Evaluation of reaching the targets of the Water Framework Directive in the Gulf of Finland.

ABSTRACT: This paper describes the development of the
EU Water Framework Directive central water quality elements
from 1970 to 2010 in the Gulf of Finland, a eutrophied subbasin
of the Baltic Sea. The likelihood of accomplishing the
management objectives simultaneously is assessed using
Bayesian networks. The objectives of good ecological status
in winter-time total nitrogen and phosphorus, summer-time
chlorophyll-a and summer-time Secchi depth have not been
met yet. In addition, the results indicate that it is unlikely for
them to be achieved in the near future, despite the decreasing
trend in nutrient concentrations over the past few years. It was
demonstrated that neither phosphorus nor nitrogen alone
controls summertime plankton growth. Reaching good
ecological status in nutrients does not necessarily lead to good ecological status of chlorophyll-a, even though a dependency
between the parameters does exist. In addition, secchi-depth status is strongly related to chlorophyll-a status in three of the four
study-areas.