Habitat Shifts by Decapods—an Example of Connectivity Across Tropical Coastal Ecosystems

Abstract

Decapod life cycles are complex and many utilize a range of habitats throughout their development. Many species tend to settle on shallow (often vegetated) inshore habitats and commonly move offshore into deeper water as they grow. The species that exhibit an inshore/offshore life history are often large individuals and may support commercial fisheries. In this chapter the habitats of a range of tropical decapods are described and likely mechanisms underlying habitat shifts are discussed. It is generally accepted that in most animals these mechanisms are aligned with maximizing the animal’s fitness. Possible mechanisms include minimizing mortality risk (μ), maximizing absolute growth rates (g), or a trade-off in which the animal chooses the habitat that minimizes the ratio of mortality risk to growth rate (minimize μ/g). There do not appear to be any studies that address these issues for tropical decapods and this is identified as an important topic for future research. Similarly, studies that have explicitly demonstrated habitat shifts in tropical decapods are rare; most shifts have been implied by comparing length frequencies in different habitats and it is recommended that future studies consider the use of natural and artificial tags to assist in more accurate characterization of connectivity between coastal habitats.