An Approach for Assessing U.S. Gulf Coast Ecosystem Restoration A Gulf Research Program Environmental Monitoring Report (2022) / Chapter Skim
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2 Environmental Trends and Indicators
2 Environmental Trends and Indicators
Pages 17-58
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From page 17... ...
. It then summarizes the current understanding of indicators that would be needed to assess cumulative effects of multiple restoration efforts relative to background trends, identifies spatial and temporal gaps in existing data collection and interpretation, and discusses the need for robust environmental data to assess critical background environmental trends that impact restoration efforts.
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From page 18... ...
The committee focused on both natural and human-induced climate change effects on GoM coastal environments, including relative sea level rise, tropical storms and hurricanes, sea surface temperature, ocean acidification, and tropicalization. Some of these drivers or pressures, like relative sea level rise, can reflect both natural and anthropogenic forces.
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From page 19... ...
Dashed white lines indicate funds expended in restoration efforts, while yellow solid lines connecting the restoration types indicate possible synergistic or antagonistic interactions. Potential environmental benefits resulting from the cumulative effects of restoration efforts are shown as a rectangle below the restoration panel.
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From page 20... ...
have 50-year subsidence estimates of greater than 22 mm/year, a measure that has implications for marsh persistence, the long-term viability of towns near the mouth of the river, and even the navigation of the lower Mississippi River. In spite of these extreme values, research suggests that tide gages in Louisiana systematically underestimate subsidence (Keogh and Törnqvist, 2019)
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From page 21... ...
. Others posit that if RSLR is greater than 3 mm/yr, marsh drowning occurs within a few centuries, and if relative sea level rise exceeds 6–9 mm/yr, Louisiana marsh conversion into open water could happen within a 50-year timeframe (Jankowski et al., 2017; Törnqvist et al., 2020)
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From page 22... ...
Relative sea level trends (mm/yr) in the Gulf of Mexico.
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From page 23... ...
. When planning restoration projects, practitioners need to be aware of the timespan for developing resilience of their projects to hurricane conditions, a critical consideration in areas where the return period is between 5 and 7 years for a hurricane and 14 and 22 years for a major hurricane landfall.7 7 See https://www.nhc.noaa.gov/climo/.
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Gulf Coast states. SOURCE: Redrawn from Keim et al., 2007.
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From page 25... ...
Storm surges have dramatic effects on coastal environments, damaging habitat, destroying forests and crops, inundating the coastline with saltwater, and moving and cutting channels through barrier islands. These effects are also not uniformly distributed across the GoM.
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From page 26... ...
Wind and wave energy; storm surge; and freshwater, sediment, and nutrient inflows associated with storm-related rainfall have potential to significantly disrupt coastal ecosystems and restoration efforts. Sea Surface Temperature Like much of the global ocean, the GoM is experiencing rising sea surface temperatures (Figure 2.6)
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Gulf Coast (Holland and Bruyere, ` 2014)
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From page 28... ...
Restoration efforts may be impacted, as increased air temperature will affect marsh plant productivity and biomass, and changes in freshwater flows will alter nutrient and sediment supply delivery patterns to marshes and estuaries. Coastal Ocean Acidification Rising atmospheric carbon dioxide (CO2)
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From page 29... ...
Increased acidification affects the formation of calcium carbonate shells and skeletons in corals and mollusks, potentially impacting the long-term success of oyster reef restoration and coral reef recovery. Tropicalization Climate-driven changes in species composition and the novel ecological interactions that follow them are occurring throughout the world.
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From page 30... ...
Many tropical organisms transported into the GoM have until recently been unable to survive its winter temperatures. However, the decreasing frequency of lethal temperatures has allowed many formerly rare tropical species to become increasingly common in coastal waters of all five Gulf states (Osland et al., 2021)
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From page 31... ...
Historic alterations in streamflow, along with future modifications, are likely to influence the success or failure of ongoing and future GoM restoration projects. Freshwater inflows control salinities in GoM estuaries and shallow coastal waters, thus defining, at least in part, environments and habitats.
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From page 32... ...
