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Marine Ecology Progress Series

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MEPS 578:19-33 (2017)  -  DOI:

Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes

Amanda W. J. Demopoulos1,*, Jennifer McClain-Counts1, Steve W. Ross2, Sandra Brooke3, Furu Mienis4

1US Geological Survey Wetland and Aquatic Research Center, Gainesville, FL 32653, USA
2University of North Carolina, Wilmington, NC 28409, USA
3Florida State University, St. Teresa, FL 32358, USA
4Royal Netherlands Institute for Sea Research, Den Burg 1790, The Netherlands
*Corresponding author:

ABSTRACT: Examination of food webs and trophic niches provide insights into organisms’ functional ecology, yet few studies have examined trophodynamics within submarine canyons, where the interaction of canyon morphology and oceanography influences habitat provision and food deposition. Using stable isotope analysis and Bayesian ellipses, we documented deep-sea food-web structure and trophic niches in Baltimore Canyon and the adjacent open slopes in the US Mid-Atlantic Region. Results revealed isotopically diverse feeding groups, comprising approximately 5 trophic levels. Regression analysis indicated that consumer isotope data are structured by habitat (canyon vs. slope), feeding group, and depth. Benthic feeders were enriched in 13C and 15N relative to suspension feeders, consistent with consuming older, more refractory organic matter. In contrast, canyon suspension feeders had the largest and more distinct isotopic niche, indicating they consume an isotopically discrete food source, possibly fresher organic material. The wider isotopic niche observed for canyon consumers indicated the presence of feeding specialists and generalists. High dispersion in δ13C values for canyon consumers suggests that the isotopic composition of particulate organic matter changes, which is linked to depositional dynamics, resulting in discrete zones of organic matter accumulation or resuspension. Heterogeneity in habitat and food availability likely enhances trophic diversity in canyons. Given their abundance in the world’s oceans, our results from Baltimore Canyon suggest that submarine canyons may represent important havens for trophic diversity. 

KEY WORDS: Stable-isotope analysis · Food web · Deep sea · Niche breadth · Slopes · Submarine canyon · US mid-Atlantic

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Cite this article as: Demopoulos AWJ, McClain-Counts J, Ross SW, Brooke S, Mienis F (2017) Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes. Mar Ecol Prog Ser 578:19-33.

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