Density distribution of krill larvae during summer seasons 2011, 2012 and 2014 in the atlantic sector of the Antarctic

ROMBOLA E; FRANZOSI C.A.; TOSSONOTT G; ALDER V.A.; MARSCHOF E

St. Andrews

Simposio; 3rd International Symposium on krill; 2017

ARK/CCAMLR

During the summer seasons of 2011, 2012 and 2014 the density of euphausiid larvae in the Atlantic sector of the Antarctic experienced large variability. In 2011 and 2012 T. macrura was the dominant species, being in 2011 more abundant than 90% that E. superba and E. frigida. Furciliae stages of T. macrura were more abundant, while E. superba and E. frigida were present mainly as Calyptopes I (~14 ind. m-2). During 2012 only 72% of the samples had larvae, E. superba and E frigida had a frequency of occurrence of 34% and 22% respectively, mainly calyptopis stages with densities lower than 100 ind/m2. In 2014, and densities of E superba were higher (more than 3000 ind/m2).The densities of E. superba were lower and their spatial distribution more restricted in comparison with historical data reported in similar dates. In 2014 the situation was widely different: E. superba densities were similar to historical data, with high values in the Marine Protected Area, T. macrura and E. frigida densities were similar to 2011 and 2014. These variations cannot be directly related with changes in the oceanographic conditions, suggesting the need of further research to clarify the mechanics of the coupling of biological and oceanographic phenomena implied in the reproduction and recruitment of euphausiids. The interanual study of the larval stages of krill could explain posible causes of the observed tendencies relating recruitment, predators needs and fisheries management.