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Building Ocean Science Partnerships: The United States and Mexico Working Together 2 Examples of Promising Science Programs and Projects This chapter describes a set of potential programs and projects that are of binational interest and scientific significance. Each topic was developed by a team of Mexican and U.S. ocean scientists. The studies described below are designed both to illustrate the existence of a wide range of possible projects of common interest and binational importance and to show the wealth of important questions that could benefit from (or require) collaboration between U.S. and Mexican scientists. The projects presented are not an exhaustive list of scientific issues and admittedly reflect the interests and expertise of members of the Academia Mexicana de Ciencias-National Research Council (AMC-NRC) Joint Working Group on Ocean Sciences (JWG). Concrete proposals, implementation plans, and other details required to initiate new research related to these and other topics depend on consultation and inclusion of scientists beyond the JWG, for example, through focused workshops. In the development of other binational ocean science activities, they should pass the test of being studies that are (1) of unique scientific concern to scientists in the United States and Mexico in waters adjacent to or significantly influenced by these nations and (2) best done collaboratively. Another source of ideas for binational research is the plan of the Southwest Regional Marine Research Program (1996). The JWG identifies here projects that should be done cooperatively because scarce resources from both countries could be used more effectively and the scientists of each nation have knowledge (not all of which has been published) unavailable to the other nation. It is possible that either nation could conduct the research alone, but the research would be more efficient if knowledgeable scientists from both nations could be involved. An effective binational collaboration in ocean science between the United
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Building Ocean Science Partnerships: The United States and Mexico Working Together States and Mexico will require sufficient human and economic resources from both nations to make the collaboration meaningful and equitable. In this regard, and given the limited resources available, only a few binational projects can be promoted at any given time, after a peer-review process to select projects that address specific binational oceanographic topics, contribute to answering interesting scientific questions, and help solve marine-related problems shared by the two nations. Project size should not be the determining factor. Some binational collaboration has been initiated with small projects involving few scientists and graduate students. Other projects, for example, those requiring regional oceanographic observations, must be larger, requiring proportionately larger budgets and involving a larger number of scientists and students. Project administration, regardless of size, does not automatically promote bureaucracy. The expeditious channeling of economic resources, minimization of binational political barriers, and granting of project organization and administration independence minimize bureaucratic barriers. The studies described below include both single-discipline and multi-disciplinary projects, classified by geographic region. In planning research on these topics, it should be recognized that insights can be gained not only by research within individual regions, but also by comparative studies among the three regions. PACIFIC OCEAN AND GULF OF CALIFORNIA REGIONS Oceanographic Setting Pacific Ocean The Pacific Ocean region shared by the United States and Mexico is dominated by the California Current, which flows southward as the eastern boundary current of the subtropical North Pacific Ocean (Figure 2.1). This surface current overlies a poleward subsurface flow. Wind-driven coastal upwelling is prevalent, especially in the summer season. The California Current is punctuated by upwelling of nutrient-rich cool waters and current jets that can extend 100 or more kilometers (km) offshore (Batteen, 1997). These features depend on coastal wind patterns that vary with climate (Bakun, 1990) and on other factors such as topography, interior ocean circulation, and instabilities of the currents. Batteen (1997) has shown that the meridional variability of the Coriolis parameter (ß effect), irregularities in the coastline geometry, and the longshore component of wind stress are key ingredients for generating the vertical and horizontal structures of the California Current System. Such structures render the currents unstable, resulting in the generation of meanders, filaments, and eddies. The coastal seafloor topography off the Californias (California and Baja California) features a narrow continental shelf, submarine canyons, basins, and is-
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Building Ocean Science Partnerships: The United States and Mexico Working Together FIGURE 2.1 Important features of the Californias and Gulf of California.
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Building Ocean Science Partnerships: The United States and Mexico Working Together lands that greatly affect regional circulation, sediment transport, and biology. This region is called the California Borderland (Figure 2.1). The coast of the Californias is also the site of many bays that provide shallow-water coastal habitats missing from the exposed outer coast. For the purposes of this report, the region of proposed cooperative activities extends from Point Conception in California to the southern tip of Baja California and the Gulf of California. There have been both extensive, long-term studies (e.g., the California Cooperative Oceanic Fisheries Investigations [CalCOFI]) and intensive studies (e.g., Coastal Upwelling Experiment [CUE], Coastal Ocean Dynamics Experiment [CODE], Ocean Prediction Through Observation, Modeling, and Analysis [OPTOMA], Coastal Transition Zone [CTZ] experiment, and Eastern Boundary Currents [EBC] experiment) of the California Current and the inshore coastal upwelling systems farther north. The U.S. Global Ocean Ecosystems Dynamics (GLOBEC) program is developing a scientific study focused on the ecosystem dynamics of the California Current System (GLOBEC, 1994). In 1997, the Center of Scientific Investigation and Higher Education of Ensenada (Centro de Investigación Científica y de Educación Superior de Ensenada [CICESE]) initiated a new program for the long-term monitoring of the waters off Baja California: Investigaciones Mexicanas en la Corriente de California [IMECOCAL], as a counterpart to the CalCOFI program, using similar methodology and occupying stations in Mexican waters that include stations of the old CalCOFI network that had been abandoned. In terms of physical oceanography, a great deal has been learned in the past three decades about the physical processes characteristic of eastern boundary currents over the continental shelf in regions where the shelf is long and straight, particularly regarding coastal upwelling, upwelling fronts, coastal jets, undercurrents, response to transient (day-to-day) winds, seasonal wind-driven shelf circulation, coastal trapped waves (periods of days to weeks), local and remote forcing, waves propagating from the equatorial Pacific Ocean, perturbations associated with the El Niño-Southern Oscillation (ENSO), and interannual variations (Huyer, 1983, 1990; Neshyba et al., 1989; Batteen, 1997). More recently, there has been progress in studying more complex phenomena such as the nature of the upwelling front and associated jets and eddies in the case where the front lies seaward of the edge of the continental shelf; the relation between coastal upwelling jets and the core of the California Current; the evolution of jets and eddies through an upwelling season; the circulation in regions of more complex bottom topography (see the special issue of the Journal of Geophysical Research, 1991); and the influence that wind forcing, coastal irregularities, and the variation of the Coriolis parameter have on the generation of many of the observed features of the California Current System (Batteen, 1997).
