Assessment of eutrophication in the Firth of Clyde: Analysis of coastal water data from 1982 to 1996

The potential for eutrophication in coastal waters of the Firth of Clyde, S cotland is assessed through statistical analysis of water quality data at o ne sampling station for the period 1982-1996. Monitoring data are presented for temperature, salinity, dissolved oxygen, chlorophyll a and plant nutri ents (nitrate, nitrite, ammonia, phosphate and silicate). Exploratory stati stical analysis is used to investigate changes in these parameters with dep th and through time. This analysis provides no evidence to suggest that nut rient concentrations have changed significantly with time. There is no indi cation of a change in the trophic status or in the potential for eutrophica tion in these waters. Concentrations of the measured parameters display gre ater variation in surface waters than at depth due to seasonal factors such as freshwater inputs and stratification. These seasonal effects are examin ed through the application of nonparametric statistical techniques to poole d data. The conclusions of the study will aid the design of future survey w ork to monitor coastal water quality, including the deployment of a towed c onstant-monitoring device. (C) 1999 Elsevier Science Ltd. All rights reserv ed.