, Russell et al.1993, Toupin
et al. 1996~. The result is less nursing opportunity, and
because fewer maternal nutrients are allocated to milk-
lower rates of milk intake. Factors that individually or col-
lectively reduce a female's ability to raise a calf also reduce
her ability to restore her body reserves, to fatten, and to breed
(Crete and Huot 1993~.
Tradeoffs therefore are inevitable: If maternal protein
or fat reserves are not replenished fast enough, calves are
weaned prematurely (Russell and White 2000~. Calf survival
is reduced by early weaning, but parturition and conception
rates increase (Davis et al. 1991, Russell and White 2000~.
Delayed weaning enhances calf survival, but extended lacta-
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
tion precludes breeding that year (Gerhart et al. 1997a,b;
Russell and White 2000~. By comparison, well-fed cows ini-
tiate weaning during the rut, and both calf survival and fe-
cundity are high.
During August and September, when insects are absent,
growth of calves and fattening of adults continue relatively
unimpeded. Milk production is low (White and Luick 1984),
and offspring graze actively (Russell et al. 1993) as they
approach nutritional independence. Although most forage
species have senesced, with a decline in quality, their high
biomass permits high rates of food intake (White et al.1975)
and, therefore, body-fat synthesis. Fattening is enhanced in
some years by the inclusion of mushrooms in the diet
(Allaye-Chan et al. 1990~. An unseasonably early, heavy
snowfall, however, can disrupt the fattening process, and
movement into more mountainous terrain increases expo-
sure to predators. Hunting by humans tends to intensify in
early autumn as well.
Females that wean their calves early, together with most
that are in good enough condition to wean at normal times,
conceive in October (Russell and White 2000~. Cows in su-
perior condition are less likely to lose their embryos early
(Crete and Huot 1993, Russell et al. 1998), and, hence, are
more likely to produce a calf the next spring.
A dietary shift from deciduous vegetation to lichens,
begun in autumn, is virtually complete by midwinter. Males
and nonpregnant females typically maintain body weight
(Steen 1968) even when weather and foraging conditions are
unfavorable. In contrast, pregnant females, faced with the
increasing metabolic demands of a growing fetus, have diffi-
culty maintaining energy and nutrient balance. They metabo-
lize muscle tissue and conserve body fat during the last tri-
mester to support early lactation (Chan-McLeod et al. 1994,
Tyler 1987~. Adequate winter nutrition increases the chances
of timely parturition and early postnatal survival (Cameron
et al. 1993, Eloranta and Nieminen 1986, Rognmo et al.
1983~.
When snow is deep or encrusted, foraging requires more
energy because caribou must dig through the snow (Fancy
and White 1985a,b; Miller 1976~. Far more serious is
ground-fast ice. During frequent freeze-thaw cycles, typi-
cally in coastal areas during late winter or early spring, veg-
etation under the snow becomes encased in ice and thus in-
accessible (Miller and Gunn 1979, Miller et al. 1982~. As
during autumn, mortality from predation and hunting can be
appreciable.
Effects on Distribution, Movements, ancl Activity Patterns
Seismic Surveys
Until recently, the location and timing of seismic testing
resulted in few conflicts with caribou in arctic Alaska. Sur-
veys on state lands through the 1990s were conducted prin-
cipally within the area of the CAH summer range, but during
OCR for page 121
EFFECTS ON ANIMALS
warming has been pronounced on the North Slope, produc-
ing longer frost-free periods during the breeding season
(Lachenbruch and Marshall 1986), which might have dis-
proportionately benefited swans there. Thus, if there have
been negative effects of oil-field development on tundra
swans, they have been insufficient to prevent the rapid
growth of the population during the past decade.
As with other species of birds, loss of habitat could re-
duce swan densities in the oil fields. Given the large territo-
ries (Ritchie and King 2000) and resulting low densities of
breeding swans throughout their range, however, it is un-
likely that the loss of less than 5% of potential breeding habi-
tat has substantially affected breeding swans in the oil fields.
Disturbance associated with facilities might be more impor-
tant than habitat loss, because swans are sensitive to human
disturbance at considerable distances (greater than 500 m
[1600 ft]) (Monda 1991~. Tundra swan broods have been
reported to avoid some areas within 100-200 m (330-660 ft)
of roads, although habitat use outside the breeding season
did not appear to be affected by roads (Murphy and Ander-
son 1993~. Ritchie and King (2000) concluded that oil-field
facilities had little influence on distribution of tundra swan
nests because the mean minimal distances from swan nests
to structures were less than the mean minimal distances be-
tween nests (Stickney et al. 1994), so territorial spacing is
more important to breeding distribution than is proximity to
artificial structures.
Predation does not seem to have influenced nest success
in the oil fields (83%) (Murphy and Anderson 1993), which
was comparable to that for tundra swans nesting in Arctic
National Wildlife Refuge (76%) (Monda et al. 1994~.
Black Brant
Nest success of black brant in the oil fields has been
chronically low, ranging from 44% to 55% (Sedinger and
Stickney 2000), in contrast to that in other colonies where
nest success is typically near 80% (Barry 1967, Sedinger et
al. 2002~. Low nest success is associated with high predator
populations in the oil fields. Modeling of this population
suggests that oil-field populations are not sustainable at such
inadequate nest success and could represent a sink popula-
tion (Sedinger and Stickney 2000~. Thus, high predator
populations associated with human activity in the oil fields
likely represent the greatest harm to nesting brant in the
region.
Black brant nesting in the oil fields are a relatively small
proportion (less than 2%) of the entire breeding population
for this subspecies (Sedinger et al. 1994, Sedinger and
Stickney 2000), although many brant broods from the
Colville River delta use the oil fields after hatching. B rant
breeding in the oil fields and in the delta increased several-
fold between 1982 and 1992 (Sedinger and Stickney 2000),
supporting the view that the growth has been sustained by
immigration from other areas.
121
13 rent nest colonially or semi-colonially (Sedinger et al.
1993) and are therefore less likely to be displaced by oil-
field structures unless the facilities are placed on or immedi-
ately adjacent to nesting concentrations. Facilities do not
seem to have displaced nesting brant (Murphy and Anderson
1993, Stickney and Ritchie 1996~. The largest nesting con-
centrations in the oil fields occur on Howe and Duck islands,
5 km (3 mi) and a few hundred meters, respectively, from
the Endicott Causeway. Similarly, large numbers of brant
broods use the salt marsh within 0.5 m (1.6 ft) of the Oliktok
long-range radar site (Sedinger and Stickney 2000~. During
nesting and brood rearing at these sites, brant responded to
humans at distances of less than a few hundred meters
(Murphy and Anderson 1993~. Brant also responded to 12%
of vehicles that passed within 300 m (980 ft), although those
responses lasted less than 5 minutes (Murphy and Anderson
1993) and likely had little effect on their nutritional status.
Observations of color marked and radio-tagged brant broods
provided no evidence that roads or other oil-field facilities
impeded movement from nests to brood-rearing areas
(Stickney 1996~. Brant goslings in the oil fields were actu-
ally larger than those from the Yukon-Kuskokwim delta at
the same age, implying greater abundance of food in the oil
fields (Sedinger et al. 2001~.
