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1.
太湖东部不同类型湖区底泥疏浚的生态效应   总被引：9，自引：1，他引：8  
为研究底泥生态疏浚对太湖东部不同类型湖区水生生态系统的影响,2012年8月于东太湖养殖湖区和胥口湾草型湖区采集沉积物和生物样品,分析疏浚对底泥污染控制、水质改善以及各生物群落结构的影响.结果表明,底泥疏浚能有效去除表层沉积物中的营养物质,降低底泥重金属含量及其潜在生态风险,但底泥疏浚对不同类型湖区水质和生物群落结构的影响存在明显差别.在富营养化较严重的东太湖养殖湖区,底泥疏浚达到了一定的改善水质的效果,浮游植物密度、生物量均不同程度降低,且群落中蓝藻所占比例下降;水生植物和底栖动物群落也在较短时间内得到恢复;胥口湾草型湖区的底泥疏浚则破坏了原先良好的水生植物群落,造成湖区整体水质下降,各主要生物类群的恢复相对缓慢.  相似文献   

2.
A meta-analysis approach was used to assess the effect of dredging induced changes in sediment composition, under different conditions of natural physical disturbance, for the structure and function of marine benthic macrofaunal communities. Results showed the sensitivity of macrofaunal communities increased as both the proportion of gravel increased and the level of natural physical disturbance decreased. These findings may be explained by the close association of certain taxa with the gravel fraction, and the influence of natural physical disturbance which, as it increases, tends to restrict the colonisation by these species. We conclude that maintaining the gravel content of surface sediments after dredging and, where practicable, locating extraction sites in areas of higher natural disturbance will minimise the potential for long-term negative impacts on the macrofauna.  相似文献   

3.
Sands for the nourishment of beaches along the Emilia-Romagna coast (northern Adriatic Sea) were dredged from an offshore area characterised by relict sands formed during the last Adriatic post-glacial transgression. The short-term effects of the sand extraction on macrozoobenthic communities were investigated before, during and 1, 6 and 12 months after dredging at three impacted stations and seven control stations. Sand extraction activities did not significantly influence the granulometry and %TOC in the sediment but caused almost complete defaunation at dredging stations. Yet, just 12 months after the extraction, the recolonisation of communities at the impacted stations was at an advanced stage. Unlike other studies on the effects of extraction of marine sand, no significant settlement of opportunistic species was observed. The limited impact of the sand extraction operation on the physical characteristics of the sediment and hydrological-sedimentary characteristics in the relict sand area should aid its rapid recovery and the restoration of the original community in a short period of time (2-4 years after dredging).  相似文献   

4.
The Orbetello lagoon, one of the largest Western Mediterranean lagoons, was affected by high algal blooms and severe anoxic crises in 1992 and 1993, with fish mortality throughout most of the lagoon and a drastic reduction of benthic species. Many measures were undertaken between 1994 and 1996 to remove the severe eutrophication of this lagoon. Such measures included harvesting of the floating seaweed biomass, removal of all wastewater and sea channel enlargement by dredging activity. The aim of the present research was to study the macrozoobenthic assemblage in 1999 and to compare it with previous research in order to assess the recovery of the lagoon. A total of 106 taxa and 45,175 individuals were collected in three areas (sea inlets, western and eastern lagoon) having different organic matter loading during winter and summer. The results of multivariate and correlation analyses indicated that trophic status and its seasonal dynamics were crucial in determining species distribution among the different areas. Moreover, comparison of the macrozoobenthic structure between winter 1995 and 1999 showed differences in species composition and structural parameters in the western and eastern lagoon, where a clear recovery of benthic assemblages was observed in 1999. However, the dominance of opportunistic species in most of the lagoon and the decrease in some structural parameters during summer suggested that this basin still presented signs of disturbance in 1999, six years after the last extended anoxic crises and even after completion of the restoration measures carried out in the environment. It was hypothesized that a secondary disturbance, sustained by a high seasonal release of nutrients from the sediments, could create considerable deviations from the expected improvement in benthic conditions.  相似文献   

5.
A project to deepen shipping and entrance channels in Charleston Harbor was conducted from 1999 to 2002. This generated approximately 22 million cubic yards of sediment for offshore disposal. Assessments of biological and physical conditions in the Charleston Ocean Dredged Material Disposal Site and surrounding areas were conducted prior to deepening (1993-94), and partway through the disposal period (2000). Results from the 2000 survey are presented and compared to the baseline survey. The study area was composed of the disposal zone and surrounding areas and divided into 20 one square mile strata. Within each stratum, benthic grab samples were collected from ten random sites for analysis of sediment composition and contaminants and macrobenthic assemblages. No contaminant levels were above effects range low levels. Results revealed that sediments in the western strata had significantly higher silt/clay content in the 2000 survey when compared to baseline sediments, while sediments east of the disposal zone were similar to baseline. Analyses were performed on a subset of the benthic data that compared baseline to 2000 conditions in western and eastern strata. The benthic communities in western strata were altered following disposal operations. The benthic community east of the disposal area was not different from baseline conditions. These alterations in the benthic community were attributed to changes in bottom habitat characteristics rather than pollution effects.  相似文献   