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Building Ocean Science Partnerships: The United States and Mexico Working Together South of the U.S.-Mexico border there has been some sampling of the California Current by CalCOFI, which was interrupted in the late 1970s. Although the CalCOFI program covered latitudes north and south of the U.S.-Mexican border, the sampling has been more intense and continuous in U.S. waters. Many important gaps persist at the southern (tropical) limit of the California Current System along Baja California and in the Gulf of California. One example of a large-scale feature that has not been sampled adequately is the California Undercurrent. This is a narrow ribbon of water from the south, approximately 20 km wide, flowing poleward, with its core located at a depth of approximately 200 meters (Batteen, 1997). This current is almost always found hugging the continental slope but occasionally intrudes onto the shelf. There is a distinct thermohaline signature of the waters within this ribbon (i.e., the Subtropical Subsurface Water) that distinguishes them continuously to the south, somewhat beyond the Gulf of Tehuantepec. The presence of poleward undercurrents is a common phenomenon along eastern ocean boundaries (see Neshyba et al., 1989; Batteen, 1997). Another large-scale feature that deserves more intensive study is the confluence of the California and Costa Rica Currents, which occurs near the latitude of Cabo Corrientes. The surface flows from north and south merge and turn westward, forming the North Equatorial Current. The seasonal shift and modulation in the position of this confluence is known only vaguely. A similar feature deserving study is the mixture of subarctic waters of the California Current, tropical waters of the Costa Rica Current, and waters outflowing from the Gulf of California in the vicinity of the mouth of the gulf. Analysis of large-scale marine wind observations (Parrish et al., 1983; Bakun and Nelson, 1991) shows that the wind-driven or Ekman transport* of water off-shore occurs year-round to at least the southern tip of Baja California. Variations—convergences and divergences—of this transport imply upwelling and downwelling in different regions along the coast.** The regions of convergence * According to Ekman's theory, the steady-state wind-driven transport of water in the ocean surface layer is proportional to the wind stress at the sea surface, is directed 90 degrees to the right (left) of the wind in the Northern (Southern) Hemisphere, and takes place in a layer (the Ekman layer) some tens of meters deep. The depth of this layer and the distribution of currents within it depend on poorly known frictional processes in the layer, but the total transport integrated over the layer depends only on the surface wind stress and the Coriolis parameter in the Ekman theory, and so can be calculated without any direct measurement of ocean currents. ** If the Ekman layer transport is convergent at a particular place, more water flows into that location than flows out, so there must be a compensating downwelling out of the layer to conserve the mass of water. Conversely, a divergent Ekman transport implies upwelling of deeper water into the Ekman layer. Since there can be no flow through a coastal boundary, equatorward winds on the West Coast produce a coastal Ekman divergence, and thus, coastal upwelling. The curl of the wind stress (a physical property involving east-west [north-south] gradients of north-south [east-west] wind stress) yields the estimate of open-ocean upwelling or downwelling in the Ekman theory. Since the equatorward winds off the West Coast have an offshore maximum, there is cyclonic wind stress curl over the shoreward side of the California Current, and thus, open-ocean upwelling there.
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Building Ocean Science Partnerships: The United States and Mexico Working Together seem to separate populations of fish such as anchovies, sardines, and mackerel. The 1982–1983 and 1997–1998 El Niño events have had dramatic impacts on the eastern Pacific Ocean off Mexico and the United States in relation to the current systems, ocean properties, marine biological systems and fisheries, and local climate. The scientific questions raised by the 1997–1998 El Niño and the data that have been generated will contribute significantly to the research agenda in the years ahead. The phenomenon affects all of the scientific problems discussed here. Gulf of California The virtually land-locked Gulf of California is an extreme physical and geological environment, characterized by such major features and processes as large tidal range, reaching 10 m during spring tides, causing extensive drying and flooding of the nearshore regions; relatively pristine and arid land areas; strong tidal streams and strong vertical mixing forced by them; wide shallow-water deposits of fine sediments in the Colorado River delta; local wind forcing of both drift currents and wave-induced mixing; strong resuspension of seabed material, probably correlated with tidal and wind-induced mixing; and circulation that may distribute particulate matter across the shelf, reaching the deeper basins near the middle of the gulf. Variability of Fisheries The social and economic concerns related to studies of the California Current System are obvious. An improved ability to monitor and predict primary and secondary productivity has potential value for improving the management of coastal fisheries and possibly allowing forecasting of catch. Forecasting the onset of ENSO events could enable the prediction of their effects on coastal ecosystems. A better understanding of the California Current System and its variations may also be useful in mitigating the effects of pollution (e.g., oil spills or pollutants from coastal communities). Fish populations in this region fluctuate considerably, apparently under the influence of global-scale climatic and oceanic variations (Figure 2.2), and are also affected by the coastal physical conditions described in the previous section, and, of course, by human fishing activities and predation by other marine organisms. Fluctuations in the abundances of organisms found in the California Current System parallel those of other stocks of the same (or similar) species in other areas of the world (Lluch-Belda et al., 1992). The specific mechanisms through which the environment provokes these significant changes are unclear, but this is one of the most important questions to be answered if proper management of
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Building Ocean Science Partnerships: The United States and Mexico Working Together FIGURE 2.2 Cycles of abundance of sardine and anchovy species worldwide, showing the coincidence of fish abundance (panels A, C, D) and sea surface temperature (SST) and air temperature (panel B). Type I and Type II fishes tend to have different cycles. Thus, Type I fish species (sardines + Benguela anchovy) have higher abundance during periods of high SST and Type II fish species (anchovies + Benguela sardine) have higher abundance during times of lower air and sea temperatures. Source: Lluch-Belda et al. (1992) (used with permission from Blackwell Scientific Publications). Note: mmt = million metric tons. fisheries is to be achieved. Working Group 98 of the Scientific Committee on Oceanic Research (Worldwide Large-Scale Fluctuations of Sardine and Anchovy Populations) (Lluch-Belda et al., unpublished report) stated: Coherent fluctuations on a decadal scale affect fish populations and the structure of their ecosystems; transitions between stages typically are abrupt. Cycles of high and low abundance of certain species—mainly evident in the temperate sardines Sardinops—alternate with abundances of other groups of species, most clearly anchovies.
