Contrasting larval transport in demersal fish and benthic invertebrates: the roles of behaviour and advective processes in determining spatial pattern

Many benthic invertebrates and demersal fish have planktonic larvae and must therefore balance dispersal to new habitat with the need to settle where survival and growth are possible. We review published studies to determine whether the discontinuity in the literature between these groups represents a real ecological difference. Specifically, we examine the roles of biological and physical processes and the scales at which these processes act in pattern formation in fish and invertebrates. For most of the physical mechanisms that influence larval transport at different scales, we find examples of fish and invertebrate studies that are important at each scale. A comparison of planktonic durations suggests that more invertebrate species have highly limited dispersal potential. Comparison of dispersal potential and geographic range suggests that planktonic duration may play a role in defining the geographic range of species in both cases. Fish larvae were generally faster swimmers than invertebrate larvae, suggesting that swimming may contribute to pattern formation at larger spatial scales. In contrast, the documented capacity to delay metamorphosis is more prevalent in invertebrates and may be related to the greater mobility of adult fish relative to invertebrates. Ultimately, similar processes operate in both groups, although sometimes at different scales.