This report presents a test survey of a new manual for monitoring of fish reproduction in lagoons 1150 and estuaries 1130 within the Habitats Directive. The method is suggested by The Swedish Agency for Marine and Water Management. The main purpose of this study was to test the new manual on a large scale and see how well it meets the standards for biogeographical monitoring. The investigation included 42 areas, representing habitats lagoons (habitat code 1150) and estuaries (habitat code 1130) in the Baltic marine basins of the Bothnian Sea and the Bothnian Bay. Fifty percent of the areas are protected within the Natura 2000 network.
The results show that there is a large variation between areas and sampling stations and that a small part of that variation is explained by sea basin, type of habitat and nature protection. Earlier studies showed other explaining factors for juvenile fish and vegetation, including topographical openness and water exchange time. Therefore, these factors should be accounted for in future investigations and analyses.
The differences among the two Baltic basins were very small, supporting the biogeographical monitoring on a marine Atlantic and Baltic level. However, a comparison with the Baltic proper should be done to further investigate differences in the marine Baltic region. The biological relevance of this division is indicated by the small differences between lagoons and estuaries observed in this study. Unfortunately, a major part of the choosen estuaries 1130 in this project were not estuaries as defined by the criteria given by the Swedish Environmental Protection Agency. The mean water discharge of the rivers entering the areas is too low. Therefore, these areas cannot be considered as representative for the habitat 1130 estuaries. Given the extent of this project, precision calculations showed that several variables (number of species, number of typical species, the Shannon diversity index and the proportion of predatory fish) were possible to sample at an acceptable level.
In the report, advantages and disadvantages of the manual are discussed. Suggestions to improve the manual are presented for the sampling as well as for preparations.
The project is a cooperation between The Swedish Agency for Marine and Water Management, The Swedish Species Information Centre and the County Administrative Boards of Uppsala, Gävleborg, Västernorrland, Västerbotten and Norrbotten. Fish sampling and presentation of the results were conducted by Naturvatten AB in cooperation with JP Aquakonsult KB, Hydrophyta Ekologikonsult, Hansen EcoResearch and Aquanalys. The project was administrated by The County Administrative Board of Gävleborg.