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Building Ocean Science Partnerships: The United States and Mexico Working Together Worldwide coincidences of such regime shifts imply links to global climate variability. There are regime shifts (Steele, 1996) presently occurring in several major oceanic ecosystems. These large-scale variations pose severe challenges to sustainable economic development and to fisheries management. Regime shifts are now hypothesized to be of far greater magnitude than interannual variation and present fundamentally different problems than usually considered by fisheries science. Existing approaches are inadequate for the management of sardine and anchovy fisheries and associated economic development because they do not account for regime shifts that occur on time scales of decades. Environmental variations seem to affect marine organisms directly through several locally different mechanisms. Indeed, many local events are related simultaneously to large-scale climatic and oceanic changes. An understanding of how climate affects fish population abundances is important not only in the Californias, but also in all of the eastern boundary current systems in the world, which are fueled by coastal upwelling and are particularly vulnerable to climate variations such as ENSO. The effectiveness of fisheries management will depend significantly on how well we understand and predict such effects. This is true not only for sardines and anchovies (which account for more than 10% of world landings), but also for many other species. Climate changes affect not merely a few fish species, but exert effects on the physical and biological characteristics of entire ecosystems, as revealed by fluctuations of other commercial fish populations (e.g., see Bakun, 1996) and of other components such as thermocline depth (Polovina et al., 1995), zooplankton volumes (Roemmich and McGowan, 1995a,b), and the abundance of marine organisms such as fish (Bakun, 1996), abalone, and other benthic species (Phillips et al., 1994; Vega et al., 1997). Regime shifts and the associated changes in abundance and distribution of critical prey species such as sardines and anchovies have profound influences on the population dynamics and status of marine mammals and seabirds. The most notable example of such effects is the drastic changes in populations of marine mammal and seabird populations associated with ENSO events (Trillmich and Ono, 1991). These long-lived species have adapted to withstand annual and decadal variations in food resources over large spatial and temporal scales. However, many species are now at historically low population levels, at least partially due to overfishing, pollution, disturbance, and habitat degradation, and may not be able to accommodate future changes in prey species and composition resulting from regime shifts. The Pacific coast of the Californias offers a unique opportunity to learn how the environment acts on both populations and ecosystems in upwelling regions. It includes several distinct upwelling zones (Southern California Bight, Pt. Banda, Pt. Eugenia, Bahia Magdalena, and larger islands of the Gulf of California) with year-round high productivity, controlled by different mechanisms in each zone.
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Building Ocean Science Partnerships: The United States and Mexico Working Together There are two arguments to support the common interest of both the United States and Mexico in studies of the physics and biology of the California Current System. First, the California Current constitutes a continuous major ecosystem fully shared by the two countries. As such, intense interdependence of populations through migratory patterns, advection, genetic interchange, and trophic relations is widely recognized. Second, the need for cooperation is increasing because the demand for marine living resources is growing. Societal concern for the environment has created a movement toward sustainable management practices, requiting new approaches for wise management. Natural and anthropogenic events and processes induce fluctuations, and possibly long-term changes in the abundance and availability of marine species, that may be as strong as those induced by harvesting. The problem of fluctuating fish populations extends well beyond scientific interest. Managing shared, uncontrollably fluctuating resources is not a trivial challenge. Further, human fishery activities profoundly influence and are in turn influenced by marine mammals and seabirds. In the face of major natural changes in abundance and availability, the management of human activities becomes considerably more complex and must extend beyond the mere assurance of sustainability. Marine harvesting needs to be managed to avoid exerting too much fishing pressure during natural collapses, yet be able to detect and exploit population booms. Switching target species during regime shifts to avoid wasting fishing infrastructure and attempting to allocate fishing effort temporally and geographically to improve efficiency will not be easy tasks without deeper insight into the fundamental ecosystem processes. Answers to some of these fundamental questions will be found most readily by comparative studies among regions around the world that exhibit similar physical and biological processes. Comparative studies can be conducted most efficiently and with the most insight if carried out cooperatively, rather than unilaterally. Binational cooperation could lead to greater progress in understanding the effects of the physical environment on fisheries in the California Current System (e.g., fish and shellfish population fluctuations caused by ENSO phenomenon [Phillips et al., 1994; Vega et al., 1997]. Studies must include socioeconomic aspects—Fisheries resources and their exploitation—and should document the enormous losses that result from unpredictable, major fluctuations in natural systems. More specifically, there are a number of important scientific questions related to the physical dynamics of the California Current System and how the physical system affects the population dynamics of commercially important fish species. The following are some examples: What is the nature of the climatic and oceanic variations, and what drives them? Are these variations predictable? Scientists have gained some degree of ability in predicting the timing and magnitude of ENSO events, even though the
