Biophysical coupling structuring the larval and juvenile fish community of the Ross Sea continental shelf: a multidisciplinary approach

In high-latitude shelf areas like the Ross Sea, the overwhelming dominance by the single taxonomic group of notothenioids is unparalleled in the fish fauna of any other marine ecosystem. Differently from adult stages which are generally benthic or benthopelagic, the early life stages of all notothenioids are pelagic and subject to oceanic transport, with this process largely influencing individual species distribution and biogeography.

As major consumers of microzooplankton and prey of several middle and top predators such as fish, penguins and seals, the early life stages of fish represent a key component in the food chain of the marine ecosystem. As a consequence, any change occurring at early life stages may cause a negative cascading effect on several trophic levels, also because larvae and juveniles are known to be among the most sensitive life stages to changes in environmental parameters, such as temperature.

After the recent establishment of a Marine Protected Area (MPA) in the Ross Sea, aiming to preserve one of the widest and pristine area in the world, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) promoted a long-term monitoring program to regularly assess the effectiveness of management actions, like the maintenance of species biodiversity and unaltered food web. Among the priorities for scientific research and monitoring plan, it was clearly stated to propose studies aimed at addressing biological and ecological questions related to species demography and life history.

In this proposal we aim at acquiring a better knowledge of the biosphere-hydrosphere interaction, investigating the biophysical coupling in structuring the larval notothenioid fish community in the Ross Sea. Adopting a multidisciplinary approach, including analyses of early life history traits, molecular ecology, otolith microchemistry, Lagrangian modelling, and oceanography, we will attempt to accomplish the following objectives: i) characterization of the larval and juvenile fish assemblage of the Ross Sea in terms of species diversity, morphology, life history traits (i.e. size, timing and location of hatching and nursery areas, pelagic larval duration, etc.), age distribution, growth rate and genetic variability, and ii) assessment of the biological-physical interactions structuring the larval and juvenile fish community in terms of environmental variables and genetic and oceanographic connectivity, aiming also to identify the relative contribution of spawning/hatching areas to nursery grounds.