6.
Dredging operations in a Swedish estuary reduced the number and diversity of benthic species. The larval recruitment in the vicinity of the dredged area was strongly affected. An overall increase in concentrations of Hg, Cd, Zn, Cu, Pb and Ni were recorded in benthic fauna. One and a half years after termination of dredging, the benthic community structure was nearly restored and the high concentrations of heavy metals had decreased considerably.  相似文献   

7.
Previous research to assess impacts from aggregate dredging has focussed on infaunal species with few studies made of fish entrainment. Entrainment evidence from hydraulic dredging studies is reviewed to develop a sensitivity index for benthic fish. Environmental monitoring attendant with the granting of new licences in the Eastern Channel Region (ECR) in 2006 offers a unique opportunity to assess the effects of dredging upon fish. Projected theoretical fish entrainment rates are calculated based upon: abundance data from 4m beam trawl sampling of fish species over the period 2005-2008; sensitivity data; and dredging activity and footprint derived from Electronic monitoring System (EMS) data. Results have been compared with actual entrainment rates and also against summary results from independent analysis of the changes in fish population over the period 2005-2008 (Drabble, 2012). The case is made for entrainment surveys to form part of impact monitoring for marine aggregate dredging.  相似文献   

8.
The present field study uses Spongia officinalis for assessing trace metals occurrence in time and space within Mediterranean rocky communities. Nine sites were selected in the Marseille area for studying spatial trends in 12 metal concentrations. Long term changes in 8 metal concentrations were assessed at sites that had been sampled before and 12 years after the opening of a treatment plant. Spongia officinalis highly concentrated all the trace metal surveyed excepted Hg and Cd. The overall contamination level registered provided a classification of the study sites which is congruent with that given by other studies on pollutant accumulation in neighbouring sandy-bottoms or benthic assemblages. Among the metals studied, Fe, Pb, Cr are those that best highlighted a pollution gradient. In the present study, only Cd concentration did not vary in space. Except for Ni, all pollutant concentrations clearly decreased between 1984 and 1999. This very impressive decrease in heavy metal concentrations within the Marseille area represents an indisputable evidence of the improvement of the seawater quality resulting from 12 years' operation of the Marseille sewage plant. Moreover, the significant decrease also recorded in the reference population at Port-Cros might reflect an overall improvement in the seawater quality of the NW Mediterranean.  相似文献   

9.
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   

10.
Acoustic diversity charts were produced for a Portuguese soft bottom mid-shelf area, depth from 30 to 90 m, using a single-beam echo sounder coupled to the acoustic systems QTC VIEW Series IV and V. A similar acoustic pattern was identified by both systems, which, after ground-truth interpretation based in available sediment and biological data, established a preliminary spatial distribution model of the benthic habitats in this coastal area. However, some of the acoustic areas were interpreted using one or very few sediment and benthic samples. A specific validation survey was conducted a posteriori, in which the positioning of the sediment and benthic community sampling sites was based on the acoustic diversity previously identified. The results clearly confirm the benthic habitats distribution model suggested by the acoustic method, indicating a high potential for the use of such approach in the identification and mapping of large-scale soft bottom coastal shelf habitat diversity.  相似文献   

11.
The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15 years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14 years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients.  相似文献   

12.
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   


13.
以太湖西五里湖为研究对象,研究了生态修复工程实施两年后,疏浚区、疏浚并水生植被重建示范区、退渔还湖区及对照区沉积物中氮、磷形态的季节变化及垂直分布特征,同时分析了各区上覆水的氮磷含量.结果表明:生态修复措施的实施对沉积物中氮磷形态分布及上覆水的氮磷含量影响显著.示范区和退渔还湖区水体中氮磷含量较低;沉积物中不同磷形态的垂直分布变化较复杂;疏浚基础上进行的水生植被重建对Lab-P、Al-P、Fe-P的吸收作用显著,对Ca-P、Org-P的影响较小;退渔还湖区沉积物磷形态以Ca-P、Org-P为主,Fe-P所占比例较低,与疏浚区不同.生态修复措施对沉积物中TN的影响较小;示范区NH 4 -N含量在秋季突增,可能与植物残体形成的有机质的分解有关.疏浚区水体中氮磷含量与对照区差别不大,沉积物中TN的平均含量还略高于对照区,因此单一的疏浚措施对水环境改善的长期作用需要进一步研究.而示范区水体及沉积物中的TN、TP含量均比较低,水生植被恢复较好,可见在减少外来污染的前提下,对湖区底泥进行疏浚并开展水生植被恢复工程应该是控制湖泊富营养化的有效途径.  相似文献   

