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Size Matters: The Contribution of Mega-Infauna to the Food Webs and Ecosystem Services of an Oregon Estuary
Citation:
DEWITT, T. H., S. Pacella, C. FOLGER, AND P. M. ELDRIDGE. Size Matters: The Contribution of Mega-Infauna to the Food Webs and Ecosystem Services of an Oregon Estuary. Presented at Pacific Estuarine Research Society, Nanaimo, BC, CANADA, April 29 - May 01, 2010.
Impact/Purpose:
Large-bodied, invertebrates are common to infaunal communities of NE Pacific estuaries (e.g., bivalves, polychaetes, burrowing shrimps), but their contribution to the ecological structure, function and ecosystem services of most estuaries has been poorly characterized because they are difficult to sample and quantify.
Description:
Large-bodied, invertebrates are common to infaunal communities of NE Pacific estuaries (e.g., bivalves, polychaetes, burrowing shrimps), but their contribution to the ecological structure, function and ecosystem services of most estuaries has been poorly characterized because they are difficult to sample and quantify. In a study of Yaquina estuary (Oregon) food webs, particular effort was made to quantify intertidal and subtidal mega-infauna using suction-excavated 40-cm diameter corers in addition to conventional sampling of macro-infauna. Additionally, the abundance and biomass of all floral and other faunal guilds (except microbial and mammalian guilds) were directly quantified or estimated from published studies, carbon and nitrogen stable isotopes were measured for abundant species, and inverse analysis was used to generate models of carbon flow within food webs of the lower and upper reaches of Yaquina estuary. Benthic invertebrates dominated the biomass and respiration among faunal guilds in both estuarine reaches, whereas biomass and respiration of birds and fish were two orders-of-magnitude smaller. Mega-infauna, particularly intertidal burrowing shrimps and bivalves, constituted most of the benthic invertebrate biomass, respiration and secondary production in both reaches, although only a small fraction of the total infaunal abundance. Mega-infauna were dominant consumers of phytoplankton, major contributors of carbon to sediment organic matter, and consumers of phytopolankton, major contributors of carbon to sediment organic matter, and facilitated carbon and nutrient flux between sediments and the water column. However, meio- and macrofauna were relatively more important as prey for fish, crabs and birds. Mega-infauna contribute directly to estuarine ecosystem services as fishery species (clams, burrowing shrimp) and indirectly by supporting fish, crab and bird populations, by accelerating carbon and nutrient cycling, and by improving water clarity through filtration of phytoplankton. Underestimation of mega-infaunal and abundance results in substantial underestimation of carbon flow in estuarine food webs and production of several ecosystem services.