They work with bacterial and phytoplankton databases from all over the globeo
The microscopic marine organisms that make up the microplankton continue to hide many secrets for science. They live in the water column and are characterized by the fact that they are not able to swim the countercurrent. This group includes an amalgam of very different organisms with very different functions, which interact with each other and depend on each other. The common characteristic is that they are less than 200 micrometers in size and can belong to three domains: Archaea, Bacteria and Eukarya (Woese et al., 1990). But within the microplankton, the knowledge that exists about phytoplankton (the plant part of the plankton) is much broader than what exists about the smallest heterotrophic organisms, bacteria. While in the first case microscopes are used to study them, bacteria are not discernible under the microscope, so they are usually considered a ‘black box’, “a homogeneous group of unknowns that together perform a basic function: degrade organic matter produced by other microbes”. This is explained by Sandra Martínez-García, distinguished researcher of the Biological Oceanography Group (GOB, CIM) and one of the scientists involved in the TRAITS project, an initiative that started a year ago led by the National Center for Biotechnology (CNB, CSIC) and in which the University of Vigo participates, as well as the University of La Laguna.
The aim of the project is to identify not only which microorganisms are present in the planktonic communities of the different ecosystems (from the most abundant to the most “rare”) but also “to be able to describe the function of each one of them within the community, whether there are competitive or cooperative relationships and which are the factors that determine the dominance of each one of them in different situations”. The work is aimed at describing functional guilds of bacteria that are able to obtain energy and nutrients in a similar way and to verify the existence of these guilds in different environments. The scientific team of the three entities works with metagenomic and metatranscriptomic databases of bacteria and phytoplankton from all over the world, from the Galician coast to polar and tropical areas.
Regarding the Vigo subproject, the aim of the CIM researchers is to find out how environmental variability affects not only heterotrophic organisms, but also the phytoplankton of the estuaries, responsible on the one hand for the high productivity of the system, but also for the toxicity events that force the closure of the bathing and facilities every year. The project is funded under the RETOS 2019 program and has a three-year duration, with completion scheduled for mid-2023.
Deciphering the ecological mechanisms that control prokaryotic communities
Marine bacteria and archaea process an important part of the organic carbon fixed by autotrophic microorganisms in the ocean. “We know that the availability of this organic carbon as well as different nutrients varies over different temporal and spatial scales,” explains Sandra Martinez. “As a consequence, the structure and functioning of marine prokaryotic communities are strongly controlled by the availability of resources”. In this sense, it is of “extreme importance to decipher the ecological mechanisms that control this organization”, which is the focus of the TRAITS project. The objective is to identify guilds composed of microorganisms that use these nutrients in a similar way in different ecosystems. For this, the researchers use genomic databases already collected and available for use, and have also planned to carry out an oceanographic campaign and experiments with microcosms and mesocosms in the Ecimat, in which, she explains, “we will subject bacterial communities in the Vigo estuary to the input of organic matter from different algal blooms in order to further study the coupling between both trophic compartments”. The information derived from this project may help to improve the information included in marine ecosystem models on the functional role of bacteria in nutrient fluxes in the ocean.
Innovative Databases
Regarding the databases used by the researchers in this project, the CIM-UVigo scientist explains that “they are innovative due to the time scales used, ranging from weeks to hours, and allow us to know for the first time the changes in the composition and functioning of the marine microplankton of the Galician estuaries on a short time scale”. The scientist explains that this is a “system with high environmental variability in which rain, nutrient inputs by upwelling and subsidence of water masses, mixing and turbulence of the water column, among others, cause significant environmental changes at very short time scales”.
A investigadora distinguida Sandra Martínez-García coordina un subproxecto centrado no noroeste da península ibérica
Fonte: DUVI