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1.
We compare foraminifera and macrofauna as bio-indicators of oil-based drill mud disposal site off Congo. The most polluted sites are characterized by poor faunas, dominated by some very tolerant taxa. Slightly further from the disposal site, there is an area with strongly increased densities, heavily dominated by opportunistic taxa. Still further, macrofauna appears to be similar to that at the reference area, but the foraminiferal meiofauna still suggests a slight environmental perturbation. The foraminiferal FIEI index, based on the species distribution in the study area, appears to be more discriminative than the macrofaunal ITI index, based on a priori definitions of the trophic guilds of the various taxa. Our comparative approach allows us to point out the benefits of (1) the use of macrofauna and foraminifera together and (2) the definition of the species groups used in biotic indices on the basis of observations made directly in the study area.  相似文献   

2.
The thermal pollution patch of Hadera power plant was used as a natural laboratory to evaluate the potential long-term effects of rise in Eastern Mediterranean SST on living benthic foraminifera. Their sensitivity to environmental changes makes foraminifera ideal for this study. Ten monthly sampling campaigns were performed in four stations located along a temperature gradient up to 10 °C from the discharge site of heated seawater to a control station. The SST along this transect varied between 25/18 °C in winter and 36/31 °C in summer. A significant negative correlation was found between SST in all stations and benthic foraminiferal abundance, species richness and diversity. The total foraminiferal abundance and species richness was particularly low at the thermally polluted stations especially during summer when SST exceeded 30 °C, but also throughout the entire year. This indicates that thermal pollution has a detrimental effect on benthic foraminifera, irrelevant to the natural seasonal changes in SST.  相似文献   

3.
《Marine pollution bulletin》2010,60(8-12):297-310
The ecological status of an environment should be evaluated by comparison with local “reference conditions”, here defined as the pre-industrial ecological status of the 19th century. This pilot study illustrates how micropalaeontological monitoring, using benthic foraminifera (protists) and associated geochemical parameters preserved in inner Oslofjord (Norway) sediments, characterise local reference conditions. In order to optimise the usefulness of the ecological information held by foraminifera and enable characterisation of temporal changes in environmental quality beyond time intervals covered by biological time-series, the Norwegian governmental macrofauna-based classification system is applied on fossil benthic foraminiferal assemblages. Quantitative comparisons demonstrate deteriorating ecological status in response to increased anthropogenic forcing (eutrophication, micropollutants), including a 73% loss in number of foraminiferal species. Despite reduced pollution during the past decades and, at one site, capping of polluted sediments with clean clay, the reference conditions are far from re-established. Micropalaeontological monitoring requires net sediment accumulation basins and careful considerations of taphonomic processes.  相似文献   

4.
Abstract Analysis of the 12 samples taken from two horizons (the pre-1991 Mount Pinatubo eruption and the post-1991 Mount Pinatubo eruption layers) of the six deep water cores that were collected along the Eastern South China Sea shows that the absolute abundance of Recent benthic foraminifera (total assemblage) in the post-eruption layer is much lower compared to the pre-eruption layer. The post-eruption layer also shows lower diversity with relative high abundance of Quinqueloculina spp., which probably form part of the recolonization fauna. These observations suggest that environmental stability plays a vital role in the distribution of foraminifera in the eastern margin of the South China Sea. The disturbance created by the immense amount of pyroclastic materials that originated from the 1991 eruption of Mount Pinatubo has resulted in the dilution and, eventually, the decimation of most of the benthic foraminifera. The species that were able to survive might have taken advantage of the small amounts of available nutrient supply. These might also be the species that were able to adapt quickly to the changes in the environmental conditions.  相似文献   

5.
Biomonitoring of estuarine pollution is the subject of active research, and benthic foraminifera are an attractive group to use for these purposes due to their ubiquitous presence in saline water and wide diversity. Here, we describe a case study of biomonitoring using benthic foraminifera in the French Mediterranean lagoon, Bages-Sigean lagoon. In this case, the major pollutants of interest are heavy metals in the sediment, particularly contaminated by Cu and Cd derived from industrial and agricultural sources. The foraminiferal assemblages of the Bages-Sigean lagoon are typical of normal paralic environments, but unusually almost completely lack agglutinated forms. The density of benthic foraminifera was shown to be more influenced by the sediment characteristics rather than heavy metal pollution. However, the relative abundance of Quinqueloculina bicostata was shown to increase in the most polluted areas and we propose that this taxon may be used as an indicator of heavy metal pollution.  相似文献   

