Antarctic Zooplankton and fish - fast food or fine dining?

Understanding the flux and flow of energy through a food web is vital when estimating the capacity of marine ecosystems to support important living resources. One such resource is Antarctic krill, which is considered to be one of the last under-exploited fishing stocks, globally. However, the Southern Ocean is undergoing rapid environmental change and to accurately predict the effects of climate change or increased fishing pressure on these ecosystems, we need a quantitative and comprehensive understanding of how energy flows through these food webs (Van de Putte, 2006, Schaafsma et al. 2018). To achieve this, quantifying the energy content of species is crucial. At an individual level, energy reserves of an organism affect life history strategies such as over-wintering behaviours and reproduction. At an ecosystem level, energy density can structure food webs and ecosystem functioning. This PhD project will measure energy content and proximate composition (e.g., lipids) of species from Sub-Antarctic and Antarctic waters from the extensive archived collection of frozen zooplankton and fish species held at BAS. Inter and intra-annual variation will be investigated alongside environmental factors that may drive variability. Literature information on physiology, diet, and population size will be used to develop bioenergetic models of predators and their prey (e.g., Pirotta et al. 2022). These models will improve our estimates of prey consumption rates for specific higher predator species, and hence our ability to predict changes in the capacity of Antarctic ecosystems to support key marine resources. This project will use biochemical methods to quantify the energy flux through the Southern Ocean food web and improve understanding of the capacity of marine ecosystems to support living resources.