Predicting how Reef fish larvae get around

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A Flinders researcher and collaborators have developed a new method to predict how reef fish larvae will move through the water when relying on the ocean’s currents, according to a new study.

Results from a new paper published in Proceedings of the Royal Society B show the quality of fish larvae influence how far they travel and where they end up, which impacts how distant populations are connected.

Lead author Dr Emily Fobert, Research Associate in biodiversity and conservation at Flinders University, says high quality larvae remained close to home while low quality larvae travelled much further to distant reefs.

“Although this early life-stage is really important for understanding how fish populations are connected, it is not well understood because of the difficulty of tracking tiny, transparent larvae through the open ocean,” says Dr Fobert.

“This finding is really important because larval size is known to strongly influence survival of fish, obviously larger is usually better, and so these small, slow growing larvae that are responsible for connecting distant populations are actually not very likely to survive very long,”

“Based on our results, fish populations are probably much less connected than we would expect if we didn’t include these characteristics in the dispersal model.”

For the study, Dr Fobert collected fish larvae, from 1-30 days old, from Port Phillip Bay in Victoria at 4 different depths ranging from the surface to the bottom and then extracted a record of growth to determine age, how big they were when they hatched, and how fast they grew afterwards.

The data was then plugged into a dispersal model to simulate how larval quality could influence travel between reefs.

“We found the quality of the larvae determined where it was found in the water from the surface to the bottom, and also influenced how far they travelled with the lower quality fish travelling greater distances,”

“Larvae that were larger at hatch and faster growing were mostly found in the bottom two depths sampled, whereas larvae that were smaller at hatch and grew slower were found near the surface. Those at the surface travel greater distances.”

IMAGE SOURCE: Creative Commons

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