Groundwater dependent ecosystems in the oceans?

Nils Moosdorf1, Julian Liklendey2, Timo Pisternick1, Yashvin Neehaul3
1 Leibniz-Zentrum für Marine Tropenforschung (ZMT)
2 Leibniz-Zentrum für Marine Tropenforschung (ZMT); Auckland University of Technology
3 Mauritius Institute of Oceanography

3.1 in Grundwasser-Oberflächenwasser-Interaktionen - vom Flussabschnitt zum Einzugsgebiet

27.03.2020, 09:45-10:00, Telemann-Saal

On land, many ecosystems rely on groundwater for their survival, particularly if groundwater levels are shallow and rain periodic. Those ecosystems are termed “groundwater dependent ecosystems” and the relevance of groundwater is immediately obvious here. Less obvious is the discharge of fresh groundwater to the sea and its impact on the coastal environment. Fresh groundwater not only transports nutrients and pollutants to the ocean, it also changes the temperature, salinity and pH of the surrounding bottom water until its effect is diluted vertically and horizontally. It is likely that the physiologically beneficial environmental conditions provided by groundwater discharge enable organisms to thrive in this particular ecological niche. We therefore expect that within the oceans ecosystems exist that to a degree are dependent on submarine groundwater discharge.

Here we present examples from different field studies that provide evidence of influences of submarine groundwater discharge on tropical fish. We found faster growing fish in a groundwater influenced tide pool and more abundant fish at submarine springs in coral reef lagoons of Mauritius, Indian Ocean (Lilkendey et al., 2019). These findings demonstrate the potential of submarine groundwater discharge to influence oceanic habitats and illuminate future challenges such as balancing anthropogenic freshwater use and fisheries’ productivity. Thus, coastal groundwater management should consider effects of groundwater discharge in the marine realm.

Lilkendey, J., Pisternick, T., Neumann, S.I., Dumur Neelayya, D., Bröhl, S., Neehaul, Y., Moosdorf, N. (accepted): Fresh submarine groundwater discharge augments growth in a reef fish. Frontiers in Marine Science.

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