Sea Urchin Ecology and Biology

This chapter discusses some of the ecological factors that affect sea urchin abundance, distribution, and vulnerability to overfishing. It then briefs about some of the biological and physiological considerations of interest to sea urchin aquaculturists, such as feeding, growth, reproductive control, and physiological adaptations relevant to intensive culture. Most sea urchins are broadcast spawners, releasing eggs and sperm into the water column where fertilization takes place, followed by development into a pelagic pluteus larval stage. Environmental cues such as day length and temperature initiate gametogenesis, and spawning is triggered by environmental cues and pheromones to coordinate gamete release. The reproductive success of broadcast spawning invertebrates has been likened to a "recruitment sweepstakes". Variability in ocean conditions and high mortality rates of larvae and newly settled juveniles mean that random events can affect the reproductive success of spawning adults during each season.