Case study: key studies

Different investigations, or studies, will be required to inform and support different stages in the investigation process. Good, quantitative and qualitative baseline surveys of the biological features of conservation importance are not enough on their own to be able to attempt to determine the causes of any changes in communities observed. It is essential to have corresponding data on important environmental variables (such as nutrients) and on other aspects of the biology of the system which may affect the features of conservation interest.

Studies required will include one or all of the following interrelated studies:

• features of conservation interest, including associated biota which might affect them;
• relevant aspects of water quality which might affect such features;
• collation and review of historical information;
• hydrological and physical regime of the lagoon, to better understand the observed pattern of, or what affects, both biological features and water quality;
• activities which might affect any of the above.

The need to undertake all of these studies, and the associated resource implications, will largely depend on the sensitivity of the features, the degree to which they are vulnerable and the level of understanding of site specific issues. At any stage in the process, should the available information indicate that there is no concern, e.g. that the features of interest do not coincide with the part of the site where elevated nutrients occur and that they are not vulnerable, then there is no need to undertake further detailed studies.

The project on the Fleet involved a number of related studies. Some of the work had already been undertaken, some was already planned, and other work was initiated. In effect, however, the site has been subject to a series of complementary studies in response to a succession of different questions (see linked figure below). There was some evidence that features of interest are sensitive to impacts due to nutrient enrichment and also evidence to suggest that the site may have low recoverability from such adverse impacts. Thus, there was a need to gather information to determine the vulnerability of the features. Again, there was sufficient evidence, but only when drawn from several sources, to indicate that the features were potentially vulnerable and to justify further work to elucidate more fully the nature and cause of the potential impact and to inform possible management measures. The figure linked below provides an overview of the links between the various studies on the Fleet and indicates the progression through studies that provide better resolution, and more confidence, in identification of the impacts, but with increasing cumulative costs.

Figure - Steps in investigating impact of nutrients in the Fleet

The approach and methods to each of the studies listed above are described in detail in relation to the Fleet investigation elsewhere, and guidance on each is outlined in the next section.

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