Penguins as Indicators of Climate Anomalies in the Southern Ocean – PICASO

The Southern Ocean plays a key role in the world climate, supports some of the most productive ecosystems, and has the most important seabird communities on Earth. The impact of climate variability on these marine ecosystems is, however, still poorly understood. But a sharp decrease in most seabird populations, coincidental with a drop in secondary production of Antarctic waters, suggests a major shift in population dynamics is underway. Still, due to the huge size of the Southern Ocean, its inaccessibility and frequent harsh sea conditions, classic oceanographic methods cannot be used routinely. Yet, Southern Ocean food chains are short, and the effect of climate on primary production is quickly transferred to top predators such as seabirds, which explains the growing interest in using them as indicators through their breeding success and survival. In particular, compared to other seabirds penguins are certainly more accessible at the population level and their study has been entirely revolutionized using new automatic identification (and weighing) technologies based on RFID (Radio Frequency IDentification), for which they are ideal organisms because they are flightless. Together with our partners, we already have a growing data set of about 10 000 penguins, for which age, breeding history and survival are known. Three species are involved, i.e. Adélie, king and little penguins. They live and breed in some of the major ecosystems of the Southern Ocean, i.e. benthic, pelagic and sea-ice environments off southern Australia, sub-antarctic islands and Antarctica, respectively. Their prey varies from krill to squid and fish. In this context, the development of biologging has opened huge prospects in enabling the investigation of the performances and strategies of penguins feeding at sea. Indeed, the ultraminiaturized GPS and recorders with which they are equipped allow the 3D analysis of their foraging trips at sea at the sub-meso scale, with sea temperature being also monitored. And yet, since penguins are expected to search and feed upon the most productive sea water columns, our consortium also involves oceanographers that are at the forefront of research on the climate variability in the Southern Ocean and/or relationship between climate and primary production. Moreover, we will use methods based on isotope-ratios in body tissues, which provide complementary information on the structure and dynamics of the trophic chains in the penguin ecosystems. Altogether, our data sets suggest that the impact of climate variability differs amongst individual birds. Their individual history might indeed shape their probability for survival and breeding success, an assumption largely supported by recent studies. In this context, our data set is quite unique in providing us access to the history of individual penguins at a huge population scale. Moreover, while variability in individual fitness is often quoted but rarely investigated, another feature of our project is that we will also investigate the immune quality, response to oxygen radicals and aging in birds of known history, in order to assess the variation in their response to climate variability. In addition, a true innovation in this project is the use of a remote controlled robot with RFID antennas to study the distribution of birds of known age and history within a colony. For the first time, this will enable us to study how a penguin colony is structured in relation to climate-induced changes in resources at sea. Finally, using a multidisciplinary and integrative approach, this project will enable us to develop global mathematical models for a better understanding of the link existing between environmental modifications and the trajectories of these populations. This will allow us to predict how the biological component of the austral ecosystems will adapt to future climate changes.