Visualizing mesopelagic food webs in the western North Atlantic using stable carbon isotope analysis of essential amino acids.

Kayla Gardner1,2, Simon Thorrold3, Leah A Houghton3, Rene Francolini3, Sarah G Glancy3, Paul Caiger4, Helena McMonagle5 and Joel Llopiz4, (1)Woods Hole Oceanographic Institution, Biological Oceanography, Woods Hole, MA, United States, (2)Massachusetts Institute of Technology, Earth and Planetary Science, Cambridge, MA, United States, (3)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (4)Woods Hole Oceanographic Institution, Woods Hole, United States, (5)Woods Hole Oceanographic Institution, Biological Sciences, Woods Hole, MA, United States
Abstract:
Mesopelagic ecosystems in the open ocean support remarkably high biomass and diversity of fishes, crustaceans, cephalopods and gelatinous organisms. Despite this impressive abundance, we remain remarkably ignorant of the ecological roles that mesopelagic animals play in the open ocean. This knowledge gap has stymied efforts to determine the effects of potential extraction of mesopelagic biomass by industrial fisheries on ecosystem services provided by the open ocean. We initiated a study of mesopelagic food webs in the Northwest Atlantic Ocean, focusing on myctophid fishes and zooplankton. using compound specific stable carbon isotope analysis. Specimens were obtained from the trawl and MOCNESS tows on two cruises in Bahamian waters and off the shelf of southern New England. Samples were returned to the lab and analyzed using gas chromatography stable isotope ratioing mass spectrometry (GC-irm-MS). The study aims to lay a foundation for determining the structure and function of mesopelagic food webs and identifying the source of carbon fueling mesopelagic communities
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