6.
Superficial bottom samples were collected near diffusers of domestic sewage submarine outfalls at Araçá and Saco da Capela, São Sebastião Channel, Brazil. The goal of this study was to investigate the distribution and composition of live benthic foraminifera assemblages and integrate the results obtained with geochemical analyses to assess human-induced changes. According to the results obtained no environmental stress was observed near the Saco da Capela submarine outfall diffusers. The foraminifera assemblage is characterised by species typical of highly hydrodynamic environments, with well-oxygenated bottom waters and low nutrient contents. In contrast, near Araçá submarine outfall, organic enrichment was denoted by high phosphorus, sulphur and, to a lesser extent, total organic carbon content. Harmful influences on foraminifera could be identified by low richness and specific diversity, as well as the predominance of detritivore feeder species, which are associated with higher organic matter flux and low oxygen in the interstitial pore water.  相似文献   

7.
The shallow subtidal macrobenthos at Port Valdez, Alaska, was examined to assess faunal adjustment following disposal of dredged sediments over a three-year period. Prior to sediment disposal, the infauna consisted of a relatively species-rich assemblage dominated by sessile polychaetes and bivalves. Six months after disposal, virtually all taxa present prior to dredging and disposal were rare or absent with opportunistic taxa dominant. Surveys performed 1.5 years after sediment disposal indicated faunal adjustment was in progress; large, sessile polychaetes and bivalves were still present in low numbers after 2.5 years. At one station, increasing organic enrichment by fish-wastes from adjacent processing plants resulted in a shift to a highly disturbed benthic assemblage. The trends in the faunal assemblage suggest that environmental conditions were still in a state of flux 2.5 years after the dredging event.  相似文献   

8.
The eastern Mediterranean is naturally highly oligotrophic, but urbanization along the Levant coast has led to raised organic and nutrient loads. This study tracks living foraminiferal assemblages at two sites near an activated sewage sludge outfall from 11/2003 to 5/2004. Oligotrophic site PL29 shows seasonal variations in O2, chlorophyll a, and organic carbon, and has an abundant, diverse benthic foraminiferal assemblage living at various in-sediment depths. At eutrophic site PL3, ∼16 years of sludge injection favor a depleted assemblage primarily of opportunist foraminifera. This site shows less seasonality, is subjected to organic matter overload, O2-stress, and periodic anoxia, foraminifera are less abundant and diverse, and live at shallower depths. The assemblages at both sites represent a common pool of species, with Ammonia tepida highly dominant. Benthic foraminifera were therefore found to be sensitive to trophic trajectories, respond on sub-seasonal time-scales, and track injection and dispersal of organic loads on the shelf.  相似文献   

9.
Hiroshi  Kitazato 《Island Arc》1997,6(2):144-157
Abstract The northern tip of the Izu-Ogasawara Arc on the Philippine Sea plate collided with the central part of the Honshu Arc in the early Quaternary. The collision history is recorded in late Cenozoic strata that are distributed widely in central Japan. To reconstruct paleotopography during the collision process, paleogeographic maps of central Japan were drawn at six time slices during the late Cenozoic. These maps were made from paleodepth data that were inferred from benthic foraminiferal fossil assemblages. Sedimentological information was also added to the maps. The paleogeographic maps show several distinctive geological features. The paleodepth of the area between the Izu-Ogasawara Arc and the Honshu Arc changed quickly from deep-sea to shallow marine during the Quaternary by means of rapid deposition of large amounts of coarse-grained detritus. The conglomerate was first deposited in a trough as deep-sea fan deposits, and filled the trough until an alluvial fan was formed. Forearc basins of the Honshu Arc facing the collision area subsided from 3 to 1 Ma. Vertical movement of the basin was inferred from a strata thickness/paleodepth correlation graph. It is thought that the tectonic inversion seen in sedimentary basins in the Kanto and Tokai regions might be closely related to the change of motion of the Philippine Sea plate. However, a basin of the Ashigara area sunk continuously without interruption until 0.7 Ma. The collision event affected strongly distribution of deep-sea benthic foraminifera. Paleogeographic maps show that a deep trough appeared in the Ashigara area between 3 and 1.5 Ma. This trough may have served as a passage for the migration of deep-sea benthic foraminifera between the Pacific and the Philippine Sea. Cold water benthic foraminiferal species occur west of the Izu-Ogasawara ridge deposited in strata during the existence of the passage.  相似文献   

