In situ orientation of fish larvae can vary among regions

Larval coral-reef fishes exhibit location-dependent orientation at regional scales, a discovery that challenges assumptions about their dispersal behavior. Research on the damselfish Chromis atripectoralis revealed significant differences in through-water swimming direction across three regions: the northern Great Barrier Reef (NGBR), central Great Barrier Reef (CGBR), and New Caledonia reef lagoon (NCRL). While larvae swam southerly at NGBR, they oriented easterly at CGBR and NCRL. Over-bottom orientation varied similarly, with strong westerly currents observed in NCRL. This regional variation suggests an evolutionary adaptation to local hydrodynamic conditions, limiting downstream dispersal. The study used in situ diver observations and GPS tracking over 20 years, providing the first evidence of such behavior at a regional scale.

Leis, J., Siebeck, U., Hay, A., Paris, C., Chateau, O., & Wantiez, L. (2015). In situ orientation of fish larvae can vary among regions. Marine Ecology Progress Series, 537, 191–203. https://doi.org/10.3354/meps11446