Abstract. During the 1st GAP Workshop at Konstanz in April 1982 comparative measurements of phytoplankton primary production by several techniques were conducted simultaneously at an offshore station in Lake Konstanz and an experimental algal pond. Suspended glass bottle exposure techniques using "C and "C uptake gave P t (mg C m~J h" •) values which varied considerably nearsurface, but estimates of area! rates for the euphotic zone £/•_, (mg C m~l h" •) which were reasonably close. In the lake, LP Z from a vertical tube exposure (with '*C uptake) was greater than rates derived for integrated bottle samples. The oxygen bottle method permitted a good estimate of compensation depth, corresponding to in situ growth studies. There were difficulties in direct comparison between O 2 and carbon methods. Correlation between them for P t was good in the lake but poor in the pond, both for suspended bottle and vertical tube methods. This series demonstrates that despite reasonable overall estimates, comparatively minor methodological differences in experimental technique can cause large variation.

The water quality management of Ruhr River Association is challenged by the dual use pattern, i. e. drinking water supply and wastewater discharge simultaneously into the same river. In the past 10 years accidental or illegal pollution occurred statistically every twenty days. Identification of water pollutants (and polluters) was often impossible because water samples could not be secured for analysis in time. The water quality surveillance system could be extended with financial support of the European Union by another two automated monitoring stations equipped with sophisticated on-line analysators (e. g. for ammonia, chromium, chlorophyll fluorescence) and biomonitors using water fleas and mussels as detectors. Monitoring strategies, methods, techniques and costs for buildings, equipment and operation are reported. Experience and results obtained so far let assume that the integrated water quality monitoring is able to prove its merits concerning reconnaissance of accidental water pollution and subsequent early warning of water works.

No abstract

According to the central aim of the European Water Framework Directive, the protection and sustained management of the aquatic ecological system, the ecological condition of a specific type of water, will be the primary parameter in future. Aiming at good ecological status in surface water bodies, population diversity and abundance of fish and macroinvertebrates is decisive. Free passage in river systems, to allow the natural migration of fish and all other aquatic organisms, is a prerequisite. To achieve this for the Ruhr River Basin a study has been commissioned in order to develop a master plan for river continuum restoration. Sustainable development aimed at promoting biodiversity in the surface water body system is a key objective. This project is complemented by investigations of the sediment--which is the nursery of the fish--in the rivers to identify river sections or tributaries which obviously provide a suitable habitat for the successful reproduction of big Salmonidae. The master plan illustrates the inherent problems of projects aimed at the restoration of fish passage in water bodies which are strongly affected by anthropogenic modifications. The results obtained may as well be transferred to other catchments with similar use patterns.

No abstract