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Isotopic insights into mesopelagic niche space and energy pathways on the southern Kerguelen Plateau

Citation

Woods, B and Walters, A and Hindell, M and Trebilco, R, Isotopic insights into mesopelagic niche space and energy pathways on the southern Kerguelen Plateau, Deep-Sea Research. Part 2, 174 Article 104657. ISSN 0967-0645 (2020) [Refereed Article]

Copyright Statement

Crown Copyright 2019 Published by Elsevier Ltd. All rights reserved.

DOI: doi:10.1016/j.dsr2.2019.104657

Abstract

Mesopelagic fish are an important but poorly understood mid-trophic component of pelagic food webs. There are major uncertainties regarding their trophodynamics and their overall contribution to the broader Southern Ocean food web. This study aimed to investigate the trophic role of mesopelagic fish in the region of the southern Kerguelen Plateau, an area of known importance to an abundant and diverse community of marine predators. We used carbon and nitrogen stable isotopes to quantify the isotopic niches of key mesopelagic fish species (six from the family Myctophidae, and one from Bathylagidae), and assessed variation along the δ15N (resource use) and δ13C (carbon source) axes between species. The assemblage of key mesopelagic fish occupied similar isotopic niche space with overlap among species in both δ13C and δ15N values. Baseline corrected δ15N values provided evidence of latitudinal trends in trophic position (TP). Trophic position estimates of taxa in the southern region of our study area spanned slightly less than 1 TP (mean TP 2.93.7); and 1 TP in the northern region (mean TP 3.24.2). We found evidence of trophic partitioning between species with differences in niche utilization (resource or habitat use). Factors reducing trophic competition include the relative importance of Euphausia superba as a prey item, vertical distribution of consumer and prey, and migratory behaviours. Size-based trophic structuring between species was evident with larger species displaying higher average δ15N values compared to smaller species. However, fish standard length explained little of the variation in δ15N values at the species level, suggesting within species changes in trophic position with body size is not a predominant driver of trophic structure in our study region. Overall, our analysis demonstrated the structural complexity and spatial variation of the food web in the region of the southern Kerguelen Plateau.

Item Details

Item Type:Refereed Article
Keywords:mesopelagic, Kerguelen, trophodynamics, food webs, micronekton, prey field, midwater trawling
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Assessment and management of terrestrial ecosystems
UTAS Author:Woods, B (Ms Briannyn Woods)
UTAS Author:Walters, A (Dr Andrea Walters)
UTAS Author:Hindell, M (Professor Mark Hindell)
UTAS Author:Trebilco, R (Dr Rowan Trebilco)
ID Code:136817
Year Published:2020
Deposited By:Ecology and Biodiversity
Deposited On:2020-01-20
Last Modified:2020-12-01
Downloads:0

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