Freshwater inflow controls salinity in downstream coastal waters and nutrient and sediment input, which can affect the restoration success of marshes, submerged aquatic vegetation, and in particular, oyster reefs. Nutrient Inputs to the GoM Nutrient inputs or loading (nitrogen and, to some degree, phosphorous)
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From page 33... ...
Gulfwide nutrient loading to the GoM has been modeled for specific points in time, but trends are not available. From the limited number of estuaries and the Mississippi River system where long-term loading estimates exist, trends are variable.
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From page 34... ...
and are anticipated to be further affected by factors such as climate change, which may impact storm frequency and intensity as well as regional to continental-scale rainfall patterns. Declines in suspended sediment loads in the Mississippi River, decreased connectivity between the river and its floodplain, sea level rise, and subsidence have contributed to the loss of Louisiana coastal wetlands (Kesel, 1988; Tweel and Turner, 2012)
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From page 35... ...
Similar to those efforts, the National Aeronautics and Space Administration (NASA) conducted a series of successful efforts to measure sea surface salinity and temperature, capturing events such as the 2011 Mississippi River flood and the effects of Hurricane Katia.15 Additionally, Vazquez-Cuervo et al.
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From page 36... ...
. The IPCC found that recent observations support that sea level rise (SLR)
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From page 37... ...
Large areas of seasonal bottom-water oxygen deficiency and hypoxic conditions on the northern GoM continental shelf adjacent to the Mississippi River have been documented since the 1950s, shown in Figure 2.10, with an acceleration of worsening severity during the 1970s (Rabalais and Turner, 2019)
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From page 38... ...
, and in nearshore GoM waters where it can impact nearshore and estuarine restoration efforts (NASEM, 2017)
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From page 39... ...
Annual assessment of the extent of hypoxia in the nearshore northern GoM show variability associated with spring rainfall in the Mississippi River watershed. Factors contributing to difficulties in synthesizing water quality monitoring in GoM coastal and estuarine areas include lack of consistent data collection and analysis methods, intermittent funding resulting in spatial and temporal gaps in data collection efforts, and lack of coordinated monitoring objectives that do not include current priority issues such as assessing the cumulative effects of multiple restoration projects.
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, but they are especially widespread in the northern Gulf. Emergent Wetlands The predominant emergent wetland type along the northern GoM is the salt marsh, which is dominated by erect and rooted herbaceous hydrophytes (Cowardin et al., 1979)
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From page 41... ...
was recently published, and it could be used to create a baseline and change analysis of coastal wetlands utilizing standardized methods. Most National Estuary Program–designated sites in the GoM maintain regular monitoring programs that include emergent wetlands assessments.
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From page 42... ...
Mangrove Forests The recent expansion of mangroves across the northern GoM and the displacement of salt marshes by the black mangrove (Armitage et al., 2015) has implications for future salt marsh restoration projects (as discussed under "Tropicalization")
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From page 43... ...
(2018) developed a conceptual model for assessing cumulative impacts of reef restoration efforts and provided a detailed assessment of a broad array of metrics useful as indicators of oyster and ecosystem health.
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From page 44... ...
Potential impacts from climatic drivers and anthropogenic stressors, as well as restoration design and implementation, can affect oyster reef restoration. Barrier Islands There continues to be considerable interest in barrier island restoration in the GoM (see Oliver and Ramirez-Avila, 2019)
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The data on which such evaluations have been based may also be useful in assessing long-term environmental trends for restoration efforts. Fishery closures in 2010 in response to the DWH spill had a significant, but in most cases short-term, impact on catches.
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In the GoM, the Gulf of Mexico Avian Monitoring Network coordinates the various monitoring efforts to support both management and restoration efforts. 38 See https://gomamn.org.
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From page 47... ...
provide a review of bottlenose dolphin research in the GoM that could be valuable in assessing this species as an integrative indicator of long-term environmental trends. Bottlenose dolphins are common in waters adjacent to highly populated and industrialized GoM coastal waters and consume large quantities of fish, which may bioaccumulate various toxins (Würsig, 2017)
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From page 48... ...
