Rapport nr 122: Kvalitetsfaktorer för EU:s vattendirektiv i kustområden: bottenfauna. Jämförelse av olika sållstorlek och provtagningsdesign i beskrivandet av bottenfaunasamhällen
AARNIO, K (2009)
AARNIO, K
Åbo Akademi, Husö biologiska station
2009
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This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-12-2246-7
https://urn.fi/URN:ISBN:978-952-12-2246-7
Tiivistelmä
EU Water Frame Directive states that all coastal water bodies have to achieve good ecological status by the year 2015. The purpose of this study was to compare the usability of different methods and sampling strategies in characterizing the zoobenthic assemblages for classification of water areas. On one hand, it was studied what effect different mesh sizes (0.5 mm and 1.0 mm) had on the results, and on the other hand, how different sampling strategies (replicate samples vs single samples) affected the results. Zoobenthos was sampled from three different archipelago areas in the Åland Islands: Färjsundet (inner archipelago), NW-Åland (middle archipelago) and Eckerö (outer archipelago). Results were analysed separately for shallow (< 10 m) and deep (>10 m) bottoms. The results showed that different mesh sizes had significant effects on the number of species, abundance, and biomass of the zoobenthos, on both shallow and deep bottoms and in all investigated areas. Many small species and juveniles of e.g. Macoma balthica were lost when using a 1.0 mm sieve. The brackish benthic index, BBI, was also affected by mesh sizes and the ecological status was higher with the 0.5 mm sieve compared with 1.0 mm sieve on several stations. Different sampling designs had no effect on the results, and the number of species,
abundance, biomass and BBI were similar when using single sample design respective replicate sample design. With respect to classification of water bodies using zoobenthos, the 1.0 mm sieve may be recommended, as it is less time consuming and more effective than using the 0.5 mm sieve. But in normal monitoring studies, the 0.5 mm sieve should be used, as important information on population structure of e.g. M. balthica is lost using the 1.0 mm sieve, and also many small species are lost. Single sample design cannot be recommended as it can lead to an overestimation of the ecological status.
abundance, biomass and BBI were similar when using single sample design respective replicate sample design. With respect to classification of water bodies using zoobenthos, the 1.0 mm sieve may be recommended, as it is less time consuming and more effective than using the 0.5 mm sieve. But in normal monitoring studies, the 0.5 mm sieve should be used, as important information on population structure of e.g. M. balthica is lost using the 1.0 mm sieve, and also many small species are lost. Single sample design cannot be recommended as it can lead to an overestimation of the ecological status.