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Trophic relationships of hake (Merluccius capensis and M. paradoxus) and sharks (Centrophorus squamosus, Deania calcea and D. profundorum) in the Northern (Namibia) Benguela Current region

Trophic relationships of hake (Merluccius capensis and M. paradoxus) and sharks (Centrophorus... The trophic relationships of two hake species (Merluccius capensis and M. paradoxus) and three shark species (Centrophorus squamosus, Deania calcea and D. profundorum) were investigated using nitrogen and carbon stable isotope signatures (δ15N and δ13C) of their muscle tissues. The sharks were more enriched in 15N than the hake, an indication of the apex predator status of sharks. Among the sharks considered, C. squamosus occupied the highest trophic level and fed primarily on benthic prey. The two species of shark from the genus Deania were not different based on δ15N or δ13C, so they had similar diets. The δ13C signatures indicated that M. capensis and sharks fed on prey derived from similar basal resources. However, there was a significant difference in δ13C between M. paradoxus and all other species examined, suggesting that they occupied different feeding niches. Isotope-based population metrics showed narrower trophic ranges in sharks than M. capensis. Carbon and nitrogen ranges indicated that hake fed on a more diverse pool of carbon sources and had generally more enhanced trophic diversity in their feeding patterns than sharks. Among the species considered, C. squamosus occupied a unique isotopic space. Our results supported the hypothesis there are trophic overlaps among these species, but some interesting differentiation was revealed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Zoology Taylor & Francis

Trophic relationships of hake (Merluccius capensis and M. paradoxus) and sharks (Centrophorus squamosus, Deania calcea and D. profundorum) in the Northern (Namibia) Benguela Current region

Iitembu, Johannes A; Richoux, Nicole B
African Zoology , Volume 50 (4): 7 – Oct 2, 2015
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Trophic relationships of hake (Merluccius capensis and M. paradoxus) and sharks (Centrophorus squamosus, Deania calcea and D. profundorum) in the Northern (Namibia) Benguela Current region

Abstract

The trophic relationships of two hake species (Merluccius capensis and M. paradoxus) and three shark species (Centrophorus squamosus, Deania calcea and D. profundorum) were investigated using nitrogen and carbon stable isotope signatures (δ15N and δ13C) of their muscle tissues. The sharks were more enriched in 15N than the hake, an indication of the apex predator status of sharks. Among the sharks considered, C. squamosus occupied the highest trophic level and fed primarily on...
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Publisher
Taylor & Francis
Copyright
© 2015 Zoological Society of Southern Africa
ISSN
2224-073X
eISSN
1562-7020
DOI
10.1080/15627020.2015.1079142
Publisher site
See Article on Publisher Site

Abstract

The trophic relationships of two hake species (Merluccius capensis and M. paradoxus) and three shark species (Centrophorus squamosus, Deania calcea and D. profundorum) were investigated using nitrogen and carbon stable isotope signatures (δ15N and δ13C) of their muscle tissues. The sharks were more enriched in 15N than the hake, an indication of the apex predator status of sharks. Among the sharks considered, C. squamosus occupied the highest trophic level and fed primarily on benthic prey. The two species of shark from the genus Deania were not different based on δ15N or δ13C, so they had similar diets. The δ13C signatures indicated that M. capensis and sharks fed on prey derived from similar basal resources. However, there was a significant difference in δ13C between M. paradoxus and all other species examined, suggesting that they occupied different feeding niches. Isotope-based population metrics showed narrower trophic ranges in sharks than M. capensis. Carbon and nitrogen ranges indicated that hake fed on a more diverse pool of carbon sources and had generally more enhanced trophic diversity in their feeding patterns than sharks. Among the species considered, C. squamosus occupied a unique isotopic space. Our results supported the hypothesis there are trophic overlaps among these species, but some interesting differentiation was revealed.

Journal

African Zoology – Taylor & Francis

Published: Oct 2, 2015

Keywords: diet; ecological role; food web; stable isotopes; standard ellipse area; trophic niche; top predators

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