Over shorter time scales, land cover can be affected by naturally occurring disturbances, such as storms, floods, and fires, and human activities, such as population change; industrial, agricultural, or urban development; deforestation or reforestation; water diversion; and infrastructure such as roads.56 Land cover affects or influences environmental conditions in many ways, including water quality, hydrology, and habitat and associated species composition. Changes in land cover can alter hydrologic regimes and runoff patterns, thus potentially acting as a stressor on environmental restoration projects and impacting the cumulative effects of multiple restoration projects.
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From page 49... ...
Data and other materials on land use change are available from the National Land Cover Database and the Coastal Change Analysis Program. Land use changes can have profound effects on coastal habitats and can interact with restoration efforts, including reduced area for restoration and increased stormwater runoff.
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From page 50... ...
In addition to large-scale oil spills, there are also numerous other incidents involving hazardous materials, the cumulative impacts of which remain unknown. In 2020 and the first 6 months of 2021, there were over 200 oil and chemical spills in the GoM.65 Oil spills in the Gulf of Mexico can occur from pipelines, wells, and transportation.
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From page 51... ...
These trends differ across the GoM, underscoring the importance of considering trends, desired outcomes, and the likelihood of restoration success in the context of the landscape in which restoration projects are implemented. This concept is more fully discussed in Chapter 3.
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From page 52... ...
RSLR rates in fast enough to keep pace subsidence stations access to water levels and Louisiana and northern with RSLR without sediment on the Gulf Coast tides Texas are among the highest replenishment inhibit the ability to NCCOS1 provides a broad https://coastalscience.noaa.gov/project/ in the nation accurately estimate array of predictive tools predicting-impacts-sea-level-rise-gulf rates of RSLR in some mexico/ areas Tropical Storms Long-term data indicate Restoration plans need to Existing data and NOAA Historical Hurricane https://oceanservice.noaa.gov/news/ and Hurricanes that intense hurricanes are include measures to address information sources Tracks cover 150 years of historical-hurricanes/ increasing in frequency more intense tropical storm are adequate to track GoM storms impacts long-term trends in storm patterns in the National Hurricane Data https://www.nhc.noaa.gov/data/ GoM Archive is comprehensive Sea Surface SST has gradually increased Rising SST can increase Existing data and The EPA SST website and https://www.epa.gov/climate-indicators/ Temperature in the GoM since the early coastal hypoxia, which can information sources program provides historic climate-change-indicators-sea-surface 1980s impact restoration efforts appear adequate to data (1880 onward) and are temperature#ref6 involving shellfish and other track long-term trends expected to be ongoing organisms in Gulf-wide SST NOAA SST satellite data https://www.aoml.noaa.gov/phod/dhos/ for GoM from 2010 to the sst.php present, expected to be ongoing Ocean and Coastal Subsurface waters in the Acidifying seawater can Especially in the NOAA's Ocean Chemistry https://www.aoml.noaa.gov/ocd/ocdweb/ Acidification northwestern GoM are affect formation of calcium southern GoM, and Ecosystems Division occ.html acidifying at a rate greater carbonate shells and many coastal and makes all relevant data than the global surface skeletons in corals, mollusks, estuarine areas and available on an ongoing basis; ocean rate.
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From page 53... ...
generally sediment inflow, and species interpretation are document a downward composition, all which can limited in many areas trend in freshwater inflow affect coastal restoration of the GoM to the GoM since the 1960s. efforts Conversely, Mississippi River discharge has increased during this period Current water data plus https://waterdata.usgs.gov/nwis/rt historical data, varies by site Nutrient Inputs Gulf-wide nutrient inputs Nutrient load reduction Long-term nutrient https://nrtwq.usgs.gov/nwqn/#/ trends are not available; has been found to be the loading estimates https://sparrow.wim.usgs.gov/marb/ trends of nutrient loading most effective restoration are limited to several from specific rivers vary technique for water quality estuaries and the https://toxics.usgs.gov/hypoxia/mississippi/ and SAV in several Florida Mississippi River nutrient_flux_yield_est.html estuaries system https://nrtwq.usgs.gov/nwqn/#/GULF https://www.ncei.noaa.gov/maps/gulf-data atlas/atlas.htm https://data.amerigeoss.org/tr/dataset/gulf of-mexico-hypoxia-dataset https://gcoos.org/hypoxia-nutrients/ 53
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From page 54... ...