A long-term color-marking and monitoring program has
allowed estimates of annual survival for adult and juvenile
brant from the oil fields. The estimates show that adults from
the oil fields have similar if not slightly higher survival rates
than those from the delta in southwestern Alaska (Sedinger
et al. 2001~. Juvenile brant from the oil fields survived the
first stage of fall migration at higher rates than did those
from the Yukon-Kuskokwim delta, probably because of their
superior growth conditions (D. H. Ward, USGS, personal
communication, 2001~.
The North Slope is particularly important as a molting
are for black brant. About one-third of the world's popula-
tion of Pacific black brant assemble in the lakes and tundra
north and east of Teshekpuk Lake to molt. During that time
they are sensitive to disturbance by aircraft, especially heli-
copters (Derksen et al.1982, Miller 1994, Miller et al.1994,
Ward and Stehn 1989~. If industrial activity expands into
this region in the form of satellite fields without permanent
road links, increased air traffic is inevitable. The fact that
brant fly long distances to molt in this area strongly suggests
it is unusually favorable as a place to molt. This assumption
is supported by analyses of the tundra vegetation in this area.
Eiclers
Spectacled (Somateriafischeri) and Steller's (Polysticta
stelleri) eiders are currently listed as threatened under the
Endangered Species Act, mainly because of their decline in
excess of 90% since the 1970s on the Yukon-Kuskokwim
delta in southwestern Alaska (Stehn et al.1993~. Threatened
status has heightened interest in the North Slope populations,
OCR for page 122
122
but the historical record is short, and there are no data with
which to compare pro- and postdevelopment populations.
Spectacled eiders nest at relatively low densities on the North
Slope (Ducks Unlimited 1998, Mallek and King 2000), so it
is difficult to acquire sufficient censuses to make inferences.
Nesting spectacled eiders do not appear to avoid oil-
field structures, although nests appear to be farther from fa-
cilities than are those of prebreeding spectacled eiders
(Anderson et al. 2000~. Nest attendance patterns in the oil
fields (Anderson et al. 2000) are comparable to those in the
delta (Flint and Grand 1999), indicating that disturbance of
incubating females does not reduce nest attendance in the oil
fields. Nest success in the oil fields (42%) (Anderson et al.
2000), however, is substantially lower than in the delta (48%,
Grand and Flint 1997; 70%, Moran 2000~. Low nest success
in the oil field is primarily associated with predation (Ander-
son et al.2000~. Despite the low nest success, the population
in the oil fields was stable over 8 years of monitoring (1993-
2000) (Anderson et al. 2000), although the relatively short
study period and the small numbers recorded (typically fewer
than 10 nests) each year make it difficult to discern actual
trends. Low nest success is cause for concern, however, and
the local population might not be sustainable without regular
. . .
mm~grahon.
Because common eiders (Somateria mollissima) nest
predominantly on barrier islands in the Beaufort Sea they
have not been close to most oil-field activities. One excep-
tion was intensive operations in 1983 near Thetis Island,
north of the Colville River Delta (Johnson 2000a). Nest suc-
cess on Thetis Island in 1983 (81 %) was higher than in other
years or at other locations on Alaska's North Slope (less
than 45%), possibly associated with removal of arctic foxes
from Thetis Island that year (Johnson 2000a). Numbers of
common eider nests on barrier islands north of the oil fields
have generally increased since 1970, possibly as a result of
placement of anthropogenic debris on the islands, which ei-
ders use as nesting cover (Johnson 2000a). Glaucous gulls
are important predators of eider ducklings, but there are no
data to evaluate the potential effects of increased glaucous
gull populations in the oil fields on survival of common ei-
der ducklings in coastal lagoons immediately north of the oil
fields (Johnson 2000a).
King eiders (S. spectabilis) have been studied for a
shorter period, but there are no apparent trends in their popu-
lations within the oil fields (Anderson et al. 2001~. They do
not appear to avoid oil field structures (Anderson et al.2001~.
Nest success in the Kuparuk oil field averaged 32% from
1993 to 2000 (Anderson et al. 2001), similar to that of other
waterfowl in the oil fields, and consistent with the hypoth-
esis that nest success rates are low in the oil fields.
Lesser Snow Goose
Like black brant, lesser snow geese (Chen caerulescens
caerulescens) nest on Howe Island and Duck Island near the
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
Endicott Causeway (Johnson 2000b). As with other birds
nesting in the oil fields, predation appears to be the principal
negative effect of oil development. Oil-field-nesting snow
geese are less than 1 % of the North American winter popula-
tion (Bellrose 1980, Johnson 2000b), but the oil-field popu-
lation has increased 10-fold since monitoring began in 1980
(Johnson 1994~. Snow geese typically rear broods in salt
marshes east of the Endicott Causeway and in freshwater
and salt marshes west of the causeway. Broods are reared
much closer to the nesting area than is normal for most other
snow geese, which often move 70 km (40 mi) for brood rear-
ing. The broods did not change their use of brood-rearing
areas after construction of the causeway (Johnson 2000b).
Nest success was generally lower than for snow geese nest-
ing at La Perouse Bay (mean 92%, Cooke et al.1995) and no
eggs hatchedin 1991 or 1992, when arctic foxes were present
on the island during the normal nest initiation period. Nest
success has been low from 1991 through 2001, with com-
plete failure some years (Alaska Audubon 2001~. Thus, the
population on Howe Island appears to be a sink.
The North Slope of the Arctic National Wildlife Refuge
supports more than 60% of the Pacific population of lesser
snow geese during fall premigratory staging (Robertson et
al. 1997), so significant effects would accumulate if indus-
trial development were to spread to that area, accompanied
by increased aircraft traffic.
Conclusions ancl Projections of Future Effects
Because of higher predator densities, increased preda-
tion on nests is the most apparent effect of oil development
on birds that nest in the oil fields. Reduced nest success is
sufficient in some cases to cause population declines, so the
apparent stability of some oil-field populations is presum-
ably the result of immigration. As industrial activity spreads
into new areas, the amount of sink habitat will increase.
Placement of oil-field facilities does not appear to have re-
duced overall densities in the oil fields, although some shore-
birds do exhibit local displacement away from facilities and
roads. Of course, the direct loss of habitat caused by place-
ment of gravel fill could have reduced numbers, but the small
areas actually covered, combined with the low densities of
breeding birds, make it impossible to measure that effect.
Similar changes are to be anticipated in newly devel-
oped areas, and it appears that controlling anthropogenic
food sources that could enhance predator populations will be
essential to minimizing effects of predation on birds. One
important unknown is how the expanded use of 3-D seismic
exploration will affect birds: To the degree that this activity
affects vegetation, it might affect breeding birds in areas of
new development.
An important consideration is that new development in
the foothills of the Brooks Range could impinge on raptor
species' nesting and hunting habitats. Assessment of the ef-
fects of human activities on breeding raptors has produced
OCR for page 123
EFFECTS ON ANIMALS
mixed information (Andersen et al. 1990, England et al.