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Building Ocean Science Partnerships: The United States and Mexico Working Together biological outcomes of these events, such as the relative abundance of sardines and anchovies, are less predictable (Lynn et al., 1995; Smith, 1995; Chavez, 1996). How should we expect climatic and oceanic variability to change if global warming occurs? What is the dynamic behavior of eddies and upwelling that allows for the maintenance of large sardine and anchovy populations throughout the year in areas ranging from subarctic to subtropical? How do these major changes affect population abundances, and by which specific mechanisms? Why do anchovy populations increase when sardine populations are scarce? Where are sardine and anchovy populations located near the southern limit of the California Current System, and do these populations vary coherently with others elsewhere? What is the offshore structure of the California Current at its southern extent, given the fairly steady Ekman transport throughout the region? Does the California Current have a relatively narrow (<100 km), highvelocity (approximately 50 centimeters per second [cm/s]) core off the Baja California coast, as it does off northern California, or is it broad and weak as described by Wooster and Reid (1963)? How do the California Current's strength and position vary with season? Is there a near-shore (i.e., over or near the shelf) coastal jet flowing toward the equator at southern latitudes, as there is in midlatitude coastal upwelling regions (e.g., Oregon, northern California)? How do the strength and position of the poleward undercurrent or countercurrent over the continental slope vary with season? Are the dynamics of this system governed primarily by coastal upwelling (i.e., offshore Ekman transport), open-ocean upwelling due to wind-stress curl (i.e., Ekman pumping), or ring/eddy dynamics? Study of the California Current's regime shifts presents a binational challenge because of the limitations of resources for such a large-scale, long-term (decadal-scale) task. The only way regime shifts in the California Current System can be studied is within the context of a larger regional or global program, for example, through the establishment of a regional ocean observing system or through links with the Climate Variability and Predictability (CLIVAR) program or other international programs designed to study decadal-scale changes and comparisons among eastern boundary current systems. The causes and effects of short-term climate variability in coastal areas of the United States and Mexico is another important topic for collaborative research. Short-term climate variability is dominated by ENSO events (on a 2- to 10-year time scale) in the Pacific Ocean and by North Atlantic Oscillation (NAO) events (on a 10- to 20-year time scale) in the Atlantic Ocean (with repercussions in the Caribbean Sea and Gulf of Mexico). The impacts of ENSO events are relatively
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Building Ocean Science Partnerships: The United States and Mexico Working Together well understood and intensively studied on the Pacific coasts of the United States and Mexico compared to those of NAO events on the Atlantic/Caribbean/Gulf of Mexico coasts of the two countries, but much remains to be understood on both coasts. The severity of the 1997–1998 ENSO event highlights the importance of improving U.S.-Mexican interactions on this topic. The scientific questions raised by the 1997–1998 ENSO event and the data that have been generated from it will contribute significantly to the research agenda in the years ahead. The phenomenon affects all of the scientific problems discussed here. The impacts of ENSO events on the Pacific Coast involve anomalous currents, surface temperatures, and runoff; increased storm damage, especially due to excessive rainfall; and the displacement of biota, including fish, beyond their normal ranges. Furthermore, ENSO events are known to impact the Caribbean Sea and Gulf of Mexico through anomalous atmospheric forcing, especially changes in surface winds and precipitation due to altered weather cycles and storm tracks. The coastal impacts of NAO events are basically unexplored; however, it has been established that sea surface temperature (SST) variability in the Caribbean Sea and Gulf of Mexico is linked to anomalous SSTs in the tropical Atlantic Ocean associated with the NAO. Climate fluctuations of the Caribbean, southern meso-America, and northern South America are associated with anomalous SST variability in both the tropical Pacific and tropical Atlantic (Enfield, 1996). The effect of ENSO is to produce rainfall deficits along the Pacific coast of meso-America during the rainy season following the period of maximum Pacific SST anomalies. However, with the possible exception of strong ENSO events, non-ENSO SST warmings in the tropical North Atlantic, especially when the South Atlantic is cool, has a stronger association with rainfall in this region, increasing it (Enfield and Alfaro, 1998). These are manifestations of the NAO. Collaborative studies of regional, short-term climate variability, including its impact on coastal circulation and ecosystems, associated with ENSO and NAO events will have obvious societal benefits (including predictability of climate). Additionally, climate variability will serve as a natural test of our understanding of the response of circulation systems and ecosystems under differing atmospheric forcing conditions. To achieve maximum effect, such collaborative studies will require cooperation among hydrologists, meteorologists, and oceanographers in multi-year investigations. Marine Mammals and Seabirds Seabirds and marine mammals rely on regional patches of high productivity that result from localized sources of nutrient influx associated with upwelling or tide-induced vertical mixing regions, bottom topography, or divergence zones (Schoenherr, 1991; Kenney et al., 1995; Macaulay, 1995). As endotherms with high metabolic rates, seabirds and marine mammals are the dominant consumers
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Building Ocean Science Partnerships: The United States and Mexico Working Together outflow, plus that of 25 Mexican rivers from nine hydrologic basins may make this a uniquely productive habitat for marine species. The significance of the throughflow and mesoscale variability for the functioning and robustness of the basin-scale ecosystem—including recruitment sources, sinks, and variability; genetic flow; and biodiversity—has yet to be determined. The carrying capacity of an ecosystem may be determined by the availability of food, space, or some other limiting factor in the system (as described by Odum, 1971). Human intervention in the IAS may reduce its carrying capacity for commercial fish stocks. Anthropogenic effects on carrying capacity can be illustrated by a species whose territorial range shrinks because it cannot tolerate low dissolved oxygen concentrations, low salinity, high sediment concentrations, and/or warm water caused by inputs from rivers. Populations of shrimp, fish, and other animals can be forced into a smaller geographical area by hypoxia, increasing the density of the populations until their needs exceed some other resource that is often related to food supply, food quality, environmental quality, or in the case of sessile benthic organisms, benthic habitat. After this range contraction occurs, the number of organisms decreases, approaching or oscillating around a