Spatial and Temporal Scales of Marine Connectivity in Bivalves: Insights from a Multidisciplinary Perspective

Understanding larval dispersal of marine organisms is important for designing effective marine protected areas and informing sustainable fisheries management. Larval exchange among populations has been assessed using a variety of techniques that include biophysical modeling, genetic markers, and geochemical analysis. Although these methods are increasingly applied to study connectivity in sedentary species such as marine bivalves, the physical and biological factors affecting their resolution are often overlooked. This study analyzed 100 articles that examined connectivity patterns of 54 bivalve species across local, regional, basin, and global scales to evaluate the spatial and temporal resolution of these methods. The findings indicated that geochemical markers have been most successfully used to estimate connectivity at spatial scales of 30–39 km, biophysical models at spatial scales of 29–210 km, and genetic markers at the largest spatial scales of 185–1,675 km. No significant correlation was found between pelagic larval duration and the extent of measured connectivity. Instead, local oceanographic currents, environmental gradients, and physical barriers emerged as principal determinants of connectivity at spatial scales of 30–250 km. Additionally, 37% of the studies examined multiple years or generations, highlighting the importance of interannually and seasonally variable oceanographic currents in influencing the extent of larval dispersal. This synthesis provides quantifiable connectivity estimates across different methods and spatial scales, offering valuable insights for integrating marine bivalve connectivity into effective area-based management.