SIDEBAR. Empirical Approaches to Measure Connectivity

It is logistically difficult to directly tag larvae to track their dispersal over large spatial scales (the rare exception is work done by Jones et al., 2005), so a variety of approaches have been developed to measure connectivity processes indirectly or passively. When the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) began in 1999, a sea change was underway in our understanding of larval connectivity: after decades of assuming that larval dispersal was widespread and that larvae rained down to the benthos from a well-mixed pool, new tools and new evidence suggested the potential for much shorter dispersal distances and considerable retention of larvae near spawning sites (see White et al., 2019, in this issue). In the subsequent two decades, PISCO scientists have used a variety of empirical and modeling tools to understand connectivity patterns. Some of these have evolved in complexity with the advent of new techniques and greater computing power (genomics, biophysical models), while others have proven to be less fruitful than originally hoped (natural markers in calcified structures). Here, we describe some of these tools.