Seasonal variation in the distribution and isotopic composition of phytoplankton in an amazon floodplain lake, brazil

To evaluate the seasonal variation and isotopic composition of phytoplankton, water samples were collected monthly between October 2007 and November 2008 in Lake Catalão, a floodplain lake at the confluence between rivers Negro and Amazon. Analyses of total chlorophyll concentration and δ13 C and δ15 N isotopic abundances were made from particulate size fractions of 30-60, 10-30 and 10 µm in the littoral, pelagic, and floating meadows regions. Chlorophyll concentration was found to be inversely associated to lake depth, and high concentrations of chlorophyll in the floating meadows zone were significant. The fraction 10 µm was the most abundant representing in average more than 40 % of the particulate matter. The δ13 C values were relatively constant during the study (-25.1 ‰ ~ -34.0 ‰), whereas the δ15 N values showed strong variability (15.6 ‰ ~ 2.4 ‰), which has been attributed to the resuspension of sediments during mixing of the water column. Mixing associated to the sudden drop in temperature during the rising water period was an important event in the trophic and isotopic dynamics of the lake. Variations in chlorophyll content were generally associated with the dilution process, in which concentration was inversely correlated to the water level, whereas abundance was directly correlated to the water level.

• Autores: Caraballo Gracia, Pedro; Forsberg, Bruce R.; Leite, Rosseval G.
• Tipo de recurso: Article of journal
• Fecha de publicación: 2014
• Institución: Universidad Nacional de Colombia
• Repositorio: Universidad Nacional de Colombia
• Idioma: spa
• OAI Identifier: oai:repositorio.unal.edu.co:unal/73154
• Acceso en línea: https://repositorio.unal.edu.co/handle/unal/73154; http://bdigital.unal.edu.co/37629/
• Palabra clave: 5 Ciencias naturales y matemáticas / Science; 57 Ciencias de la vida; Biología / Life sciences; biology; Amazon; floodplain lake; size-fractionated phytoplankton; stable isotopes; lago de inundación; fitoplancton; isótopos estables
• Rights: openAccess
• License: Atribución-NoComercial 4.0 Internacional