The missing link : pelagic prey field prediction for Southern Ocean predators

• Main Author: Green, DB
• Format: Thesis
• Language: English
• Published: 2022
• Subjects: mid-trophic prey fields; marine predators; ecosystem modelling; micronekton; Antarctic krill; spatial ecology; foraging ecology; population modelling; Antarctic; Southern Ocean; Antarc*; Antarctic Krill; Elephant Seal; Elephant Seals; Eudyptes chrysolophus; Macaroni penguin; Mirounga leonina; Southern Elephant Seal
• Online Access: https://eprints.utas.edu.au/47576/; https://eprints.utas.edu.au/47576/1/Green_whole_thesis.pdf

Bottom-up processes affecting the availability of prey play a fundamental role in driving the distribution of higher marine predators. Yet, adequate representation of environment – prey – predator linkages remains a major barrier to understanding marine predator responses to environmental change. A key limitation is the difficulty in obtaining synoptic prey observations at spatial and temporal scales relevant to foraging predators because the micronekton groups that dominate the prey of diving/higher predators are notoriously difficult to observe and sample. Simulated prey fields, derived from environmentally forced models are an emerging alternative approach for representing biomass and spatial dynamics of hard-to-observe mid-trophic prey. One such model, SEAPODYM (Spatial Ecosystem and Population Dynamics Model), has been used to skilfully represent the spatial dynamics and biomass of marine biota at multiple trophic levels. My thesis considers SEAPODYM’s utility in filling the mid-trophic prey gap between marine predators and the biophysical environment in the rapidly changing Southern Ocean. I first explored the relationship between modelled estimates of mid-trophic biomass derived from SEAPODYMand foraging distribution, behaviour and success of two cosmopolitan Southern Ocean predators, the southern elephant seal (Mirounga leonina) and macaroni penguin (Eudyptes chrysolophus). I compared model-derived mid-trophic prey metrics with the spatial distribution of tracked elephant seals to identify important seal habitat. Next, I considered whether interannual variability in modelled prey biomass could be related to predator foraging success, as indicated by average arrival mass of macaroni penguins at the onset of breeding. Results from these studies indicated SEAPODYM’s spatially explicit prey field estimates could provide useful insights into both predator foraging behaviour and success, highlighting potential for their use in identifying current foraging behaviour and forecasting the impacts of climate-driven ...