The structure of the smallest plankton has a potentially large ecological impact

2023-11-10 12:11:01

A new study of Institute of Marine Sciences (ICM-CSIC) has revealed the mechanisms that structure the communities of the plankton smallest in the ocean, the picoplanctonfrom the surface to approximately 4,000 meters deep.

These microscopic organisms They are important because they play a key role in the cycle of various nutrients and in the carbon fixation. Furthermore, they are essential for the proper functioning of the marine food webs.

Until now it was unknown how ecological mechanisms vary that influence the distribution of picoplankton in the different ocean layers. However, this work suggests that the way of structuring these communities is mainly determined by changes in environmental selection (by microorganisms that proliferate in different environments) and the dispersionwhich establishes how different species are transported.

Understanding the mechanisms that structure plankton communities will allow us to better understand the impacts of global change on marine ecosystems.

This has consequences for our understanding of the effects of global change, since it implies that future environmental changes will impact the environmental selectionwhich could cause changes in the current structure of marine picoplankton and, consequently, in the set of marine ecosystemswith effects that are still difficult to predict.

“Knowing the ecological mechanisms that structure the communities of the smallest plankton in the ocean has implications for basic science, as it can help us advance in the field of microbial ecology and biogeography. In addition, it will allow us to better understand the impacts of global change on marine ecosystems,” he explains. Ramiro Logaresresearcher at the ICM-CSIC and co-author of the article that was published this week in the journal Science Advances.

Also participating in the study were the Spanish Institute of Oceanography (IEO-CSIC) of Gijón, the University of Las Palmas de Gran Canaria (ULPGC), the National Museum of Natural Sciences (MNCN-CSIC) and the Federal University of São Carlos (UFSCar, Brazil).

Differences between picoplankton communities are positively correlated with environmental variability and water masses; That is, the more heterogeneous the environment, the more different the microbial communities tend to be.

To prepare it, the team analyzed more than 450 samples collected in different parts of the planet during oceanographic campaigns Malaspina 2010 and Hotmix. These samples cover the epi- (0-200 meters), meso- (200-1,000 meters) and bathypelagic (1,000-4,000 meters) zones, which has allowed us to obtain a complete picture of communities picoplanktonic at different depths.

The environment and dispersion, key factors

One of the most relevant findings of the study is that the mechanisms that influence the structure of picoplanktonic communities vary with depth. In this sense, the analyzes indicate that the influence from environmental variability decreases with depth, while the barriers to dispersion of microorganisms increase as we enter the deep ocean.

“This suggests that differences in habitat heterogeneity and barriers to dispersal, such as different bodies of water and bottom topographyplay an important role in shaping these communities,” he points out. Pedro Jungerthe main author of the work.

Another notable result of the research is that the differences between picoplankton communities are positively correlated with environmental variability and water masses, that is, the more heterogeneous the environmentthe more different microbial communities tend to be.

Lastly, it is suggested that in semi-closed or closed seas and with great environmental variability due to historical or geographical factors, as is the case of the Mediterranean, the microbial communities they tend to be more differentiated than in other oceanic regions.

However, the study highlights the importance of understand the biogeography of picoplankton in the current context of global change, since these communities are considered barometers from ocean ecological health and can provide a lot information on climate impacts. In fact, according to the scientists, “picoplankton responses to environmental variability could inform conservation policies by acting as early indicators of changes in the health of marine ecosystems.”

“By unraveling the mechanisms that structure these communities we can predict better how these organisms will respond to environmental changes and its possible impacts on marine ecosystems,” they conclude.

Reference:

Younger, PC et al. “Global biogeography of the smallest plankton across ocean depths”. Science Advances (2023)

Rights: Creative Commons.