Increase in sea temperature can affect development of coloration in a benthic shark

Here are some interesting but bad news findings about the impact of climate change on the development of young sharks from an experiment conducted by Connor Gervais at the Rummer Lab:

“Small benthic shark may not develop their coloration patterns under predicted end-of-centery temperature (32°C)”

Epaulette sharks (Hemiscyllium ocellatum) are small (70–90 cm), oviparous long-tailed carpet sharks commonly found on reef flats from Papua New Guinea to Australia. Sharks reared at annual summer average temperatures (~28 °C; 24.114° S, 152.717° E) develop distinct colouration and patterning in ovo (n=16). Upon hatching (n = 11), their namesake epaulettes are clearly defined (Fig. 1a). But sharks hatching from eggs reared at predicted end-of-century temperatures (32 °C) displayed irregular colouration and patterning (Fig. 1b). All except for one 32 °C hatchling died after 3 days, and none had developed the distinct epaulette observed in control sharks. The surviving hatchling was maintained
at 32 °C for 30 days post-hatch and then slowly transitioned to control temperatures (28 °C). Even after 120 days post-hatch, the neonate’s patterns were still not properly developed (Fig. 1d).


The left panels are current day temperatures, and the right panels are sharks that developed under temperatures predicted to occur on the Great Barrier Reef Marine Park by 2100.

These patterns are important for the ecology and survival of these small benthic sharks. Inded it can further affect their camouflage ability to hide from predators or alternatively impact their social behaviour. Further research is needed but this is certainly a bad news for this species for which it was found good abilities to deal with increasing CO2 (see published paper here).


Gervais C, Mourier J, Rummer J (in press) Developing in warm water: Irregular colouration and patterns of a neonate elasmobranch. Marine Biodiversity. Link to PDF



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