Quantifying dispersal variability among nearshore marine populations

Abstract

Dispersal drives diverse processes from population persistence to community dynamics. However, the amount of temporal variation in dispersal and its consequences for metapopulation dynamics is largely unknown for organisms with environmentally driven dispersal (e.g., many marine larvae, arthropods, and plant seeds). Here, we quantify variation in the dispersal kernel across seven years and monsoon seasons for a common coral reef fish, Amphiprion clarkii, using genetic parentage assignments. Connectivity patterns varied strongly among years and seasons in the scale and shape but not in the direction of dispersal. This interannual variation in dispersal kernels introduced temporal covariance among dispersal routes with overall positive correlations in connections across the metapopulation that may reduce stochastic metapopulation growth rates. The extent of variation in mean dispersal distance observed here among years is comparable in magnitude to the differences across reef fish species. Considering dispersal variability will be an important avenue for further metapopulation and metacommunity research across diverse taxa.

Persistence of a reef fish metapopulation via network connectivity: theory and data

“…This span was three times the 8 km mean dispersal distance for yellowtail anemonefish (Catalano et al . 2020), suggesting that most larvae would be retained within the study region. The 19 patches were separated by sand flats and, in total, covered 20% of the coastline in the study region (Fig.…”

Stochastic nature of larval dispersal at sea

“…In their recent study, Catalano et al (2021) surveyed a metapopulation of the anemonefish Amphiprion clarkii , sampling nonlethally many adults and newly settled juvenile fish within 19 distinct coral reef patches spanning 30 km of coastline in the Philippines for seven years. Since anemonefishes live in close association with their host sea anemones, matching adults and juveniles using parentage analysis can reveal direct links between anemones and quantify dispersal between distinct reefs.…”

“…Parentage analysis in natural populations can be challenging, when the proportion of sampled candidate parents is small and the number of markers is limited. Catalano et al (2021) overcame this challenge using a genetic data set comprising more than 1000 SNPs. They then fit probabilistic dispersal kernels using a maximum likelihood approach and built a statistical framework to quantify dispersal variation among years and seasons in terms of magnitude and directionality.…”

“…While stability can arise from volatility, the results from Catalano et al (2021) indicate that the direction and magnitude of correlations in larval dispersal (synchrony vs. asynchrony) might depend on the geographic scale and other concomitant factors such as local geographic and oceanographic settings. Their results also serve as a reminder of the complexity of larval dispersal in marine populations, and that long‐term time‐series data are fundamental to our understanding of natural processes.…”

“…Their results also serve as a reminder of the complexity of larval dispersal in marine populations, and that long‐term time‐series data are fundamental to our understanding of natural processes. Catalano et al (2021) demonstrate we now have the tools and capacity to better understand what shapes variation in dispersal and connectivity in marine seascapes.…”