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Fate and Effects of Anthropogenic Chemicals in Mangrove Ecosystems: A Review
Citation:
LEWIS, M. A., R. PRYOR, AND L. WILKING. Fate and Effects of Anthropogenic Chemicals in Mangrove Ecosystems: A Review. ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 159(10):2328-2346, (2011).
Impact/Purpose:
Summarize the fate and effects of anthropogenic chemicals on mangrove ecosystems and associated biota.
Description:
The role of anthropogenic chemicals in the decline of plant-dominated, fringe ecosystems such as mangroves is important to understand. Mangrove global coverage has been reduced approximately 50% in recent years and the presence of toxic chemicals may be a contributing factor. This review summarizes the scientific literature for fate and effects of non-nutrient contaminant concentrations in mangrove sediments, plant tissues, and chemical toxic effect concentrations. The chemical- related literature for mangroves is skewed for reports describing sediment contamination and bioaccumulation for trace metals. Concentrations for as many as 22 trace metals have been reported in mangrove sediments. Some concentrations have exceeded numerical, sediment quality guidelines suggesting adverse biological effects. However, these effects cannot be confirmed due to lack of supporting phytotoxicity results. Bioaccumulation results are available for at least 11 trace metals, 12 mangrove tissues, 33 mangrove species and 53 species of mangrove habitat-associated biota. Results have been specific to species, tissues, life stage and season but concentrations of tissue-accumulated chemicals and bioconcentration factors have usually been low for mangroves. Tissue-effect levels for most accumulated contaminants are unknown which limits biological interpretation of this literature. Toxicity tests have been conducted with at least 8 mangrove species and 8 species of mangrove-associated fauna. The toxic effects of petrochemicals have been reported more frequently than those for herbicides and trace metals. At least 23 effect parameters, most sublethal, have been monitored in the usual potted toxicity tests of 3 to 6 months duration. Generalizations and extrapolations for toxicity between species and chemicals are restricted by the scarcity of data and lack of experimental consistency. The lack of a substantial fate and effects database, even for most herbicides, hinders regional and larger scale chemical risk assessments. It also limits resource/restoration activities and validation of regulatory, effect-based criteria assumed to be protective of this flora. Conclusions and research recommendations for mangroves parallel those for the often adjacent seagrass ecosystems further substantiating the scientific uncertainty concerning the fate and effects of shoreline toxicants on shallow saltwater flora.