1995, Grubb and Bowerman 1997, Schueck and Marzluff
1995, Schueck et al. 2001~. Andersen et al. (1990) detected
shifts in home ranges of less than 1 km in response to mili-
tary training activity in southern Colorado. Schueck and col-
leagues (2001), however, detected little effect on the num-
ber, distribution, or behavior of raptors in the Snake River
Birds of Prey National Conservation Area in response to
military training activity, although they noted that raptors
responded to firing of live ammunition. When effects of
weather were removed from the analysis, effects of military
activity on raptor distribution were further reduced (Schueck
and Marzluff 1995~. England and colleagues (1995) docu-
mented reduced fledging success for Swainson's hawks (Bu-
teo swainsoni) in urban relative to rural areas of the Central
Valley of California. That research group attributed reduced
fledging success of urban nests to the distance the birds had
to travel to foraging areas rather than to disturbance around
nest sites. Grubb and Bowerman (1997) reported that fixed-
winged aircraft elicited a response from nesting bald eagles
less than 30% of the time at distances greater than 500 m
(1,600 It). Bald eagles flew less than 5% of the time in re-
sponse to those disturbances. Helicopters less than 500 m
(1,600 ft) from nests, in contrast, elicited flight responses
about 10% of the time (Grubb and Bowerman 1997~. It is
difficult to evaluate the potential effect of 3-D seismic ex-
ploration on prey for raptors, such as ptarmigan (Lagopus
lagopus) and arctic ground squirrels. Direct effects on these
populations are unlikely, but any changes in vegetation and
soils over large areas could reduce habitat quality for prey,
thereby reducing their populations. Given the relatively
small effects of large disturbances and the location of raptor
nests on cliffs and steep lakeshores and river banks, it should
be possible to conduct oil development in the foothills of the
Brooks Range with small effects on nesting raptors, espe-
cially if aircraft and other human activities near nests are
regulated.
Future industrial development will likely occur in a
warming climate that would probably affect timing and suc-
cess of reproduction of many bird species. Tundra vegeta-
tion also is likely to change. Shrubs are likely to increase at
the expense of herbs, favoring some species over others. Not
enough information is available at present to evaluate how
likely such effects are to occur and how they will accumu-
late with the effects of oil and gas activity.
Finclings
.
Shifts in nesting distribution of shorebirds have oc-
curred in response to oil-field facilities, but because of insuf-
ficient information the committee cannot determine whether
the displacement has affected oil-field populations.
· Inadequate disposal of garbage has resulted in artifi-
cially high densities of gulls, ravens, and mammalian preda-
tors in the oil fields. The resulting increased predation of
123
birds' nests and young has likely made some oil-field popu-
lations dependent on immigration from more productive
populations elsewhere. That is, nesting areas that might have
been source habitats have become sink habitats. However,
population counts alone cannot reveal such effects.
· Future development in the foothills of the Brooks
Range could affect nesting raptors.
· If development moves into the Teshekpuk Lake area
of the National Petroleum Reserve-Alaska, molting water-
fowl could be adversely affected, especially brant.
· A major oil spill associated with shoreline or off-
shore oil development would endanger molting flocks of
waterfowl in nearshore lagoons.
FISH
The life cycles of freshwater and diadromous fishes on
the North Slope are adapted to the region's long winters and
low productivity (Craig 1984, 1989; Power 1997~. After
break-up, fish move quickly during the brief summer into
many habitats, often at great distances from the wintering
area. For example, arctic cisco (Coregonus autumnalis) from
the Colville River can return to spawning areas more than
600 km (370 mi) from the wintering area (Gallaway and
Fechhelm 2000~. Locating a suitable wintering area at the
end of the summer is critical to survival. Craig (1989) esti-
mated that substantially less than 5% of stream habitat re-
mains available to fish by late winter. These widespread
movements and the greatly restricted area of habitat avail-
able to fish in winter make many of these species highly
vulnerable to the effects of oil and gas exploration and
development.
Nearly 40 species of fish are routinely caught during
studies in freshwater and nearshore habitats of the North
Slope (Bendock 1979, Cannon et al. 1987, Craig and
Haldorson 1981, Fechhelm et al. 1984, LGL Alaska Res.
Assoc. 1990-1996, Moulton et al. 1986~. Others are caught
occasionally, but they tend to be rarer or associated with
offshore marine areas.
Seventeen of the frequently occurring species com-
monly enter the subsistence harvest. Arctic cisco and broad
whitefish (Coregonus nasus) have the highest subsistence
value. An average of 18,500 kg (40,800 lb) of arctic cisco
was harvested annually from the Colville River delta each
fall from 1985 to 1998, with an additional 3,200-4,000 kg
(7,100-8,800 lb) taken near Kaktovik (Craig 1987, Fuller
and George 1997~. The broad whitefish harvest by North
Slope villages is estimated to be more than 28,000 kg
(62,000 lb) annually (Fuller and George 1997, Hepa et al.
1997~.
Fishes along the North Slope have three principal life
histories: freshwater, diadromous, or marine. Diadromous
fishes move between freshwater and the sea during their
lives. The term includes anadromous species, which spawn
in freshwater and grow in the sea; catadromous species,
OCR for page 124
124
which do the reverse; and those species that can spend sub-
stantial amounts of time in either environment, but not nec-
essarily mainly to reproduce or mainly to grow. The term
diadromous is applied to ciscoes, whitefishes, and Dolly
Varden char (Salvelinus malma) that migrate each year be-
tween freshwater and coastal habitats (Gallaway and Fech-
helm 2000~. Most freshwater species spend their entire lives
in rivers and lakes of the North Slope and generally avoid
saline waters, although some, such as arctic grayling
(Thymallus arcticus) and round whitefish (Prosopium
cylindraceum), move down river to enter low-salinity estua-
rine waters during early summer.
Diadromous species, such as Dolly Varden char, arctic
cisco, broad whitefish, and least cisco (Coregonus sardi-
nellaJ, migrate each summer between upriver overwintering
areas and feeding grounds in coastal waters. That group is
more abundant along the Beaufort Sea coast than along the
northeastern Chukchi coast, possibly because of a lack of
large rivers and because of the Chukchi's less-productive
coastal region (Fechhelm et al. 1984~.
Most marine species inhabit deeper offshore waters and
are rarely reported in the North Slope coastal zone. Notable
exceptions along the Beaufort Sea coast are arctic cod,
fourhorn sculpin (Myoxocephalus quadricornis), and arctic
flounder (Pleuronectes glacialis), which specifically migrate
into shallow, low-salinity coastal waters and estuaries dur-
ing summer. Those species, along with capelin (Mallotus
villosus) and Pacific herring (Clupea harengus pallasi), also
dominate the fish biota along the Chukchi Sea coast (Fech-
helm et al. 1984~.
Diaciromous ancl Freshwater Fishes
Diadromous fishes in the Beaufort Sea exist in two ma-
jor population centers: the Mackenzie River system of
Canada in the east and the Colville River and Arctic Coastal
Plain systems of Alaska in the west (Craig 1984~. Most of
the major river systems along the 600 km (370 mi) coastline
between the Mackenzie and Colville rivers originate in the
Brooks Range (Craig and McCart 1975~. The rivers are shal-
low and provide little over-wintering habitat except for that
associated with warm-water perennial springs (Craig 1989~.
Dolly Varden char and arctic grayling are the two principal
species that inhabit mountain streams, although lakes asso-
ciated with the drainages can contain lake trout (Salvelinus
namaycush), arctic char (Salvelinus alpinus), and arctic gray-
ling. Ninespine sticklebacks (Pungitius pungitius) also are
prevalent in drainages within the western mountain streams.
