Remote Sensing of Biologically Reworked Sediments: A Laboratory Experiment     

Annelies De Backer  Stefanie Adam  Jaak Monbaliu  Erik Toorman  Magda Vincx  Steven Degraer 《Estuaries and Coasts》2009,32(6):1121-1129

The present study aims to test the application of remote sensing to address the impact of bioturbation on physical sediment properties. Therefore, a laboratory experiment was developed, using microcosms mimicking a marine intertidal water–sediment interface to test the influence of Corophium volutator densities on sediment properties. Three main variables (water content, clay content, and mean grain size) were measured in three treatments (no Corophium, 5,000 Corophium per square meter, and 20,000 Corophium per square meter) after 16 days of bioturbation. Results obtained with conventional—destructive—techniques showed a significant increase of water content and a significant, but small decrease of clay content in the presence of Corophium. The remote sensing technique detected the impact of Corophium on water content as an increase in absorption at 1,450 nm, but was not able to detect the animal impact on clay content. This study demonstrates that remote sensing data could be significantly modified by bioturbation activities and that remote sensing can be applied in the laboratory to address the impact of bioturbation on sediment properties. This possibly opens new perspectives for long-term experiments concerning the role of bioturbation on sedimentary processes.  相似文献   

Generation and expulsion of oils from Permian coals of the Sydney Basin,Australia     

Manzur Ahmed  Herbert Volk  Simon C. George  Mohinudeen Faiz  Linda Stalker 《Organic Geochemistry》2009,40(7):810-831

Organic geochemical and petrological assessment of coals/coaly shales and fine grained sediments, coupled with organic geochemical analyses of oil samples, all from Permo–Triassic sections of the Southern Sydney Basin (Australia), have enabled identification of the source for the widely distributed oil shows and oil seeps in this region. The Permian coals have higher hydrogen indices, higher liptinite contents, and much higher total organic matter extract yields than the fine grained sediments. A variety of source specific parameters obtained from n-alkanes, regular isoprenoids, terpanes, steranes and diasteranes indicate that the oil shows and seeps were generated and expelled predominantly from higher plant derived organic matter deposited in oxic environments. The source and maturity related biomarkers and aromatic hydrocarbon distributions of the oils are similar to those of the coals. The oil-coal relationship also is demonstrated by similarities in the carbon isotopic composition of the total oils, coal extracts, and their individual n-alkanes. Extracts from the Permo–Triassic fine grained sediments, on the other hand, have organic geochemical signatures indicative of mixed terrestrial and prokaryotic organic matter deposited in suboxic environments, which are significantly different from both the oils and coal extracts. The molecular signatures indicating the presence of prokaryotic organic matter in some of the coal extracts and oils may be due to thin sections of possibly calcareous lithologies interbedded within the coal measures. The genetic relationship between the oils and coals provides new evidence for the generation and expulsion of oils from the Permian coals and raises the possibility for commercial oil accumulations in the Permian and Early Triassic sandstones, potentially in the deeper offshore part of the Sydney Basin.  相似文献   

Changes in North Sea macrofauna communities and species distribution between 1986 and 2000     

Ingrid KrönckeHenning Reiss  Jacqueline D. EggletonJohn Aldridge  Magda J.N. BergmanSabine Cochrane  Johan A. CraeymeerschSteven Degraer  Nicolas DesroyJean-Marie Dewarumez  Gerard C.A. DuineveldKarel Essink  Hans HillewaertMarc S.S. Lavaleye  Andreas MollStefan Nehring  Richard NewellEivind Oug  Thomas PohlmannEike Rachor  Mike RobertsonHeye Rumohr  Michaela SchratzbergerRebecca Smith  Edward Vanden Berghe  Jan van DalfsenGert van Hoey  Magda VincxWouter Willems  Hubert L. Rees 《Estuarine, Coastal and Shelf Science》2011,94(1):1-15

The North Sea Benthos Project 2000 was initiated as a follow-up to the 1986 ICES North Sea Benthos Survey with the major aim to identify changes in the macrofauna species distribution and community structure in the North Sea and their likely causes.The results showed that the large-scale spatial distribution of macrofauna communities in the North Sea hardly changed between 1986 and 2000, with the main divisions at the 50 m and 100 m depth contours. Water temperature and salinity as well as wave exposure, tidal stress and primary production were influential environmental factors on a large (North Sea-wide) spatial scale.The increase in abundance and regional changes in distribution of various species with a southern distribution in the North Sea in 2000 were largely associated with an increase in sea surface temperature, primary production and, thus, food supply. This can be most likely related to the North Sea hydro-climate change in the late 1980s influenced by the variability in the North Atlantic Oscillation (NAO). Only one cold-temperate species decreased in abundance in 2000 at most of the stations. Indications for newly established populations of offshore non-native species were not found.Differences in macrofauna community structure on localised spatial scales were predominantly found north of the 50 m depth contour off the British coast along the Flamborough Head Front towards the Dogger Bank, off the coast of Jutland and at the Frisian Front. These changes were most likely attributed to stronger frontal systems in 2000 caused by the increased inflow of Atlantic water masses in relation to the hydro-climate change in the late 1980s.  相似文献   

Salt response of the freshwater microalga Scenedesmus obliquus (Turp.) Kutz is modulated by the algal growth phase     

