Nature: Numbers Of Formanifera - Ocean Food Chain Keystone - Have Dropped 25% In Past 80 Years

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The ocean's planktonic foraminifera, microscopic animals with hard shells made of calcium carbonate, are struggling to survive as waters heat up and become more acidic.

A new study in the journal Nature analyzed almost 200,000 datasets from 1910 to track how these organisms respond to changing ocean conditions. The findings paint a concerning picture: their populations have dropped by 25% in the last 80 years.

"Our data shows that planktonic foraminifera, which play a crucial role in the ocean's carbon cycle, are struggling to survive in a rapidly changing climate," said lead researcher Sonia Chaabane of the European Centre for Research and Teaching in Environmental Geosciences and the Max Planck Institute for Chemistry. "These organisms are like sentinels, warning us of the drastic effects that warming and acidification have on marine ecosystems."

These little animals are doing everything they can to stay alive. Many species are moving toward cooler waters near the poles at speeds up to 10 kilometers per year. Others are swimming deeper into the ocean to escape rising surface temperatures. But these survival strategies might not be enough. Some scientists warn that many species could face conditions beyond what they can handle by 2100.

EDIT

https://www.thecooldown.com/green-tech/planktonic-foraminifera-ocean-acidification-climate-change/

Original Article

Migrating is not enough for modern planktonic foraminifera in a changing ocean

Abstract

Rising carbon dioxide emissions are provoking ocean warming and acidification1,2, altering plankton habitats and threatening calcifying organisms3, such as the planktonic foraminifera (PF). Whether the PF can cope with these unprecedented rates of environmental change, through lateral migrations and vertical displacements, is unresolved. Here we show, using data collected over the course of a century as FORCIS4 global census counts, that the PF are displaying evident poleward migratory behaviours, increasing their diversity at mid- to high latitudes and, for some species, descending in the water column. Overall foraminiferal abundances have decreased by 24.2 ± 0.1% over the past eight decades. Beyond lateral migrations5, our study has uncovered intricate vertical migration patterns among foraminiferal species, presenting a nuanced understanding of their adaptive strategies. In the temperature and calcite saturation states projected for 2050 and 2100, low-latitude foraminiferal species will face physicochemical environments that surpass their current ecological tolerances. These species may replace higher-latitude species through poleward shifts, which would reduce low-latitude foraminiferal diversity. Our insights into the adaptation of foraminifera during the Anthropocene suggest that migration will not be enough to ensure survival. This underscores the urgent need for us to understand how the interplay of climate change, ocean acidification and other stressors will impact the survivability of large parts of the marine realm.

Main

Ongoing anthropogenic carbon dioxide (CO2) emissions are warming and acidifying the ocean1,2, leading to water-column stratification3 and altering ecological niches6. These effects are particularly severe for organisms producing a calcium carbonate shell or skeleton because acidification impedes calcification faster than warming favours it7. Furthermore, the increasing remineralization of organic matter in the upper water column8,9, in response to ocean warming, could alter the availability of nutrients.

Ocean warming has already induced changes in planktonic habitats due to the inability of plankton to adapt fast enough to the increased physiological stress5,10,11. Comparable environmental crises have occurred in the geological past, but at much slower rates. For instance, significant surface ocean acidification has been reported from the last deglaciation and the onset of the Holocene12. Predictive models suggest that future warming and acidification will escalate, with negative ecological consequences for calcifying plankton13,14,15 and with plankton communities shifting polewards16,17. However, the capacity of plankton to acclimate to ongoing (that is, on decadal timescales) changes, and to migrate in three dimensions, has been, until now, untested due to the previous lack of spatially and vertically resolved time series.

Among oceanic zooplankton groups, the PF are ubiquitous calcifying micro-organisms whose global distribution and fossil record make them an ideal model for bridging the geological and historical records of biodiversity. The presence and abundance patterns of PF are significantly influenced by temperature18. The displacement of PF over the last deglaciation (20–12 thousand years ago) showed a spatially heterogeneous pattern, highlighting the complex response of PF communities, and rendering the straightforward prediction of future changes difficult19. The adaptation of PF to the climate transition from the Last Glacial Maximum to the Holocene has been demonstrated as plausible through modelling and the fossil record. However, the current rate of change exceeds that of the last deglaciation by several orders of magnitude20.

EDIT

https://www.nature.com/articles/s41586-024-08191-5

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1. Formanifera