10.
梅梁湾是太湖北部最大湖湾,也是太湖生态环境问题最严重的区域之一,近年来对太湖治理力度不断加大,然而对其生态状况演变的认识尚不清晰。本文基于长期监测及文献资料,获得1980s以来太湖梅梁湾底栖动物及环境因子数据,分析底栖动物种类组成、优势种、丰度的时空变化,应用非度量多维尺度分析(NMDS)和随机森林(RF)分析群落结构演变及其与环境因子的关系。结果表明,梅梁湾1980—2019年共记录到44属(种)底栖动物,以摇蚊幼虫和软体动物为主,总丰度年际变化显著,40年来底栖群落结构发生显著变化,优势种经历了由较敏感的软体类为主到以耐污寡毛类、摇蚊幼虫等为主的转变。综合NMDS和随机森林分析结果,梅梁湾底栖动物群落演变大致可分为4个阶段:1980s及以前,物种多样性丰富,以河蚬(Corbicula fluminea)等大型软体动物为优势种;1990s—2007年,底栖动物群落快速退化,以耐污种占优;2008—2016年,水生态略有恢复,河蚬等清洁种略有回升;2017—2019年,耐污种优势度和丰度反弹。近40年来梅梁湾底栖动物群落变化主要受底质氮磷、有机质和水体营养盐、蓝藻水华等环境因子变化的影...  相似文献   

11.
An in situ experiment was done to evaluate the dose-dependent response of mussel biodeposition on benthic communities and biogeochemical fluxes. Natural benthic communities were exposed to 7 different levels of mussel biodeposition (equivalent to that produced by 0-764 mussels m−2) over 50 days. Benthic communities responded as predicted from the Pearson, T.H., Rosenberg, R., 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanogr. Mar. Biol. Annu. Rev. 16, 229-311 model of organic enrichment. Total abundance and species richness decreased with increasing biodeposition. The abundance and biomass of opportunistic species (Capitella spp.) increased in the mesocosms subject to the greatest biodeposition. Sensitive species Tellina agilis and Pherusa plumosa tended to decrease in abundance and biomass with increasing biodeposition. The biotic index M-AMBI responded clearly to increased biodeposition and may be a useful tool for assessing the effect of mussel biodeposition on the benthic environment. These results are important for the construction of predictive models for determining environmental carrying capacity for bivalve aquaculture.  相似文献   

12.
In the 20th century an important industrial plant operated on the coastal area of Bagnoli. After its closing, an integrated study of environmental characterisation aimed at restoration started. The survey conducted was based on chemical and sedimentological analyses integrated with benthic foraminifera analyses. Statistical analysis of the data shows sectors with a distinct type and degree of pollution. Particularly, pollution linked to the silty sediment fraction, mainly due to Pb and Zn, was recognised in front of the southern sector of the plant. The study of benthic foraminifera provides evidence for a pollution-tolerant character in some species like Haynesina germanica and Quinqueloculina parvula. In addition, two species among the 113 recognised show high percentages of abnormal specimens. These percentages show a statistical correlation with some pollutants (PAHs, Mn, Pb and Zn). In addition, Energy Dispersive Spectrometry shows small amounts of Fe ions included in deformed tests of Miliolinella subrotunda. Because the number of these deformations is positively correlated to the concentration of PAHs, Mn and Zn, the inability of some specimens to exclude the foreign elements from the crystalline reticulum of the test could be attributed to the potential toxic effect of these pollutants.  相似文献   

