Rapport nr 91: Bottenfauna och hydrografi i området mellan kust och öppet hav i den åländska skärgården
NORKKO, A; BONSDORFF, E (1994)
NORKKO, A
BONSDORFF, E
Åbo Akademi, Husö biologiska station
1994
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Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:951-650-505-8
https://urn.fi/URN:ISBN:951-650-505-8
Tiivistelmä
In 1994 zoobenthos and hydrography was studied on 29 stations in the Åland archipelago. These stations which are all in the depth-range of 20 to 40 m, represent two categories: the exposed stations in the transition-zone between the shallow coastal bottoms and the open sea, and the sheltered bottoms in the inner and middle archipelago. The main emphasis of the study was on zoobenthos, but in order to faciltate interpretation of the biotic data hydrography, chemistry and basic sediment characteristics were included. The main aim of the study was to create a baseline {19 new stations) of the situation on the bottoms of this depthstrata. Further aims were to campare the two categories of bottoms and to identify possible longterm changes that may have occured on the previously visited stations since the 1970's.
Clear differences were identified in regard to the physical, chemical and biological characteristics between the two categories of bottoms.
The results revealed that the bottoms at the interface between shallow coastal bottoms and the open sea are in fairly good condition and of importance from a productional point of view. These bottoms however, exhibit clear signs of structural disturbance with elevated abundance and biomass values. The sheltered bottoms exhibit natural differences from the exposed, but are also more affected by the local sources of nutrients. An analysis of the situation 1976178 and 1993194 gives further evidence of the ongoing process of eutrophication with increased total abundance and biomass. It is conluded that the nutrient load remains the main source of stress in the Aland archipelago waters.
Clear differences were identified in regard to the physical, chemical and biological characteristics between the two categories of bottoms.
The results revealed that the bottoms at the interface between shallow coastal bottoms and the open sea are in fairly good condition and of importance from a productional point of view. These bottoms however, exhibit clear signs of structural disturbance with elevated abundance and biomass values. The sheltered bottoms exhibit natural differences from the exposed, but are also more affected by the local sources of nutrients. An analysis of the situation 1976178 and 1993194 gives further evidence of the ongoing process of eutrophication with increased total abundance and biomass. It is conluded that the nutrient load remains the main source of stress in the Aland archipelago waters.