Trophic structure of the bathyal benthos at an area with evidence of methane seep activity off southern Chile (similar to 45 degrees S)

TitleTrophic structure of the bathyal benthos at an area with evidence of methane seep activity off southern Chile (similar to 45 degrees S)
Publication TypeJournal Article
Year of Publication2014
AuthorsZapata-Hernandez G., Sellanes J., Thurber AR, Levin L.A
JournalJournal of the Marine Biological Association of the United Kingdom
Volume94
Pagination659-669
Date Published2014/06
Type of ArticleArticle
ISBN Number0025-3154
Accession NumberWOS:000337295700002
Keywordsbathyal megafauna; Chile Triple Junction; community structure; continental-margin; feeding ecology; food-web structure; gulf-of-mexico; habitat heterogeneity; isotopic niche; methane seeps; ne atlantic; new-species gastropoda; nitrogen isotopes; stable isotopes; stable-isotope analysis; trophic ecology; width
Abstract

Through application of carbon (C) and nitrogen (N) stable isotope analyses, we investigated the benthic trophic structure of the upper-slope off southern Chile (similar to 45 degrees S) including a recent methane seep area discovered as part of this study. The observed fauna comprised 53 invertebrates and seven fish taxa, including remains of chemosymbiotic fauna (e.g. chemosymbiotic bivalves and siboglinid polychaetes), which are typical of methane seep environments. While in close-proximity to a seep, the heterotrophic fauna had a nutrition derived predominantly from photosynthetic sources (delta C-13 > -21 parts per thousand). The absence of chemosynthesis-based nutrition in the consumers was likely a result of using an Agassiz trawl to sample the benthos, a method that is likely to collect a mix of fauna including individuals from adjacent non-seep bathyal environments. While four trophic levels were estimated for invertebrates, the fish assemblage was positioned within the third trophic level of the food web. Differences in corrected standard ellipse area (SEA(C)), which is a proxy of the isotopic niche width, yielded differences for the demersal fish Notophycis marginata (SEA(C) = 5.1 parts per thousand) and Coelorinchus fasciatus (SEA(C) = 1.1 parts per thousand), suggesting distinct trophic behaviours. No ontogenic changes were detected in C. fasciatus regarding food sources and trophic position. The present study contributes the first basic trophic data for the bathyal area off southern Chile, including the identification of a new methane seep area, among the furthest south ever discovered. Such information provides the basis for the proper sustainable management of the benthic environments present along the vast Chilean continental margin.

DOI10.1017/s0025315413001914
Short TitleJ. Mar. Biol. Assoc. U.K.
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Student Publication: 
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