Reproductive adaptations of Antarctic benthic invertebrates

The majority of Antarctic benthic invertebrates so far studied do not produce pelagic larvae, but develop non-pelagically by means of egg capsules, brooding or viviparity. The predominance of protected development in the Antarctic benthos is primarily due to the short period of summer phytoplankton abundance and the low sea temperature. Such conditions make it difficult for a larva to complete pelagic development before food becomes scarce in the surface waters. Prosobranch gastropods illustrate some important aspects of Antarctic benthic invertebrate reproduction. Species which develop non-pelagically have an aseasonal or prolonged spawning period. They produce a small number of large yolky eggs which remain in the benthos and develop slowly, giving rise to large, fully competent juveniles. Conversely, one species with free development has a short, synchronous spawning period during early summer, producing larvae which can benefit from the phytoplankton bloom. Protected development by means of brooding will limit dispersion, but transport on floating algae and by anchor ice may partially compensate for this in the Antarctic.