14.
A suite of management options for a prawn trawl fishery in Torres Strait, Australia was assessed for impacts on the benthic fauna using a dynamic management strategy evaluation approach. The specification of the management options was gained through consultation with stakeholders. Data for the model was drawn from several sources: the fleet data from fishery logbooks and satellite vessel monitoring systems, benthic depletion rates from trawl-down experiments, benthic recovery rates from post-experiment recovery monitoring studies, and benthic distribution from large-scale benthic surveys. Although there were large uncertainties in the resulting indicators, robust measures relevant to management were obtained by taking ratios relative to the status quo. The management control with the biggest effect was total effort; reducing trawl effort always led to increases in benthic faunal density of up to 10%. Spatial closures had a smaller benefit of up to 2%. The effect of closing a set of buffer zones around reefs to trawling was indistinguishable from the status quo option. Closing a larger area, however, was largely beneficial especially for sea cucumbers. When the spatial distributions of fauna prior to fishing were accounted for, fauna with distributions positively correlated with effort improved relative to those negatively correlated. The reduction in prawn catch under effort reduction scenarios could be ameliorated by introducing temporal closures over the full-moon period.  相似文献   

15.
Cover of the main reef benthic groups, and abundances and taxonomic richness of octocorals were surveyed in the reefs of Hong Kong, and related to spatial and water quality gradients. Nutrient and particle concentrations are high throughout the area, with concentrations declining from the south towards the north-eastern region. Regression tree analyses showed that hard coral cover was most strongly related to water clarity, that macroalgal cover was highest in areas with high wave action and high water clarity, and that crustose coralline algae were negatively related to sedimentation. Octocoral communities (42 species in 23 genera) were dominated by zooxanthellae-free taxa; those few species with zooxanthellae were restricted to reefs with low wave action and high water clarity in the north-eastern region. The water quality gradient spans from conditions that are marginal for zooxanthellate octocorals while still supporting diverse scleractinian communities, towards an estuarine endpoint where zooxanthellate octocorals cease to exist and hard coral communities are reduced to a few resilient colonies. The data suggest that the types, abundances and richness of zooxanthellate octocorals, and the shift from zooxanthellate to azooxanthellate octocoral communities, may act as useful indicators of water clarity in regions where long-term water quality data are unavailable.  相似文献   

16.
To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled using spatially random designs in 1994, 1998, or 2003. Benthic community condition was assessed on a four-category scale and the area in each category estimated. Overall, benthic macrofauna in Southern California were in good condition during 2003, with 98% of the area in reference condition or deviating only marginally. There was no evidence of disturbance near Channel Islands or small wastewater discharges, and virtually none on the mainland shelf. In contrast, bay and estuary macrofaunal communities were more frequently disturbed with nearly 13% of the area supporting disturbed benthos. The condition of the mainland shelf did not change substantially over the 9-year period, with 1.6-2.8% of the area in poor benthic condition. Southern California benthic condition evaluations may be improved by extending the depth and salinity ranges of assessment tools, and improving trend detection methods.  相似文献   

17.
An in situ monitoring of the sediment characteristics and macrobenthic communities was undertaken at a marine fish culture site in subtropical waters of Hong Kong before and after the deployment of biofilters which were made of cement concrete artificial reef (AR) structures. According to the distance to the boundary of the fish cages, 6 points were selected as sampling stations: 2 at the fish cages, 2 near the boundary of the fish culture area, and 2 reference sites further away from the culture area. Bimonthly sediment samples were collected for analysis of silt-clay fraction (SCF), moisture content (MC), total organic carbon (TOC), total Kjeldahl nitrogen (TKN) and total phosphorus (TP). The macrobenthos (>0.5mm) present in the sediment were sorted, identified and enumerated. TOC, TKN and TP levels at the fish cage stations were consistently higher than those at the reference stations over the 1-year pre-AR and 2-year post-AR deployment monitoring period. The diversity of macrofauna was significantly reduced at the fish cage stations relative to the reference sites. The intermediary stations near the fish culture area showed a transitional state of disturbance. Over the 2-year post-AR deployment period, TOC, TKN and TP showed a decreasing trend at the fish cage and intermediary stations. More diverse macrofaunal communities were recorded at the fish cage stations, with species diversity H'increasing from 0-1 at the beginning of the AR deployment to H'>2 at the end of the study. The present results demonstrated that artificial reefs can improve the benthic abiotic environment and biotic conditions beneath fish rafts which are deteriorated due to farming activities.  相似文献   

