Use of plants for toxicity assessment of estuarine ecosystems

Estuarine ecosystems are bring rapidly degraded by environmental toxicants from municipal and industrial wastes, agricultural runoff, recreational boa ting, shipping, and coastal development, ranking them as the most anthropog enically degraded habitat types on earth. Toxicity tests are used to establ ish links between adverse ecological effects and the toxicity of environmen tal chemicals. However, most toxicity tests used for regulating the release of chemicals into the environment have used animals as test species, with the erroneous assumption that toxicant levels protective of fish or inverte brates are also protective of plants. Most plant toxicity tests have used t errestrial crop plants, whereas the few aquatic test species used have been primarily freshwater algae. Even though estuarine and marine vascular plan ts are highly vulnerable to environmental chemicals, phytotoxicity studies using native coastal plants have been limited, and no such studies are requ ired for testing by regulating agencies. The relevance of toxicity tests of estuarine sediments and of wastes entering the estuary should depend on th e use of estuarine and marine plant species. This review summarizes toxicit y testing of marine plants used in biomonitoring, phytotoxicity, biotransfo rmations of toxicants, bioaccumulation, and phytoremediation. Challenges to marine plant testing are discussed and include developing standard test pr otocols, identifying species with minimal salinity and toxicant interaction , defining and choosing a suitable sediment for sediment-bound toxicant tes ting, selecting endpoints with low variability, producing viable seeds, and culturing test plants. Progress in acquiring a suitable database is being made, but at a rate that is inadequate to create the sound, scientific foun dation needed for safeguarding our estuarine ecosystems in the near future.