Övervakning av mjukbottenfaunanlängs Sveriges västkust Rapport från verksamheten år 2003

• Summary in English The soft-sediment macrofauna of the west coast of Sweden is monitored by comission of the Swedish Environmental Protection Agency in collaboration with “Bohuskustens vattenvårdsförbund” and the counties of Västra Götaland and Halland. The purpose is to detect long time changes in the marine environment, principally those caused by eutrophication and oxygen deficiency. 31 localities along the west coast of Sweden are sampled once a year in May. Four samples are taken with a 0.1m2 Smith-McIntyre grab at 12 localities and two samples at 19 localities. The red-ox condition of the sediment are measured at each locality. All fauna retrieved on a 1mm sieve are taxonomically identified and counted. This report is based on all the samples from 2002, and localities which are sampled with 4 replicates from 2003. A total of 27.488 individuals belonging to 248 different taxa were identified in the 2002 sampling program. Neither the red-ox measurements nor the oxygen measurements, performed within the monitoring program of the Swedish Meteorological and Hydrological Institute, indicate that there had been any periods with severe oxygen deficiency at any of the localities during the period May 2002 to May 2003. The major change in the fauna structure during the same period is that high abundance and biomass of the opportunistic sub surface deposit feeding polychaet Scalibregma inflatum has decreased in the deeper parts of Skagerrak, especially in the northern area. This, together with that the number of species and individuals has decreased at all localities deeper than 50m in northern Kattegatt and Skagerrak is a strong indication of a decreased organic input into these water masses. Analysis of similarity in the community structure between all localities, show that the species composition differs in some respect depending on how exposed the localities are situated. Localities along the coast and in the outer archipelago are dominated by species typical for an environment with a strong bento-pelagic coupling. Sub-surface deposit feeders, which are more typical in hydrodynamic calmer environments, are more dominant in localities at greater depth in the open sea. In the inner archipelago and fjords surface deposit feeders are dominant among the fauna. Calculation of a Benthic Quality Index (BQI) shows that all localities had a high or good environmental status according to the European Union Framework Directive. One locality was classified as “moderately affected”. This locality is situated in a small depression with a high content of detritus close to the harbour of Göteborg. It is also noteworthy that the localities in Brofjorden close to the refinery are classified to have the same environmental status as the localities in the archipelago outside the fjord.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

Monitoring

Benthic fauna

Swedish westcoast

community structure

hydrodynamics

bento-pelagic coupling

organic input

Publikations- och innehållstyp

vet (ämneskategori)

rap (ämneskategori)