DEVELOPMENT OF A TECHNIQUE FOR LAKE HABITAT SURVEY (LHS): PHASE 1
The importance of European lakes for conservation and resource use is widely recognised, yet a systematic procedure for classifying lake characteristics and habitat quality is lacking. The Water Framework Directive (WFD) requires the assessment of ‘ecological status’, in which the hydromorphological (or physical) features of standing waters is a key management consideration. The WFD has acted as an important driver for the development of a Lake Habitat Survey (LHS) method that can systematically characterise and assess the physical habitat of lakes and reservoirs. This report describes Phase 1 of the project titled “Development of a technique for Lake Habitat Survey (LHS)” (project code WFD40). Funding was provided primarily by Scotland and Northern Ireland Forum for Environmental Research (SNIFFER) and Scottish Natural Heritage (SNH). This project was carried out by the Environmental Systems Research Group, University of Dundee, hereafter referred to as the contractors.
Beyond immediate WFD applications, LHS has a potentially valuable role in systematising the monitoring and management of conservation interests, e.g. monitoring internationally significant habitats, such as Special Areas of Conservation, assessing the condition of sites notified as Sites of Special Scientific Interest and wider applications in environmental impact assessment and restoration programmes. From the outset of the project it was envisaged that the LHS protocol could contribute to the work of a CEN (Comité Européen de Normalisation) Task Group on the development of a guidance standard for assessing the hydromorphology of standing waters.
A scoping study carried out by Rowan et al. (2003) involved a literature review, consultations with environmental and lake management experts throughout Europe, and produced a prototype LHS scheme to be tested. This Phase 1 study reports the further development of LHS, including a comprehensive field testing programme carried out in the UK during the summer of 2004. As part of the development process, the aim was to restrict field data collection to those data that cannot readily be obtained from desk-based resources. Detailed information on physical habitat (e.g. substrate types and riparian vegetation), is recorded at a number of sampling plots around the lake shore. Shoreline and in-lake characteristics and pressures, such as angling, erosion, and grazing, are recorded over the entire lake. Data on hydrological regime are obtained where possible.
Two levels of LHS were developed. The full version (LHS) involves a boat-based deployment with 10 sampling plots (Hab-Plots) located around the perimeter of the lake and profiling of temperature, oxygen and light penetration at the deepest point of the lake (Index Site). An abridged version (LHScore), designed for rapid deployment, is foot-based, uses only four Hab-Plots and omits the Index Site measurements. The contractors tested both full LHS and LHScore surveys at 10 principal test sites across Great Britain while, through collaboration with UK environment and conservation agencies (SEPA, EA, SNH and EHS), LHScore was deployed on a total of approximately 300 lakes in Scotland, England, Wales and Northern Ireland. Summary metrics relating to the degree of site modification, the Lake Habitat Modification Score (LHMS), and a measure of diversity and naturalness of physical structure through the Lake Habitat Quality Assessment (LHQA) were also developed. Methods of data interpretation for the WFD, Habitats Directive, and general ecological assessment were also investigated using results from the 2004 surveys.
The potential of remote sensing and geo-spatial databases (collectively desk-based data sources) in meeting LHS survey requirements was also reviewed. It was concluded that some desk-based data sources could provide useful metrics for LHS, in particular the Great Britain Lakes database (GBLakes), and that previewing an aerial photo prior to arrival at the lake was useful to orient surveyors in the field. Aerial photography and satellite imagery was able to provide useful catchment and riparian information, but shore and littoral information and human pressures were less confidently observed. The present inconsistencies in data availability between agencies and other potential surveyors may prevent further desk-based sources from being used extensively in LHS.
The results of the survey indicated that a high degree of reproducibility (70 - 90 %) can be achieved between different surveyors examining the same features. The introduction of a comprehensive training and accreditation programme should further ensure high quality in the data recorded. Comparison of the boat-based versus shore-based approaches indicated that the former was preferable overall owing to ease of access, speed of deployment, and the ability to gain Index Site information. Analysis also confirmed that a minimum of 8-10 Hab-Plots are required to capture habitat variation on heterogeneous lakes. LHMS and LHQA scores were obtained for the 10 principal test sites, and LHMS scores were also derived for a sample of 34 environment and conservation agency sites. The LHMS has clear applications as a WFD screening tool, for identifying hydromorphological quality elements at reference condition lakes and for identifying physical measures for the improvement of lake ecology (programmes of measures). The LHQA provides a measure of site naturalness and habitat complexity (which may be associated with biodiversity), and has wider applications for site management.
Following the inaugural field season of LHS a workshop was held to review the protocol, with expertise drawn from participants from the UK, Europe and the US. Revisions are discussed in this report, and the field form has been amended and is included in the appendices. The next phase in LHS development requires the following: (i) establishment of a training program to improve surveyor confidence and data quality, (ii) deployment of the revised LHS, including wider geographical application across European regions (eventually this should encompass the full range of biomes), (iii) further testing of quality indices for the WFD and other requirements, in particular exploring the linkages between ecological function and hydromorphological alteration, and (iv) the continued development of an LHS database which can be queried to extract information and which is accessible to relevant stakeholders.
Keywords: Lake Habitat Survey, Hydromorphology, Water Framework Directive, Lake Habitat Modification Score, Lake Habitat Quality Assessment.
Copies of this report are available from the Foundation in electronic format on CDRom at £20.00 + VAT or hard copy at £35.00, less 20% to FWR members.
N.B. The report is available for download from the SNIFFER Website