Biocoenosis and thanatocoenosis of diatoms in a western Galician Ria
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AuthorsBernárdez, P. (Patricia); Varela-Rodríguez, M. (Manuel); Pazos, Y. (Yolanda); Prego, R. (Ricardo); Francés, G.
Seasonal variability of diatom abundances was measured in the water column, sediment traps and in the underlying sediment from the Pontevedra ría. Seasonal variations of the diatom species in the water column were indicative of ocean influence, river influx and water column stratification. Additionally, analysis of diatom distribution and other biosiliceous components was studied in 27 surface sediment samples. The marine planktonic assemblage in the surface sediments is located in the outer area of the ría. It is mainly composed by Chaetoceros resting spores (R.S.) together with Thalassionema nitzschioides, Leptocylindrus danicus R.S. and Paralia sulcata. Higher abundances of freshwater assemblages are limited to the inner ría, as well as crysophycean cysts and phytoliths, where the Lérez River has its strongest influence. The benthic group is also restricted to the innermost and shallow areas where shallow water depths allow for growth. Factor analysis distinguished between estuarine ...