CELLULAR AND ULTRASTRUCTURAL-CHANGES IN THE ENDODERM OF THE TEMPERATESEA-ANEMONE ANEMONIA-VIRIDIS AS A RESULT OF INCREASED TEMPERATURE

Exposure of the temperate sea anemone Anemonia viridis Forskal to incr eased seawater temperature (from 16 to 26-degrees-C) reduced the lysos omal latency of coelenterate tissues. Lysosomes in the mesenterial fil aments of anemones were destabilised by increased temperature, with gr eater destabilisation in heat-shocked symbiotic anemones than in heat- shocked aposymbiotic anemones in the early stages of the experiment. L ysosomal enzyme activity in zooxanthellae from heat-shocked symbiotic anemones was associated with the algal membranes and the cytoplasm of degenerate algal cells. While the relationship between host coelentera te and symbiotic alga may confer many benefits under ''normal'' condit ions, comparison of the responses of symbiotic and aposymbiotic anemon es to heat shock suggests that there may be disadvantages for symbioti c anemones under stress.