Contributions of larval biology to crustacean research: a review

Many aquatic crustaceans pass through a complex life cycle comprising a benthic juvenile-adult and a pelagic larval phase. In the study of aquatic ecology, meroplanktonic larvae are therefore considered as principal components of benthic-pelagic coupling processes. As a consequence of radical transitions of life style, larvae differ from conspecific adults in their ecology, behaviour, nutrition, morphology, and physiology. Ontogenetic changes of these traits, as well as carry-over effects of larval condition on postmetamorphic fitness of benthic juveniles, are subjects of the interdisciplinary field of larval biology. Larval biology is thus not only an intrinsic part of lifehistory studies, but contributes essential information also to various other biological disciplines, including the broad area of crustacean research. For economically important species, it provides critical information for the development of aquaculture techniques or for the management of sustainable fisheries. Inferring from heritable ontogenetic patterns, comparative studies of larval morphology also aid the identification of phylogenetic relationships within and among higher taxa (“Evo-Devo” perspective). On the other hand, larval traits may be modified by environmental factors, which link larval ecology to developmental biology (“Eco-Devo” approach). Patterns of larval dispersal, mortality, and recruitment are crucial for the stability of benthic populations and communities. These aspects of “supply-side ecology” have also consequences for patterns of biogeographic distribution, population connectivity, genetic diversity, and the formation of metapopulations. In addition, the spread of introduced species in recipient regions may be explained or predicted through developmental and ecophysiological traits of their larvae. In evolutionary biology, knowledge of reproductive and developmental adaptations is crucial for the understanding of limnic and terrestrial invasions by originally marine crustaceans.