| Popis: |
By regular, quantitative sampling during two years 13 050 specimens of Amphiura filiformis were collected at a locality in the Oresund (27 m depth, muddy sand). The material included all stages from newly settled to adults. Three settling periods were registered with maximum numbers of newly settled from 6200 to 6800 · m−2. The mean disc diameter at settling was 0.3 mm, after 1 year 0.6 mm and after 2 years 1.6 mm. The adults had disc diameters of 4–9 mm. Consequently, the juvenile life lasted at least 3 years.} During all seasons there was a remarkable paucity of individuals with disc diameters between 2 and 4 mm. No age groups were found among the adults. Altogether, there is every possibility of a long life span — maybe 25 years. The density of adults has been stable for at least 20 years and was during the study period 575 · m−2 (mean), max. 1050 · m−2. Compared with other European populations the density was high and, therefore, I conclude that conditions are favourable for Amphiura filiform... |