18.
Phaeocystis blooms are of major importance in the Eastern English Channel, where they significantly contribute to spring organic matter input with chlorophyll concentrations commonly higher than 30 microgl(-1) in the water column. Post-bloom deposition of Phaeocystis derived mucilaginous compounds has been shown to have a major importance on benthic intertidal systems, but resulting mineralization processes and consequences on the macrobenthic compartment remain poorly documented in subtidal areas. In this frame, a study was performed along the French coast of the English Channel to quantify mineralization processes, as well as potential consequences on subtidal sediments, especially their geochemistry and associated macrofaunal communities. Seven stations were studied along a depth gradient during four cruises: before (March), during (April, May) and after (June) the spring bloom. Sediment characteristics and organic carbon content were described, as well as sediment-water fluxes of oxygen and ammonium. Macrofaunal characteristics were also analyzed. Stations were chosen as representative of the various benthic communities present in the area, which are directly linked to the granulometric characteristics of the sediments. To account for the general functioning of the water column, characterized by a coastal flow where higher concentrations of Phaeocystis are generally recorded, similar communities were sampled inshore and offshore, when possible: (i) the Abra alba community located only close to the coast, (ii) the Ophelia borealis community located inshore and offshore, and (iii) the Amphioxus lanceolatus community located inshore and offshore. Generally, low exchange rates of oxygen and ammonium were measured (respectively, in the range 50-150 micromol O2 m(-2)h(-1) and -25 to 35 micromol NH4+ m(-2)h(-1)) between the water column and the muddy-sand to coarse sand permeable sediments, as a consequence of the low organic carbon content due to the high hydrodynamic forcing. As a consequence of organic matter accumulation in surficial sediments probably resulting from Phaeocystis post-bloom deposition, an increase of sediment oxygen demand and ammonium release was clearly evidenced up to 660 micromol O2 m(-2)h(-1) and 205 micromol NH4+ m(-2)h(-1) in May, only in stations located close to the coast (<8 kms), in the A. alba community. Despite those significant biogeochemical changes in surficial sediments, no significant consequence was pointed out on macrofauna, neither in the O. borealis and A. lanceolatus communities, nor in the coastal A. alba community. Most of the temporal variations recorded might be attributed to the common spring population dynamics, but this study highlights the potential use of geochemical parameters as a forewarning signal of benthic disequilibrium.  相似文献   

19.
Lu L 《Marine pollution bulletin》2005,51(8-12):1034-1040
Univariate and multivariate methods were used to study soft-bottom macrobenthos collected in December 2002 from the coastal waters of Singapore. The univariate parameters and community structure of benthic communities were related to environmental variables. Three samples were taken with a 0.1 m2 Van Veen grab (33 × 30 × 15 cm) at each station from 12 sampling stations of two different geographical areas. The water depth ranged from 6.5 m to 34.0 m. The mean values of species number, abundance and species diversity (H′) were 24 species/grab, 77 animals/grab and 3.35/grab, respectively. A total of 172 species was recorded. Total petroleum hydrocarbons were strongly negatively related to species number, abundance and species diversity, suggesting that petroleum hydrocarbons have harmful effects on macrobenthic communities. The BIO-ENV analyses for all stations identified median particle size, silt–clay content, salinity and Zn as the major environmental variables influencing the infaunal patterns. However, separate analyses for two areas produced stronger correlations and different best-correlated environmental variable combinations. Total petroleum hydrocarbons were the only common factor in both areas, showing the importance of petroleum contamination in determining the community structure of benthic infauna in Singaporean waters.  相似文献   

20.
林莉  董磊  潘雄  杨文俊 《湖泊科学》2023,35(2):411-422
三峡水库举世瞩目,是长江保护与治理的关键性枢纽工程,水库自2003年蓄水运行后库区水沙条件均发生了显著改变,对库区水生态环境产生了深远影响。本文系统综述了三峡水库蓄水运行后库区的水流动力特性和泥沙淤积特性,总结了蓄水后水库的新水沙运动情况;从水库蓄水运行后水质参数特征,营养物质、重金属和典型有毒有机污染物的赋存特征等方面,分析了三峡水库库区新水沙变化条件下的水环境响应特征;基于水库蓄水前后浮游植物、底栖动物等重点生物群落的现存量和群落特征变化规律,探索了三峡水库新水沙变化条件下库区的水生态响应特征;最后对未来三峡水库运行下的水生态环境效应研究提出展望,本文可为三峡水库水生态环境保护科学研究和管理提供新的认识和决策参考。  相似文献   

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