About a quarter of all carbon dioxide emissions (CO₂) is absorbed by the World Ocean. When this absorption takes place, the CO₂ It interacts with seawater, causing the pH of the ocean to drop, a process known as ocean acidification. This leads to a decrease in the concentration of carbon ions. Some sea creatures, such as pinnipeds, rely on carbon ions to build and protect their shells. Pteropods play an important role in the marine ecosystem.

However, understanding of specific pterygoid features such as life cycles and population dynamics remains limited. This can be explained by factors such as their small size (some species of sea butterflies are less than a millimeter in size) and low survival rates in long-term captivity. A team of marine scientists recently conducted a study on the life cycles, abundances and seasonal fluctuations of sea butterflies in the northeastern Scotia Sea. This region is experiencing some of the most rapid climate changes in the Southern Ocean.

British Antarctic Survey researcher and corresponding author of the study published in Frontiers in Marine, Dr. Science . “Life cycle knowledge of this important organism could improve the estimate of the impact of ocean acidification on the Antarctic ecosystem.”

Population stability is essential for the survival of the species

For their study, the scientists collected the sea butterflies in a sediment trap, a sampling device anchored to a depth of 400 meters. “It’s impossible to observe the entire life cycle of sea butterflies in the lab, so we had to piece together information about their egg laying, growth rate and population structure,” added Dr Vicky Peck, researcher and co-author at the British Antarctic Survey. . – the author of the work. “Using the sediment trap samples, we successfully reconstructed their life cycle for one year.”

For the two dominant species collected – limacina rangii And Limacina retroversa – scientists have observed contrasting life cycles that lead to different sensitivities to changing oceans. L. Rangiian arctic species, both adults and juveniles can be found during the winter. L. retroversaa subpolar species, it seems to be found only in winter as adults.

During the coldest time of the year, ocean water is more acidic than at other times of the year because lower temperatures increase the dissolution of CO2. ₂ In the ocean, the researchers write that the then-existing life stages of sea butterflies were more susceptible and vulnerable to increased levels of ocean acidification. The truth is that adults and teenagers L. Rangii coexistence in the winter may give them a survival advantage. If a cohort is vulnerable, the overall stability of the population is not threatened. However, with L. retroversa If one cohort is removed, the entire population may be vulnerable.

Prolonged exposure is a challenge to survival

The researchers noted that although species are affected differently, none are likely to remain intact when exposed to adverse conditions for extended periods of time.

As ocean acidification increases in intensity and duration, they begin to coincide with spawning events in the spring. The scientists warned that this could endanger the most vulnerable life stage, the larvae, and endanger future populations.

To find out how such a scenario could happen in the Scotia Sea, the research team will continue to study the sea butterflies that live there. “The next step will be to focus on multi-year sediment trap samples to identify potential inter-annual life-cycle variability associated with environmental change,” said Dr Jessie Gardner of the British Antarctic Survey, lead author of the study.