Reconstructing source-sink dynamics in a population with a pelagic dispersal phase

Many marine species have a larval phase. In this phase, larvae drifts with the prevailing ocean currents before settling in nursery locations. In such cases, the spawning locations can be represented as sources and the settling locations of the juvenile or adult stages as sinks. Population connectivity and directionality of flow between sources and sinks can have important implications for management and conservation. The reconstruction of source-sink dynamics is often hampered by limited knowledge of the spatial distribution of either the source or sink components or lack of information on the strength of the linkage for any source-sink pair. In the case of marine species, these problems may be mitigated through the use of particle drift simulations based on an ocean circulation model. However, when simulated particle trajectories do not intersect sampling sites, the corroboration of model drift simulations with field data is hampered.

This recently published article, co-authored by PMEL scientists Carol Ladd and Wei Cheng, uses an ocean circulation model of the Bering Sea, along with a new statistical approach for reconstructing source-sink dynamics, to overcome the aforementioned problems. The research is motivated by the need for understanding observed changes in jellyfish distributions in the eastern Bering Sea since 1990. By contrasting the source-sink dynamics reconstructed using data from the pre-1990 period with that from the post-1990 period, it appears that changes in jellyfish distribution since 1990 resulted from the combined effects of higher jellyfish productivity and longer dispersal of jellyfish because of a shift in the ocean circulation starting in 1991.