Euphausiid larvae from Terre Adélie

The distribution of euphausiid larvae along the coast of Terre Adélie, Antarctica, was assessed using oblique tows of a double-framed bongo net during summers from 2004 to 2009. Larvae of Euphausia crystallorophias and Thysanoessa macrura were observed. For E. crystallorophias larvae, the calyptopis I
stage was dominant along the coast, while the most commonly observed stage of T. macrura was the furcilia. In summer 2004, the distribution of E. crystallorophias larvae were correlated with abiotic factors, including depth and sea surface salinity, whereas those of T. macrura larvae were correlated with biotic factors, especially chlorophyll a and nitrate. Moreover, developmental stages of both species increased in age from west to east in the survey area, with younger developmental stages (metanauplius and calyptopis I) in the western part of the region and older stages (calyptopis II and III and furcilia I to VI) in the eastern part near the Mertz Glacier Tongue (MGT). It is suggested that these patterns could be linked with the water circulation and wind: near the MGT gyres could concentrate all developmental stages of both species near the coast, while katabatic winds near Dumont d’Urville will promote larval advection seawards, with younger stages near the coast and older stages further offshore.