Environmental factors associated with phytoplankton succession in a Mediterranean reservoir with a highly fluctuating water level

• Published in: Environmental monitoring and assessment 2015-10, Vol.187 (10), p.633-633, Article 633
• Main Authors: Fadel, Ali, Atoui, Ali, Lemaire, Bruno J., Vinçon-Leite, Brigitte, Slim, Kamal
• Format: Article
• Language: English
• Subjects: Algae; Algal blooms; Aphanizomenon ovalisporum; Aquatic ecosystems; Aquatic plants; Atmospheric Protection/Air Quality Control/Air Pollution; Autumn; Bacillariophyceae; Biodiversity and Ecology; Cellulose acetate; Ceratium hirundinella; Chlorophyta - growth & development; Cyanobacteria; Cyanobacteria - growth & development; Earth and Environmental Science; Earth Sciences; Ecology; Ecology, environment; Ecosystems; Ecotoxicology; Environment; Environmental factors; Environmental Management; Environmental monitoring; Environmental Monitoring - methods; Environmental Sciences; Eutrophication; Fresh Water - chemistry; Growth conditions; Hydrology; Irrigation; Lakes; Lebanon; Life Sciences; Light intensity; Mediterranean Sea; Microbiology and Parasitology; Microcystis aeruginosa; Monitoring/Environmental Analysis; Nitrates; Nutrient availability; Nutrient concentrations; Phosphorus; Phytoplankton; Phytoplankton - growth & development; Plankton; Reservoirs; Sciences of the Universe; Seasons; Seawater - chemistry; Temperature; Thermal stratification; Toxins; Water bodies; Water levels; Water quality; Water temperature
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-015-4852-4

Eutrophication and harmful algal blooms have become a worldwide environmental problem. Understanding the mechanisms and processes that control algal blooms is of great concern. The phytoplankton community of Karaoun Reservoir, the largest water body in Lebanon, is poorly studied, as in many freshwater bodies around the Mediterranean Sea. Sampling campaigns were conducted semi-monthly between May 2012 and August 2013 to assess the dynamics of its phytoplankton community in response to changes in physical-chemical and hydrological conditions. Karaoun Reservoir is a monomictic waterbody and strongly stratifies between May and August. Changes in its phytoplankton community were found to be a result of the interplay between water temperature, stratification, irradiance, nutrient availability and water level. Thermal stratification established in spring reduced the growth of diatoms and resulted in their replacement by green algae species when nutrient availability was high and water temperatures lower than 22 °C. At water temperature higher than 25 °C and low nutrient concentrations in summer, blooms of the cyanobacterium Microcystis aeruginosa occurred. Despite different growth conditions in other lakes and reservoir, cyanobacterium Aphanizomenon ovalisporum dominated at temperatures lower than 23 °C in weakly stratified conditions in early autumn and dinoflagellate Ceratium hirundinella dominated in mixed conditions, at low light intensity and a water temperature of 19 °C in late autumn. We believe that the information presented in this paper will increase the knowledge about phytoplankton dynamics in the Mediterranean region and contribute to a safer usage of reservoir waters.