Using primary productivity as an index of coastal eutrophication: The units of measurement matter

Abstract

Eutrophication is a serious environmental and economic problem in coastal marine ecosystems worldwide. It has recently been recommended that measurements of primary productivity, being a sensitive and accurate indicator of eutrophication, should be mandatory when monitoring and assessing the ecological status of coastal waters. The units of primary productivity chosen for eutrophication assessment will be very important because not all measures of primary productivity vary monotonically (or even straightforwardly) with changes in aquatic fertility. Volumetric expressions of primary productivity (rates of carbon fixation per unit volume of seawater) may prove to be the most sensitive and most reliable measures to use when evaluating the eutrophication status of coastal marine ecosystems. Another potential measure of primary productivity, the light-saturated rate of photosynthesis per unit Chlorophyll a (P:B Chl) ratio, is unsuitable for the assessment of aquatic ecosystem responses to nutrient enrichment. © The Author 2006. Published by Oxford University Press. All rights reserved.