Large-scale, multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park
Abstract
Larval dispersal is the key process by which populations of most marine fishes and
invertebrates are connected and replenished. Advances in larval tagging and genetics
have enhanced our capacity to track larval dispersal, assess scales of population con-
nectivity, and quantify larval exchange among no-take marine reserves and fished
areas. Recent studies have found that reserves can be a significant source of recruits
for populations up to 40 km away, but the scale and direction of larval connectivity
across larger seascapes remain unknown. Here, we apply genetic parentage analysis to
investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus
maculatus and Plectropomus leopardus) within and among three clusters of reefs sepa-
rated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69
juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the
total juveniles sampled, respectively) were genetically assigned to parent individuals
on reefs within the study area. We identified both short-distance larval dispersal
within regions (200 m to 50 km) and long-distance, multidirectional dispersal of up to
~250 km among regions. Dispersal strength declined significantly with distance, with
best-fit dispersal kernels estimating median dispersal distances of ~110 km for P. mac-
ulatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that
established reserves form a highly connected network and contribute larvae for the
replenishment of fished reefs at multiple spatial scales. Our findings highlight the
potential for long-distance dispersal in an important group of reef fishes, and provide
further evidence that effectively protected reserves can yield recruitment and sustain-
ability benefits for exploited fish populations.