Regional Variation in Marine Mammal Diet Determined Using Highly Branched Isoprenoid (HBI) Diatom Biomarkers

Charlotte Alexander

MRes – September 2013

School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth, U.K.

By September 2008, the Arctic sea had experienced two sequential years of extreme summer minimum sea ice coverage. Variations in Arctic sea ice thickness and extent can have a significant impact on the biological communities that live in the Arctic.

As a main primary producer for ice covered oceans, ice-associated algae provide an important contribution to marine Arctic ecosystems. Through the production of lipids, such as HBIs, they provide the energy required for reproduction and growth of many marine organisms, and the timing and quality of the production of these lipids can be responsible for defining the structure of biological communities here.

Here the presence of certain source specific HBIs within regional Arctic food webs was analysed to investigate the ability of these lipids to provide information on the feeding behaviour of important Arctic species.

A total of 559 ringed seal samples were analysed, of which 558 were found to contain at least some of the seven commonly occurring HBIs. The presence and abundance of the HBIs are found to vary in accordance with sampling year and sampling month which may be a reflection of environmental conditions and specific algal growth requirements. Variations in HBI presence and abundance were also identified in accordance with a number of biometric characteristics. Of particular significance was the effect of the 2007 sea ice minimum which was found to have a selective impact on HBI presence and abundance between seal gender, seal age and seal weight.

The new results obtained in this study have extended the previous known presence of HBIs to all ringed seals analysed, presenting the potential use of HBIs as a form of biomarker throughout Arctic ringed seal communities at least.

Copyright 2013 C. Alexander. All rights reserved.

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