Persistent blooms of surf diatoms (Bacillariophyceae) along the Pacific coast, USA. III. Relationships between diatom populations and environmental variables along Oregon and Washington beaches (1977 and 1978)

Abstract

The surf diatom populations and environmental conditions at 13 beaches along the Oregon and Washington coasts were studied from June 1977 through August 1978. Spearman rank correlation coefficients were calculated for 14 environmental variables and seven species. Cell numbers of four of the species (Chaeloceros armalum, ASlerionella socialis, Biddulphia aurita, and Aulacodiscus kittonil) were positively correlated with rainfall and river discharge and negatively correlated with air temperature, water temperature, salinity, upwelling, daylength, and nitrogen (nitrate and ammonium) concentrations. These four species are stable members of the surf ecosystem. The remaining three species (Thalassiosira pacifica, Skeletonema costatum, and Asterionella glacialis) exhibited weaker correlations that were consistently opposite in direction to the correlation coefficients calculated for the surf diatoms, above.