Phytoplankton and nutrient dynamics in the north-east Irish Sea

Results are presented for a suite of surveys investigating the distribution of phytoplankton and nutrient salts in the northeast Irish Sea during 1996. The ratio of one nutrient salt to another was calculated and it was noted that winter N:P ratios were greatest in less saline inshore waters. Elevated levels of both N and P were observed to be associated with regions of industrial and riverine inputs. Phytoplankton community data is linked to environmental variables via a multivariate statistical analysis. Results of this analysis suggest that winter TON and silicate concentrations may best explain variations in the spring phytoplankton community structure. A bloom of the prymnesiophyte Phaeocystis pouchetii was recorded in waters in the north of the study area and which appears to be associated with nutrient poor waters.