Assessment of benthic changes during 20 years of monitoring the Mexican Salina Cruz Bay

In this work a non-parametric multivariate analysis was used to assess the impact of metals and organic compounds in the macro infaunal component of the mollusks benthic community using surface sediment data from several monitoring programs collected over 20 years in Salina Cruz Bay, Mexico. The data for benthic mollusks community characteristics (richness, abundance and diversity) were linked to multivariate environmental patterns, using the Alternating Conditional Expectations method to correlate the biological measurements of the mollusk community with the physicochemical properties of water and sediments. Mollusks community variation is related to environmental characteristics as well as lead content. Surface deposit feeders are increasing their relative density, while subsurface deposit feeders are decreasing with respect to time, these last are expected to be more related with sediment and more affected then by its quality. However gastropods with predatory carnivore as well as chemosymbiotic deposit feeder bivalves have maintained their relative densities along time.     

Relating Benthic Infaunal Community Structure to Environmental Variables in Estuaries using Nonmetric Multidimensional Scaling and Similarity Analysis

In 1994, 19 stations were sampled (2 replicates/station) with Young grabs in association with the EMAP-Estuaries Carolian Province Base Monitoring in Florida. A total of 295 unique benthic infauna taxa and 9647 individuals were identified and enumerated. Environmental data (bottom-water quality, sediment grain size, sediment metals, and organics) and benthic community data were analyzed using hierarchical agglomerative cluster analysis and ordination via nonmetric multidimensional scaling. Bray-Curtis similarities and Euclidean distance were used as the distance measures for biotic and abiotic data, respectively. Multivariate analyses were complemented by examining incremental contributions of benthic taxa to similarity values using a percentage similarity technique. A low-salinity site in a tributary to the St. Johns River had benthic communities uniquely different from those of moderate-to high-salinity sites. A diverse assemblage of polychaetes, gastropods, bivalves, amphipods, sipunculans, and phoronids was consistently associated with relatively unimpacted sites in the Indian River Lagoon. Infaunal community structure in the northern portion of the study area was influenced by the nearby Atlantic Ocean. Community shifts in association with latitudinal gradients and concentrations of sediment metals and organics were apparent. The nonparametric multivariate techniques used in this study were particularly effective at delineating and defining fine-scale community differences.     

Benthic Biological Processes and EH as a Basis for a Benthic Index

It is proposed that the common measures of benthic community condition can be augmented with a vertical EH profile taken through the benthic bioturbation zone. Sediment EH, an electrochemical measure of oxidized and reduced compounds in sediment porewater, measures the integrative consequences of all metabolic and transport processes of the benthic community. Biota, especially microbiota, metabolize carbon using a variety of electron acceptors, including O2, SO4 and some nitrogen and metal compounds. Motile benthic macrofauna ingest and transport particles, ventilate deep burrows and anoxic sediment with overlying seawater while sedentary suspension-feeding fauna deposit suspended organic matter onto the sediment surface. Collectively, these metabolic and behavioral processes advect particles and seawater between bottom water and deep sediment and define the overall structure of porewater chemistry. That structure creates a full spectrum of biogeochemical conditions of solubility, reactivity, and microbial metabolism which remineralizes excess organic carbon and most organic contaminants, defines solubility of trace metals, and pushes the vertical EH profile toward oxidizing conditions. It is proposed that a standard EH probe inserted downward through the bioturbation zone will provide a general measure of this resulting porewater chemistry and thus the impact of feeding, irrigation, and metabolism of the total macro, meio, and microbenthic community. If such a measure can be validated it will permit extended measurement of community function and reduced efforts in measuring community structure.     

Empirical assessment of incorporating sediment quality triad data into a single index to distinguish dominant stressors between sites

Benthic infaunal community structure, sediment contamination, and sediment toxicity data (Sediment Quality Triad) were condensed into a single index based on the area of tri-axial plots, which were examined in relation to various habitat parameters. The purpose was to assess its utility for evaluating the relative impact of contaminants versus other stressors on benthic communities. The regression relationship between the areal index and the Effects Range?CMedian quotient (ERMq) was used to separate contaminant-impacted sites from sites impacted by hypoxia in Chesapeake Bay. Regression using the areal index and bottom oxygen confirm the utility of the approach. Data from Delaware, Galveston, and Biscayne Bays were also examined to determine if the approach may be effective in other estuaries.     

西湖与青山水库底栖动物群落的研究

通过对杭州市的两个主要水体西湖和青山水库的底栖动物群落包括种类组成、优势种群、生物量等的比较研究。西湖和青山水库底栖动物群落主要由寡毛类和摇蚊幼虫组成 ,存在适应低溶氧、耐有机污染的种群。从底栖动物群落生态学角度评价了西湖和青山水库水体的营养化程度。     

Benthic communities of streams related to different land uses in a hydrographic basin in southern Brazil

Different land uses affect the characteristics of a hydrographic basin, reflected in the river water quality, and consequently affecting the aquatic biota. The benthic community closely reflects the alterations caused by different human activities. In this study, the effects of different land uses were evaluated by analysis of the benthic community structure in streams with urban, agricultural and pasturage influences, as well as areas in better-conserved regions. The abiotic parameters showed distinct seasonal variability, which did not occur with the benthic organisms. A degradation gradient was observed among the study sites, in the headwaters-agriculture-pasture-urban direction. By the CCA its possible to observe that the density of organisms tended to increase along this gradient, whereas richness, diversity, evenness, and EPT families decreased. The most intense effects of land use on the benthic community composition, richness, and diversity were observed in urban areas (F (1,4) = 16.0, p = 0.01; F (1,4) = 8.97, p = 0.04; respectively). In conclusion a trend in the benthic community is observed in to predict alterations caused for the different land uses, mainly, when the source point pollution, as the case of urban area.     

