New research reveals varied foraminifera life strategies that impact fossil records

New research by an iC3-affiliated project reveals that a key plankton species employs two distinct survival strategies, challenging previous assumptions about its life cycle and offering new insights into past climate conditions.

Plankton as climate indicators

Plankton, drifting organisms in the world's oceans, are crucial for reconstructing historical climate changes. 

Foraminifera, tiny single-celled plankton, build shells from seawater constituents, with chemical compositions reflecting the ocean conditions of their time. When these shells fossilize on the seabed, scientists can analyze them to gain snapshots of ancient marine environments.

Diverse life strategies

Traditionally, it was believed that the foraminifera G. bulloides began life near the ocean surface with small, spiny shells, growing larger and descending to deeper waters as they aged, eventually losing their spines before dying and settling on the seabed. 

However, research by the iC3-affiliated ARCLIM project indicates a more complex scenario. They observed that G. bulloides adopts two different survival strategies:

1. Rapid Growth, Short Lifespan: Some individuals grow quickly, developing large shells, lose their spines early, and die young.
2. Slow Growth, Extended Lifespan: Others exhibit slower growth, retain their spines even after death, and can live for several months.

Implications for climate research

This finding implies that smaller shells may belong to older individuals, contrary to previous beliefs.

Understanding these varied life strategies is vital for accurately interpreting fossil records.

Larger individuals that build their shells over weeks provide information about short-term ocean conditions, while smaller, long-lived ones offer insights into several months.

Ignoring these differences could lead to inaccuracies in reconstructing past climate changes. 

This research underscores the importance of considering the life cycles of foraminifera in climate studies, enhancing our ability to develop precise overviews of Earth's climatic history and better predict future climate changes.

The study “Large-scale culturing of the subpolar foraminifera Globigerina bulloides reveals tolerance to a large range of environmental parameters associated to different life-strategies and an extended lifespan” is available open access in the Journal of Plankton Research. Lead author Freya Sykes can be contacted by email or on LinkedIn.

This blog is based on a research summary originally published in Norwegian language by Forskning.no.