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11.
H. Lippert K. Iken C. Volk M. Kck E. Rachor 《Journal of experimental marine biology and ecology》2004,310(2):131-146
The development of chemical defences in marine organisms is supposed to be driven by intense pressure of predation and competition. While benthic communities in tropical and also Antarctic regions are thought to be mainly structured by intra- and interspecific interactions, these factors are proposed to be less important in northern high latitudes. Consequently, selective pressure for chemical defence should be low in these regions. To investigate the incidence of chemical defence against predation in northern high latitudes, crude extracts of 18 abundant sessile or slow-moving invertebrate species (4 sponges, 3 actinians, 1 soft coral, 4 bryozoans, 3 ascidians and the egg mass of a gastropod) from Kongsfjord (Spitsbergen) were tested for feeding deterrent activity. Laboratory assays were performed by offering artificial food with extracts to two different predators, the amphipod Anonyx nugax which is a common species in Kongsfjord, and the starfish Asterias rubens from the North Sea. Of the 18 extracts tested, 2 (Haliclona viscosa, Hormathia nodosa) exhibited significant feeding deterrent effects in the amphipod assay. Furthermore, 6 extracts had a significantly stimulating effect on the amphipod feeding, and 10 extracts did not affect consumption. In the starfish assay, only the crude extract of H. viscosa was significantly rejected. For H. viscosa, feeding deterrence could be established for two pure compounds, and for H. nodosa for one fraction. The present data show that feeding deterrent compounds are present in sub-Arctic marine invertebrates from Kongsfjord but are less abundant than in temperate, tropical and Antarctic species. 相似文献
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Macrozoobenthic community structure was studied in two surveys along a transect of 13 stations following the submersed Pleistocene
Elbe valley in the south-eastern North Sea during May to June 2000 and March 2001. Two replicates of bottom samples were taken
with a van Veen grab of 0.1 m2 sampling size. In order to analyse the benthic macrofauna communities, the animals obtained were identified and counted,
and MDS and cluster analysis were performed. Out of 200 taxa identified, 84 were polychaetes, 46 molluscs, 40 crustaceans,
15 echinoderms, and 15 belonged to other groups. Mean abundance was 4,860 individuals per m2, mean biomass 32.9 g ash free dry mass per m2. Mean diversity was 1.76 and mean evenness 0.54. The macrofauna of the Pleistocene Elbe valley is composed of three associations
according to the cluster analysis. Each association is described by a combination of characterizing and discriminating species.
An Amphiura-brachiata―Tellimya-ferruginosa-association was found in the south-eastern part of the depression, whereas a transitional association with elements of both
assemblages lead to an Amphiura-filiformis―Galathowenia-oculata―Nuculoma-tenuis-association in the north-western part of the valley. In the context of the entire southern North Sea, both associations are
small-scale substructures, and as such are contained in the Nucula-nitidosa-community and the Amphiura-filiformis-community, respectively. A north-westward shift of the community of the southern Elbe valley was found and discussed as a
possible consequence of warm winters of the last decades. 相似文献
13.
Abundance and spatio-temporal distribution of meroplankton (larvae of invertebrate benthos) in the central Barents Sea and their dependence on abiotic factors were investigated. Samples were taken in different depth intervals on a south-north transect in the marginal ice zone in May 1997. At several locations sampling was repeated in June 1997. In May, total meroplankton abundances varied between 0.1 ind. m-3 and 32.0 ind. m-3, but mainly fluctuated around 10-15 ind. m-3. They were strongly affected by the mass occurrence of single species. At the northern, heavily ice-covered stations numbers decreased significantly. Larvae of 27 types were found. Polychaetes represented the most diverse group (13 species), followed by echinoderms (8 species). Larvae of only one bivalve species were found (Mya truncata), but with very high abundances (86 ind. m-3). Other taxa were represented only by single specimens. In June, total abundances were similar. The same species were present but the distribution patterns were less distinct, diversity values were higher and most larvae were further developed than in May. Distribution patterns of the larvae were to a large extent determined by physical processes in the area of the Polar Front, which acted as a distinct barrier in surface waters. In May, four meroplankton assemblages were distinguished, each associated with a different water mass. Most of the larvae have also been found in other investigated Arctic areas and belong to species with an Atlantic-Boreal-Arctic or Boreal-Arctic distribution. The relatively high numbers of larval types found in this study indicate that indirect development with pelagic larval stages plays a role in benthic recruitment in this sub-Arctic region. The relevance of these observations for the so-called Thorson rule is discussed. 相似文献
14.