Incidence of stress in benthic communities along the U.S. Atlantic and Gulf of Mexico coasts within different ranges of sediment contamination from chemical mixtures

Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73–100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).     

Monitoring the sedimentary carbon in an artificially disturbed deep-sea sedimentary environment

An area of 0.6 km(2) in the manganese nodule field of the Central Indian Basin was physically disturbed and sediments discharged in the near bottom waters to simulate seabed mining and study its impact on benthic ecosystem. An estimated 2 to 3 tonnes of sedimentary organic carbon (C(org)) was resuspended into the water column during a 9-day experiment. The majority of the sediment cores from within the disturbed area and areas towards the south showed a ~30% increase in C(org) content as well as an increase in carbon burial rates after disturbance, though with a reduction in carbon/phosphorus ratios. High specific surface area (SSA~25 m(2) g(-1)) and low C(org)/SSA ratios (mostly <0.5) are typical of deep-sea sediments. The increased C(org) values were probably due to the organic matter from dead biota and the migration and redeposition of fine-grained, organic-rich particles. Spatial distribution patterns of C(org) contents of cores taken before and after disturbance were used to infer the direction of plume migration and re-sedimentation. A positive relationship was observed between total and labile C(org) and macrobenthos density and total bacterial numbers prior to disturbance, whereas a negative relationship was seen after disturbance owing to drastic reduction in the density of macrofauna and bacteria. Overall decrease in labile organic matter, benthic biota and redistribution of organic matter suggest that the commercial mining of manganese nodules may have a significant immediate negative effect on the benthic ecosystem inducing changes in benthic community structure.     

Nutrient dynamics between sediment and overlying water in the inner part of Izmir Bay, Eastern Aegean

In this article a concept is described in order to predict and map the occurrence of benthic communities within and near the German Exclusive Economic Zone (EEZ) of the North Sea. The approach consists of two work steps: (1) geostatistical analysis of abiotic measurement data and (2) calculation of benthic provinces by means of Classification and Regression Trees (CART) and GIS-techniques. From bottom water measurements on salinity, temperature, silicate and nutrients as well as from punctual data on grain size ranges (0–20, 20–63, 63–2,000 μ) raster maps were calculated by use of geostatistical methods. At first the autocorrelation structure was examined and modelled with help of variogram analysis. The resulting variogram models were then used to calculate raster maps by applying ordinary kriging procedures. After intersecting these raster maps with punctual data on eight benthic communities a decision tree was derived to predict the occurrence of these communities within the study area. Since such a CART tree corresponds to a hierarchically ordered set of decision rules it was applied to the geostatistically estimated raster data to predict benthic habitats within and near the EEZ.     

Assessing differences in macrofaunal assemblages as a factor of sieve mesh size,distance between samples,and time of sampling

With increasing cascading effects of climate change on the marine environment, as well as pollution and anthropogenic utilization of the seafloor, there is increasing interest in tracking changes to benthic communities. Macrofaunal surveys are traditionally conducted as part of pre-incident environmental assessment studies and post-incident monitoring studies when there is a potential impact to the seafloor. These surveys usually characterize the structure and/or spatiotemporal distribution of macrofaunal assemblages collected with sediment cores; however, many different sampling protocols have been used. An assessment of the comparability of past and current survey methods was in need to facilitate future surveys and comparisons. This was the aim of the present study, conducted off the Oregon coast in waters 25–35 m deep. Our results show that the use of a sieve with a 1.0-mm mesh size gives results for community structure comparable to results obtained from a 0.5-mm mesh size, which allows reliable comparisons of recent and past spatiotemporal surveys of macroinfauna. In addition to our primary objective of comparing methods, we also found interacting effects of seasons and depths of collection. Seasonal differences (summer and fall) were seen in infaunal assemblages in the wave-induced sediment motion zone but not deeper. Thus, studies where wave-induced sediment motion can structure the benthic communities, especially during the winter months, should consider this effect when making temporal comparisons. In addition, some macrofauna taxa-like polychaetes and amphipods show high interannual variabilities, so spatiotemporal studies should make sure to cover several years before drawing any conclusions.     

