Prey-mediAted environmental effects on marine Predators: EXplaining ecological responses from individual to population scales – APEX

To counteract the difficulty of observing the marine environment, I will develop an innovative prey survey method using a sailing drone equipped with an echosounder, providing for the first time a continuous index of prey biomass and spatial distribution at a fine spatio-temporal resolution throughout multiple seabird breeding seasons. The use of a drone rather than more classical oceanographic survey will allow a continuous monitoring of the prey (and oceanographic conditions) along the entire breeding seasons (~6 months), which is evidently impossible for oceanographic survey due to financial costs and human ressources. Further the small size of the drone will enable us to monitor very coastal and shallow areas, which have been shown to be important for little penguins.
Simultaneously, we will pursue the long-term monitoring of little penguins. This relies on a combination of a manual monitoring of reproduction (nest occupancy, number of chicks, etc.) and the automated detection and weighing monitoring situated on penguin paths between the colony and the sea. This automated system allows the estimation of foraging trip duration as well as the amount of mass gained during these trips (presently more than 50,000 trips recorded over the last 20 years). Finally, the use of loggers also gives us information on where penguins forage and at which depth, as well as the energy they spend wile foraging. Energy expenditure will be derived from accelerometry after a step of calibration of accelerometry using doubly labelled water.
Using both surveys, prey accessibility will be defined as the proportion of prey situated within the foraging volume of penguins (estimated through biologging data). The effect of accessibility but also aggregation indices etc. on penguin life-history traits (foraging efficiency, breeding success, chick growth, etc.) will then be investigated.

soon to come

APEX is an interdisciplinary project providing key methodological, empirical and theoretical advances in ecology. The development of an automated monitoring system of prey using a sailing drone (coupled with a detailed seabird monitoring) will serve as a proof of concept for other marine ecosystems. This project follows the need of a better monitoring of marine ecosystems urged by the Decade of the Oceans of the United Nations. It answers Sustainable Development Goals 13 and 14 by increasing our knowledge of the effects of climate change on marine ecosystems, and provides insights into the spatial management of oceans. Finally, APEX will be a unique opportunity of capacity building and science dissemination with the training of students, diffusion of knowledge through movies and informative panels exposed at the extremely frequented visitor center of the Penguin Parade.

soon to come

APEX will assess and unravel the mechanisms underlying climate and abiotic environmental effects on population dynamics in a marine top-predator. Scientists largely agree that climate effects on individuals and populations operate not only directly by modifying individual physiology and behavior, but also indirectly through changes in habitat or food supply. Yet, the difficulty to monitor the oceans resulting in the absence of data on prey, or in a mismatch between the required and available spatio-temporal resolution of these data, makes it hard to comprehensively study prey-predator interactions and their consequences on population dynamics. Here, I propose to develop a holistic approach integrating prey population dynamics within the study of environment-predator relationships in one of the most rapidly changing marine environments on Earth (Bass Strait, Australia), using little penguins as a model system. Theoretical work predicts that seabird life-history traits should respond non-linearly to changes in prey biomass, and key thresholds in prey biomass below which predator populations collapse have previously been identified. Yet, the discrepancy between these thresholds and what is really consumed by seabirds suggests that other processes are at play. In APEX, I will test the hypothesis that the key factor to which predators respond is not prey biomass, but prey accessibility. To do so, I will develop an innovative prey survey method using a sailing drone equipped with an echosounder, providing for the first time a continuous index of prey biomass and spatial distribution at a fine spatio-temporal resolution throughout multiple seabird breeding seasons. Prey accessibility will be defined as the proportion of prey situated within the foraging volume of penguins (estimated through already available biologging data). How prey accessibility constrains penguin foraging energy balance and performance will be studied to identify the underlying mechanisms of prey-predator relationships. To comprehensively integrate these results, I will use multivariate analyses simultaneously investigating: 1) the 3D-abiotic environment (via satellite data and oceanographic models), 2) prey abundance and accessibility to penguins, 3) penguin foraging and 4) penguin life-history traits (unique long-term dataset of life-history traits, >20yrs) enabling the characterization of direct and indirect effects of the environment on a marine top-predator. Finally, to transfer knowledge acquired from the individuals to population level, I will develop a new framework of population models incorporating individual heterogeneity in life-history traits and/or responses to environmental and prey variability.
APEX is an interdisciplinary project providing key methodological, empirical and theoretical advances in ecology. The development of an automated monitoring system of prey using a sailing drone (coupled with a detailed seabird monitoring) will serve as a proof of concept for other marine ecosystems. This project follows the need of a better monitoring of marine ecosystems urged by the Decade of the Oceans of the United Nations. It answers Sustainable Development Goals 13 and 14 by increasing our knowledge of the effects of climate change on marine ecosystems, and provides insights into the spatial management of oceans. Finally, APEX will be a unique opportunity of capacity building and science dissemination with the training of students, diffusion of knowledge through movies and informative panels exposed at the extremely frequented visitor center of the Penguin Parade.