Temporal and spatial variability of phytoplankton photosynthetic characteristics in a southern European estuary (Douro, Portugal)

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Azevedo, IC (Author) Other; Duarte, P (Author) Other; Adriano Bordalo (Author) ICBAS

Journal

Title: Marine Ecology - Progress Series

Vol. 412

Pages: 29-44

ISSN: 0171-8630

Publisher: Inter-Research Science Publishing

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 5 Citations

Other information

Authenticus ID: P-003-BX8

DOI: 10.3354/meps08669

Abstract (EN): The timescales of variability in photosynthetic parameters and the relationships between environmental variables and photosynthetic response are important issues for an accurate estimation of phytoplankton primary production, a major feature of aquatic systems. In the present study, variability in phytoplankton photosynthetic parameters of the Douro estuary was analyzed using data from photosynthesis-irradiance (P-E) incubations performed during seasonal tidal cycles, as well as during monthly surveys carried out along a salinity gradient. Tidal surveys were conducted in October 2003 and January, May, and July 2004. Monthly surveys were conducted from December 2002 to December 2003. Diel variability in P-E parameters was highest during the summer survey. The highest values of the biomass-specific maximum photosynthetic rate P-max were generally observed around noon or in the afternoon, and correlated positively with photosynthetic efficiency alpha. Seasonal variability in P-max and alpha was mostly related to temperature and light, whereas photoacclimation seemed to be the most important factor in diel variability. Spatially, variability increased upstream for mean P-max and alpha values, associated with higher chlorophyll a concentration and temperature. By combining a temperature-limiting function with the Steele P-E equation, 60% of P-max variation was explained. Analysis of inter-seasonal, intra-seasonal, and diel variability of photosynthetic parameters suggests that, in the Douro, photosynthetic parameters P-max and alpha are most variable at a seasonal timescale, while for optimal light intensity E-opt, diel variability was, as expected, highest. Thus, predictive models of primary productivity should take into account this seasonal variability when looking at larger timescales.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16