A new study by researchers from Plymouth University claims that the acidification of the ocean could be negatively altering the population dynamics of marine species and preventing them from being able to adapt to future climate change. In particular, the study examines the gastropod 'Hexaplex trunculus' and its response to ocean acidification over numerous generations, and found that they trade-off the maintenance of their shells in order to compensate for the living conditions of acidified oceans, which poses a higher cost of living.
The team also found that the higher cost of living, which stems from changes in the energy budget, is likely different for males and females and at the population level, and those who contribute to reproduction change year-on-year, which is causing a genetic drift that may hinder the ability of organisms to adapt to the acidification of the ocean.
"Despite growing evidence for direct impacts on specific species, few studies have simultaneously considered the effects of ocean acidification on individuals and population level demographic processes," Ben Harvey, who participated in the research, said in a press release. "By using carbon dioxide vents as natural laboratories, we have found that ocean acidification may hamper normal breeding habits and reduce the potential for species to adapt."
During the course of the study, the team examined 'H. trunculus' at three sites near Isola Vulcano in Sicily, each with different CO2 levels. The results showed that those at the CO2-rich site had a significantly shorter mean shell length as well as thinner shells than those at the neutral-CO2 sites. Furthermore, there were fewer females present in the acidic pH site, compared to the control pH sites where the ratio was around 50 percent.
The team also relocated some of the specimens from one site to another after 14 days of exposure and then analyzed their physiological response through their metabolic rate - they found higher metabolic rates in specimens that were exposed to acidic waters, suggesting acclimatization.
"Acclimatization can buffer populations against the immediate impacts of ocean acidification, and even provide time for adaptation," said Samuel Rastrick, who participated in the research. "However, it can also result in stress-induced energetic trade-offs, and unless organisms can compensate for the extra costs caused by ocean acidification, then they may suffer negative consequences in the form of reduced growth, development and reproduction."
"Should organisms be unable to maintain their energy budgets, then they may lack the necessary energy to contribute to future generations," added Pippa Moore, co-author of the study.
The findings were published in the Jan. 29 issue of Scientific Reports.
