Clownfish under threat from warming ocean waters, which are damaging the anemones that serve as its home
The clownfish, the colorful swimmer propelled to reputation by the 2003 cinema Finding Nemo, is under threat from warming ocean waters wreaking havoc with sea anemones, the structures that serve as its home, a study has found.
Closely related to corals, ocean anemones are invertebrate marine beings that live in symbiosis with algae, which provide them with food, oxygen and colour.
Clownfish, also known as anemonefish, in turn use the structures as shelter to lay their eggs and create their young- maintaining the anemones clean in return.
For the study, published in the publication Nature Communications, a research squad monitored 13 pairs of orange-fin anemonefish living among the coral reefs of Moorea Island in the South Pacific.
They were monitored before, during and after the El Nino weather event that in 2016 caused major coral bleaching as the Pacific Ocean warmed.
Half of the anemones in the study “bleached”, expelling the algae that live on them and turning bone white, the team received. This happens in response to environmental stress, such as ocean warming or pollution.
” Among the clownfish living in the bleached anemones, the scientists find a drastic autumn( -7 3 %) in the number of viable eggs ,” said a statement from France’s CNRS research institute.” These fish were laying eggs less frequently and they were also laying fewer and less viable eggs .”
No changes were observed among fish with unbleached abodes.
Blood samples proved a sharp increase in levels of the stress hormone cortisol in the affected fish, and a” significant drop” in sexuality hormones that decide fertility, the team reported.
The health of the anemones and the fisheries sector improved three to four months after the end of the warming event.
Further research is needed, the team said, to examine the effects of a longer, or more intense, warming period, and whether affected fish would deal better or worse with a new bleaching episode.
Exceptional ocean warming events are predicted to become more frequent as the average global temperature rises. Virtually 200 nations agreed under the 2015 Paris agreement to limit warming to two degrees Celsius( 3.6 degrees Fahrenheit) over industrial levels.
A level of about 1C has already been reached and scientists fear the ceiling is likely to be shattered, with potentially disastrous consequences for the Earth’s climate.
In June last year, a study said many of the real-life Nemos swimming in children’s fish tanks around the world were caught using cyanide- another threat to the species.
Finding Nemo, the movie about the quest of a young fish separated from its household, resulted in more than a million clownfish being harvested from tropical reefs as pets.
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