Trophic relationships of a subtidal fish assemblage in the Francisco Coloane Coastal Marine Protected Area, southern Chilean Patagonia

ABSTRACT

A combination of stomach content and nitrogen (δ¹⁵N) and carbon (δ¹³C) stable-isotope analysis was used to assess the trophic interactions and feeding habits of three notothenioid coastal fish (Champsocephalus esox, Patagonotothen tessellata and Patagonotothen cornucola) and one exotic salmon species (Oncorhynchus tschawytscha) with diverse life habits (benthic and benthopelagic) in the Francisco Coloane Coastal Marine Protected Area, southern Chile. The stomach contents of C. esox were mainly fish; those of P. cornucola and O. tschawytscha were crustacean decapods, Munida gregaria. A cluster analysis on isotope data and stable-isotope Bayesian ellipses detected two different predator groups, one with benthopelagic habits (C. esox and O. tshawytscha) and one with benthic habits (P. cornucola and P. tessellata). These results were supported with similar isotopic trophic level of each group. We suggest that the exotic salmon O. tschawytscha is a generalist predator with a broad trophic niche that may compete with the native notothenioid C. esox, as both have equivalent trophic levels with substantial overlap. This preliminary study is the first on trophic relationships of a subtidal fish assemblage within a remote ecosystem of fjords and channels in Chile’s southern Patagonia.

KEYWORDS:

• Notothenioidei
• exotic salmonid
• trophic level
• feeding habits
• Magellan region
• sub-Antarctic

ABBREVIATIONS:

• ANOVA: analysis of variance analysis; CMPA: Coastal Marine Protected Area; HSD: Tukey’s honest significant difference test; IRI: index of relative importance; SEAc: standard ellipse area corrected for sample size; TL: trophic level

Acknowledgements

We thank the tourism company Expedición FitzRoy for logistical support during fieldwork, especially Juan José Salas and the crew of the M/N Forrest. Also, we thanks Dr Francisco Elgueta for his on-site assistance with fish surgery and throughout the fieldwork activities. Finally, we thank José Saavedra for his help with the taxonomic identification of invertebrate taxa.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

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Additional information

Funding

This study was funded by Chile’s National Commission for Scientific and Technological Research (CONICYT) Regional Program (Programa Regional) and Linking Science and the Enterprise Project (Proyecto de Vinculación Ciencia-Empresa), project number CONICYT-VCE 5N000003.