A study found new global records of abundant ghost fossils from three Jurassic and Cretaceous warming events (94, 120, and 183 million years ago), suggesting that coccolithophores were more resilient to past climate change than was previously thought.
Scientists have found a remarkable type of fossilisation that has remained almost entirely overlooked until now.
The fossils are microscopic imprints, or ‘ghosts,’ of single-celled plankton, called coccolithophores, that lived in the seas millions of years ago.
Their discovery is changing our understanding of how plankton in the oceans is affected by climate change.
Declines in the abundance of these fossils have been documented from multiple past global warming events, suggesting that these plankton were severely affected by climate change and ocean acidification.
However, the new study presents new global records of abundant ghost fossils from three Jurassic and Cretaceous warming events (94, 120 and 183 million years ago), suggesting that coccolithophores were more resilient to past climate change than was previously thought.
Coccolithophores are single-celled algae living in the upper layers of the world’s oceans.
They calcify marine phytoplankton that produce up to 40% of open ocean calcium carbonate and are responsible for 20% of the global net marine primary productivity.
They build exoskeletons from individual CaCO3 plates consisting of chalk and seashells.
Though carbon dioxide (CO2) is produced during the formation of these plates, coccolithophores help in removing it from the atmosphere and ocean by consuming it during photosynthesis.
At equilibrium, they absorb more CO2 than they produce, which is beneficial for the ocean ecosystem.
Despite their microscopic size, coccolithophores can be hugely abundant in the present ocean, being visible from space as cloud-like blooms.
After death, their calcareous exoskeletons sink to the seafloor, accumulating in vast numbers, and forming rocks such as chalk.
Coccolithophores are important in today’s oceans, providing much of the oxygen we breathe, supporting marine food webs, and locking carbon away in seafloor sediments.
They are a type of microscopic plankton that surround their cells with hard calcareous plates, called coccoliths, and these are what normally fossilize in rocks.
The term ‘plankton’ refers to the group of organisms which float in the surface waters of the rivers, lakes and oceans.
Includes both microscopic plants like algae (phytoplankton) and animals like crustaceans and protozoans (zooplankton) found in all aquatic ecosystems, except certain swift moving waters.
The locomotory power of the planktons is limited so that their distribution is controlled, largely, by currents in the aquatic ecosystems.
The growth rate, productivity and species diversity of plankton in tropical waters especially in mangrove waters are high.