Rapport nr 81: Den högre brackvattenvegetationen I nordvästra Åland 1991, samt en jämförelse av läget 1963 och 1965
HALDIN, D (1992)
HALDIN, D
Åbo Akademi, Husö biologiska station
1992
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Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:951-650-066-8
https://urn.fi/URN:ISBN:951-650-066-8
Tiivistelmä
A survey of phytobenthos was carried out in 1991 in NW Åland, N. Baltic Sea. The investigation covered 35 sites along a transect from the sheltered inner-archipelago through semi-sheltered shores to unsheltered outer-archipelago areas. The study was done partly to get a picture of the species' diversity in the area, and partly to relocate stations and compare the situation to that of the early 1960's. The distribution of the phytobenthos was also compared to the general hydrographical situation. The comparison with earlier data (1963, -65) was based on an abundancy-scale ranging from 1 to 5, with 5 indicating the greatest density between shoots. The shallow parts of every site were surveilled on foot between lines drawn ten meters apart (sampling was done using different rakes within the marked grid). From one meters depth until the depths at which no macrophytes could be found, samples were taken at one-meter intervals.
The archipelago area studied does not, based on the temporal comparison of phytobenthos, seem grossly affected by e.g. eutrophication, as few large-scale changes were recorded. This makes the area suitable for future monitoring and comparisons to follow any dramatic changes in the environment. Except for accumulation of soft bottoms in the inner archipelago-areas and growing amounts of reed, no significant changes in species-composition or -occurrence were recorded in the 42 species registered.
The archipelago area studied does not, based on the temporal comparison of phytobenthos, seem grossly affected by e.g. eutrophication, as few large-scale changes were recorded. This makes the area suitable for future monitoring and comparisons to follow any dramatic changes in the environment. Except for accumulation of soft bottoms in the inner archipelago-areas and growing amounts of reed, no significant changes in species-composition or -occurrence were recorded in the 42 species registered.