A catastrophic change in a european protected wetland: From harmful phytoplankton blooms to fish and bird kill. (1st November 2022)

• Record Type: Journal Article
• Authors: Demertzioglou, Maria; Genitsaris, Savvas; Mazaris, Antonios D.; Kyparissis, Aris; Voutsa, Dimitra; Kozari, Argyri; Kormas, Konstantinos Ar; Stefanidou, Natassa; Katsiapi, Matina; Michaloudi, Evangelia; Moustaka-Gouni, Maria
• Is Part Of: Environmental pollution. Volume 312(2022)
• Publication Date: 2022-11-01
• Subjects: Ramsar -- Mass mortality event -- Sediment seed/egg bank species -- Ecological interactions -- Ecological degradation -- Ecosystem functioning; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.120038
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Understanding the processes that underlay an ecological disaster represents a major scientific challenge. Here, we investigated phytoplankton and zooplankton community changes before and during a fauna mass kill in a European protected wetland. Evidence on gradual development and collapse of harmful phytoplankton blooms, allowed us to delineate the biotic and abiotic interactions that led to this ecological disaster. Before the mass fauna kill, mixed blooms of known harmful cyanobacteria and the killer alga Prymnesium parvum altered biomass flow and minimized zooplankton resource use efficiency. These blooms collapsed under high nutrient concentrations and inhibitory ammonia levels, with low phytoplankton biomass leading to a dramatic drop in photosynthetic oxygenation and a shift to a heterotrophic ecosystem phase. Along with the phytoplankton collapse, extremely high numbers of red planktonic crustaceans- Daphnia magna, visible through satellite images, indicated low oxygen conditions as well as a decrease or absence of fish predation pressure. Our findings provide clear evidence that the mass episode of fish and birds kill resulted through severe changes in phytoplankton and zooplankton dynamics, and the alternation on key abiotic conditions. Our study highlights that plankton-related ecosystem functions mirror the accumulated heavy anthropogenic impacts on freshwaters and could reflect a failure in conservation and restoration measures. Graphical abstract: Image 1 Highlights: A mass fauna kill followed changes in plankton dynamics and abiotic factors. Blooms of harmful phytoplankton species blocked biomass flow in the lake's food web. High ammonia levels led to phytoplankton collapse and drop of photosynthetic oxygen. Extremely high numbers of red Daphnia individuals were visible through satellites. Disclosure of the mass fauna kill was observed due to water level decrease.