Distribution and growth of larval and adult Thysanoessa macrura (Euphausiacea) in the Bransfield Strait region, Antarctica

Abstract

Thysanoessa macrura was the most common euphausiid in the W Bransfield Strait region, with highest abundances of 5000 individuals per 1000 m3 in Gerlache Strait in December 1986 and 4500 ind. 1000 m-3 in January 1987, which coincided temporally and spatially with the annual spring bloom of phytoplankton. With the progression of the austral summer, high larval abundances extended into Bransfield Strait. A discrete spawning period prior to December 1986 gave rise to a distinct cohort which persisted through March 1987. The study area was highly variable in phytoplankton biomass. Waters of northern Gerlache Strait reached 25 mg chl a m-3 in January 1987, whereas Drake Passage always had <2.0 mg chl a m-3 from December 1986 to March 1987. No differences in development or growth rate were found in regions with different levels of algal biomass. -from Author