Patterns and trends in marine population connectivity research

Research into marine population connectivity (MPC)-the rate of transfer of organisms between locations-is important for our understanding of how marine systems operate as well as our ability to conserve them effectively. The large body of research in this field has never been quantitatively assessed to identify the manner in which research effort has been expended. We conducted an extensive quantitative literature review of > 1000 studies and analysed the 'What?' and the 'How?' of MPC research. Publication rates increased dramatically in the mid-2000s, due to a surge of studies utilising genetic techniques and assessing larval dispersal, but studies assessing post-larval movement have not increased at the same rate. The MPC literature is dominated by bony fish, similar to 3 times more prevalent than the next most common taxonomic class (malacostracan crustaceans). The dispersal of some habitat-forming organisms (e.g.seagrasses, kelps) have been studied extensively (particularly corals), whereas other groups have received minimal attention (e.g. mangroves and saltmarshes). Spatially, studies have been concentrated around Europe, North America and Australia, in contrast to regions such as eastern and southern Asia and western Africa. These taxonomic, habitat and geographic biases are likely to impact our ability to predict and manage for connectivity in these systems due to the large variance in life-history traits and abiotic conditions between well-studied and under studied systems. We recommend that researchers refocus efforts towards under-studied regions, taxa and habitats to obtain a more representative understanding of the scales of connectivity and connectivity's role in maintaining populations.