Small runs of pink salmon (Oncorhynchus gorbuscha) occur
in the Sagavanirktok and Colville rivers, and spawning popu-
lations of chum salmon (O. keta) inhabit the Colville and
Mackenzie rivers (Craig and Haldorson 1986, Moulton
2001~. The remaining salmon species consist of individuals
from southern populations (Bering Sea) that are incidental
visitors to the Beaufort Sea (Craig and Haldorson 1986~.
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
Three species arctic cisco, broad whitefish, and arctic gray-
ling are examined here in detail. These three use the com-
plete range of habitats affected by the North Slope oil and
gas development, and at their various life stages they are
vulnerable to the consequences of development. The few
diadromous species found along coastal region of the north-
east Chukchi Sea likely originate from large river systems in
the southeast Chukchi Sea or along the Beaufort Sea
(Fechhelm et al. 1984~.
Arctic Cisco
Arctic cisco in the Alaskan Beaufort Sea originate from
spawning grounds in the Mackenzie River system of Canada
(Gallaway et al.1983,1989~. Fry emerge by spring ice break-
up in late May to early June and are swept downstream to
coastal waters, where they begin feeding in the brackish
waters near the Mackenzie delta. Young-of-the-year are
transported away from the Mackenzie region by wind-gen-
erated currents. In years with predominant easterly winds,
some young-of-the-year are transported westward to Alaska
by wind-driven coastal currents (Colonel! and Gallaway
1997, Fechhelm and Fissel 1988, Fechhelm and Griffiths
1990, Gallaway et al. 1983, Moulton 1989, Schmidt et al.
1991, Underwood et al. 1995~. They arrive in the Prudhoe
Bay area from mid-August to mid-September. In summers
with strong and persistent east winds, enhanced westward
transport can carry the fish to the Colville River where they
take up winter residence. After entering the Colville River,
they return to the river every fall for wintering in the brack-
ish portion of the delta until the onset of sexual maturity at
about age 7, at which point they migrate back to the
Mackenzie River to spawn (Gallaway et al. 1983~.
Juvenile arctic cisco are abundant enough to support a
commercial fishery in the Colville River and a subsis-
tence fishery at Nuiqsut (Brower and Hepa 1998, George
and Kovalsky 1986, George and Nageak 1986, Moulton
1997~.
Possible Accumulation of Effects
Recruitment of young arctic cisco into the Alaskan
Beaufort Sea is a function of wind-generated coastal cur-
rents, so facilities that interrupt the movement of fish along
the coast could lead to reduced recruitment. The presence of
multiple similar structures would cause effects to accumu-
late. To affect recruitment, a structure would modify the
coastal habitat in such a way as to hinder young arctic cisco
from reaching the Colville River, the most suitable winter-
ing area. The hindrance could result from modifying the
coastal environment so that westward movement is delayed
enough that they fail to reach the Colville River in the re-
cruitment year. The available data indicate that arctic cisco
recruitment has not been affected by existing causeways
(NSB/SAC 1997~.
OCR for page 125
EFFECTS ON ANIMALS
In an environment where heat is at a premium, the warm
coastal waters are important to diadromous fishes (Craig and
Haldorson 1981~. Facilities that disrupt this narrow coastal
band could disrupt the coastal movements of arctic cisco and
other diadromous species (Hachmeister et al. 1991, Hale et
al. 1989~. Any future operations that discharge warm water
could serve as attractants that would prevent fish from mov-
ing to wintering areas at the proper time. The potential for
effects to accumulate arises when multiple facilities affect
the same populations of fish.
Broacl Whitefish
Broad whitefish are common in lakes and streams of the
Arctic Coastal Plain, most abundantly in large rivers, such as
the Colville, Ikpikpuk, and Chipp rivers, that have deep, low-
velocity channels and a multitude of connected lakes. They
are also in the Sagavanirktok River, but its steeper channel
gradient and low number of connected lakes limit that popu-
lation. During summer, some broad whitefish enter small
tundra streams.
The fish use a variety of habitats through their life cycle.
Spawning is in deep portions of large rivers in the fall. In the
Mackenzie River in Canada, broad whitefish spawn in the
lower river just upstream of marine influence. Similarly, the
anadromous population in the Colville River spawns in the
main river upstream of the delta. Bendock and Burr (1986)
identified a prespawning migration in August. During the
spring flood, age-O and juvenile broad whitefish enter a vari-
ety of available habitats, including seasonally flooded lakes,
lakes connected to stream systems, river channels, and
coastal areas. Fish that use perched lakes remain in the lakes
until they reach maturity, then return to the river in the spring
of the year in which they will spawn. Broad whitefish that do
not enter perched lakes either enter the coastal region and
adjacent small drainages to feed or remain within the river
system to feed in low-velocity channels, tapped lakes, or
drainage lakes. In fall, they move out of the shallow feeding
areas and return to the deep wintering areas in the main river
or lakes. Fish from the Sagavanirktok River population move
through the Prudhoe Bay coastal region and enter lakes at-
tached to small drainage systems (Morris 2000~.
During summer, broad whitefish are distributed
throughout the drainages and coastal plain water bodies. The
highest abundance in coastal marine waters is near river del-
tas (Furniss 1975, Griffiths et al.1983, Moulton and Fawcett
1984, Moulton et al. 1986, Schmidt et al. 1983), although
large fish move at least between the Colville River and
Prudhoe Bay region. When they are in coastal waters, broad
whitefish show a strong preference for nearshore habitats,
appearing only rarely offshore or near barrier islands (Craig
and Haldorson 1981, Moulton et al. 1986~.
The main overwintering areas in the Colville River are
upstream from the Itkillik River. Most broad whitefish leave
the delta after ice forms and move upstream beyond the in-
125
fluence of salt water. In the Sagavanirktok River, wintering
areas have been identified in both the east and west channels
within 20 km (12 mi) of the river mouth (Morris 2000~.
Possible Accumulation of Effects
Because of the wide range of habitats used by broad
whitefish populations in the Sagavanirktok and Colville riv-
ers, the potential for effects to accumulate is high. They use
nearly all stream systems between Barrow and the Saga-
vanirktok River, they enter a large number of lakes associ-
ated with the streams, and they move widely along the coast,
ranging as far east as the Canning River. As a result, they are
vulnerable to facilities that change the distribution of fresh-
water and the coastal nearshore band. Because many rear in
lakes, they are vulnerable to excessive water withdrawal and
the introduction of contaminants.
Arctic Grayling
Arctic grayling is the second-most-widespread freshwa-
ter fish on the North Slope, after ninespine stickleback. It
occurs in most stream systems and in many lakes (Moulton
and George 2000~. Grayling typically overwinter in deep
areas within larger rivers the Colville, Kuparuk, Saga-
vanirktok, and Canning. Wintering areas are limited or non-
existent in smaller tundra streams (Hemming 1993~. During
or after ice break-up, adult grayling move into tributary
streams for spawning. Streams with sand or gravel substrates
seem to be most heavily used.
After spawning, adults disperse to summer feeding
areas, moving downstream in the tributary to feed on drift
insects, moving into lakes, or returning to the main river.
Grayling embryos hatch after about three weeks. Young-of-
the-year (age-O) grayling feed in tributary streams until late
summer, then move into the main river for wintering. Juve-
niles, which do not participate in spawning migrations, move
in spring from wintering areas into small streams, lakes, or
shallow areas within the main river to find suitable feeding
areas.