sample collection United States, including the Annual assessment of the every 5 years GoM extent of hypoxia in the nearshore northern GoM Data go back to 2000 https://tidesandcurrents.noaa.gov/hab/ show variability associated gomx.html with spring rainfall in the Mississippi River watershed Two sites provide access to https://www.epa.gov/waterdata/water data from all five Gulf states quality-data-wqx https://www.waterqualitydata.us/
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From page 55... ...
interpret information status and trends and 2010, primarily due Addressing issues associated on emergent wetlands to open water conversion, with losses would benefit at the Gulf-wide scale; The Digital Coast includes https://coast.noaa.gov/digitalcoast/ and, to a lesser extent, restoration efforts interpretation and diverse data and analytical from development and reporting generally and mapping tools urbanization lag data collection by several years Most current and Handley et al., 2007 comprehensive GoM assessment Seagrass/SAV For areas where seagrass Water clarity adequate to Data sources are Most current and Handley et al., 2020 maps are available, the support seagrass growth varied, and support comprehensive GoM Gulf experienced an overall and reproduction is key to for future Gulf-wide assessment gain in seagrass extent of seagrass restoration success assessments is not almost 24% between two assured Analysis of data from 1987 Handley and Lockwood, 2020 time periods (1987–2002 to 2017 and 2004–2017) ; gains are associated with improved water quality Mangroves Gulf-wide trends since 2004 The effects of the ongoing The National Wetlands Status and trends 1998–2004, Dahl et al., 2011 in mangrove areal extent are colonization of salt marshes Status and Trends mangroves included in the not known in the northern GoM will be program estimates estuarine shrub classification an important consideration a 0.2% loss in areal in salt marsh restoration extent between 1998 projects and 2004 Oyster Beds Gulf-wide trends in the Potential impacts from Oyster landing by state and extent and condition of climatic drivers and year are available oyster reefs are currently anthropogenic stressors, as unknown well as restoration design and implementation, can affect oyster reef restoration 55
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From page 56... ...
qt results, with some species an indicator of ecosystem the various bird improving, some remaining condition monitoring efforts https://www.audubon.org/content/ stable, and others declining audubon-coastal-bird-survey https://ebird.org/home https://partnersinflight.org/what-we-do/ science/databases/ Fredrick and Green, 2019a Marine Mammals The 2018 NOAA assessment Common bottlenose dolphin Monitoring is ongoing Regularly developed stock https://www.fisheries.noaa.gov/national/ found insufficient data to status and trends could be and expected to assessments include status marine-mammal-protection/marine determine population trends integrative indicators of continue to meet and trends (if detectable) of mammal-stock-assessment-reports-species long-term environmental requirements of the all GoM species; began with stock#cetaceans -- -dolphins health Marine Mammal 1994 amendment of Marine Protection Act Mammal Protection Act 2 See https://gomamn.org/.
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From page 57... ...
qt science_center_objects=0#qt-science_ center_objects Land Cover Urban land cover in coastal Changes in land cover can The Multi-Resolution USGS National Land Cover https://www.mrlc.gov/ areas around the GoM alter hydrologic regimes Land Characteristics Database includes data from increased by 15% between and runoff patterns, Consortium3 2001 onward 1996 and 2010, with some thus potentially affecting generates land cover geographic areas, including environmental restoration information at a Houston and Tampa, projects and impacting the national scale for increasing at much higher cumulative effects of multiple a wide variety of rates restoration projects environmental, land management, and modeling applications Oil Spills Oil and hazardous spills Because of the amount of NOAA's Office of Response https://incidentnews.noaa.gov/ in the Gulf of Mexico are oil activity in the Gulf, there and Restoration has tracked ongoing stressors, the effects are likely to be continuing and recorded oil spills and https://response.restoration.noaa.gov/ of which are complicated impacts on organisms, other incidents since 1985 resources/maps-and-spatial-data by the naturally occurring communities, and habitats hydrocarbon seeps in this https://response.restoration.noaa.gov/oil region and-chemical-spills 3 See https://www.mrlc.gov. NOTES: Data sources for long-term monitoring of Mississippi River status and trends are not included.
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