1) GRAMMI: The Groundwater discharge to the Mediterranean Sea from a microbial perspective:
Diversity, functioning and connectivity at the terrestrial-marine interface
Retos-Investigación 2018 (Modalidad-JIN, RTI2018-099740-J-I00) Agencia Estatal de Investigación. 2019-2021
The discharge of groundwater from coastal aquifers to the coastal ocean (i.e., the so-called submarine groundwater discharge, SGD) represents a relevant hydrologic pathway, delivering large amounts of nutrients, pollutants and other terrestrial elements to the sea with large effects on coastal ecosystems. However, SGD-driven processes have been poorly studied from a microbiological point of view: On the one hand, the below-ground mixing of seawater and groundwater results in areas of active microbial activity and diverse communities that can modify the chemistry of the groundwater reaching the ocean, but almost nothing is known about the microorganisms inhabiting the coastal aquifers, much less studied than inland groundwaters. On the other hand, SGD can largely influence marine microbial communities through the delivery of chemical compounds but also microorganisms, yet the potential consequences of these groundwater inputs on marine microbial communities, specially on planktonic microorganisms and the biogeochemical cycles they control, remain unknown.
GRAMMI's main objective is to study the microbial dimension of SGD in coastal areas of the Mediterranean Sea, considering the diversity, functional potential and connectivity of microbial communities at this terrestrial-marine interface. Working in close collaboration with experts in SGD processes (Jordi Garcia-Orellana and Valentí Rodellas from the Universitat Autònoma de Barcelona), and with microbiologists and biogeochemists from ICM-CSIC (Josep M. Gasol, Andrea G. Bravo), we have started to characterize the microbial communities found along the whole hydrologic continuum, from the coastal groundwater to the open coastal sea, providing a first depiction of these hidden coastal microbial reactors.
2) PATCHI: Patchiness and small-scale variability in the microbial dimension of submarine groundwater discharge
Consolidación 2023 (CNS2023-144233) Agencia Estatal de Investigación. 2024-2026
PATCHI will expand GRAMMI's results by characterizing the microbial aspects of SGD at small spatial scales that are seldom considered (centimeters/meters), both within the coastal aquifer close to the shoreline and right at the discharge points in the sea. Combining cross-shore porewater transect samplings in various Mediterranean beaches and in situ “natural groundwater addition” experiments, PATCHI will describe in detail the spatial variability in taxonomic composition and functions of i) the groundwater microbes driving changes in SGD and ii) the marine microbes exposed to SGD.
Spatio-temporal samplings will be performed across different coastal aquifer sites in order to elucidate the microbial diversity hidden in these systems, its environmental drivers and its role in biogeochemical cycling at the land-sea interface. Finally, the potential consequences of these groundwater inputs for the structure and functioning of marine microbial communities will be investigated. This project integrates different disciplines (chiefly microbiology, hydrogeology and oceanography) and will combine field samplings, experimental manipulations and modern molecular techniques such as sequencing methods, microscopic visualization, and techniques that allow linking taxonomy to activity to gain insight into the microbial dimension of SGD processes.
3) MINIOM: Prokaryotic miniaturization and the hidden microbial diversity: ecology and dispersal of ultra-small cells along the terrestrial-marine continuum
Generación de Conocimiento 2022 (PID2022-142480NB-I00) Agencia Estatal de Investigación. 2023-2026
The discovery of ultra-small prokaryotes (i.e., Bacteria and Archaea) has expanded our knowledge of microbial life at the lower size limit and has evidenced that, with most commonly used sampling and sequencing techniques, we may be missing a large fraction of the actual prokaryotic diversity present in natural ecosystems. In the ocean, recent studies have unveiled that some ultra-small prokaryotic groups may be more relevant than hitherto assumed, harboring a large metabolic diversity with unknown impacts on oceanic biochemical cycles. At the same time, other ultra-small groups may be normal-sized cells that miniaturize and inactivate in response to unfavorable conditions, making up the so-called microbial “seed banks” that can reactivate if conditions change. Despite the relevance of these two groups, almost nothing is known about the biogeography and role of ultra-small prokaryotes in natural ecosystems, largely limiting our capacity to understand or even predict microbial responses to environmental changes.
MINIOM will aim at exploring the abundance, diversity, dispersal and role of ultra-small planktonic prokaryotes (hereafter UMP) in marine ecosystems but also in coastal groundwaters connected to the sea, where these tiny microbes have been recently found to be abundant and might also play key roles in coastal marine ecosystems. MINIOM is designed as a multi-approach project that aims at getting a holistic view of the UMP fraction of microbial communities through the joint use of genomics, flow cytometry and microscopy techniques, and combining experiments and field data. All this will allow estimating the magnitude and the role in the ocean of this hidden but presumably important ultra-small fraction of prokaryotic diversity.
4) MACGNET: Microbial actors in coastal groundwater: Interdisciplinary network for the study of subterranean estuaries and their role in marine ecosystems
Redes de Investigación 2022 (RED2022-134834-T) Agencia Estatal de Investigación. 2023-2025
Integrating microbial information into coastal groundwater studies is challenging because it requires a highly interdisciplinary and multi-ecosystem research that is rarely performed, involving not only freshwater, terrestrial and marine microbial ecologists but also hydrogeologists, physicists and biogeochemists. However, in recent years there has been an increase in the number of microbial investigations in subterranean estuaries, highlighting the need and timeliness of pursuing such interdisciplinary efforts.
The Research Network MACGNET brings together specialists in the different disciplines involved in the study of coastal aquifers and SGD around the Iberian Peninsula (namely hydrogeology, geochemistry, microbial ecology), and which are needed for the correct interpretation and understanding of the microbial information obtained from these poorly understood systems. Starting from an already available large microbial and hydrogeochemical dataset obtained from several subterranean estuaries along the Spanish coast, and comprising a multidisciplinary team of researchers, MACGNET offers a platform to discuss and share data for improving the scientific outcomes of past and current collaborations, as well as to provide opportunities for new associations. The proposed tasks include workshops for knowledge exchange between disciplines, the design and unification of sampling and analytical protocols or the creation of a database of Iberian subterranean estuaries, among others. These joint activities will advance our knowledge of the status, threats and relevance of subterranean estuaries, aiming to provide a comprehensive view of the processes taking place at these poorly studied land-sea transition zones as well as of the importance of SGD in coastal sites.
