Insights into spatial distribution patterns of early stages of the Antarctic silverfish, Pleuragramma antarctica, in the platelet ice of Terra Nova Bay, Antarctica

The Antarctic silverfish, Pleuragramma antarctica, is ecologically important for connecting lower and upper trophic levels within the coastal marine Antarctic food web. In recent decades, populations of silverfish have exhibited a declining trend in some regions of the Antarctic, in particular the western Antarctic Peninsula. It is of paramount importance to elucidate its life history and to characterize the areas that are crucial for the reproduction of the species: spawning, hatching and nursery areas. Presently, the overall available knowledge is scant and spatially restricted. In this study, we assessed the spatial scales of variation in the distribution patterns of eggs and newly hatched larvae, and their vertical distribution within the platelet ice layer underlying fast ice at Terra Nova Bay. We found that (1) distribution patterns of eggs and larvae abundance significantly changed at a spatial scale of kilometers, while they did not at scale of tens of kilometers and hundreds/tens meters, and (2) eggs were not homogeneously distributed under the solid ice; in particular, the egg abundance was highest at -2.5 m within the platelet ice and dramatically declined more in depth. This study thus allowed shed light on distribution patterns of eggs and early-hatched larvae of the Antarctic silverfish. Such information will be useful to better understand the ecological processes possibly producing the patterns we have observed and then identify further reproduction and nursery areas around the Antarctic continent.