VARIATIONS IN THE REPRODUCTIVE-CYCLE OF ACROCNIDA-BRACHIATA (ECHINODERMATA, OPHIUROIDEA) ACCORDING TO ENVIRONMENT IN THE BAY OF DOUARNENEZ (BRITTANY)

The annual reproductive and somatic cycles of the brittlestar Acrocnida brachiata are described using gonad and gut indices for intertidal and subtidal populations in the Bay of Douarnenez, France. Oocyte size frequency diagrams complement the gonad study in the subtidal population. Clearly marked reproductive cycles are defined in both populations. Accelerated gonad growth takes place in spring and the gonads reach the peak of development in May-June each year. Spawning is completed by the end of August. Oocytes reach a mean diameter of 150 μm and a new generation of oocytes appaears in the ovaries during the spawning period. The gut indices show a clear inverse relationship with the gonad indices in the intertidal population, but this relation is not well revealed in the subtidal population. © 1990, Marine Biological Association of the United Kingdom. All rights reserved.