The Roles of Chemical Cues in the Life Cycle of Bivalves: Spawning, Settlement, and Metamorphosis

Spawning, settlement, and metamorphosis represent the most challenging events for hatchery bivalve production. To enhance bivalve aquaculture, hatcheries have relied on a range of chemical compounds to induce these biological processes. Yet, despite the apparent importance of chemical cues, there is little knowledge on chemosensory systems and the role of chemical communication in bivalves. This review aims to compile the existing knowledge of the chemicals used in hatcheries to induce spawning and to improve settlement and metamorphosis in some economically important bivalves. A lack of recent studies regarding this topic has resulted in stagnation in the development of new approaches and products for use in aquaculture. This review explores the natural chemical cues and how they act in the natural environment, and the efforts made by hatcheries, through the use of synthetic inducers, to optimize bivalve production and overcome the challenges associated with spawning, settlement, and metamorphosis. Furthermore, it discusses the current knowledge on the chemical nature of spawning-inducing pheromones. The synthesis of synthetic pheromones for spawning, settlement, and metamorphosis induction may improve bivalve aquaculture and efficiency. Nevertheless, more research is needed to fully understand the chemical communication and chemosensory systems of bivalves.