new, lower carrying capacity. Understanding large-scale and long-term IAS processes requires ample measurements over a large geographic area for a long time. Efforts should continue at two levels: Process Studies: Specific processes should be elucidated through studies of cause-and-effect linkages using intensive experiments, for example, relating food supply to carrying capacity. Monitoring: Long-term monitoring should be designed for observing variability among a suite of correlated variables. Such monitoring is necessary to discover linkages among biological components of ecosystems and between the ecosystem and the environment. For example, little is known about deep-sea communities, so they have not been integrated into a whole-ecosystem view. Funding for long-term monitoring is difficult to sustain and examples of long-term, regular monitoring are rare in the United States and virtually non-existent in Mexico. Such monitoring is crucial for documenting trends in environmental conditions and for understanding processes that vary on interannual and decadal time scales. The National Autonomous University of Mexico's (Universidad Nacional Autónoma de México, UNAM) Institute for Ocean Science and Limnology (Instituto de Ciencias del Mar y Limnología [ICMyL]) and Texas A&M University's (TAMU's) Department of Oceanography have established a collaboration comparing the benthic food chains of the continental shelves of the northern and the southern Gulf of Mexico. This study has utilized the research vessels Gyre (TAMU) and Justo Sierra (UNAM). A basic theme of the research is to gain better understanding of carbon cycling in relation to continental shelf shrimp
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Building Ocean Science Partnerships: The United States and Mexico Working Together and finfish fisheries. Although rather simplified models can now be constructed based on the information collected by this group (Soto and Escobar, 1995; Rowe et al., 1997), much remains to be learned about how physics and primary production limit or control these important fisheries. Regional studies such as those described here differ to some degree from a broader, large-scale IAS study of biophysical coupling because the economically important target species depend on more localized estuaries as nursery grounds. A natural extension of this research would be to make it more interdisciplinary and to involve a larger number of investigators. Necessary expertise in the areas of phytoplankton ecology, benthic ecology, and physical oceanography is available at many U.S. and Mexican institutions throughout the region. The mesoscale features of meanders, rings, and fronts associated with the Loop Current, together with seasonally varying inflow of the Mississippi River and 25 Mexican rivers, shape much of the biological oceanography of this region (Vidal and Vidal, 1997). Sedimentary Dynamics and Environmental Impacts on the Coastal and Oceanic Zones of the Gulf of Mexico Land-ocean interactions affecting the marine sedimentary environment in the western Gulf of Mexico are complex and vary among regions of the coastal ocean. These variations are due to differences in (1) river discharges of sediments and contaminants from both Mexico and the United States; (2) collision of Loop Current anticyclonic tings against the continental slope and shelf; (3) longshore currents and waves; and (4) human activities such as sewage discharge, dam building, coastal urban development, tourism, oil and gas exploration and extraction, and fisheries. These factors have contributed to short- and long-term changes in the marine sedimentary environment (Aguayo and Estavillo, 1985; Aguayo, 1988; Aguayo and Gutiérrez-Estrada, 1993; Gutiérrez-Estrada and Aguayo, 1993). The Gulf of Mexico can serve as a natural laboratory, offering the opportunity to understand the dynamics of several marine geological environments, from tidal flat to abyssal plain, subject to distinctive climate conditions along the margin of the gulf. The observable geology results from the continuous subsidence of the continental margin and sea-level changes due to variations in climate and continental ice sheets; both factors control sedimentary cycles and the suite of resulting sedimentary structures (Aguayo and Marín, 1987; Aguayo and Carranza-Edwards, 1991). However, to understand regional and local sedimentary environments in detail and to develop predictive models, systematic, fundamental research is necessary to describe and quantify (1) river discharges of sediments to the coastal zone; (2) riverine input versus coastal erosion and redistribution; and (3) role of the collision of Loop Current anticyclonic rings against the continental slope-shelf in sediment transport, dispersion, and deposit. The following are some of the questions that arise:
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Building Ocean Science Partnerships: The United States and Mexico Working Together How does geography (climate, physiography, and hydrology) control sediment load, flow regime, and water quality? How are sedimentary settings affected by erosional, depositional, and nondepositional processes? How do tectonic settings (local or regional) affect the dynamics of the sedimentary environments (subsidence, emergence, or stationary)? Oil- and Gas-Associated Seeps in the Southern Gulf of Mexico The southern Gulf of Mexico has the same geologic history as the northern gulf; it is underlain by thick salt deposits that extrude through bottom sediments as mountainous structures called diapirs. These structures often have oil and gas deposits associated with them, as demonstrated by the extensive oil and gas resources now being developed offshore in both Mexico and the United States. Unique communities of organisms utilizing energy sources associated with the oil or gas deposits and brine pools have been observed over a broad range of depths in the northern Gulf of Mexico. These communities have a large biomass and a composition resembling in form—and to some degree in function—those surrounding hydrothermal vents. Such communities have not been observed in the southern Gulf of Mexico, but it is logical that they should occur there also. This is supported by records of oil slicks on the water surface in Campeche Bank and the discontinuities in bathymetric profiles that suggest the existence of gas seepage. An obvious new area of collaboration among biologists, geochemists, geologists, and geophysicists would be to look for and describe the distribution of the oil and gas seep communities, if they exist, in the southern Gulf of Mexico. The study of hydrocarbons as alternate carbon sources to slope communities is an interesting question that needs to be answered. This would assist the Mexican Petroleum Corporation (Petroleos Mexicanos [PEMEX]) in finding potential oil and gas deposits, as it has assisted oil and gas exploration in the offshore waters of the United States. Such information would also aid the study of the physiological ecology of deep-sea organisms. Marine Environmental Quality Binational research and monitoring could contribute to reducing the effects of marine pollution in the IAS, including pollution from nutrients, toxic materials, oil, and debris from land and marine sources. The northern Gulf of Mexico has been studied extensively with respect to its chemical constituents. For 10 years, the Status and Trends Program of the National Oceanic and Atmospheric Administration (NOAA) has monitored pollutant levels in oysters (Crassostrea virginica ) and sediments (Long and Morgan, 1990; Sericano et al., 1995). More recently, the U.S. Environmental Protection Agency (EPA) started the Environ-
