The Influence of Biophysical Factors on the Connectivity of Holoplanktonic Copepods

Abstract

Although there are few obvious physical dispersal barriers in the ocean, holoplanktonic copepods exhibit species-specific distribution patterns and significant genetic structure within ocean basins and gyres. To explain these patterns, a flexible biophysical model to examine connectivity of various species of holoplanktonic copepods across the Atlantic Ocean basin was developed and implemented. These tools include an individual-based model (IBM) forced by a physical model to examine the effects of interactions among biological traits and the physical environment on connectivity. This model allows for the characterization of meaningful variability in biological responses to the environment both among individuals and across species. First, distribution and connectivity patterns for a generic model species are explained by linking influential life history traits, including ontogenetic vertical migration, diel vertical migration, reproduction, development, and mortality, to environmental factors such as food concentration, temperature, and ocean currents. Results are discussed with respect to distributions of various life history traits, and resulting community dynamics across the ocean basin, including how these might vary with environmental changes in the future. Second, the new model is applied to a case study for the globally-distributed copepod, Pleuromamma xiphias, to disentangle underlying drivers of genetic structure. We compare our model results to the observed spatial distribution of genetic variation across the Atlantic basin to assess model performance and gain insight into the functional traits that affect connectivity.