Räumliche Verbreitung von Phyto- und Zooplankton im nördlichen Roten Meer


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Abstract

The aim of the expedition MET 44/2 (Feb. - Mar. 1999) with RV „Meteor“ was to study the biological and physical relationships in the Gulf of Aqaba and the northern Red Sea. The investigated samples of zoo- and phytoplankton were taken in that program. The selected stations form a transect from the head of the Gulf of Aqaba to the northern Red Sea. Day and night catches were taken. Position VI in the southern Gulf of Aqaba was sampled three times over two weeks to investigate the changes between the winter and the spring situation. The zooplankton samples were taken with a multiclosing net (9 nets) with a meshsize of 150 µm over the whole water column. The phytoplankton samples came from the Rosette from different dephts of the first 100 m. Profiles of temperature and salinity show slight differences between the situation in the Gulf of Aqaba and the northern Red Sea. The profiles for temperature indicate a small decrease of temperatur between 300 and 500 m. The nutrient concentrations imply strong differences between the investigated stations. The copepods were the most frequent group of the whole zooplankton community at all investigated stations with 76 - 79 % in the northern Red Sea and 84 - 88 % in the Gulf of Aqaba. Appendicularians, mollusks, ostracods and chaetognaths contribute more than 1% to the community. The vertical distribution shows at all stations a similar pattern. The upper 200 - 300 m hold the highest amount of the whole zooplankton community. Ostracods can be in high amounts in deeper regions too. Station 157 is an exception concerning the vertical distribution. There is an even distribution in the upper 400 m. Differences between day and night stations can be clearly seen. The highest zooplankton concentration are distributes in deeper regions at day stations than at night. The dominant group of the copepods were the calanoids on all stations with 62 - 79 %. Oithonids and poecilostomatids take part with 10 - 20 % of the Copepod community. The highest concentration of copepods is in the upper 300 m. The meaning of the calanoids is decreasing with depth while the poecilostomatids are increasing. Pleuromamma indica, a calanoid species, was taken to investigate distributional differences between the sex and the copepodit stages. The youngest copepodit stages (CI - CII) did not occur in the samples. Copepodit III stages only occurred in the northern Red Sea and the southern Gulf of Aqaba. The females domineer in the Gulf of Aqaba, while the northern Red Sea is domineeres by the males. Day and night differences were observed for the older Copepodit stages (CIV - CV) and the adults. The investigation of Position VI shows an increase of the standing stock and a higher concentration if the zooplankton to the upper 100 m. The chl a concentration does not increase, but the maximum is changing from 10 down to 50 m in the watercolumn. The community analysis shows that the two stations in the southern Gulf of Aqaba are similar. Including the different depth horizonts, the analysis shows that the cluster are build vertically. The community change is at the depth of the above mentioned temperature change. The phyto- and microplankton distribution of the upper 100 m shows different pictures. While at the stations of the southern Gulf (165, 167) the abundances are very high, we found low abundances at the other stations. The vertical distribution is different as well. The differences can be seen in the chl a concentrations. The dominant group at all stations are the coccolithophorids, followed by diatoms and dinoflagellates.



Item Type
Thesis (Diplom)
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Not peer-reviewed
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Published
Eprint ID
32158
Cite as
Cornils, A. (2001): Räumliche Verbreitung von Phyto- und Zooplankton im nördlichen Roten Meer , Diplom thesis, Christian-Albrechts-Universität Kiel.


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