COLLABORATIVE RESEARCH: Penguin Foraging Reveals Phytoplankton Spatial Structure in the Ross Sea

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AbstractThe Ross Sea is believed to contributes a huge portion (~1/3) of the primary productivity of the Southern Ocean and is home to a similar large portion of the top predators (e.g. 38% of Adelie, 28% of Emperor penguins) of the Antarctic sea ice ecosystem. The trophic pathways in this system are complex in both space and time. One scenario for the Ross Sea ecosystem is that diatoms are grazed by krill, which are in turn the preferred food of fish, penguins and other predators. Phaeocystis colonies, on the other hand lead to grazing by pteropods and other organisms that are a non-favoured food source for top predators. Remotely sensed chlorophyll, indicating all phytoplankton, is then suggested to be a relatively poor predictor of penguin foraging efforts. This is also consistent with notion that algal species composition is very important to penguin grazing pressure, mediated by krill, and perhaps resulting in selective depletion. This collaborative research sets out to use an autonomous glider, equipped with a range of sensors, and informed by satellite chlorophyll imagery to be combined with 3-dimenisonal active penguin tracking to their preferred foraging sites. The effect of localized grazing pressure of krill on the appearance and disappearance of algal blooms will also be followed. Overall the objective of the research is to reconcile and explain several years of the study of the foraging habits and strategies of (top predator) penguins at the Cape Crozier site (Ross Island), with the dynamics of krill and their supporting algal food webs. The use of a glider to answer a primarily ecological questions is subject to moderate to high risk, and is potentially transformative.