New study reveals how ocean density affects plankton's carbon sequestration
Research led by Dr. Stergios Zarkogiannis uncovers how marine plankton adapt their shell-building processes in response to changes in ocean density, impacting carbon absorption.
Recent research published in the Royal Society Open Science has uncovered pivotal insights into the relationship between ocean density and the ability of marine plankton to sequester carbon. The study, led by Dr. Stergios Zarkogiannis from the Department of Earth Sciences at the University of Oxford, reveals that physical ocean properties, specifically density, significantly influence how planktonic foraminifera—microscopic organisms that play a crucial role in the carbon cycle—incorporate carbon into their shells.
Traditionally, scientists have studied how chemical factors, such as ocean acidification, affect the biomineralization process of marine plankton. However, this research highlights the need to consider physical influences, such as density and salinity, when assessing the calcification processes of these organisms. Dr. Zarkogiannis's investigation focused on the planktonic foraminifera species Trilobatus trilobus, which is sensitive to changes in ocean conditions.
The findings indicate that T. trilobus is adept at adjusting its shell-building process in response to varying levels of ocean density. When ocean density decreases, which occurs due to factors such as the melting of ice sheets that introduce freshwater into the seas, T. trilobus compensates by reducing its calcification efforts. This adjustment helps the organism maintain buoyancy, preventing it from sinking. Interestingly, this reduction in calcification leads to changes in the chemical composition of the surrounding waters, increasing their alkalinity and enhancing their capacity to absorb atmospheric CO2.
Dr. Zarkogiannis explained, "Our findings demonstrate how planktonic foraminifera adapt their shell architecture to changes in seawater density... This natural adjustment, potentially regulating atmospheric chemistry for millions of years, underscores the complex interplay between marine life and the global climate system." The study's results suggest that in future oceans, affected by climate-driven changes such as freshening from melting ice, less calcification by these organisms could significantly influence ocean alkalinity and CO2 absorption rates.
The research involved analysing modern T. trilobus fossil shells recovered from deep-sea sediment sites along the Mid-Atlantic Ridge. Employing advanced techniques like X-ray microcomputed tomography, Dr. Zarkogiannis was able to reconstruct the shells in three dimensions and examine their structural configurations against various environmental parameters.
The study's outcomes show that in equatorial waters, the species produces thinner shells to maintain buoyancy, while in denser subtropical regions, it generates thicker shells. Dr. Zarkogiannis stated, "Although planktonic organisms may passively float in the water column, they are far from passive participants in the carbon cycle... By actively adjusting their calcification to control buoyancy... these organisms also regulate the ocean's ability to absorb CO2."
While these findings provide essential insights into the adaptation mechanisms of T. trilobus and its role in the carbon cycle, further research is required to explore how similar mechanisms might affect other planktonic organisms, including those that utilise silica or organic materials for shell formation.
There remains a gap in understanding whether the observed buoyancy regulation affects calcification across a broader spectrum of marine organisms. Future investigations by Dr. Zarkogiannis will aim to determine the applicability of these principles across different groups and oceanic environments. The significance of this research lies in its contribution to the growing body of knowledge regarding the adaptive strategies of marine ecosystems in the face of climate change, potentially informing future carbon removal initiatives.
Source: Noah Wire Services