As with most arctic freshwater fish, arctic grayling are
strongly limited in abundance by the availability of winter-
ing habitat. Many streams across the Arctic Coastal Plain are
devoid of grayling or contain only a few juveniles because
they are far from suitable wintering areas and lack dispersal
routes that allow free passage during both spring and late
summer.
Possible Accumulation of Effects
Disruptions to flow patterns that affect arctic grayling
movements can affect survival, and the proliferation of roads
and culverts across wetlands and streams creates the poten-
tial for effects to accumulate. Delays in the upstream spawn-
ing migration were common in the early stages of oil-field
OCR for page 126
126
development, when culverts were too small to handle break-
up flows. Road-crossing and culvert designs now include
fish passages, so effects should be less than in the early years
of development.
The distribution of arctic grayling has expanded because
of habitat alterations in the oil-field region. Some of the
large, deep gravel pits excavated for oil-field construction
material filled with water after abandonment to form large
artificial lakes that provide abundant wintering habitat. Hem-
ming (1988) reported that a mine site connected to the
Sagavanirktok River contained 88 times more water than the
largest wintering areas reported within the river itself. Two
of the deep gravel pits were connected to small tundra
streams that appeared to contain suitable spawning and rear-
ing habitat but lacked wintering areas. Arctic grayling of
various ages were introduced over several years and eventu-
ally developed reproducing populations (Hemming 1995~.
The cumulative effect of these large gravel pits is to increase
the available freshwater wintering area. It is not known
whether the amount of habitat added by the gravel pits out-
weighs possible loss of habitat attributable to hampered mi-
gration caused by roads and pads, but with the recently in-
creased attention to structural design it is likely that most of
the migration problems have been solved.
There is a reasonable amount of information on fish-
passage problems and ways to mitigate them (Ott 1993~. The
rehabilitation and success of habitat restoration in many of
the North Slope gravel pits are well documented (Hemming
1988, 1993, 1995; Hemming et al. 1989~.
Effects in Freshwater Systems
Effects in streams and lakes can accumulate through
disruption of drainage patterns combined with water with-
drawal and contamination. Hershey and colleagues (1999)
demonstrated that the landscape controls biological interac-
tions in lakes through facilitating or limiting fish dispersal.
Activities that affect dispersal through alterations to drain-
age patterns can ultimately affect the assemblage of fishes in
different habitats. Water withdrawals affect the amount of
water present during winter, which can affect fish survival.
Drainage Patterns
Drainage patterns are altered by the construction of
roads or pads in or across wetlands or drainage areas. To
date, 2,338 ha (5,777 acres) of gravel pads, including more
than 875 km (544 mi) of roadways, have been constructed in
association with oil-field development on the North Slope
(Chapter 4~. Much of the gravel fill has been in wetlands
where drainage has been blocked by road construction. Dur-
ing spring ice break-up, there is substantial flow across ex-
pansive wetlands into lakes and streams. When long stretches
of gravel road interrupt flow, the difference in water surface
elevation from one side of the pad to the other can produce
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
high-velocity water flow in the cross-pad drainage structures,
usually culverts, that can inhibit upstream fish movements
and delay migration to various summer habitats. The delays
are particularly problematic for arctic grayling, which spawn
shortly after break-up and often undertake long, rapid migra-
tions from wintering areas to spawning sites.
An opposite effect can occur in mid- to late summer
when stream flow is low. Fish that disperse during or after
break-up must leave small drainages and shallow lakes to
reach wintering areas before those waters freeze because
there are often limited or no opportunities for overwintering
within the habitats used for summer feeding. Fish that can-
not leave will freeze. An inadequate number or improper
placing of culverts or modifications to the stream bed can
cause flow to go below the surface or to be spread too shal-
low to allow downstream movement when flow levels are
reduced in late summer.
Large quantities of gravel have been used to construct
the oil-field infrastructure. In the early period of develop-
ment and pipeline construction, much of the gravel was ob-
tained from gravel deposits within floodplains. But concerns
arising from this practice prompted the FWS to study the
effects of floodplain gravel mining on the floodplains physi-
cal and biotic processes (Woodward-Clyde Consultants
1980~. The study identified numerous examples of habitat
modification, including increased channel braiding, loss of
wintering areas, spreading of flow, and restriction of fish
movements, including mortality caused by stranding. The
study also set forth guidelines for gravel mining that mini-
mize floodplain damage (Joyce et al. 1980~. In response to
agency concerns, and results of the FWS study, new gravel
mines were primarily in upland sites during the 1980s. Some
of these were flooded when mining ceased and used as reser-
vations, with the long-term goal of establishing aquatic habi-
tat. Recently, some new mines have been in floodplains,
again following established guidelines.
Water Withdrawal
Use of freshwater has increased in recent years because
of expanded oil-field development and increased explora-
tion. In the early years of exploration, water was obtained
from any source, including rivers during winter. Bendock
(1976, as cited in Winters et al. 1988) documented water
withdrawals from the Sagavanirktok River that depleted
water in wintering areas and increased mortality to fish in
the area. Much of the water needed in the established oil
fields is now obtained from reservoirs that are replenished
with runoff during spring ice break-up; most of the water
used in exploration is taken from lakes.
Ice thickness has a great influence on the distribution of
fish in lakes across the Arctic Coastal Plain. Most lakes in
the existing development area between the Colville and
Sagavanirktok rivers are less than 2 m (6.5 ft) deep, few fish
are present, and effects have been minimal. As development
OCR for page 127
EFFECTS ON ANIMALS
spreads into regions with deeper lakes, such as the Colville
delta and the eastern part the National Petroleum Reserve-
Alaska, there is greater potential for having fish populations
within lakes. Under current Alaska Department of Fish and
Game (ADF&G) policy, water withdrawals from fish-bear-
ing lakes are limited to 15% of the estimated minimum win-
ter water volume. This policy was adopted to allow some
water use while preserving most of the water for wintering
fish, and the criterion was set arbitrarily because there were
no data to support a different withdrawal volume. Fish popu-
lations in lakes subjected to this maximum allowable with-
drawal appear to be unaffected, but data on consequences
are limited, and there has been no research to determine the
effects of withdrawals on populations of invertebrates in the
lakes or on vertebrate food supplies.
The current practice for ice road construction is to per-
mit withdrawals from a large number of lakes along a de-
sired route, then to allow the ice road contractor to draw
from the nearest suitable lake. This allows for maximum
construction flexibility, but it complicates the tracking of
withdrawal volumes: Much more water is permitted for
withdrawal than is used. Between 1998 and 2001, for ex-
ample, Phillips Alaska obtained annual permits for with-
drawals of more than 8.3 billion L (2.2 billion gal), but
used less than 908 million L (240 million gal) in any given
year (Table 8-2~.
For lakes that do not support wintering fish, there is
essentially no current regulation of winter water withdraw-
als, and the amount estimated to be present during summer is
typically set as the withdrawal limit. Because ice thickness
grows to 1.2-1.5 m (4-5 ft) by the time withdrawals are
needed in January through March, there is substantially less
water available than the permitted amount, thus the full
amount is not really available for use and the actual with-
drawal is considerably less than that permitted. This practice
essentially allows withdrawal of all remaining unfrozen wa-
ter in the lake at the time of withdrawal. The effects of such
withdrawals on lake flora and fauna have not been analyzed.
