It is called Cotylorhiza tuberculata and it is one of the most typical jellyfish in the Mediterranean Sea. This species establishes a symbiotic relationship with small algae called zooxanthellae, whose presence seems to modulate the negative effects of the decrease in pH in the oceans on the survival of this jellyfish. These are the conclusions of a study that has just been published in the journal PLOS ONE that has studied the consequences of environmental changes caused by climate change on the population dynamics of this species.
Jellyfish blooms
In recent decades, the appearance of blooms or proliferations of jellyfish has been related to environmental variations and changes in the ecosystem of anthropic origin. Overfishing, eutrophication, increased temperatures and ocean acidification are some of the factors that have been attributed to the massive appearance of jellyfish on the coasts. These blooms have been, for example, very striking on the coast of the Mar Menor in recent years.
It has been suggested that, at the community level and within the same trophic level, species more tolerant to environmental changes caused by climate change could replace more vulnerable species. “ The dominance within the community of a few generalist organisms could lead to the proliferation of other more opportunistic ones, such as jellyfish. For this reason, the joint effect of heating and acidification on gelatinous organisms is beginning to be studied ”, explains Angélica Enrique-Navarro, CSIC scientist at ICMAN-CSIC and principal investigator of the study
“The objective of the study was to know the consequences of the rise in temperature and the decrease in pH in the oceans that the Intergovernmental Panel on Climate Change (IPCC) foresees on the population dynamics of the jellyfish C. tuberculata . For this, the expected future conditions in the Mediterranean Sea (for the year 2100) were reproduced in a controlled laboratory environment under a scenario of high CO2 emissions (RCP8.5, IPCC 2013) ”, the expert indicates. The results reveal that C. tuberculata polyps reproduce prolifically under the conditions projected for the end of the century.
A gradual acclimatization
“The high tolerance to environmental changes evidenced by the polyps of this jellyfish will allow the species to carry out a gradual long-term acclimatization, adapting to the expected temperature and acidification conditions. The presence of zooxanthellae (symbiotic microalgae) in this species modulates the negative effects of the decrease in pH on its survival ”, he states. However, not everything is good news: “warming and acidification may affect the transition phase from polyp to jellyfish and the formation of ephrae, compromising their survival”, explains the scientist.
Source: CSIC
