Planktonic foraminifera are small marine organisms vital for the carbon cycle of the oceans. A new study conducted by several esteemed institutions, including the CEREGE research center in Aix-en-Provence, Aix-Marseille University, the Center for the Synthesis and Analysis of Biodiversity (CESAB) in Montpellier, and the Max Planck Institute for Chemistry in Mainz, indicates that these populations are experiencing a rapid decline due to rising ocean temperatures and acidification. Increased levels of CO2 are leading to more acidic waters, which pose challenges for these single-celled organisms in forming their shells, jeopardizing their existence. While some foraminifera are shifting towards cooler waters to adapt, the pace of environmental changes is outstripping their ability to cope.
A study featured in Nature suggests that many species of planktonic foraminifera might encounter extreme environmental conditions by the end of this century, conditions that could exceed their ability to survive. Planktonic foraminifera are single-celled entities found in seawater, many of which possess a calcium carbonate shell. In tropical areas, the altering environmental conditions could lead to further extinctions, affecting marine ecosystems and the ocean’s capacity for carbon storage. An international team of scientists from France, Germany, the Netherlands, Japan, and Spain scrutinized nearly 200,000 datasets from as far back as 1910 to understand how these organisms respond to climate change.
The findings reveal that many species are migrating towards the poles in search of cooler waters, moving at speeds of up to 10 kilometers per year. Additionally, some species are relocating to deeper ocean layers to evade rising temperatures at the surface. However, despite these adaptations, foraminifera populations have diminished by 25% over the last 80 years. Tropical species have been particularly affected, facing significant declines due to extreme warming that disrupts their reproductive processes. The increased CO2 levels and ocean acidification also hinder the formation of calcium carbonate (CaCO3), the material used by foraminifera to construct their shells. With fewer shells being formed as a result, less carbon is sequestered when these shells eventually sink to the ocean floor.
Sonia Chaabane, the lead author of the study and a researcher at CEREGE and the Max Planck Institute for Chemistry, stressed the importance of these findings: “Our data indicate that planktonic foraminifera, which are crucial for the ocean’s carbon cycle, are finding it increasingly difficult to survive in a rapidly changing climate. These organisms act as indicators, alerting us to the severe impacts that warming and acidification are inflicting on marine ecosystems.” Bioindicators like foraminifera may help us gain a more comprehensive understanding of the complex interactions between climate and ecosystems, rather than relying solely on individual assessments. “As climate change progresses, researchers are left pondering the adaptive strategies that different species of planktonic foraminifera may adopt in the future,” notes Ralf Schiebel from the Max Planck Institute for Chemistry.
This research was supported by the French Foundation for Biodiversity Research (FRB) as part of the Centre for the Synthesis and Analysis of Biodiversity (CESAB) and received co-funding from the Max Planck Institute for Chemistry (MPIC) in Mainz, Germany, as well as the INSU LEFE program and the Initiative d’Excellence d’Aix-Marseille Université — A*MIDEX.
