Influence of tidal conditions and River volume on Phytoplankton distribution and composition in the Pas estuary (Northern Spain)
Luisa Pérez, Juan C. Canteras

Phytoplankton composition and distribution was studied in a small estuary of Cantabria from February to December 1985 under different tidal conditions. 239 Species were identified, all of which showed a high degree of tolerance to salinity changes. The volume of the river exerted great control over the selection and abundance of the species. The community consisted of small cells with high growth rates. Species of clearly fluvial influence (Rhoicosphenia curvata, Asterionella formosa, Scenedesmus quadricauda) as well as estuarine species (Skeletonema costatum, Nitzschia closterium, Buddulphia moboliensis) occurred. Tidal condition did not affect the specific composition of the community, but the number of individuals observed was always greater at low tide. At all times there was a downward longitudinal gradient of abundance form the innermost to the otumost stations. Variations in the volumes of marine and fresh waters throughout the annual cycle determine the structure of the community.

Keywords: phytoplanton, species, composition, annual cycle, estuary, Northern Spain.
Contents of this volume Sci. Mar. 54(1) : 77-88 Back PDF
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