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Building Ocean Science Partnerships: The United States and Mexico Working Together mental Monitoring and Assessment Program (EMAP) (Summers et al., 1992), a more ambitious effort that is attempting to develop and validate indicators of environmental health including, but not limited to, pollutant levels. One of the environmental indicators proposed by EMAP is the "Benthic Index" (Engle et al., 1994), which discriminates between healthy and degraded conditions. A similar level of study does not exist on the Mexican side of the gulf, and there is not much basic information regarding levels and trends of pollutants on an IAS-wide scale. International monitoring efforts exist in the IAS on a wider scale, mainly under the auspices of the Sub-Commission for the Caribbean and Adjacent Regions (IOCARIBE) of the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO). IOCARIBE's Pollution Monitoring Programme in the Caribbean (CARIPOL) was a productive program (Atwood et al., 1987a). A database with thousands of records of floating and stranded tar and of dissolved or dispersed hydrocarbons has been compiled and is now archived at NOAA (Atwood et al., 1987b). One important conclusion is that approximately 50% of the oil in the IAS comes from the Atlantic Ocean. Regretfully, this program was terminated. A new program, Caribbean Environmental Program-Pollution (CEP-POL), is administered jointly by IOCARIBE and the United Nations Environmental Programme (UNEP). Another international effort was the first phase of the International Mussel Watch, which was designed to assess the levels of organochlorine compounds in bivalves (Sericano et al., 1995). Samples of bivalves were collected from 76 locations along the coastlines of the Americas, excluding the United States and Canada, and the results were compared with those of NOAA's Status and Trends program. The idea behind this project was that the use of organochlorine pesticides, primarily for antimalaria campaigns, was more widespread in the southern portion of the continent and that pollution by organochlorine compounds would be more serious in the southern Gulf of Mexico. However, one of the major findings was that "contamination is significantly higher along the northern coast of the Gulf of Mexico" (Sericano et al., 1995). The search for reliable indicators of environmental health has focused on the use of "biomarkers," that is, "a biological response that can be specified in terms of a molecular or cellular event, measured with precision and confidently yielding information on either the degree of exposure to a chemical and/or its effect upon the organism or both" (GESAMP, 1995). Various environmental indicators have been proposed, including some for tropical coastal ecosystems, such as the frequency of mutations in red mangroves, Rhizophora mangle (Klekowsky et al., 1994); histopathological lesions in oysters, Crassostrea virginica (Gold et al., 1995); and oxygenases associated with cytochrome P-450 and metallothioneins (GESAMP, 1995). The variability between sexes and changes associated with
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Building Ocean Science Partnerships: The United States and Mexico Working Together gonadal development or spawning are generally unknown, complicating the use of such biomarkers. In contrast to the Sericano et al. (1995) study, some published results indicate that the levels of pollutants along the southern coast of the Gulf of Mexico are of the same magnitude or even higher than those in the northern gulf, for example in the Coatzacoalcos River (Gallegos, 1986; Botello et al., 1996), Laguna de Terminos (Gold-Bouchot et al., 1995; Botello et al., 1996), and Tampico (Sericano et al., 1995). This is particularly true for petroleum hydrocarbons (Gold et al., 1995a,b; Botello et al., 1996). The Gulf of Mexico is an ideal place for binational pollution studies, including fates and effects of pollutants and transport mechanisms. Many of the same species live in the estuaries and bays throughout the region, but there are enough differences in climate, the presence of other species, overall diversity, and other factors to allow for the generalization and validation of existing environmental indicators. The existence of binational monitoring programs is highly desirable and would contribute to scientific goals. Joint research on biomarkers and validation of environmental indicators in tropical marine ecosystems, which are more diverse and more stable climatically, is also highly desirable. This kind of information would be very valuable for coastal zone management. Oil, Hazardous Materials, and Marine Debris Oil production, refining, and transport occur in the IAS at high levels, and the petroleum industry is a major contributor to the economies of many countries bordering the IAS (Botello et al., 1996). To place the environmental importance of the petroleum industry in perspective, the Yucatan Strait (between Cuba and Mexico) is considered to be one of the three straits in the world most likely to have a tanker accident, and the IAS is considered the second most likely region in the world to have such an accident (Reinberg, 1984). A study conducted for the U.S. Coast Guard (Reinberg, 1984) concluded that the Gulf of Mexico and the Caribbean have the most intricate pattern of tanker traffic and declined to designate any part of these bodies of water as low-risk areas (Botello et al., 1996; Figure 2.6). Pollution by oil has been identified by the IOC (1992) as one of the major potential environmental problems in the IAS. It can particularly affect the small island states that depend on tourism as their main economic activity, yet do not themselves gain a direct benefit from petroleum production (IOC, 1992). Marine debris is becoming a major concern in the IAS because the economies of many countries in the region depend on tourism. A committee co-sponsored by several state Sea Grant programs in the United States and by IOCARIBE organizes biannual workshops with participation from many countries in the IAS. The CEP-POL program has as one of its components a marine debris monitoring program, under whose auspices a pilot study was conducted in Puerto Rico, Colombia, and Mexico and is being expanded to include additional countries.
