Seasonal changes in the metabolism of the calcareous sponge Clathrina clathrus (schmidt)

1. 1. Seasonal variations in the metabolism of the calcareous sponge Clathrina clathrus from the Mediterranean, have been studied for a 27 month period by measuring the oxygen consumption of cell suspensions and by determining protein, sugar, lipid and carotenoid content. 2. 2. Proteins and sugars rise from winter to spring and remain high in summer and autumn, carotenoids are significantly higher in the cold season, lipids show no year variation. 3. 3. The oxygen consumption shows a sharp peak in summer, being otherwise rather constant. 4. 4. Relatively lower Q₁₀ values can be detected in sponges experiencing decreasing seawater temperatures (from September to March). 5. 5. Results suggest the existence in C. clathrus of a year cycle with a hypo-activity period in winter. 6. 6. Biochemical variations seem to be related both to changes in seasonal feeding and to metabolic/ physiological responses caused by cyclic climatic events. 7. 7. However, seasonal variations are low, indicating a certain tendency to maintain biochemical homeostasis.