The broad aim of research in the Freshwater Sciences Research group is to understand the behaviour of rovers and lakes in catchments in order to model their important physicochemical and biological properties.
We emphasise the use of models to manage rivers and lakes. There are three research themes: catchments and river quality, including groundwaters; fate of chemicals in lakes and; lake ecology. The group co-operates with UK and Irish end-users of the research.
Our research in all the three areas supports the management of rivers and lakes, particularly the implementation of the Water Framework Directive and the effects of climate change on water resources.
Catchments and river quality, including groundwaters
This research focusses on the loss of nutrients from agricultural land and the changes in chemical and biological quality of rivers that result. The sources and pathways of phosphorus loss have been identified and ways that they can be controlled evaluated; the CHASM (Catchment Hydrology And Sustainable Management) and Backwater TRACE (Trans-boundary River-basin Action for Community and Environment) projects have been particularly important in developing this work. A new methodology for assessing the quality of rivers using biological characteristics, CBAS (Canonical Correspondence Based Assessment System), was developed using macrophytes in rivers and supported by the NS Share (North South Shared Aquatic Resource) project. Work on groundwaters has just started and a survey of the fauna in groundwaters in Ireland is underway.
Fate of chemicals in lakes
The focus has been on models for nutrients, particularly new methodologies, and on one of the main responses of lakes to increased nutrient concentrations, oxygen depletion in deeper waters. While nutrient models were a big topic in lakes over twenty years ago, they perform poorly in nutrient rich lakes and so this has been an area of emphasis. A model for de-oxygenation in lakes has been developed and it has highlighted that our understanding of oxygen consumption in sediment is poor and so this is priority for further work. All this work has increased relevance because of the additional pressures on lakes as a result of climate change.
This research theme has two active areas, bioassessment methodologies and lake models. The CBAS methodology has been extended from rivers to macrophytes and macroinvertebrates in lakes and a review of the approaches to bioassessment in the context of the Water Framework Directive has been completed; the latter was undertaken to contribute to the review of the Directive that is to take place. The ECOPATH model has been widely used to integrate understanding and model biological properties in estuaries and parts of the ocean, but much less so for lakes. In order to evaluate the usefulness of this methodology for lakes, an ECOPATH model was created for Lough Neagh. This was a substantial piece of work and it required careful collation and collection of a wide range of biological information for the lake. The model was then used to identify the changes in the ecology of the lake that may result from the recent arrival of the invasive Zebra Mussel to the lake.