Meet Dr. Dewi Langlet, a scientist at the Evolution, Cell Biology and Symbiosis Unit at the Okinawa Institute of Science and Technology (OIST), who is on a fascinating quest to understand the mysteries of foraminifera, single-cell organisms with shells made of calcium carbonate. Dr. Langlet and his collaborators have achieved a groundbreaking discovery – they have shown for the first time that the burrowing of single-celled organisms in marine ecosystems profoundly impacts oxygen distribution and bacterial diversity in sea sediments. This incredible breakthrough has been published in the prestigious journal Biogeosciences.
Foraminifera are no ordinary marine organisms. They have been in existence for approximately 550 million years and when they come to the end of their life cycle, their shells accumulate on the ocean floor, eventually becoming part of the ocean sediment.
Despite their microscopic size, ranging between 63 and 500 micrometers in diameter, foraminifera are ‘big’ compared to other single-cell organisms, and each species has a unique shape. These remarkable creatures reside in marine sediments, from estuaries to the deep sea, and their biology has long remained an enigma.
Dr. Langlet is focused on unraveling the secrets of how foraminifera move within the sediment and how their activities impact the entire sea bottom ecosystem.
Bioturbation, the process in which organisms disturb the sediment by creating burrows and moving within it, has far-reaching consequences. It influences the mixing of sediment particles, regulates water flow through the sediment, and alters the chemical composition of the sediment.
The “tillers of the soil,” or bioturbators, play a crucial role in determining nutrient availability, providing food and shelter for many species, and contributing to various natural processes and outputs known as ‘ecosystem services’ that are immensely beneficial to humans.
Dr. Langlet and his team embarked on a mission to investigate whether foraminifera affect oxygen distribution in the sediment as they move or create burrows, something that had long been hypothesized but never been proven due to the challenges of detecting the microscopic impact of these organisms.
Previous studies have shown that larger multicellular organisms, such as worms, can increase the penetration of oxygen in sediment by creating burrows. However, this phenomenon had never been observed in single-cell organisms like foraminifera.
The scientists have revealed that through their burrowing activities, foraminifera engineer their entire ecosystem at a small-scale, enabling them to inhabit deeper sediment layers where oxygen is typically scarce. The impact of their burrowing extends beyond oxygenation, influencing organic matter and bacterial diversity, and ultimately shaping the availability of food in the sediment.
Uncovering enough foraminifera for their research posed a significant challenge. Dr. Langlet and his team needed to isolate and study numerous foraminifera for their experiment, a time-consuming and demanding task. The results of their study promise to advance our understanding of foraminifera and their vital role in marine ecosystems. To dive deeper into their fascinating discoveries, read more here.