Seasonal, lunar, and diel patterns in spawning by the giant barrel sponge, Xestospongia muta

Abstract

Temporal patterns in giant barrel sponge (Xestospongia muta) spawning were compiled from 32 observations spanning 17 years and three Caribbean locations (Florida, Belize, and Haiti). The records were analyzed for patterns in seasonality, lunar periodicity, and diel rhythm to develop a predictive spawning window. Results indicate that spawning is concentrated from mid-April to late May. Most spawning events occurred around the first quarter moon; a smaller pulse occurred just before the third quarter moon. All spawning events were observed in the morning and fell within 779–987 min of the previous night’s sunset. Eggs of X. muta were all negatively buoyant and blanketed the areas within and surrounding the sponge; this limited gamete dispersal may be the driver behind heavily localized genetic retention.