The University of Southampton
University of Southampton Institutional Repository

The tropho-spatial ecology of deep-sea sharks and chimaeras from a stable isotope perspective

The tropho-spatial ecology of deep-sea sharks and chimaeras from a stable isotope perspective
The tropho-spatial ecology of deep-sea sharks and chimaeras from a stable isotope perspective
Chondrichthyans (sharks, rays and chimaera) are one of the most speciose groups of higher order predators on the planet and are often cited as playing an important functional role in many ecosystems. However, most studies to date have focused on oceanic and shelf habitats, and there is limited information on the ecological role that chondrichthyans play in the deep-sea. This research aims to examine the trophic and spatial ecology of deep-sea chondrichthyans using stable isotope analysis. Stable isotopes of carbon and nitrogen vary among different trophic levels and between spatially separated areas, and therefore provide a potential tool for uncovering some ecological characteristics of deep-water chondrichthyans.

In this study, I found that on a global scale, oceanic sharks appear to transfer nutrients over large spatial scales, whereas sharks found in shelf habitats couple ecologically varied food webs close to their capture location. Although global data is limited for deep-sea sharks, in the northeast Atlantic it appears that sharks found on seamounts are more tightly coupled to pelagic production than their counterparts on the continental slopes. Continental slope habitats may provide access to more isotopic niches, where sharks integrate nutrients from benthic and pelagic nutrient pathways. On the other hand, chimaeras appear to fill a unique role feeding on benthic prey items that are inaccessible to other fishes (e.g hard shelled benthic animals). Depth gradients in nutrient availability are reflected in the bathymetric distribution patterns of chondrichthyan families, with depth segregations likely reducing interspecific competition for resources. For some of the largest shark species in this ecosystem, such as Portuguese dogfish (Centroscymnus coelolepis) and leafscale gulper shark (Centrophorus squamosus), whole life-history ecology was recovered from sequential analysis of eye lens proteins. Both these species appear to undertake relatively consistent latitudinal migrations linked with ontogeny and reproductive development.

This study reveals the ecological characteristic of diverse deep-sea chondrichthyan assemblages, and how trophic and spatial behaviours facilitate the transfer of nutrients in these ecosystems. Subsequently, chondrichthyans likely play an important role in deep-sea ecosystems and should be managed appropriately within fisheries.
University of Southampton
Bird, Christopher Stephen
f442dbea-c334-4b93-9cb7-1f00e731f146
Bird, Christopher Stephen
f442dbea-c334-4b93-9cb7-1f00e731f146
Trueman, Clive
d00d3bd6-a47b-4d47-89ae-841c3d506205

Bird, Christopher Stephen (2017) The tropho-spatial ecology of deep-sea sharks and chimaeras from a stable isotope perspective. University of Southampton, Doctoral Thesis, 163pp.

Record type: Thesis (Doctoral)

Abstract

Chondrichthyans (sharks, rays and chimaera) are one of the most speciose groups of higher order predators on the planet and are often cited as playing an important functional role in many ecosystems. However, most studies to date have focused on oceanic and shelf habitats, and there is limited information on the ecological role that chondrichthyans play in the deep-sea. This research aims to examine the trophic and spatial ecology of deep-sea chondrichthyans using stable isotope analysis. Stable isotopes of carbon and nitrogen vary among different trophic levels and between spatially separated areas, and therefore provide a potential tool for uncovering some ecological characteristics of deep-water chondrichthyans.

In this study, I found that on a global scale, oceanic sharks appear to transfer nutrients over large spatial scales, whereas sharks found in shelf habitats couple ecologically varied food webs close to their capture location. Although global data is limited for deep-sea sharks, in the northeast Atlantic it appears that sharks found on seamounts are more tightly coupled to pelagic production than their counterparts on the continental slopes. Continental slope habitats may provide access to more isotopic niches, where sharks integrate nutrients from benthic and pelagic nutrient pathways. On the other hand, chimaeras appear to fill a unique role feeding on benthic prey items that are inaccessible to other fishes (e.g hard shelled benthic animals). Depth gradients in nutrient availability are reflected in the bathymetric distribution patterns of chondrichthyan families, with depth segregations likely reducing interspecific competition for resources. For some of the largest shark species in this ecosystem, such as Portuguese dogfish (Centroscymnus coelolepis) and leafscale gulper shark (Centrophorus squamosus), whole life-history ecology was recovered from sequential analysis of eye lens proteins. Both these species appear to undertake relatively consistent latitudinal migrations linked with ontogeny and reproductive development.

This study reveals the ecological characteristic of diverse deep-sea chondrichthyan assemblages, and how trophic and spatial behaviours facilitate the transfer of nutrients in these ecosystems. Subsequently, chondrichthyans likely play an important role in deep-sea ecosystems and should be managed appropriately within fisheries.

Text
Bird, Chris_PhD_Thesis_Nov_17 - Author's Original
Available under License University of Southampton Thesis Licence.
Download (20MB)

More information

Published date: 20 November 2017

Identifiers

Local EPrints ID: 416886
URI: https://eprints.soton.ac.uk/id/eprint/416886
PURE UUID: bdaa2d67-7389-4342-bb71-67cd26e3a631

Catalogue record

Date deposited: 12 Jan 2018 17:30
Last modified: 14 Mar 2019 05:20

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×