Food Web Structure of the Alaskan Nearshore Shelf and Estuarine Lagoons of the Beaufort Sea

• Published in: Estuaries and coasts Vol. 35; no. 2; pp. 416 - 435
• Main Authors: Dunton, Kenneth H., Schonberg, Susan V., Cooper, Lee W.
• Format: Journal Article
• Language: English
• Published: New York Spring Science + Business Media 01.03.2012; Springer-Verlag; Springer Nature B.V
• Subjects: Barrier islands; Biogeochemistry; Biological magnification; Brackish; Climate change; Coastal plains; Coastal Sciences; Coastal waters; Coasts; Deltas; Earth and Environmental Science; Ecology; Environment; Environmental Management; Estuaries; Food; Food chains; Food webs; Freshwater & Marine Ecology; Gastropoda; Lagoons; Marine ecology; Marine fish; Marine fishes; Particulate organic matter; Predators; Rivers; Sea water; Seas; Sediments; Shoals; SPECIAL SECTION: THE ARCTIC OCEAN ESTUARY; Streams; Trophic levels; Water and Health; Water column; Beaufort Sea; PNW, Beaufort Sea; USA, Alaska, Arctic Coastal Plain; INE, USA, Alaska; Arctic coast; Climate change; Demarcation Bay; Camden Bay; Stable isotopes; Trophic structure; Benthic community structure; Beaufort Sea; Food webs; Nitrogen; Carbon; Estuarine lagoon
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-012-9475-1

The eastern Alaska Beaufort Sea coast is characterized by numerous shallow (2-5 m) estuarine lagoons, fed by streams and small rivers that drain northward from the Brooks Range through the arctic coastal plain, and bounded seaward by barrier islands and shoals. Millions of birds from six continents nest and forage during the summer period in this region using the river deltas, lagoons, and shoreline along with several species of anadromous and marine fish. We examined biogeochemical processes linking the benthic community to the overall food web structure of these poorly studied but pristine estuaries, which are largely covered by 1.8 m of ice for 10 months annually. In summer, these lagoons are relatively warm with brackish salinities (5-10°C, S= 10-25) compared to more open coastal waters (0-5°C, S> 27). The stable isotopie composition of organic materials in sediments (i. e., benthic particulate organic matter) and water column suspended particulate organic matter from both streams and lagoons are largely indistinguishable and reflect strong terrestrial contributions, based upon δ¹³C and δ¹⁵N values (-25.6%o to -27.4%o and 1.4%o to 3.3% o, respectively). By comparison, shifts toward more heavy isotope-enriched organic materials reflecting marine influence are observed on the adjacent coastal shelf (-24.8%o to -25.4%o and 3.4%o to 5.3%o, respectively). The isotopie composition of lagoon fauna is consistent with a food web dominated by omnivorous detritovores strongly dependent on microbial processing of terrestrial sources of carbon. Biomagnification of ¹⁵N in benthic organisms indicate that the benthic food web in lagoons support up to four trophic levels, with carnivorous gastropod predators and benthic fishes (δ¹⁵N values up to 14.4% o) at the apex.