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A new method for processing clay-rich unconsolidated sediments for paleoecological investigations 总被引：1，自引：0，他引：1
A method is described for processing flocculated clay-rich sediments which avoids acetolysis and heavy liquid separation. Twin 80 (Merck index 1983) is used for deflocculation. Microsieves separate the recovered organisms according to size. Taxonomic identification and quantitative evaluation of the organisms can be performed in counting chambers or on permanent slides. Algae, cysts and exospores of dinoflagellates, pollen grains and zooplankton remains can be recovered. 相似文献
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N. Robinson P.A. Cranwell G. Eglinton S.C. Brassell C.L. Sharp M. Gophen U. Pollingher 《Organic Geochemistry》1986,10(4-6)
Lake Kinneret, a relict lake from the Neogene, is characterised by the dominance among its phytoplankton of the dinoflagellate Peridinium cinctum. The lipid geochemistry of Lake Kinneret is discussed herein in terms of the biology, chemistry and hydrology of the lake. Lipids isolated from two sediment sections (surface and 15 cm deep), obtained from the deepest point of Lake Kinneret, include: (1) 4α-methyl-5α (H)-stanols and related derivatives characteristic of P. cinctum, the novel sterol 4a-methylgorgosterol, and peridinosterol and 4α-methylgorgostanol, not previously reported to occur in lacustrine sediments; (2) C30 and C32 alkane-1,15-diols, not previously reported to occur in contemporary lacustrine deposits, and (3) products of early diagenesis. Many similarities were observed with the more widely studied marine dinoflagellates and marine sediments with dinoflagellate input. 相似文献
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T. Berman Y. Z. Yacobi U. Pollingher 《Aquatic Sciences - Research Across Boundaries》1992,54(2):104-127
The general features of phytoplankton seasonal succession, abundance and distribution in Lake Kinneret, as based on observations from 1970 through 1989, are summarised. Throughout this period of observation, the large, thecate dinoflagellatePeridinium gatunense formed an annual, late winter to early spring bloom resulting in very high standing stock levels. The dominance of these dinoflagellates has a profound impact upon the lake ecosystem. In the summer and fall the phytoplankton assemblage consisted mainly of nanoplanktonic green and blue-green algae and diatoms. Picophytoplankton, mainly picocyanobacteria, were present in low numbers during the dinoflagellate bloom but reached maximum abundance (105 cells · ml–1) in the epilimnion during the summer and fall. Within a given year, chlorophyll concentrations correlated well with estimates of wet weight biomass, derived from microscope counts. However, interannual averages of chlorophyll did not correlate closely with those for wet weight biomass. Both wet weight biomass and chlorophyll standing stocks fluctuated more than 2 fold from 1970 through 1989 but no extreme, long-term, continuous trend of increase or decrease was observed. Thus, phytoplankton has remained relatively stable although there has been a significant rise in the levels of summer-fall biomass since 1981. The main factor responsible for this may have been increased available phosphorus; the abundance of phytoplankton did not show any clear, long-term relation to that of herbivorous zooplankton. 相似文献
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The dynamics of theCeratium hirundinella population and the abundance of dinocysts in the plankton and sediments were studied in Lake Sempach in 1988. In 1987, a rich population ofCeratium (380 cells ml–1) accompanied byPeridinium spp. developed in the lake. The dinocysts were found entrapped in a kind of flocs, in the deepest part of the lake, in the upper flocculent layer. The number of viable cysts ofCeratium in the sediments decreased gradually from April to July 1988. TheCeratium population increased slowly starting in April, and reached a maximum number in August (31 cells ml–1).Peridinium willei reached 100 cells ml–1. Newly formed cysts ofCeratium were recorded in the plankton and sediments at the end of July — beginning of August. They appear in the sediments as separate cells. Their number increased gradually, reaching a maximum of 600 cysts l–1 at the end of October.Ceratium formed more cysts than didPeridinium, but the rate of survival of theCeratium cysts appears to be lower than that ofPeridinium cysts. In addition to their biological functions, the cysts also have an impact on the ecosystem as carriers of nutrients from down to up and from up to down. 相似文献
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