13.
The aim of this study is to develop a new method for classification of marine benthic quality according to the European Union Water Framework Directive. Tolerance values to environmental disturbance were determined in an objective analysis for benthic species along the Swedish west coast by using 4676 samples from 257 stations. Based on a combination of the species tolerance values, abundance and diversity, a benthic quality index (BQI) was calculated for the assessment of environmental status at a particular station. The qualification of BQI was evaluated in relation to known spatial and temporal gradients of disturbance.  相似文献   

14.
This study reports the longitudinal distribution of sediment properties, including inorganic and organic contaminants, and the structure of the benthic community in Obidos lagoon, a coastal system permanently connected to the sea and with negligible freshwater sources. Sediments from the upper to central lagoon consist of fine particles (91%) and from the lower lagoon of sands (94%). Chemical composition is strongly correlated to the percentage of fine particles. Contamination is relatively low in those sediments suggesting the effect of diffuse sources. The increase in organic matter content from down- to upstream areas was associated with the dominance of opportunistic species, while sensitive and indifferent species to organic enrichment were mainly associated to the clean sandy downstream area. The marine biotic index (AMBI) was suitable for the discrimination of the biological and environmental gradients in the Obidos lagoon and was highly related with the gradient of organic matter content in this system.  相似文献   

15.
Records of the past neodymium (Nd) isotope composition of the deep ocean can resolve ambiguities in the interpretation of other tracers. We present the first Nd isotope data for sedimentary benthic foraminifera. Comparison of the ?Nd of core-top foraminifera from a depth transect on the Cape Basin side of the Walvis Ridge to published seawater data, and to the modern dissolved SiO2–?Nd trend of the deep Atlantic, suggests that benthic foraminifera represent a reliable archive of the deep water Nd isotope composition. Neodymium isotope values of benthic foraminifera from ODP Site 1264A (Angola Basin side of the Walvis Ridge) from the last 8 Ma agree with Fe–Mn oxide coatings from the same samples and are also broadly consistent with existing fish teeth data for the deep South Atlantic, yielding confidence in the preservation of the marine Nd isotope signal in all these archives. The marine origin of the Nd in the coatings is confirmed by their marine Sr isotope values. These important results allow application of the technique to down-core samples.The new ?Nd datasets, along with ancillary Cd/Ca and Nd/Ca ratios from the same foraminiferal samples, are interpreted in the context of debates on the Neogene history of North Atlantic Deep Water (NADW) export to the South Atlantic. In general, the ?Nd and δ13C records are closely correlated over the past 4.5 Ma. The Nd isotope data suggest strong NADW export from 8 to 5 Ma, consistent with one interpretation of published δ13C gradients. Where the ?Nd record differs from the nutrient-based records, changes in the pre-formed δ13C or Cd/Ca of southern-derived deep water might account for the difference. Maximum NADW-export for the entire record is suggested by all proxies at 3.5–4 Ma. Chemical conditions from 3 to 1 Ma are totally different, showing, on average, the lowest NADW export of the record. Modern-day values again imply NADW export that is about as strong as at any stage over the past 8 Ma.  相似文献   

16.
This study tested the hypothesis that, during recent years, the benthic macroinvertebrate fauna of the large basin of the Swan-Canning Estuary has changed in ways consistent with deteriorating environmental conditions in that estuary. Between 1986/7 and 2003/4, the compositions of that fauna altered markedly at the species and even family levels. Thus, the densities and number of species of molluscs, and especially of crustaceans, which are particularly susceptible to environmental stress, declined, while those of the more tolerant polychaetes increased. However, taxonomic distinctness declined consistently only at one of the four widely-spaced sampling sites and the dispersion of samples did not differ markedly between periods, indicating that the benthic fauna has not undergone such extreme changes as in the nearby Peel-Harvey Estuary. It is thus proposed that benthic macroinvertebrates can act as important indicators of the severity of environmental degradation in microtidal estuaries in regions where such perturbations are increasing.  相似文献   

17.
The impact of continuous disposal of fine-grained sediments from maintenance dredging works on the suspended particulate matter concentration in a shallow nearshore turbidity maximum was investigated during dredging experiment (port of Zeebrugge, southern North Sea). Before, during and after the experiment monitoring of SPM concentration using OBS and ADV altimetry was carried out at a location 5 km west of the disposal site. A statistical analysis, based on the concept of populations and sub-sampling, was applied to evaluate the effect. The data revealed that the SPM concentration near the bed was on average more than two times higher during the dredging experiment. The disposed material was mainly transported in the benthic layer and resulted in a long-term increase of SPM concentration and formation of fluid mud layers. The study shows that SPM concentration can be used as an indicator of environmental changes if representative time series are available.  相似文献   

