A species of copepod, known as Acartia tonsa, can survive in aquatic areas affected by climate change, as discovered by a research team from the University of Connecticut, Jinan University in China and the University of Vermont.
Copepods are small crustaceans that exist in most marine habitats and are responsible for feeding many organisms. Marine life has been impacted by alterations resulting from climate change in areas like increased ocean acidification, which disrupts habitats, marine populations and food supply.
Hans Dam, a UConn marine sciences professor, pointed out in a recent UConn Today article, “previous studies showed [copepods] are not particularly sensitive to pH changes,” and only “shows the ability to acclimate rather than adapt.” This was due to studies being small, only focusing on a single or a few generations of copepods’ reaction to a single stressor. This can become problematic because copepods are too important to be subject to overly simplified inferences. The research team’s new study on 25 generations will take the time to focus on adaptation and actively consider ocean warming and acidification (OWA).
pH is a measure of how acidic water is, with water naturally varying between about 6.5 and 8.5 on the pH scale. For reference, milk, tap water, and bottled water exist within a 6 to 8.5 range.
Their research found that, although the copepods adapted after the first studied generation exposed to OWA lost over 50% of their population, by the 12th generation, there were more declines which were attributed to a lack of fitness among the population. The copepods were never able to fully recover from the initial reduction.
“Though the copepods were able to adapt, the adaptation was limited because fitness was never fully recovered, and the researchers suspect there are some antagonistic interactions at play, leading to a tug of war situation between adaptation to warming and to acidification,” according to the UConn Today article.
James deMayo, co-author of the recently published research in Nature Climate Change and a UConn Ph.D. student, added that OWA effects are not static, but rather differ for every generation or organism, especially when generations of species are located far apart.
“While within intermediate generations, organisms might be very well adapted, in later generations, the effects of warming and acidification start to behave differently on the population,” said DeMayo. “It’s not a static, expected result for how organisms or their populations are going to continue to grow.”
Although small, copepods support the ocean’s food system and suck out CO2. Without them, the ocean only becomes more acidic.