Annual trend patterns of phytoplankton species abundance belie homogeneous taxonomical group responses to climate in the NE Atlantic upwelling.
Phytoplankton is a sentinel of marine ecosystem change. Composed by many species with different life-history strategies, it rapidly responds to environment changes. An analysis of the abundance of 54 phytoplankton species in Galicia (NW Spain) between 1989 and 2008 to determine the main components of temporal variability in relation to climate and upwelling showed that most of this variability was stochastic, as seasonality and long term trends contributed to relatively small fractions of the series. In general, trends appeared as non linear, and species clustered in 4 groups according to the trend pattern but there was no defined pattern for diatoms, dinoflagellates or other groups. While, in general, total abundance increased, no clear trend was found for 23 species, 14 species decreased, 4 species increased during the early 1990s, and only 13 species showed a general increase through the series. In contrast, series of local environmental conditions (temperature, stratification, nutrients) and climate-related variables (atmospheric pressure indices, upwelling winds) showed a high fraction of their variability in deterministic seasonality and trends. As a result, each species responded independently to environmental and climate variability, measured by generalized additive models. Most species showed a positive relationship with nutrient concentrations but only a few showed a direct relationship with stratification and upwelling. Climate variables had only measurable effects on some species but no common response emerged. Because its adaptation to frequent disturbances, phytoplankton communities in upwelling ecosystems appear less sensitive to changes in regional climate than other communities characterized by short and well defined productive periods.
Centro Oceanográfico de A Coruña, Instituto Español de Oceanografía, Apdo. 130, E15080 A Coruña, Spain. Electronic address: antonio.bode@co.ieo.es.
Antonio
A
Bode
Departamento de Matemáticas, Facultad de Ciencias, Universidad de A Coruña, Campus de A Zapateira 76, 15071 A Coruña, Spain.
M Graciela
MG
Estévez
Centro Oceanográfico de A Coruña, Instituto Español de Oceanografía, Apdo. 130, E15080 A Coruña, Spain.
Manuel
M
Varela
Departamento de Matemáticas, Facultad de Ciencias, Universidad de A Coruña, Campus de A Zapateira 76, 15071 A Coruña, Spain.
José A
JA
Vilar
D001267:Atlantic Ocean; D002980:Climate; D004777:Environment; D010839:Phytoplankton / Q000502:physiology*; D011157:Population Dynamics; D012621:Seasons; D013030:Spain
Biodiversity; Climate; Plankton; Series; Upwelling