Bacterioplankton Activity in a Meso-eutrophic Subtropical Coastal Lagoon

The aim of this study was to investigate whether the bacterioplankton activity in the meso-eutrophic Conceição Lagoon would increase significantly under allochthonous inputs of inorganic nutrients and organic carbon. Abundance and biomass of bacterioplankton were evaluated under three treatments: light (14 h light/10 h dark), complete darkness (dark-control), and nutrient (C + N + P—dark, 100 : 10 : 1) enrichments during 72 h. Nutrient enrichments promoted a significant increase in abundance (maximum of 19.0 ×109 cells·L−1 in the first 32 hours) and biomass of the heterotrophic bacterioplankton, which induced the formation of large clusters. Bacterial biomass remained constant in the non-enriched incubations (dark-control and light). Bacterial growth rates were significantly higher after nutrient additions (1.35 d−1), followed by control (0.79 d−1), and light (0.63 d−1) treatments, which were statistically equal (). Bacterial production rates were also significantly higher under nutrient additions (1.28 d−1), compared to the control and light (0.50 d−1 and 0.44 d−1, respectively), demonstrating that bacterial growth and production in this meso-eutrophic lagoon are under an immediate “bottom-up” regulation, followed by a potential top-down effect. These facts reinforce the urgency on improving the local wastewater management plan in order to prevent further expansion of anoxic waters.

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Schmitz Fontes Maria L., Fernandes Heloísa, Brandão Manoela, Hennemann Mariana Coutinho, Aparecida Loss Raquel, de Souza grinevicius Valdelúcia Maria Alves, Tonetta Denise, Cesca Karina, Hessel Silveira Mônica, Bedin Mara, Recouvreux Derce, Vasconcellos Antônio Regina (2018). Bacterioplankton Activity in a Meso-eutrophic Subtropical Coastal Lagoon. International Journal of Microbiology. 2018https://w3. (3209605). 8p..,

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