Struktureigenschaften und Nahrungsbedarf der Zoobenthosgemeinschaften im Bereich des Lomonossowrückens im Arktischen Ozean = Structures and nutrition requirements of macrozoobenthic communities in the area of the Lomonossov Ridge in the Arctic Ocean
Deubel, H. (2000). Struktureigenschaften und Nahrungsbedarf der Zoobenthosgemeinschaften im Bereich des Lomonossowrückens im Arktischen Ozean = Structures and nutrition requirements of macrozoobenthic communities in the area of the Lomonossov Ridge in the Arctic Ocean. Berichte zur Polar- und Meeresforschung = Reports on Polar and Marine Research, 370. Alfred-Wegener-Institut für Polar- und Meeresforschung: Bremerhaven. 147 pp. https://dx.doi.org/10.2312/BzP_0370_2000
Part of: Berichte zur Polar- und Meeresforschung = Reports on Polar and Marine Research. Alfred-Wegener-Institut für Polar- und Meeresforschung: Bremerhaven. ISSN 1618-3193; e-ISSN 1866-3192, more
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| Abstract |
The macrozoobenthos communities of the northern Laptev Sea as well as the permanently ice-covered regions of the central Arctic in the area of the Lomonossov Ridge are described, and an assessment of the nutrition requirements of the macrofauna on the basis of biomass data is carried out. The taking of samples was carried out during two expeditions of the RV Polarstern in the summers of 1995 and 1998 as well as an expedition with the Swedish ice-breaker "Oden" (Arctic Ocean '96) in the Arctic. The expedition of the Polarstern ARK XI/1 (07.07-20.09.1995) went to the the northern shelf of the Laptev Sea in the area of the Lomonossov Ridge and the bordering deep sea basin up to 81°N. Further samples were taken in the central area of the ridge and the deep sea basin between 85°N and 89°N during the expedition Arctic Ocean '96 (12.07-28.09.1996). This examination was completed by one sample of the Lomonossov Ridge from the expedition ARK XI/1a (27.06-28.07.1998) (= 83°N). Altogether, the invertebrates macrofauna of 82 large box corers (= stations) were evaluated which were obtained from depths between 40 and 4170 m. The number of species, the abundance and the biomass of the macrofauna showed a clear relation to the different depths; on the Lomonossov Ridge a latidudinal reduction was proved. In this context, 23.452 individuals were registered, which were spread over 474 species and 13 taxonomic main groups. By way of a cluster analysis, 7 station groups were identified according to their different stock of species and were named after their occurrence in the examination area. One of these groups ("communities") can be found on the flat shelf and is characterized by a comparably high diversity if species as well as high abundances respectively biomasses. Stations on the ridge and on the flanks of the Lomonossov Ridge at 81°N were combined in a second group. Between the two groupings there is a zone on the continental flank which is populated by two communities: one is a central flank community which is accompanied by a border community: the latter consists of two stations of various depths. Stations of the deep areas of the Amundsen and the Macarov basin on both sides of the Lomonossov Ridge (<81°N) were combined in a further group. The stations of the central Arctic were separated in two communities: the stations of the Lomonossov Ridge close to the pole up to a water depth of 1335 m were combined in one group, and those between depths of 1700 m and 4170 m in another. The composition, the abundance and the structure of diversity of the individual station groups are compared and described considering biotic and abiotic factors. Polychaets, molluscs, crustaceas and echinodermates are the most significant macrobenthic animal groups. Concerning the number of species, the polychaetes dominated in the shallower communities and the crustaceas in greater depths. Molluscs were partly found in high abundances and were of significance in every station group. Particularly species of Yoldiella and Cuspidaria represented important discriminators or came close to the definition of a character species. Echinodermates were regularly found in the samples, but only in a small abundance due to the used large box corer. In contrast to the distinct depth zones it was shown, that there is no clear west-east gradient on the Laptev shelf and the Lomonossov Ridge concerning the composition of species of the communities. It results, that the Lomonossov Ridge does not represent a zoogeographic borderline of distribution for the macrofauna. The analysis of the feeding structure showed that deposit feeding species dominated in the entire area of examination. Carnivores were equally found in greater number and were responsible, in some station groups, for the separation towards other macrozoobenthic communities. In the sample material only few suspension feeders were found. Though, higher population densities of suspension feeders on the flanks of the Lomonossov Ridge indicated more favourable conditions of currents and the nutrition available there. It is shown, that the quantity and quality of the available nutrition has a significant influence on the structure and the composition of arctic benthos communities. In order to calculate the needed organic carbon as nutrition, the biomass of the macrofauna was analysed. The determination of the annual production (somatic) was done empirically. The following estimation of the nutrition requirements was based on two different calculations: in the examination area, the macrofauna needs up to 8,3 mg/m² respectively 15 mg/m² of organic carbon. The assessment of the nutrition requirements, though, relates mostly to the somatic production. A comparison of the calculated need with the oxygen consumption of the sediment nuclei showed that the macrozoobenthos supply 15 % respectively 25 % of the daily oxygen consumption at the most. The least macrobenthic parts were found to be 0.5 % respectively 1 % in greater depths. In a comparison of data on primary production rates and the found nutrition requirements of the macrozoobenthos, it is shown that the macrofauna on the Laptev shelf is not exposed to a particular nutrition limit during the summer months. In contrast, the sediment fauna of the more northern, permanently ice-covered regions of the arctic, needs a lateral supply of organic material from the more productive zones. Therefore, a clear south-north gradient can be found along the Lomonossov Ridge. |
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