Taha Mohamed El-Katony  Magda Faiz El-Adl 《中国海洋湖沼学报》2020,38(3):802-815

Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of growth. The alga was cultured on BG11 growth medium and subjected to 0, 30, 100, and 200 mmol/L NaCl for a period of 20 d, during which algal cultures were harvested at 4-d intervals. The salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth phases. The sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to salinity. The concentrations of chlorophylls a and b, soluble sugars, proteins as well as those of K+ and Na+ in the alga exhibited peaks at the initiation of the exponential phase of growth, with increasing magnitude in proportion to the increase in the level of salinity. Nevertheless, whereas soluble sugars of the alga peaked at initiation of the exponential phase, starch concentration progressively increased with culture age, reaching saturation towards the stationary phase. Whereas the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for starch. The present results point to fast acclimation of S. obliquus to salt stress post a brief salt shock, utilizing soluble sugars, K+ and Na+ for osmotic adjustment. Increasing salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars, proteins, K + and Na + concentrations of the algal cells, particularly at the early stages of growth. However, the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth.  相似文献   

Planetary nebulae as tracers of galaxy stellar populations     

Alberto Buzzoni  Magda Arnaboldi  Romano L. M. Corradi 《Monthly notices of the Royal Astronomical Society》2006,368(2):877-894

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Spatial distribution of phytoplankton in Spring 2004 along a transect in the eastern part of the North Sea     

Pavel Škaloud  Magda Řezáčová  Marianne Ellegaard 《Journal of Oceanography》2006,62(5):717-729

We report the results from a 250 km long transect, from the Danish coast to the North Sea at 55°30′ N, which was sampled every 32 km in order to study the composition and distribution of phytoplankton, and their dependence on the distance from the coast, depth and other environmental factors. Altogether 144 species of algae were identified by light, epifluorescence and electron microscopy. Some ecological preferences were found on the basis of measured environmental parameters and compared with the literature. Possible controlling mechanisms for the distribution patterns of the plankton algae were analyzed by multivariate statistics. Only distance from the coast was found to be a significant factor for algal distribution along the transect. Three main areas of the transect were found: the coastal, middle and oceanic areas. Diatoms, mainly the centric ones, were the most abundant group of algae. The other less abundant groups were Dinophyceae, Dictyochophyceae, Prasinophyceae and Chlorophyceae. The pattern of distribution of diatoms and dinophytes along the transect was more or less similar, with larger numbers of cells found close to both the eastern and western parts of the transect, although the species composition was different. Some species were found to prefer coastal waters, other species were characterized as oceanic, and several species were found at all stations. Porosira glacialis showed an atypical distribution along the transect, with highest abundances at both coastal and oceanic stations.  相似文献   

Mortality in megafaunal benthic populations caused by trawl fisheries on the Dutch continental shelf in the North Sea in 1994   总被引：4，自引：6，他引：4  

Bergman  Magda J. N; van Santbrink  Jan W 《ICES Journal of Marine Science》2000,57(5):1321-1331

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A bio-engineered soft-bottom environment: The impact of Lanice conchilega on the benthic species-specific densities and community structure   总被引：2，自引：0，他引：2  

Marijn Rabaut  Katja Guilini  Gert Van Hoey  Magda Vincx  Steven Degraer 《Estuarine, Coastal and Shelf Science》2007,75(4):525-536

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Small- to large-scale geographical patterns within the macrobenthic Abra alba community     

Gert Van Hoey  Magda Vincx  Steven Degraer 《Estuarine, Coastal and Shelf Science》2005,64(4):751-763

The Abra alba community is widely spread in the coastal zone of the English Channel and the Southern Bight of the North Sea. The community is located on shallow, fine muddy sands. Its spatial distribution can be broken up into a number of isolated patches (Atlantic French, British and German coast) and one large continuous distribution area (northern France up to the Netherlands). The aim of this study is to investigate the geographical patterns within the macrobenthic A. alba community at different scales: the community's full distribution range (i.e. large scale) and a selected area with a continuous distribution of the A. alba community (i.e. small scale) in relation to structuring environmental variables. Therefore, an analysis of newly collected samples along the Belgian coastal zone was combined with available information on the A. alba community throughout its distribution range. Although the community structure shows a high similarity across the full distribution range of the A. alba community, large- as well as small-scale changes in community composition were observed: the Belgian Continental Shelf (BCS) should be considered as a major transition from the rich southern to the relatively poorer northern distribution area of the A. alba community. At a large scale (i.e. full distribution range), the differences in community structure are expected to result from (1) the specific hydrodynamic conditions in the English Channel (Atlantic ocean waters) and the Southern Bight of the North Sea, with a consequent differential connectivity between the different areas and (2) the climatological and related faunal shift from temperate (English Channel) to boreal conditions (German Bight). At a small scale (i.e. within the continuous distribution area), structural and functional community aspects may result from geographic differences in (1) detrital food availability, related to riverine input and pelagic productivity, along and across the coastline and (2) the amount of suspended matter, impoverishing the A. alba community when excessively available.  相似文献   

Isolation and expression analysis of FTZ-F1 encoding gene of black rock fish (Sebastes schlegelii)     

Muhammad Shafi  WANG Yanan  ZHOU Xiaosu  MA Liman  Faiz Muhammad  QI Jie  ZHANG Quanqi 《中国海洋大学学报(英文版)》2013,12(1):183-189

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