Linda Luck Sean M. Bellairs Natalie A. Rossiter‐Rachor 《Ecological Management & Restoration》2019,20(3):214-221
Weed invasion is a major threat to Australian tropical savannas, and controlling weeds is essential for successful re‐establishment of native species on disturbed sites. Gamba Grass (Andropogon gayanus) is an African grass which has invaded large areas of tropical savanna across northern Australia. Current management strategies in northern Australia focus on fire and glyphosate to effectively control mature plants; however, re‐establishment of infestations from the soil seed bank remains a major challenge to eradication efforts. This study focused on the effects of soil seed bank treatments on Gamba Grass recruitment on a mine site in northern Australia. Adult Gamba Grass plants within test plots were killed with glyphosate to exclude resource competition. Chemical, physical and biological treatments were then applied, and the treatment effects on subsequent Gamba Grass seedling emergence and survival quantified. Seedling emergence was significantly reduced by three of the four residual herbicide treatments tested. The most effective herbicide treatments, dalapon and sulfometuron, reduced emergence by 90% compared to the standard glyphosate treatment alone. This equated to a reduction in Gamba Grass seedling emergence from 1 seedling/m2 to 1 seedling 10 m?2, a major improvement for Gamba Grass management. These residual herbicide treatments significantly reduced the population density of Gamba Grass for at least 5 months after emergence. The physical and biological treatments did not have a significant effect on seedling emergence. This significant reduction in Gamba Grass seedling emergence and survival can substantially improve Gamba Grass management. Reducing re‐colonisation from the soil seed bank using residual herbicides provides a valuable management tool for land managers, integrating readily with established strategies for controlling the mature plants. 相似文献
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Harinandanan Paramjyothi Brett P. Murphy Michael J. Lawes Natalie A. Rossiter‐Rachor Anna E. Richards 《Ecology and evolution》2020,10(9):4021-4030
Northern Australia's savannas are among the most fire‐prone biomes on Earth and are dominated by eucalypts (Eucalyptus and Corymbia spp.). It is not clear what processes allow this group to dominate under such extreme fire frequencies and whether a superior ability to compete for nutrients and water might play a role. There is evidence that eucalypts are adapted to frequent fires; juvenile eucalypts escape the fire trap by growing rapidly in height between fires. However, non‐eucalypts are less able to escape the fire trap and tend to have stand structures strongly skewed toward suppressed juveniles. The mechanisms that drive these contrasting fire responses are not well understood. Here, we describe the results of a controlled glasshouse seedling experiment that evaluated the relative importance of nutrient and water availability in determining height growth and biomass growth of two eucalypt and one noneucalypt tree species, common in northern Australian savannas. We demonstrate that growth of eucalypt seedlings is particularly responsive to nutrient addition. Eucalypt seedlings are able to rapidly utilize soil nutrients and accumulate biomass at a much greater rate than noneucalypt seedlings. We suggest that a seasonal spike in nutrient availability creates a nutrient‐rich microsite that allows eucalypt seedlings to rapidly gain height and biomass, increasing their likelihood of establishing successfully and reaching a fire‐resistant size. Our results extend our understanding of how eucalypts dominate northern Australian savannas under extremely high fire frequencies. 相似文献
17.
Lysek N Rachor E Lindel T 《Zeitschrift für Naturforschung. C, Journal of biosciences》2002,57(11-12):1056-1061
The brominated pyrrolo[2,3-b]indole deformylflustrabromine was isolated as a new natural product from the bryozoan Flustra foliacea, collected in the North Sea. Deformylflustrabromine appears to be the missing link in the biosynthetic sequence from flustrabromine to flustraminol A. Flustramines A, D, and dihydroflustramine C were determined as other major constituents of the investigated sample. Deformylflustrabromine is cytotoxic against the human colon cancer cell line HCT-116 (IC50 5.8 microM). 相似文献
18.
Sen Mui Tan Markus Kapp Christin Flechsig Kerstin Kapp Johannes E. Rachor Matthias Eyrich Juergen Loeffler Hermann Einsele Goetz U. Grigoleit 《Cytotherapy》2013,15(4):492-506
Background aimsDendritic cells (DC) have been vigorously investigated as an immunological basis for therapeutic vaccination against cancer and infections, even among patients after allogeneic stem cell transplantation.MethodsEffective induction of cell-mediated immunity strongly depends on the ability of DC to (i) migrate to the draining lymphoid organs mediated by chemokine receptors, (ii) prime T cells through high expression of costimulatory molecules and major histocompatibility complexes and (iii) secret Th1-polarizing cytokines such as Interleukin-12 (IL-12). However, there is no protocol to generate fully matured and functional DC according to methodical requirements of current good manufacturing practice (CGMP) guidelines.ResultsWe established a protocol conforming to CGMP standards that permits the generation of fully matured and functional DC on the basis of cell culture in adherence bags with the use of serum-free media with a maturation cocktail, containing tumor necrosis factor-alpha/Interferon-alpha/polyinosinic:polycytidylic acid. Our DC superiorly display three critical features for an effective induction of cell-mediated immunity without evidence of exhaustion, along with its ability to prime infectious or tumor-specific T cells in a short-term cell culture.ConclusionsOur newly developed protocol offers an attractive method to produce fully matured Th1-polarizing DC with proven migratory and stimulatory capacity for any clinical application according to CGMP standards. 相似文献
19.
D. Piepenburg N. V. Chernova C. F. von Dorrien J. Gutt A. V. Neyelov E. Rachor L. Saldanha M. K. Schmid 《Polar Biology》1996,16(6):431-446
Composition and distribution of megabenthic communities around Svalbard were investigated in June/July 1991 with 20 Agassiz
trawl and 5 bottom trawl hauls in depths between 100 and 2100 m. About 370 species, ranging from sponges to fish, were identified
in the catches. Species numbers per station ranged from 21 to 86. Brittle stars, such as Ophiacantha bidentata, Ophiura sarsi and Ophiocten sericeum, were most important in terms of constancy and relative abundance in the catches. Other prominent faunal elements were eunephthyid
alcyonarians, bivalves, shrimps, sea stars and fish (Gadidae, Zoarcidae, Cottidae). Multivariate analyses of the species and
environmental data sets showed that the spatial distribution of the megabenthos was characterized by a pronounced depth zonation:
abyssal, bathyal, off-shore shelf and fjordic communities were discriminated. However, a gradient in sediment properties,
especially the organic carbon content, seemed to superimpose on the bathymetric pattern. Both main factors are interpreted
as proxies of the average food availability, which is, hence, suggested to have the strongest influence in structuring megabenthic
communities off Svalbard.
Received: 28 April 1995/Accepted: 18 November 1995 相似文献
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