Effects on invertebrates are not likely to be significant be-
cause during winter most invertebrates inhabiting shallow
lakes are in freeze-tolerant resting stages. The potential ef-
fects of reduced water levels on vegetation and waterfowl
nesting or feeding have not been evaluated.
TABLE 8-2 Phillips Alaska Water Permits
Winter
Year
Lakes
Permitted
Withdrawal
Limit
(million L)
Total Used
(million L)
Percentage
Used
1998-1999
1999-2000
2000-2001
26
41
24
8,477.4
8,468.7
8,944.1
771.1
886.2
344.5
9.1
10.5
3.9
SOURCE: Phillips Alaska, Inc., data files submitted to Alaska Department
of Natural Resources.
127
An additional issue associated with water withdrawals
from fish-bearing lakes is the potential to remove fish during
pumping. In recent years, as construction of ice roads has
increased in the vicinity of Nuiqsut, residents have reported
finding fish frozen into the roads. Contracts issued for ice
road construction specify that water is to be screened to avoid
removing fish, but contractors sometimes fail to install
screens. In some cases, sampling to identify the presence of
fish before water withdrawal used gear that was not appro-
priate for detecting smaller species, such as ninespine stick-
leback and Alaska blackfish (Dallia pectoralis). The prob-
lem can be aggravated when lighted shacks are placed over
the hole from which water is withdrawn. Ninespine stickle-
back, in particular, are drawn to the light, then are sucked up
with the water and spread on the road. Procedures have been
adopted recently to prevent taking fish with water for road
construction.
Seismic Effects
When seismic exploration was conducted with explo-
sives, there was a great potential for harming fish that were
exposed to large, rapid changes in ambient pressure. The
advent of vibrating equipment has reduced concern, because
the energy it generates is much less than that generated by
explosives. The ADF&G blasting standards require that the
instantaneous change in pressure resulting from any explo-
sion must remain below 0.02 megapascals (MPa, 2.7 psi).
Results of a recent field test involving vibrators on ice, over
water, indicate that peak pressure changes below a vibrator
(under 1.2 m [4 ft] of ice) can be as low as 0.01 MPa (1.57
psi). In addition, the energy velocity appears to be many
times slower than velocities known to harm fish. Peak sound
pressure levels associated with vibroseis exploration, calcu-
lated at 7.3 m (24 ft) from the source, appear to be about 12
dB lower than sound pressure levels associated with airguns.
When converted to energy, the vibroseis machines transfer
many times less energy to the water than do airgun arrays
(W. Morris, ADF&G, personal communication, 2002~. The
effects of summertime seismic exploration with airguns on
coastal and marine fish in the Beaufort Sea have not been
investigated.
Coastal Development
Coastal development that poses the greatest risk of caus-
ing effects that accumulate in nearshore habitats includes
facilities that change physical conditions that are important
to nearshore biota. Such structures include causeways that
modify water temperature and salinity.
Two major causeways have been built into the nearshore
region to support oil-field activities (Table 8-3~. The Prudhoe
Bay West Dock was built in the winter of 1974-1975 primar-
ily to support off-loading of large modules used to develop
the field; it was modified in 1981 to support the intake struc-
OCR for page 128
128
ture for the Prudhoe Bay waterflood facility to supply water
needed for injection into the oil reservoirs. The causeway
runs from the east end of Simpson Lagoon to the west en-
trance to Prudhoe Bay. The second major causeway, in the
middle of the Sagavanirktok River delta, was built to sup-
port facilities for the Endicott oil field.
Accumulation of effects is a concern when multiple
causeways affect the same fish population. The migratory
stocks found along the Beaufort Sea coast are likely to en-
counter multiple causeways during their annual summer
feeding movements. From the late 1970s to late 1980s, there
was substantial concern over the potential effects of the two
long causeways to migrating fishes, especially for the integ-
rity of the nearshore band of relatively warm, low-salinity
coastal water that is used by migrating fish (Craig 1984~.
Causeways built perpendicular to shore disrupt the east-west
flow of the coastal currents, and that can alter fish move-
ments within the band. Permits issued by the U.S. Army
Corps of Engineers and the North Slope Borough for cause-
way construction included stipulations for monitoring the
effects of the causeway on fish movements and habitat,
among other issues. Initial monitoring studied the West Dock
Causeway between 1981 and 1984 and then the West Dock
and Endicott causeways between 1985 and 1987. In 1988,
the U.S. Army Corps of Engineers concluded that signifi-
cant harm to habitat had been demonstrated and that further
monitoring for effects on fish populations was not required
(Hachmeister et al. 1991~. Those effects, as summarized
Ross (1988), included degradation of habitat quality in the
nearshore region, alteration to fish movements and fish use
of the Prudhoe Bay area, and changes to fish community
structure.
The North Slope Borough, with the advice of its Scien-
tific Advisory Committee, determined that the findings were
not supported by the existing data, however, and decided to
continue the causeway-monitoring program under its per-
mitting authority. The effects described by Ross (1988) were
TABLE 8-3 Causeway Construction, Nearshore Beaufort
Sea
Facility
Length of
Year Fill (m)
Notes
East Dock
West Dock
Initial dock
Emergency extension
Waterflood extension
Breach retrofit
Endicott
Initial causeway
Breaches (2)
Breach retrofit
pre- 1974
1974-1975
1975-1976
1981
1996
1985 8,000
1986 -60, -150
1994 -200
350
1,340
1,524
1,125 -18 m breach
-200 at 1,520-1,720 m
SOURCE: U.S. Army Corps of Engineers permitting documents arid cause-
way monitoring reports.
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
used to frame a set of hypotheses that were then used to
design the monitoring investigations. The North Slope Bor-
ough monitoring program focused its investigations on four
. .
main Issues:
· effects of causeway-induced changes in circulation
and hydrography on the migration of young-of-the-year arc-
tic cisco from Canada to the Colville River,
· effects of causeway-induced changes in circulation
and hydrography on the nearshore migration corridor used
by most species of diadromous fish,
· changes to temperature and salinity of the nearshore
habitat and ramifications of those changes to the population
of broad whitefish inhabiting the Sagavanirktok River, and
· effects of causeway-induced changes to fish and fish
habitat on the fisheries that harvest arctic and least cisco in
the Colville River.
The North Slope Borough's program showed that the
causeways, particularly the West Dock Causeway, interfere
most notably with the eastward movement of juvenile least
ciscoes and humpback whitefish moving from the Colville
River into the Prudhoe Bay area during early summer
(Fechhelm 1999, Fechhelm et al. 1989, Gallaway and
Fechhelm 2000, Moulton et al.1986~. Juvenile Dolly Varden
char also might be affected (Hachmeister et al. 1991~. The
movement of young-of-the-year arctic cisco from the
Mackenzie River into the Alaskan Beaufort Sea region did
not appear to be affected by the causeways (NSB/SAC 1997~.
Retrofitting of breaches in both causeways in 1994 and 1996
appears to have reduced the effect of the interference to least
cisco and humpback whitefish (Coregonus pidschian) mi-
grations (Fechhelm 1999~.
