Biologically based water quality management

A method of reporting water quality and assessing compliance with targets, based on the Biological Monitoring Working Party score system, is proposed. The use of the technique enables biologists to present operations managers, and other professionals, with quality data from any freshwater habitat in the form of a simple index. Results obtained can be compared with predefined targets based on river use, National Water Council class, or both. It may also be used to assess the degree of pollution in specific cases. The method is currently being used throughout the Anglian Water Authority region for small stream monitoring and, in some Divisions, for the presentation of all biological results. The technique has the potential to fully integrate biological monitoring into an operational role.     

The Tucker opening-closing micronekton net and its performance in a study of the deep scattering layer

An opening-closing, single-sample net system designed to capture micronektonic organisms is described. The net is opened and closed at the mouth by mechanical time-release devices, and can be hauled from small ships on hydrographic wire. Data are presented from a series of 4 hauls made with this system during a study of sonic scattering layers. The population maxima of euphausiids, sergestid prawns and physonect siphonophores corresponded to the level of the main scattering layer. Fishes were concentrated below the layer, and amphipods above it.     

Monitoring degradation of poly(hydroxybutyrate) by fracture toughness measurements

The fracture behavior of poly(hydroxybutyrate) is described in terms of classical fracture mechanics. The fracture toughness (measured byG _c, the strain energy release rate, andK _c, the stress intensity factor) was monitored during physical aging and during chemical degradation with methylamine. A change in the measuredK _c value was found after degradation by methylamine which does not seem to be due solely to the measured thickness changes. The work lays the foundation for studies monitoring changes in fracture behavior during environmental degradation.Presented at the 4th International Workshop on Biodegradable Plastics and Polymers, October 11–14, 1995. Durham, New Hampshire.