The protection of nature values and functioning of aquatic ecosystems is the subject of several legal commitments and international agreements. European legislation includes the Water Framework Directive (WFD) as well as the Wild Bird and Habitat Directives (BHD). In addition, different competences derive from local, regional, national or multilateral and international initiatives, each with its own objectives and targets. Clearly these commitments apply on different spatial scales (Europe, North Sea area, country, river basin). Consequently, evaluations of present regulations that aim to protect environments optimally adopt an integrated, hierarchical structure. Under this approach, particular commitments aim at sustainable and integrated management but may focus on a different spatial level of the ecosystem and its functioning. Accordingly, objectives at each level aim at proper functioning of the ecosystem in a way that the commitments are respected. Each level feeds back to the higher level in order to avoid contradictions. Once the objectives are set, quantitative indicators or measurement endpoints have to be defined to measure the actual status and to compare the ecosystem state with references set by the conservation goals. Depending on the scale, indicators are either based on integrated data or represent an explicit measure of the state of the ecosystem. Therefore, any monitoring scheme should provide a wide range of information so that for each level of assessment the necessary information can be deduced. Restoration measures will then aim at restoring the processes that generate the required habitats and species populations. The potential for recovery remains since most species and functional groups persist, albeit in greatly reduced numbers. This proposal describes habitat needs for fish in estuaries, defined as parts of a river under tidal influence, to assure a good status of fish populations as defined by the Water Framework Directive (EU Water Framework Directive, WFD, 2000). This good status is obtained when the conservation goals are fulfilled. A good habitat quality, a proper ecosystem functioning and a good carrying capacity will assure that conservation goals are achieved. Conservation goals for fish are refined. The tidal Schelde is taken as a case study but this approach can be applied to all North Sea estuaries. As such, this report informs to the objectives of the HARBASINS project. In particular, the HARBASINS project addresses the question as to how different approaches by regions in Europe, with respect to legal implementation of European law and site specific management experiences, result in improved estuarine functioning and health as reflected by the structure of the estuarine fish community. In this context, estuarine fish are used as a top component in the ecosystems and one which has a high public and political resonance, hence often being (with wading birds) the end point for the management of the systems. An accompanying report will consider similar aspects for estuarine wading birds. HARBASINS - Conservation goals. In this report, and in order to make the method widely applicable and thus not reliant on the particular species inhabiting any single estuary, we firstly classify fishes into guilds with relevance for the formulation of conservation goals. We describe general and guild-specific conservation goals for fish. Based on literature, habitat requirements are defined and then this information is used to define habitat needs allowing a general functioning of the estuarine ecosystem and provide some suggestions to achieve these needs. In addition we describe habitat needs at a guild level. A fish-based tool to assess the present status relative to the conservation goals will be developed and reported in another document. |