The causeway studies revealed that, when wind is from
the east, a wake eddy forms on the west side of the cause-
ways that allows cold, high-salinity water to reach the sur-
face (Colonel! and Niedoroda 1990, Gallaway and Fechhelm
2000~. That cell of cold water on the west side of West Dock
is the mechanism that most likely impedes fish movements.
Because the wake eddy on the west side of Endicott Cause-
way is offshore of the Sagavanirktok delta, its effects on fish
movements are less pronounced. Various researchers have
noted that the density of epibenthic fauna (mysids and am-
phipods), which constitute the main foods of diadromous
fish and sea ducks, was particularly high along the west side
of West Dock (Feder and McGee 1982, Moulton et al.1986,
Robertson 1991), perhaps as a result of the wake-eddy effect
in the lee of the causeway under east winds.
Gallaway and Fechhelm (2000) concluded that fish
populations in the region appear to be fluctuating in response
to naturally occurring physical phenomena. Effects of the
existing causeways have been at least partially mitigated with
retrofitted breaches.
In addition to the causeways, large intake pipes are used
to withdraw water from the nearshore region. The Prudhoe
OCR for page 129
EFFECTS ON ANIMALS
Bay waterflood facility, constructed in 1981, can supply 350
million L (92.4 million gal) of seawater per day (4.07 m3/s
[5.32 yd3/s]), with an estimated 2.55 km3 (0.61 mi3) to be
used over 20 years (USACE 1980~. There are also seawater
intakes at Endicott (44 million L [11.6 million gal] per day)
and Kuparuk (95 million L [25.2 million gal] per day). Moni-
toring of the intakes and marine bypass systems was con-
ducted after start-up for the Prudhoe Bay and Kuparuk wa-
terflood facilities from 1984 to 1987 to assess entrainment
and impingement (Dames and Moore 1985-1988~. Fish were
rarely observed during the monitoring studies, and most of
those that entered the system passed successfully. However,
approximately 1.5 million fish larvae of 9 species were esti-
mated to have been entrained in the Prudhoe Bay facility in
1985. The intakes were judged to perform as designed and
predicted, and monitoring was discontinued after 1987.
Beaufort Sea causeways are among the most intensively
studied anywhere. From 1978 to 1997, the West Dock and
Endicott causeways were monitored for changes to physical
oceanography, coastal processes, sedimentation patterns,
fish populations and movements, fish growth, subsistence
landings, fish-species diversity, benthic invertebrate popula-
tions, epifaunal populations, river hydrology, vegetation, and
bird habitat use. Annual reports of the monitoring efforts
were produced that summarized the results of the annual in-
vestigations. A decade of investigations on oceanographic
changes related to the two major causeways was summa-
rized by Colonell and Niedoroda (1990), Hachmeister and
colleagues (1991), Hale and colleagues (1989), and Nie-
doroda and Colonell (1990~.
The spatial extent of the causeways is relatively limited;
the two receiving most of the attention are on either side of
Prudhoe Bay. Some of the fish that encounter the causeways,
including arctic cisco, however, move between the Colville
and Mackenzie rivers at least twice during their lifespan.
Some of the least cisco, humpback whitefish, and broad
whitefish move between the Colville and Canning rivers for
the summer feeding (Fechhelm et al. 2000, Griffiths et al.
2002~. The effects of causeways in this region on those fish
population could accumulate if the breach retrofits have not
completely eliminated movement and habitat changes. Any
effects resulting from the causeways will exist until the struc-
tures are removed, or are made porous enough that fish
movements are unaffected.
Future Scenario
The potential effects on freshwater systems have be-
come clear during the development of the existing oil fields,
so those effects probably will be addressed during the design
and permitting of new fields and field expansions. The prob-
ability for serious effects is low, assuming due diligence by
the responsible resource agencies. There will be new chal-
lenges, however, as exploration and development practices
change. For example, exploration to the east and south will
129
be hampered by the reduced availability of water during
winter. In addition, because those areas have more hills and
valleys, the grades for roads will be more extreme. The cur-
rent technology based on ice road access is not likely to be
feasible in those areas. Similarly, current field development
depends on a ready supply of gravel for road and pad con-
struction. Development of fields in the National Petroleum
Reserve-Alaska, where gravel is scarce, will need to rely on
other materials for road and pad construction, and the conse-
quences associated with alternative materials will need to be
examined.
Future coastal developments could include more docks
and causeways to transport structures or oil to shore. Given
the adversarial history of causeway impact assessment, con-
struction of new causeways probably will be approached
carefully with substantial scrutiny by regulatory agencies.
Each potential causeway site along the Beaufort Sea coast is
unique with respect to currents and the ways that fish use the
region. Therefore, the design constraints on each proposed
causeway will be site-specific. Nonetheless, long solid-fill
causeways are likely to be problematic and therefore are
unlikely to be permitted. New docks are likely to be rela-
tively small bulkhead structures near water deep enough to
allow barges to approach the shore, so as to minimize the
offshore reach of the docks. Where shallow water requires a
longer reach, docks will likely have numerous large bridged
beaches that allow freer flow of water and minimize the im-
pediments to fish movements.
Finclings
· During the early years of development, gravel min-
ing for roads and pads often interrupted both ice-sheet flow
and stream flows, and hence fish movement. The permitting
process and the regulatory environment for protecting fish
have improved over time and are generally effective. Proper
construction and placement of bridges and culverts have
greatly reduced effects but have not eliminated them.
· Guidelines for gravel mining and subsequent habitat
rehabilitation or enhancement in and near active floodplains
have been developed. Since 1989, arctic grayling have been
introduced to several of the deep gravel pits that now pro-
vide productive fish habitat. One effect of these large gravel
pits is to increase the available freshwater wintering area; it
is likely that the tradeoff is positive and the negative effects
are less than would have occurred if the gravel had been
taken from active floodplains.
· The energy produced by vibration equipment used to
acquire seismic data is not an issue because the vibrations
are below threshold known to affect fish in streams and lakes
crossed during the seismic investigations. The potential ef-
fects of airguns on Beaufort Sea fish have not been studied.
· Because of a lack of information it is not possible to
determine whether biota associated with North Slope lakes are
protected by regulations that cap water withdrawal from lakes.
OCR for page 130
130
· Existing causeways near Prudhoe Bay do not affect
the westward recruitment of arctic cisco into the Colville
River and associated rearing areas. Blockage of young least
cisco and whitefishes moving eastward from Colville to
Prudhoe Bay was demonstrated under certain wind condi-
tions in some years at the West Dock Causeway. This block-
age has been reduced by the breach retrofit installed in 1996.
· The effectiveness of breach design for existing or
new causeways has not been resolved. Breaches are effec-
tive, but there is more to be learned about the best or most
appropriate design and placement of them. The North Slope
Borough's Scientific Advisory Committee recommends that
breaches be required in any causeway that extends across the
nearshore zone, which seems to be appropriate.
· Seawater intakes have been designed to prevent en-
trainment and impingement of fishes.
· Large-scale industrial development could harm
widely distributed fish, such as grayling, arctic cisco, broad
whitefish, and other species in other areas, by interfering
with their migration patterns or their overwintering habitat.
Recommenclations
· Monitoring of rehabilitated deep gravel pits should
continue to evaluate the long-term viability of these sites as
aquatic habitat.
· The current baseline of 15% of minimum winter wa-
ter volume that is allowed to be removed from fish-bearing
lakes should be evaluated to determine the degree to which
that criterion prevents loss of fish and invertebrates.
