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- Milbrink, Göran
(författare)
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Composition and abundance of oligochaetes in Scandinavian lakes in the 1970s in full compatibility with the "morpho-edaphic index" : Do these relationships still hold 40 years later?
- 2020
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Ingår i: Proceedings Of The 14th International Symposium On Aquatic Oligochaeta. - : MAGNOLIA PRESS. - 9781776708697 - 9781776708703 ; , s. 77-88
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Konferensbidrag (refereegranskat)abstract
- In the 1960s it became fairly well-known that biological indices through their supposedly integrative power could be more robust measures of the water quality than separate chemical data. Oligochaetes and chironomid larvae in the bottom fauna hereby played an important role. Precision, however, increased dramatically if the relationship between oligochaetes and the so-called morpho-edaphic index, i.e. the average total phosphorus content in mu g/l divided by the mean depth (in meters) of the lake (Ryder et al., 1974), was used in stead (Milbrink, 1978). The percentage composition and total abundance of oligochaetes in a number of lakes or selected basins of large lakes in southern Sweden and Norway were thus tested against this index in the 1970s. In logarithmic scales these relationships turned out to be more or less linear. The immediate conclusions were then that this method of classifying lakes could be of considerable scientific as well as practical value. Today we know a lot more about the ecological preferences of oligochaete species and characteristic species associations. The oligochaete fauna of the large lakes of southern Sweden, Malaren, Vattern, Vanern and Hjalmaren, have been studied in detail over many years- over 100 years in the first three of these lakes and in the last lake for over 50-years. Effects of generally applied advanced sewage treatment in Sweden since the late 1960s are easily recognizable in the material. We have a situation of oligotrophication. With our new knowledge it comes natural today to study changes in species composition after trophic change and to investigate if the above close relationships in abundance are still largely linear.
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| 2. |
- Schmelz, R. M., et al.
(författare)
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Astacopsidrilus hibernicus sp. nov. (Phreodrilidae, Oligochaeta, Annelida) from Irish peatlands
- 2020
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Ingår i: PROCEEDINGS OF THE 14TH INTERNATIONAL SYMPOSIUM ON AQUATIC OLIGOCHAETA. - : Magnolia Press. - 9781776708697 ; , s. 34-44
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The discovery of a large and flourishing population of Phreodrilidae in terrestrial peatlands in northwest Ireland was surprising on two counts: these oligochaete worms are usually aquatic and most of the species occur in the Southern Hemisphere. The phreodrilids were discovered in a project that targeted Enchytraeidae, therefore methods adapted to the investigation of enchytraeids could be applied, including the study of living animals and properly fixed whole mounts. DNA sequencing was also performed. All worms identified here belong to one species, new to science, and placed in the genus Astacopsidrilus, because of the ventral position of the spermathecal pores and the opening of the female funnels inside the spermathecal vestibule. Astacopsidrilus hibernicus sp. nov. is mainly distinguished by thick segmental cushions of epidermal gland cells on the dorsal side of the posterior body half. Male sexual organs and spermathecae are comparatively small and without the oftenobserved bizarre modifications common in species of this family. DNA sequencing yielded a fragment of the 16S rRNA gene. This is the first description of a phreodrilid species from Europe; the few previous recordings of this family in Ireland and the United Kingdom had been left unidentified.
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