Examining the response of top marine predators to ecological change using stable isotope proxies
Abstract
Monitoring the response of upper trophic level animals to ecological change is important
to understanding the state and stability of ecosystems. Marine predators
integrate information over large geographical scales and are relatively long-lived; furthermore,
many of these organisms are restricted to terrestrial or freshwater habitats
at certain times during their life history and are accessible to researchers. This thesis
investigated the response of marine predators to ecological change at a variety
of spatial and temporal scales using stable isotope ratio methods with the aims of
developing meaningful proxies, or indices, of variability in marine ecosystems.
The first study explored the intrinsic (i.e. ontogenetic) and extrinsic (i.e. environmental)
factors important to modulating variation in the stable isotope ratios of
C and N in tooth dentin of male Antarctic fur seals (Arctocephalus gazella) in the
Southern Ocean. In the second study, long-term records of variation in δ¹⁵N and δ¹³C values of Atlantic salmon (Salmo salar) scales and grey seal (Halichoerus grypus)
tooth dentin provided evidence for large-scale climate forcing across the eastern
North Atlantic. In the following study, a more detailed examination of intra- and
inter-individual stable isotope variation in Atlantic salmon within a single year was
undertaken in an attempt to better understand recent declines in somatic condition
of these fish.
The last two studies were concerned with the development of high resolution sampling
of fish otoliths using secondary mass spectrometry (SIMS) and the application
of this technique to reconstructing the thermal and metabolic histories of individual
Atlantic salmon from intra-otolith δ¹³C and δ¹⁸O values.
Stable isotope proxies can be used to document shifts in trophic dynamics and
animal movement that may be associated with ecological change. Using multiple
tissues, elements and species, such studies provide unique monitoring tools at a
range of spatial and temporal scales.
Type
Thesis, PhD Doctor of Philosophy
Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.