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The use of blue mussel farming in the Baltic Sea for mitigating eutrophication through nutrient bioextraction has recently been under debate, with emphasis on potential local negative effects induced by farmed mussels, based on theoretical scenarios. Here, we broaden the discussion by presenting an assessment of the faunal community around a noncommercial mussel farm, after two years of operation in a relatively well-oxygenated water area. It is the first large-sized farm (25 tonnes) in the northern Baltic proper. The biotic conditions at this mussel farm did not deviate negatively from the surrounding reference areas. The total abundance and species richness of sediment-dwelling fauna were higher at the farm site, which also showed a distinct zoobenthic species composition including many bioturbators which may provide extra protection against hypoxia. A snapshot view of water quality indicated relatively low P and chlorophyll-a concentrations at the farm. We caution against drawing conclusions from our study that are too far-reaching primarily because the mussel farm in question being smaller than those referred to in the debate. However, the study presents an important initial assessment of the functioning of a pilot mussel farm in the Baltic proper and provides baselines for future investigations and guidelines for improved sampling design. [ABSTRACT FROM AUTHOR]

Many studies worldwide have emphasized the need to mop the potential of commercial ports to function as receiver and donor areas for nonindigenous species (NIS). In this study, the macroinvertebrate composition of hard and soft sea bottoms, hydrographical conditions, and traffic connections of fonr Finnish coastal harbours (Naantali, Koverhar, Porvoo, Hamina) were investigated and compared with 'natural' reference areas lacking anthropogenic constructions. The harbours hosted macroinvertebrate communities fairly similar to those found in adjacent reference areas, but sediment community diversity was slightly higher in harbour basins relative to in surrounding areas. A total of eight NIS were registered in the study. With regard to hydrography, NIS that tolerate low salinities, low temperatures and eutrophic conditions are most likely to survive local conditions and hence pose a potential risk for larger areas of the Baltic Sea. A ship traffic analysis revealed that the most important donor and recipient areas of ballast water to and from the study harbours are coastal harbours of other parts of the Baltic Sea and of the North Sea. Some suggestions are made for future harbour surveys along the Finnish coast. [ABSTRACT FROM AUTHOR]

Plants are referred to as calciphilic (calcicole) or acidophilic depending on their relation to lime. We censused the vascular plant flora on seven shell gravel deposits from the Littorina Age and in two reference areas with naturally high species richness on the Åland Islands, assuming that a higher proportion of calciphilic plants would be found on the shell gravel deposits than elsewhere. Both the total number of plants and the number of calciphiles showed a significant positive correlation with the calcium (Ca) concentrations of the soils, but the highest number of species and proportions of calciphilic species were not found on shell gravel, but at intermediate to high Ca-levels in areas affected by man and domestic animals. We did not observe a strong influence of Ca on the species distribution patterns, otherwise than possibly indirectly via a raised pH-value. On the contrary, the strongest explanatory environmental variable seemed to be phosphorus, P. This in turn raises further questions: Should we rather use the world alkaphilic? Are plants Ca-dependent or Ca-tolerant? Could the whole story be about P and not Ca? When switching the analytical focus sites to species, Ca-neutral species were on average found at more sites than moderately or strongly calciphilic species. In a species-based ordination, the calciphiles also clustered significantly differently from the Ca-neutral species, both when analysing all species simlutaneously and when analysing a subset of the most widely distributed species. The exact meaning of this is hard to evaluate, but it may give a hint that many calciphiles could be poor generalists and that the Ca concentration not always was sufficiently high at all shell-gravel sites. It also demonstrates the functionality of dividing species into these four groups with regard to Ca dependency, especially if the Ca-neutral group solely consists of acidophilic species. This is also in support for a continuing use of calciphilic plants as indicators for rough assessments or initial screenings of plant diversity in applied conservation. [ABSTRACT FROM AUTHOR]