· An initial study of the effects of withdrawing water
from lakes that have no fish should assess the degree to
which current water use affects other biota associated with
these water bodies.
OTHER MARINE ORGANISMS
Coastal developments that pose the greatest risk of ac-
cumulation of effects to nearshore habitats include industrial
structures that change the physical conditions that are im-
portant to nearshore biota, especially causeways that alter
water temperature and salinity.
Effects of Oil on Marine Plankton and Benthic Organisms
The degree to which surface oil spills affect benthic
communities depends on many factors, including the weather
at the time of the spill, the biotic composition of the commu-
nities and their sensitivity to oil, and how deep they are (NRC
2003~. Oils produced on the North Slope rise to the surface
rather than sinking to the sea floor. Although surface slicks
undergo some natural dispersion, the amount of oil reaching
benthic organisms is less than one part per million
(Humphrey et al. 1987, McAuliffe et al. 1981~. Shallow
benthic communities are vulnerable if oil strands on shore-
CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS
lines and is mobilized into the nearshore subtidal zone.
Sometimes cleanup actually mobilizes oil to cause fairly high
concentrations in nearshore subtidal areas. If there is a high
load of suspended sediments in nearshore waters, oil can be
adsorbed onto particles and be deposited in the nearshore
subtidal area where it affects epibenthic organisms. Subsur-
face spills from pipelines released over extended periods
could affect benthic communities close to the release.
Epibenthos and infauna are usually not abundant in very
nearshore waters in the Beaufort Sea. Boulder patch com-
munities are in deeper water and are only likely to be af-
fected if a subsurface spill occurs in the immediate vicinity.
If chemical dispersants are used, short-term exposure to
fairly high concentrations of dispersed oil is possible. Short-
term exposure to dispersed oil (from a single surface spill) is
not likely to cause mortalities of the benthos. Mortalities
could be caused from a prolonged surface leak that is repeat-
edly treated. Recovery of benthic epifauna is likely to be
more rapid than is recovery of infauna. Recovery of boulder
patch communities would probably take several years (Mar-
tin 1986~.
Oil spills on or under spring ice would diminish primary
production either as a result of toxic effects or because the
oil would block light that passes though the ice sheet (Schell
et al. 1982~.
Some species of phytoplankton are more sensitive to oil
than are others (NRC 2003~. They can be affected by a sur-
face oil slick or if dispersants are used and more oil enters
the water column. The affected standing stock and primary
production return to pre-spill conditions rapidly through
natural transport of organisms from surrounding areas and
rapid reproduction of these populations (Trudel 1986a). Fish
larvae and eggs can be harmed by spilled oil, and oil can be
ingested by higher trophic-level organisms with prey or as a
result of prey contamination (NRC 2003~. Thus, the effects
of spills on phytoplankton communities generally are local-
ized and short lived enough so that recovery occurs before
effects accumulate.
Many zooplankton species, especially as larvae, are sen-
sitive to oil. Studies of zooplankton have followed several
oil spills, and localized, short-lived effects have been de-
tected. There are seldom changes in biomass, however, be-
cause of high reproduction rates and rapid recruitment from
other areas (Trudel 1986b).
Effects on Biological Processes ancl Marine Communities
Studies of the Boulder Patch indicate that development
of its kelp-community depends on four factors: There must
be a hard substrate for attachment of algae and associated
invertebrate fauna. There must be free (unfrozen) water un-
der the winter ice canopy and protection from extensive ice-
gouging and reworking at the bottom. There must be an ero-
sional rather than depositional sedimentary environment
(Coastal Frontiers Corporation and LGL Ecological Re-
OCR for page 131
EFFECTS ON ANIMALS
search Associates, Inc.1998; Dunton et al.1982~. Those fac-
tors can exist in the vicinity of both natural and anthropo-
genic hard substrates.
As part of the Endicott environmental monitoring pro-
gram, studies were conducted to measure long-term coloni-
zation of bare boulders placed at sites in the Stefansson
Sound Boulder Patch. Colonization initially was slow, being
negligible (Martin et al.1988) or sparse after 3 years (Dunton
et al.1982~. Five to six years were required before full colo-
nization was achieved (Martin and Gallaway 1994~. The
slow appearance of colonizing organisms and the presence
of uncommon species led Martin and Gallaway (1994) to
suggest that Boulder Patch species disperse as relatively
long-lived, slow-growing larvae. Species that fail to colo-
nize could have a nonmotile dispersal stage or otherwise be
limited in ability to disperse.
After 2 years in Stefansson Sound at drill island BF-37,
red algae, particularly Phyllophora truncata and Phycodrys
rubens, and one animal, a small hydroid, had colonized
gravel-filled bags (Toimil and Dunton 1983~. No organisms
were observed on the loose gravel at the base of BF-37. Dur-
ing inspections in 1994 and 1996 of gravel-filled bags and
concrete mats placed as protective armor on Tern and
Northstar exploratory drill islands, divers reported algae,
worms, and soft coral (Craig Leidersdorf, Coastal Frontiers
Corporation, personal communication cited in Wilson
2001a). A 1998 survey reported algae about 2 m (6.5 ft) long
consisting of two distinct blades, probably representing 2
years growth, attached to coarse gravel (3-5 cm [1.2-2 ink)
lying near the toe at 6 m (20 ft) on Tern Island's western
slope (C. Leidersdorf, Coastal Frontiers Corporation, per-
sonal communication cited in Wilson 2001a). In the Stefans-
son Sound area, algae of this size likely would have been
kelp, and those with distinct blades likely would have been
Laminaria. Leidersdorf believed the plants colonized the
gravel at the base of the island (Wilson 2001a).
Laminaria solidungula and L. saccharine attached to
coarse gravel have been collected along the eastern shore of
131
the Endicott Causeway after heavy easterly storms. Those
plants with attached gravel were presumably moved west-
ward along the bottom by surge and wave action created by
storm winds and deposited along the causeway shoreline
(Busdosh et al. 1985~. It is possible that the kelp at the base
of Tern Island were moved along the seabed by westerly
storm conditions and deposited there.
Finclings
· Other than those caused by permitted discharges and
physical alterations or addition of structures, there have been
few measurable effects on marine invertebrate communities
from oil exploration and production operations on the North
Slope.
· Hard substrates added to the marine environment in
the form of causeways and artificial islands have been colo-
nized slowly by benthic invertebrates.
· The Boulder Patch community has not been affected
by oil operations.
· Monitoring is frequently required as a condition of
discharge permits to ensure that discharges do not exceed
water quality standards, are not toxic to marine organisms,
and do not degrade water quality or pose a threat to human
health. Most of the records of the monitoring programs are
retained by the principal permitting agency, the U.S. Envi-
ronmental Protection Agency, and are not readily available.
Records also are kept by individual operators, but they are
not summarized, and few annual reports are available.
· Oil operations have not had measurable population
effects on epibenthic invertebrates, the sessile invertebrates
of the Boulder Patch communities. The epontic communi-
ties under the ice have not been specifically studied, but it is
unlikely that operations have affected them.
· The committee found no data showing that dis-
charges to the Beaufort Sea have had effects on biota. The
trend is toward using disposal wells instead of discharging
wastes directly to the ocean.
Representative terms from entire chapter:
oil fields
