Tiny meiofauna influence key processes on the seafloor
Meiofauna—microscopic animals that live on the sea floor—can both increase oxygen uptake and help reduce methane release from the sediment. This according to new research from the University of Gothenburg. Yet, their ability to sustain these benefits is hindered by microplastic pollution and intensifying environmental stressors linked to climate change.
Tiny but mighty, meiofauna make up a third of all animal life on Earth. These microscopic creatures—less than 1 mm in size, including tardigrades, copepods, nematodes, and foraminifera—live in the spaces between sand and mud particles. A single tablespoon of sediment can contain hundreds of these organisms.
“When we walk barefoot along the beach and feel sand squish between our toes, they are right there between the grains of sand,” says Adele Maciute, doctoral student in marine chemistry, Department of Marine Sciences, University of Gothenburg.
Reducing methane release and consuming oxygen
Meiofauna are difficult to study because of their tiny size. As a result, researchers have very limited knowledge of both their biology and their role in marine systems. To address this knowledge gap, in her research, Adele Maciute presents an ultrasensitive microsensor-based method for measuring respiration of animals weighing as little as ~0.03 percent of the weight of a single eyelash.
Using miniature 3-mm glass vials—smaller than a grain of rice—she discovered that meiofauna solely by respiring contribute about 3-33 percent to total oxygen uptake.
“Additionally, our findings show that meiofauna may help mitigate methane release from the sediment, while larger animals increase the release of methane,” says Adele Maciute.
Microplastics disrupt natural behaviour
As these tiny organisms are among the most common biological components of the sea floor, they can help us assess the health of the oceans by how they respond to environmental stressors. These tiny creatures are highly sensitive to changes in their habitat.
Adele Maciute's studies show that even current microplastic pollution levels interfere with animals’ movement through the sediment, disrupting their natural behaviour. This in turn can affect chemical processes on the seabed.
“In addition, my research showed that with climate change intensifying stressors, such as increasing coastal erosion and stronger river flows, shape meiofauna diversity, favouring quick-reproducing, colonizer nematode species. Thus, continuing climate change may lead to dominance of shorter-lived, smaller species, rather than long-lived, larger individuals,” says Adele Maciute.
Contact
Adele Maciute
Doctoral student in marine chemistry, Department of Marine Sciences, University of Gothenburg
Email: adele.maciute@gu.se
Link to thesis: "Tiny titans: Impact of Meiofauna diversity and activity on coastal sediment biogeochemistry".
Writer: Annika Wall
Marine meiofauna are invertebrates smaller than 1 millimetre and larger than 32 micrometres, such as tardigrades, copepods, rotifers, nematode worms, and foraminifera. These animals are a very important part of marine ecosystems. They feed on bacteria and other microscopic organisms and are themselves food for small fish, large worms, and crabs, for example. Meiofauna react differently to different disturbances and stressors. They can therefore provide important insights into the health of the ocean.
Meiofauna are the most abundant group of animals in the sea, especially nematodes and copepods, which occur in very large numbers. A rough estimate is that there are ten thousand trillion nematodes in the ocean (1021). Many meiofauna move through sediments, excreting mucus and stimulating bacterial growth, which helps to move nutrients, stabilise sediment grains and thus help prevent erosion.
Source of information: NOAA Ocean Exploration
