COVID-19 lockdown moderately increased oligotrophy at a marine coastal site

8 pages, 4 figures, 2 figures, supplementary figures https://doi.org/10.1016/j.scitotenv.2021.151443.

COVID-19 has led to global population lockdowns that have had indirect effects on terrestrial and marine fauna, yet little is known on their effects on marine planktonic communities. We analysed the effect of the spring 2020 lockdown in a marine coastal area in Blanes Bay, NW Mediterranean. We compared a set of 23 oceanographic, microbial and biogeochemical variables sampled right after the strict lockdown in Spain, with data from the previous 15 years after correcting for long-term trends. Our analysis shows a series of changes in the microbial communities which may have been induced by the combination of the decreased nitrogen atmospheric load, the lower wastewater flux and the reduced fishing activity in the area, among other factors. In particular, we detected a slight decrease beyond the long-term trend in chlorophyll a, in the abundance of several microbial groups (phototrophic nanoflagellates and total prokaryotes) and in prokaryotic activity (heterotrophic prokaryotic production and β-glucosidase activity) which, as a whole, resulted in a moderate increase of oligotrophy in Blanes Bay after the lockdown.

Data from the specific sampling in 2020 were supported by the MIAU project of the Spanish Ministerio de Ciencia e Innovación, MICINN (RTI2018-101025-B-I00), while previous years were supported by many Spanish and EU projects. Other projects of the MICINN also supported this research: DOGMA (PID2020-112653GB-I00), DIVAS (PID2019-108457RB-I00), and HICCUP (RTI2018-095083-B-I00). We thank Amanda Con and Juan Rodríguez for providing data of the Blanes WWTP. We sincerely thank Irene Forn, Carolina Antequera, Arturo Lucas, Elisabet Laia Sà and Vanessa Balagué for their invaluable laboratory work. The work of the authors was supported by Generalitat de Catalunya Grups de Recerca Consolidats 2017SGR1568 and 2017SGR1011. This study acknowledges institutional support from the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S).

Peer reviewed