18.
Temporal changes in the composition of soft bottom macrobenthic assemblages at Reunion Island (Southwest Indian Ocean) were studied in the context of a long-term environmental monitoring programme studying the impacts of effluents of industrial sugar cane refineries that are transferred to shallow and deep coastal environments by different pathways: surface discharge and deep underground injection. Seven stations (between 20 and 160 m depth) were surveyed between 1994 and 2003 on the industrial zone. One additional station was surveyed on a reference site. Spatio-temporal changes in the composition of macrobenthic communities were assessed using several diversity indices, ABC curves, MDS and associated ANOSIM tests and biotic indices. Among the 171 taxa recorded, polychaetes were dominant (89 species), followed by crustaceans and molluscs. The analysis of spatial changes in the composition of macrobenthos showed the existence of distinct benthic communities along the depth gradient. Temporal changes in macrobenthos composition were most prominent at the shallowest station. They mainly corresponded to the decline of several initially dominant taxa and the increase of the Eunicid polychaete Diopatra cuprea. This station further showed increasing macrofaunal abundance, biomass and sediment organic content over time, concomitant with decreasing sediment grain sizes. In deeper environments, temporal changes were much smaller. Macrofaunal abundance and species richness increased progressively, suggesting a moderate impact on benthic ecosystems resulting from slight enrichments due to effluents rich in organic matter. Our results highlight an original response to disturbance pattern involving opportunistic Eunicidae species (D. cuprea) not previously described. Moreover, they allow for the comparison of the impact on macrofauna caused by industrial effluents exported by two distinct and different pathways in a tropical coastal high-energy marine environment.  相似文献   

19.
The results of a monitoring programme to assess the spatial impacts associated with ongoing dredged material disposal activity at a dispersive, coastal disposal site (southwest UK) are described. Benthic impacts were assessed using benthic community structure and secondary productivity estimates.Analyses of univariate indices (including secondary production) and multivariate community structure revealed differences between stations inside and those outside the disposal site were minimal. Generally, stations within and outside the disposal site were characterised by the same species. Regression models indicated that the variability in biological structure and secondary production was predominantly accounted for by natural variables (e.g., depth, sediment granulometry) with only a small amount of residual variability being due to contaminant variables. Thus, the elevated levels of certain contaminants in the vicinity of the disposal area were not sufficient to result in significant ecological or ecotoxicological changes. We ascribe such findings partly to the dispersive nature of the disposal site.  相似文献   

20.
Macroinvertebrates play a key role in freshwater lentic and lotic ecosystems. The macroinvertebrate benthic community of a shallow Mediterranean lake (Lake Pamvotis, NW Greece) was studied. The benthic assemblage was sampled monthly at five sites during a period of 1 year (Apr. 1998–Mar. 1999). In addition hypolimnetic water quality variables were monitored over the same period at each site.

The aim of the study was (a) to describe the intra-annual and spatial variability in benthic communities, (b) to relate possible community changes to environmental conditions and (c) to evaluate the responses of the lake's ecological status on community indices.

The benthic fauna of Lake Pamvotis was found to be very limited with a total of 10 species belonging to five taxonomic groups. The oligochaete community comprised 80% of the total benthic fauna with Potamothrix bavaricus as a new record for the Lake Pamvotis and Potamothrix hammoniensis, being the dominant benthic species represented more than 61% of the total benthic fauna. Chironomus plumosus was the most abundant chironomid species contributing with about 6% of the total benthic fauna, and Chaoborus flavicans with 19% was the important dipteran. Almost all benthic species showed the same intra-annual seasonal pattern, with peak population densities during spring and early summer except P. hammoniensis which predominated during the whole sampling period. Dissolved oxygen and temperature seemed to be the main environmental factors affecting community indices.

Benthic communities are affected by human disturbances in Lake Pamvotis shifting their composition to more tolerant taxa, reflecting also the eutrophic to hypertophic character of the lake.  相似文献   


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