Spatial connectivity in an adult-sedentary reef fish with extended pelagic larval phase

Area of Science:

• Marine Biology
• Population Genetics
• Fisheries Science

Background:

• Understanding marine fish larval dispersal is crucial for conservation and fisheries management.
• Long pelagic larval durations (PLD) present unique challenges for studying demographic connectivity.
• Previous research often indicates limited dispersal in reef fishes, emphasizing local retention.

Purpose of the Study:

• To investigate population structure and demographic connectivity in the grey triggerfish (Balistes capriscus).
• To estimate dispersal distances and identify factors influencing connectivity in this species with a prolonged pelagic larval stage.
• To assess the relative importance of local retention versus long-distance dispersal for grey triggerfish recruitment.

Main Methods:

• Analysis of genetic variation (allele frequencies) across populations of grey triggerfish.
• Utilized moment and maximum-likelihood estimations to infer dispersal parameters.
• Employed simulation methods to model dispersal distance distributions based on genetic data.

Main Results:

• Genetic analysis revealed homogeneous allele frequencies and weak isolation-by-distance across a 3,100 km coastline.
• Dispersal estimates indicated large neighborhood sizes, with dispersal distribution parameter σ around 780-914 km.
• Simulations showed substantial long-distance dispersal, with 90% of events exceeding 1,800 km.

Conclusions:

• Grey triggerfish exhibit significant long-distance larval dispersal, challenging assumptions of limited connectivity in reef fishes.
• Local recruitment is highly dependent on nonlocal spawning stocks, suggesting a reduced role for local retention.
• The extended pelagic phase associated with Sargassum habitats likely facilitates this extensive connectivity.