Reproductive Strategies of Antarctic Ascidians

SAHADE R; BOTTA, VANINA; TATIÁN, M

Nápoles

Congreso; 7th Tunicate Meeting.; 2013

Primary production pulses and temperature have been signed among the most important factors in determine reproduction traits in Antarctic benthic fauna. It has also been suggested that different development strategies would determine reproductive cycles in benthic organisms. This study focus on whether reproduction of Antarctic ascidians is continuous, as to be expected from the lecithotrophic nature of larvae or if it is limited to the summer, as to be expected from the distinct seasonality in primary production. Five species, Ascidia challengeri, Cnemidocarpa verrucosa, Corella eumyota, Molgula pedunculata and Pyura setosa were sampled over 15 months. The reproductive cycles were examined by histological analysis of the gonads. Reproduction of these suspension feeders seems to be decoupled from the pulses of primary production, except for P. setosa which showed their reproductive peaks coincident with chlorophyll-a pulses. Although reproduction in A. challengeri and C. eumyota did not show a significant relation to chlorophyll-a levels the vitellogenesis in these species took place during the austral summer. C. verrucosa and M. pedunculata reproduced during winter showing a marked vitellogenic period previous to spawning. These results were striking because these are phylogenetically close organisms and living under the same environmental pressures. Also because reproduction during the Antarctic winter could appears as energetically disadvantageous especially for filter feeders. Whether these reproductive strategies are phyllogenetically fixed traits for these species or local ecological adaptations is still an open question. Energetic implications of these cycles as well as their possible relation to small-scale distribution patterns are discussed.