Lift HISTORY STUDIES ON THE RED SEA SOFT CORAL XENIA MACROSPICULATA GOHAR, 1940. I. ANNUAL DYNAMICS

ABsTR@cr Xenia macrospiculataGohar, 1940is a dominant xeniid species on the coral reefs of the Gulf of Eilat. The colonies are dioecious and the gonads develop along the four lateral and two sulcal mesenteries, except for the anthocodial part ofthe polyps. The population starts to reproduce at a markedly early age of two years and the percentage of sexually mature colonies increases with coral size. The sex ratio of the population is significantly skewed toward a higher abundance of males. A synchronization of gonadal development occurs among the polyps within a colony. In every annual cycle the development of initial gonadal primordiastartsin September or October and it lasts until April-May. In addition to these gonads, more oocytes and sperm sacs continue to appear along the mesenteries of male and female colonies during the succeeding 7-8 months. Due to the prolonged period of gonadal initiation, the population contains colonies in various stages of development. The successivematuration of gametesstarts everyannual cyclein May and lasts for 4—5 months. During this time polyp cavities become filled with an unusual compact arrangement of various sizesof oocytes or sperm sacs. The early age of first reproduction combined with the prolongedgametogenic season increasethe reproductivepotential of X. macrospiculataand contribute to its high abundance at the studied reefs.