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Building Ocean Science Partnerships: The United States and Mexico Working Together FIGURE 2.6 Principal oil tanker routes in the IAS. Source: Adapted from Botello (1996). Land-Based Sources of Pollution Land-based sources account for approximately 80% of all pollutants entering the ocean (UNEP, 1995), including contaminants such as persistent organic pollutants (pesticides and petroleum hydrocarbons), sewage, and trace metals. A United Nations protocol recently has been adopted to control and diminish the quantity of pollutants entering the ocean from sources on land (UNEP, 1995). Reduction of land-based sources of pollution is extremely difficult to accomplish because of the widely dispersed sources related to virtually all sectors of the land-based national economies (Botello et al., 1996). There is very little information about present levels and trends of persistent pollutants in the IAS region. The status of oil pollution has been reviewed by IOCARIBE (IOC, 1992; Botello et al., 1996). CEP-POL has promoted a number of pilot studies of point sources of pollution, including concentrations of organochlorine pesticides and hydrocarbons. What is lacking are systematic observations that will, if sustained over time, lead to valid conclusions about IAS-wide levels and trends. Because inputs to the ocean are diffuse and the dispersal is so dependent on time-variable ocean circulation, only long-term, systematic measurements can reveal significant trends and large-scale patterns of pollutant levels. There is a need to evaluate the sources, fates, and effects of persistent pollut-
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Building Ocean Science Partnerships: The United States and Mexico Working Together ants throughout the region and to link these observations with circulation models, so as to enable the predictions that are crucial for coastal zone management and planning. MARINE NATURAL PRODUCTS A good basis exists for collaboration between Mexico and the United States in the area of marine natural products chemistry. Both countries have strong academic programs in chemistry, pharmacology, marine biology, and marine ecology, which are the primary disciplines required for this multidisciplinary field. Differences between the two countries result primarily from the way science is practiced and funded. In the United States, research programs tend to be goal-oriented whereas in Mexico research programs are discipline oriented. For example, U.S. funding agencies such as the National Cancer Institute and the National Sea Grant College Program have provided financial support to foster interdisciplinary goal-oriented research programs in the United States that reward chemists and pharmacologists for collaborating to discover new pharmaceuticals. These programs are not without their problems, but when properly managed they can be very effective in fostering both basic and applied research in marine natural products chemistry, pharmacology, and marine biology. One of the more surprising results of drug discovery programs has been the degree to which they have stimulated advances in marine science disciplines. Examples included basic studies of symbiosis and the role of symbiotic microorganisms in the biosynthesis of pharmacologically active compounds, actions of bioactive compounds to protect the producing organism from predation (chemical ecology), basic studies in marine ecology that must precede a major harvesting program, aquaculture research, and studies in marine biodiversity. Mexican researchers and funding agencies might wish to examine the feasibility of interdisciplinary research programs related to marine natural products chemistry, learning from the successes and mistakes experienced by U.S. programs. The strength of both Mexico and the United States in the area of biotechnology offers the potential for substantial collaborative efforts on this topic. Pharmaceutical companies often play a considerable role in drug discovery and commercialization. With this in mind, any academic drug discovery program, particularly a program based on international cooperation, should clearly address the legal issues of patent rights and the sharing of potential financial rewards before the program starts. Few academic discoveries have led to pharmaceuticals, however, largely because pharmaceutical companies prefer to develop their own discoveries. Academic groups should place good research above commercial application while acknowledging that the latter might result from the former. For collaboration in marine biotechnology and drug development to work, it is important that use of natural products derived from U.S. and Mexican organisms receive equitable patent protection and distribution of royalties.
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Building Ocean Science Partnerships: The United States and Mexico Working Together Conservation of Marine Biological Diversity* The conservation of biological diversity has become both a scientific and a political goal of the 1990s. Whereas this concept seems well defined when applied to tropical rain forests, its application to marine environments is poorly understood. It is absolutely certain that we have described only a small percentage of the marine organisms in the intertidal zone and that our knowledge of deep- and midwater organisms is even more sparse. Because we do not know what exists, we cannot know what to conserve. Current efforts in Mexico in the area of marine biological diversity include the definition of priority areas along the coast and open-ocean environments, based on criteria of the highest diversity. Large databases are being created primarily with the major taxa represented in formal collections of museums and research institutions. Criteria proposed by Sullivan (1997) are also being applied. Documents that have recognized the status of marine biological diversity by regions and habitats were published by Salazar-Vallejo and González (1993). At this moment, the National System of Protected Areas (Sistema Nacional de Areas Protegidas [SINAP]) recognizes 59 protected areas along all coasts of Mexico, representing different levels of protection (e.g., Biosphere Reserves, national parks, refuges, protected areas, and reserves) in habitats such as dunes, beaches, reefs, coastal lagoons, mangroves, marshes, and islands. A major effort is still needed to consider the real value of habitats integrated in Large Marine Ecosystems. A joint effort is required to unify the efforts started in the United States with the existing efforts in Mexico. Many people believe that the rain forests provide a habitat for many species that may contain important pharmaceutical agents and that destruction of the rain forests will deprive science of the opportunity to discover these agents. Yet the invertebrates found on tropical and subtropical reefs are known to be a far more productive source of pharmacologically active compounds, according to statistics accumulated by the National Cancer Institute (data from J.H. Cardellina and P.T. Murphy, quoted in Gatson, 1994). Research on marine biodiversity, with an eventual goal of conservation, is an area of U.S.-Mexico cooperation that would receive both political and popular support. However, such research has its detractors because commercial fishing and destruction of marine habitats for urban and industrial development are among the principal factors contributing to the reduction of marine biodiversity. Research on marine biodiversity requires significant financial support for taxonomic studies on both sides of the border. It requires collaboration between marine biologists, marine ecologists, and biological oceanographers, which is strangely lacking in some areas because of the competition among these disciplines for scarce resources. Ultimately, it will require the involvement of scientists from other fields to evaluate the potential value of newly described organ- * See also NRC (1995).
