The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Movement patterns in pelagic sharks: stable isotope evidence

Currently Active: 
Yes

Pelagic marine predators' abundance has drop by > 90% in the last 25 years due to overfishing and by catch. Conserving the remaining populations requires a thorough understanding of their spatial ecology. Migratory predators' movements however are difficult to reconstruct. Despite recent advances, electronic tags are expensive and only a few large individuals can be studied. Stable Isotope Analysis (SIA) allows reconstructing movements indirectly, but currently requires a better understanding of the isotopic variability in marine environments.

Project Overview

Intra-annual variability
Intra-annual variability

Background

Static isoscape methods involve measuring baseline isotope values at known locations and interpolating between points, and assume negligible temporal variation. Regression-based methods identify and use the relationships between tissue isotopes and environmental variables to build predictive isoscapes.

Alternatively, geolocation can be achieved without using isoscapes: areas of highest correlation between contemporary time series of tissue isotopes and environmental variables are the most likely locations of isotopic assimilation.

 

 

 

 

CO2 Model
CO2 Model

Aims and Methodology

1) Implement existing models predicting spatio-temporal variation in POM isotope values:

coupling physiological measures of stable isotope fractionation by phytoplankton into global biogeochemical models (e.g. NEMO)

2) Use these models to reconstruct movement patterns in pelagic, highly migratory sharks:

Sampling of essential amino acids in shark skin, muscle and blood;

Coupling models of tissue turnover time into global biogeochemical models;

Testing inferred movement patterns using smart-tagged sharks.

Global Biogeochemical Models

Marine isotopic gradients are extremely dynamic compared to terrestrial ones, complicating the interpretation of stable isotopes. Global biogeochemical models predict likely isotope values in carbon-containing components ([CO2aq], DIC and POM) based on SST, [CO2aq] and phytoplankton growth rates. Despite being still insufficiently accurate to predict actual isotope values, these models provide tools to explore temporal stability of spatial isotopic gradients, and thus to assess the feasibility of using SIA for geolocation in specific marine systems.

Key Contacts

Miss Sarah Magozzi (Postgraduate Research Student)

Dr Clive Trueman (Supervisor)

Dr Kirsteen MacKenzie (Supervisor)

Dr Andrew Yool (Supervisor)

Dr Ken Collins (Supervisor)

Related Projects

 http://www.nemo-ocean.eu

PhDs and Other Opportunities

Visit GSNOCS

Associated research themes

Geochemical Ecology

Related research groups

Geochemistry

Staff

Share this research project Facebook Google+ Twitter Weibo

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.

×