Environmental Science in the Coastal Zone Issues for Further Research (1994) / Chapter Skim
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8 Coastal Wetlands: Multiple Management Problems in Southern California...
8 Coastal Wetlands: Multiple Management Problems in Southern California...
Pages 107-123
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From page 107... ...
In fact, only two have been included in the Environmental Protection Agency's National Estuary Program: San Francisco Bay and Santa Monica Bay, and only four of the 19 National Estuarine Research Reserves are on the Pacific Coast. Of these, Elkhorn Slough and Tijuana Estuary are in California.
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From page 108... ...
In the San Diego area, salt marshes have declined drastically. The acreage of tidal salt marsh in Tijuana Estuary, San Diego Bay and Mission Bay is only 13 percent of its historic area (San Diego Unified Port District, 1990)
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From page 109... ...
A concern that is peculiar to semi-arid regions is salinity dilution, which occurs when intermittent streams that normally provide seasonal fresh water to coastal lagoons become year-round rivers due to wastewater discharge. Some effects of dry-season flows to coastal wetlands have been documented.
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From page 110... ...
To handle the effluent from both plants, a 12-foot-diameter outfall is being constructed to carry up to 300 millions of gallons per day of wastewater to the ocean. This outfall would cross Tijuana Estuary and damage a 200-foot-wide swath of endangered species habitat during construction.
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From page 111... ...
Despite laws that protect wetlands and endangered species, regulatory agencies still permit habitat alterations if mitigation plans promise compensation. Lost habitat is usually replaced by restoring disturbed wetlands, with a net loss of wetland acreage and often a decline in habitat quality (Zedler, 1991)
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From page 112... ...
An Attempt to Compensate for Lost Endangered Species Habitat The San Diego Bay mitigation was a habitat conversion. Disturbed high marsh/transition was converted to low marsh for a federally endangered bird (the light-footed clapper rail)
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From page 113... ...
Lower functional value of restored or created wetlands does not compensate for lost endangered species habitat. Even if 3:1 or 4:1 compensation is required, a larger area of unusable habitat will not replace the functional value of one acre that is critical to the endangered population.
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From page 114... ...
The objective is to "relate the location and extent of seagrass and salt marsh habitats to the production of living marine resources in an estuary or region" (Sutherland, 1991~. Although this program has provided some support for the soil amendment experiment in San Diego Bay, most of the funding has been for research in East Coast and Gulf Coast habitats.
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From page 115... ...
It is not sufficient for managers to worry only about the loss of fish and shellfish habitat, because endangered species are often jeopardized by wetland loss in southern California. Management models cannot be derived by extrapolation from data of East Coast and Gulf Coast estuaries, where inflows are more predictable and where plants and animals are more tolerant of brackish water.
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From page 116... ...
1991. The challenge of protecting endangered species habitat along the southern California coast.
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From page 117... ...
Urban runoff degrades coastal water bodies; noise, lights, and human activities occur immediately adjacent to endangered species habitats. There is constant pressure to use wildlife preserves.
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From page 118... ...
Agriculture: Minimal agricultural efforts are carried out along the coast; however, there are agricultural activities in the Tijuana River Valley, several areas of floriculture inland of coastal lagoons, and vegetable farming on the marine terrace at Camp PendIeton. Problem: Non-point source pollutants and irrigation runoff flow into coastal wetlands.
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From page 119... ...
Tijuana Estuary is a national estuarine research reserve; it includes a state park and a national wildlife refuge for endangered species. At San Diego Bay, the Sweetwater Marsh is a national wildlife refuge.
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From page 120... ...
The higher elevations of coastal marshes support rare and endangered plants (the salt marsh bird's beak) and insects (mudflat tiger beetles)
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From page 121... ...
1.42 1.89 1.90 2.02 2.09 Population dynamics genetic structure and diversity minimum viable population sizes community development processes (rates, rate-limiting processes) below ground vegetation processes Linkages between communities and habitats Trophic dynamics food web analysis emergent insect communities Exotic species biology dispersal mechanisms competitive effects trophic effects Habitat inventory determination of estuarine acreage and habitat types community profiles on sites with long-term data base
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From page 122... ...
of salinity dynamics (modal & extreme) Effects of anticipated sea level rise Marsh morphology role of extreme events comparisons between marsh types Water Quality Research Needs Nutrient dynamics process rates budgets organic matter accumulation and decomposition rates effects of alternating wet-dry cycles effects of altered hydrology Criteria for vegetation Urban runoff
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From page 123... ...
Coastal Wetlands 1.81 1.90 1.17 1.29 1.59 1.65 1.94 2.48 Impacts of development Treatment strategies Restoration Research Needs Inventory of projects and monitoring Habitat architecture habitat size to sustain minimum viable population sizes and functionality habitat heterogeneity landscape linkages and corridors buffer zone requirements Site selection criteria identification of potential sites consideration of regional habitat biodiversity urban problems Monitoring and evaluation of success assessment and standardization of functionality evaluation criteria assessment of appropriate temporal scales of monitoring assessment criteria for urban projects where no natural sites remain for comparison assessment of structure (e.g., canopy height) as surrogates for function Methodology identification of desired initial conditions establishment of desired initial conditions independent tests of design strategies acceleration of functional development trajectory incorporation of effects of rare/stochastic events in design Economic evaluation of adequacy of mitigation/restoration options as compensation for loss Source: Williams and Zedler, 1992.
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