Planktonic Foraminifera: The Alarming Decline of Oceanic Sentinels

**Planktonic foraminifera** are crucial single-celled marine organisms that contribute significantly to the ocean's carbon cycle. A recent study by an international team, including scientists from the **CEREGE research center**, **Aix-Marseille University**, the **Center for the Synthesis and Analysis of Biodiversity (CESAB)**, and the **Max Planck Institute for Chemistry**, highlights an alarming decline in these populations due to **ocean warming and acidification**. The study, published in *Nature*, analyzed nearly 200,000 datasets since 1910 to examine how these organisms respond to climate change. With **rising CO2 levels and acidifying waters**, foraminifera are struggling to form their calcium carbonate shells, a vital component of their survival. The study finds these species are migrating poleward, up to 10 kilometers per year, and deeper into the ocean to escape rising surface temperatures. Despite these shifts, foraminifera populations have decreased by **25% over the last 80 years**, with tropical species experiencing the most significant losses due to disrupted reproductive cycles. **Sonia Chaabane**, the study's lead author, emphasizes that foraminifera serve as bioindicators, highlighting the drastic effects of climate change on marine ecosystems. The ongoing changes could lead to further extinctions, reducing the ocean's capacity to store carbon. The research's implications suggest a need for understanding complex climate-ecosystem interactions and developing adaptation strategies for these crucial marine organisms.