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Building Ocean Science Partnerships: The United States and Mexico Working Together isms as resources for drag discovery and biotechnology. The conservation of biodiversity will require cooperation among nations that share common ocean areas to ensure that actions by one nation do not cause detrimental effects in the shared area. An open border for such scientific research, subject to strict reporting requirements, should be a primary goal of a U.S.-Mexico binational marine science collaboration. Marine Biotechnology* Marine biotechnology, which may be defined as the search for commercial uses of marine biology, biochemistry, and biophysics, is a fledgling field of study having substantial potential. At the simplest level, there is a sense that organisms living in a saline medium, often at high pressures or temperatures, contain biochemical agents that may be of use to industry in marine biotechnology. Neither the United States nor Mexico can match Japan's investment in this field (Rinehart et al., 1981; Faulkner, 1983), and there is evidence that the European Union is accelerating its investment in marine biotechnology. A research collaboration between the United States and Mexico could yield considerable benefits for both countries, because the United States is experiencing a boom in biotechnology while some of the most promising locations in which to perform marine biotechnology field research are in Mexico. The microbial and invertebrate biodiversity found in the Gulf of California makes it a prime target for ''bioprospecting.'' From 1970 to 1985, studies of the chemistry of a rather limited selection of marine algae and invertebrates from the Gulf of California resulted in the discovery of several antimicrobial, antineoplastic, and anti-inflammatory agents (Rinehart et al. 1981; Faulkner, 1983). A reinvestigation of these sources using modem mechanism-based bioassays may lead to the discovery of new biomedical agents. The opportunity to sample marine microorganisms, including extreme thermophilic bacteria from the geothermal vent systems and extreme halophiles from salt ponds, can significantly expand the biomedical potential of Gulf of California organisms. The fledgling marine biotechnology industry has shown considerable interest in extreme thermophilic marine bacteria because they produce enzymes that are stable and efficient at high temperatures and pressures and are therefore attractive for use in industrial processes. The hydrothermal vent systems in the Guaymas Basin are known to be an excellent source of extreme thermophiles (Vidal, 1980; Jørgensen et al., 1992), but there are also many shallow-water seeps, salt ponds, mangrove swamps, and other unique marine microenvironments that could provide a diversity of microorganisms useful to the biotechnology industry. It is almost impossible to predict the future directions of marine biotechnology research or the benefits that could accrue. It is safe to say, however, that * See also NRC (1994a).
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Building Ocean Science Partnerships: The United States and Mexico Working Together marine biotechnology is lagging behind the leading edge of biotechnology but that this situation will improve as the field becomes better organized. For example, an initial meeting of California researchers interested in marine biotechnology resulted in an unexpectedly broad array of research topics being presented. Both the organizers and the participants were surprised at the diversity of existing research. A similar U.S.-Mexico conference on marine biotechnology could be used to initiate binational collaborations in this field. REGIONAL CLIMATE CHANGE Of the several modules of IOC's proposed global ocean observing system (GOOS) (see Chapter 3), perhaps the most mature is the climate module for reasons of technical readiness and scientific urgency. Fundamental understanding of climate change must ultimately be global, but efforts to document changes and to make climate change and impact predictions of practical use to society must be done region by region. If global warming occurs, no individual nation will be affected primarily by the global average temperature rise; rather, nations will be affected by the temperature rise and associated effects in their region. It is certain that atmospheric CO2 concentration has risen during the industrial age, and that global temperatures have risen about 0.5 °C in the past century. The relative importance of natural variation versus human activity in forcing the temperature change is subject to ongoing study. Model predictions of global warming are beset by uncertainty, particularly if one tries to predict regional patterns of change instead of global averages (Speranza et al., 1995, p. 425). The ocean plays a major role in the climate system. It is an enormous thermal flywheel because of its huge heat capacity relative to that of the atmosphere, and it is a key reservoir of carbon. Exchange of CO2 gas across the sea surface depends on physical processes, some of which are poorly known for the full range of complex conditions (from calms to hurricanes) to which the surface is subject. In ocean surface waters, biological processes take up CO2 (e.g., photosynthesis by phytoplankton and carbonate removal by corals), and carbon falls to the sea-floor and is sequestered in sediments. These biological processes or "pumps" may both affect and be affected by the changing state of the atmospheric climate and carbon systems. The effectiveness of the ocean in removing CO2 directly affects forecasts of atmospheric buildup; similarly, if the climate changes in the future and forces a different ocean circulation, the distribution and effectiveness of these biological processes may change. Joint U.S.-Mexican contributions to solutions of these questions in the form of (1) careful, high-quality, long-term measurements of key carbon and climate system variables in the region of common interest and (2) scientific efforts designed to interpret such measurements and place them in global context can be important parts of the worldwide effort to understand climate change.
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Building Ocean Science Partnerships: The United States and Mexico Working Together The area of joint U.S.-Mexican interest spans extensive tropical and subtropical regions, where it is naturally easier to detect trends in long time series of some ocean variables because of the reduced synoptic-scale and seasonal noise relative to the situation at high latitudes. This advantage should be used in the selection of sites and variables to be studied.
Representative terms from entire chapter: