Composition and distribution of meiofauna, including nematode genera, in two contrasting Arctic beaches

摘要

The meiofauna of two tidal beaches, one exposed and one more sheltered, on Bjornoya (Bear Island) was investigated in summer 2000. Both meiofaunal densities and composition seem to be controlled by physical properties of the sediment, which in turn are controlled by exposure. The moderately and poorly sorted sediments in the sheltered beach were more abundant in terms of meiofaunal densities than the well sorted sediments in the exposed beach (254-481 individuals in 10 cm(2) vs 7-269 individuals in 10 cm(2), respectively). In total, seven higher meiofaunal taxa were found. Turbellaria were the numerically dominant taxon in the exposed beach. In the sheltered beach, Turbellaria also dominated, followed by Nematoda and Harpacticoida. The vertical distribution of the meiofauna was in accordance with what has been reported from other intertidal beaches. Nematoda were studied in detail and their densities ranged over 0.7-7.7 individuals in 10 cm(2) in the exposed beach and 2.7-186.0 individuals in 10 cm(2) in the sheltered beach. Nematodes were identified to genus level and a total of eight nematode genera were found. Sediment community respiration, measured as oxygen consumption, ranged between 2.3 cm(3) O-2 m(-2) h(-1) in the exposed beach and 7.3 cm(3) O-2 m(-2) h(-1) in the sheltered beach (respectively, the equivalent of 24 mg and 75 mg of organic carbon metabolised per day). Values from the sheltered site are within the range of results registered in much warmer localities.