The effect of nitrogen loading on a brackish estuarine faunal community: A stable isotope approach

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Coastal ecosystems worldwide face increased nutrient enrichment from shoreline and watershed development and atmospheric pollution. We investigated the response of the faunal community of a small microtidal estuary dominated by Ruppia maritima (widgeon grass) in Maine, United States, to increased nitrogen loading using an in situ mesocosm enrichment experiment. Community response was characterized by assessing quantitative shifts in macroin-vertebrate community composition and identifying changes in food web structure using stable carbon and nitrogen isotope ratios of producers and consumers. The community was dominated by brackish water invertebrates including midge larvae, oligochaetes, damselfly larvae, amphipods, and ostracods. Experimental nutrient additions resulted in significantly lower densities of herbivorous chironomids and predatory damselflies and greater densities of deposit feeding oligochaetes. Grazing midge larvae (Chironomidae: Dicrotendipes, Cricotopus) consumed epiphytic algae under both natural and enriched conditions. Deposit feeding Chironomus was dependent on allochthonous sources of detritus under natural conditions and exhibited a shift to autochthonous sources of detritus under enriched conditions. Predatory Enallagma primarily consumed grazing chironomids under all but the highest loading conditions. Experimental nutrient loading resulted in an increase in generalist deposit feeders dependent on autochthonous sources of detritus.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The effect of nitrogen loading on a brackish estuarine faunal community: A stable isotope approach
Series title Estuaries
DOI 10.1007/BF02803538
Volume 27
Issue 3
Year Published 2004
Language English
Contributing office(s) Patuxent Wildlife Research Center
Description 460-471
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Estuaries
First page 460
Last page 471
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