Preliminary study of the distribution and photophysiology of the temperate phototrophic sponge Cymbastela sp. from South Australia

Abstract

The distribution and photophysiology of two forms of Cymbastela were investigated. One form, which fitted the description of C. notiana, was found in the gulf waters of South Australia. A second form was found on the protected sides of islands along the oceanic coast of Victor Harbor in South Australia. Both forms are rare but when present occur at depths of 5-15 m in association with foliaceous red and brown macroalgae.

A fully automated respirometer was used in situ to investigate the photokinetics of the oceanic form at West Island (SA) during winter (June 1993) and summer (January 1994). Owing to the rarity of this sponge only four samples, three in the winter and one in the summer, were investigated. This form of Cymbastela was capable of photosynthetically compensating on a net 24-h basis at 4.5 m depth in the winter, whereas it was a net producer at that depth during the summer. Photokinetic measurements were used to model the phototrophic production of this sponge. This model predicts that sponges would generally compensate at a depth of 11 m in winter. These results are tentative, however, because sample sizes are small owing to the rarity of this species.