Assessing the Effects of Non-Point Source Pollution on American Samoa’s Coral Reef Communities

Surveys were completed on Tutuila Island, American Samoa, to characterize reef development and assess the impacts of non-point source pollution on adjacent coral reefs at six sites. Multivariate analyses of benthic and coral community data found similar modern reef development at three locations; Aoa, Alofau, and Leone. These sites are situated in isolated bays with gentle sloping foundations. Aoa reefs had the highest estimates of crustose coralline algae cover and coral species richness, while Leone and Alofau showed high abundances of macroalgae and Porites corals. Aoa has the largest reef flat between watershed discharge and the reef slope, and the lowest human population density. Masefau and Fagaalu have a different geomorphology consisting of cemented staghorn coral fragments and steep slopes, however, benthic and coral communities were not similar. Benthic data suggest Fagaalu is heavily impacted compared with all other sites. Reef communities were assessed as bio-criteria indicators for waterbody health, using the EPA aquatic life use support designations of (1) fully supportive, (2) partially supportive, and (3) non-supportive for aquatic life. All sites resulted in a partially supportive ranking except Fagaalu, which was non-supportive. The results of this rapid assessment based upon relative benthic community measures are less desirable than long-term dataset analyses from monitoring programs, however it fills an important role for regulatory agencies required to report annual waterbody assessments. Future monitoring sites should be established to increase the number of replicates within each geological and physical setting to allow for meaningful comparisons along a gradient of hypothesized pollution levels.     

中国北方河流底栖动物群落季节性演替对水生态环境质量评价的影响

大型底栖动物是评价水生态质量最常用的生物类群,鉴于水生昆虫的生活史特点,在一年当中群落结构会发生季节性变化,如何利用底栖动物数据准确评价水生态质量状况,反映客观实际,值得探讨。将黑龙江省2012—2015年水生生物试点监测47个采样点的108组底栖动物数据进行比较,对群落结构的相似性、物种的更替率和BMWP指数评价结果进行分析,探讨群落的演替及BMWP指数的变化规律。结果表明不同时间采集的样品底栖动物群落之间存在较大差异,评价的结果也存在差异,越是水环境质量好的区域,这种差异越明显。利用底栖动物评价水生态状况,宜选择长时间段的多个采集数据,经统计整理后,利用复合样方(年均值)的特征,评价一段时间内(如以年为单位)的水生态质量状况,使评价结果更具准确性。     

江苏地表水体大型底栖无脊椎动物生物多样性状况研究

大型底栖无脊椎动物群落结构与水体水质和水生态系统健康状况关系密切,其受外界干扰后群落结构的变化趋势可以反映水体受污染的性质和程度。2008年,对江苏省主要饮用水源地,长江、京杭大运河等主要河流及太湖等重点湖泊开展底栖动物调查与评价研究,共设置调查点位154个。江苏主要饮用水源地底栖动物的物种数量为78种,主要河流发现底栖动物96种,主要湖泊底栖动物发现65种。从物种多样性指数评价结果看,主要湖泊的底栖生物多样性状况优于地表水源地和主要河流,丰富和较丰富所占比例合计达58%;主要河流的评价结果最差,丰富和较丰富所占比例合计仅达30.7%,存在11.3%物种多样性极贫乏的点位,且大部分水体底栖动物组成以耐污种为主,优势种为极耐污的霍甫水丝蚓,水质状况劣于饮用水源地和主要湖泊。     

Combining Logistic Models with Multivariate Methods for the Rapid Biological Assessment of Rivers Using Macroinvertebrates

This work represents an attempt to define a simple method to classify the relative degree of disturbance of sites in lotic systems on the basis of comparison of their faunistic composition with reference sites. Two ecotypes were selected in northern Portugal where benthic invertebrates were sampled in reaches with different levels of contamination. As a first stage, previous Geographic Information System information was used to define reference sites in each ecotype. Afterwards, multivariate techniques and non linear estimation models were combined to assess biological quality. This method allowed us to quantify sites according to increasing levels of contamination, after the probabilities of occurrence of taxa along a gradient of contamination taking into account the reference condition. The results suggest that this method is sensitive to organic pollution, easy to interpret, namely the species tolerance, and could be a good framework to establish regional rankings depending on the ecological impact of river sites.     

Environmetrics to evaluate marine environment quality

The environmetric data analysis of analytical datasets from sediment and benthic organisms samples collected from different sampling sites along the coast of Black Sea near to City of Varna, Bulgaria has given some important indications about the bioindication properties of both type of samples. Various multivariate statistical methods like cluster analysis, principal components analysis, source apportioning modeling and partial least square (PLS) modeling were used in order to classify and interpret the parameters describing the chemical content of the coastal sediments (major components, heavy metals and total organic carbon) and benthic organisms (heavy metals). It has been shown that seriously polluted coastal zones are indicated in the same way by all benthic species, although some specificity could be detected for moderate polluted regions' e.g. polychaeta accumulated preferably Co, Cr, Cu, and Pb; crustacea - As, Cd, and Ni; mollusca - Zn. The identified latent factors responsible for the dataset structure are clearly indicated and apportioned with respect to their contribution to the total mass or total concentration of the species in the samples. The linear regression and PLS models indicated that a reliable forecast about the relation between naturally occurring chemical components and polluting species accumulated in the benthic organisms is possible.     

Influence of environmental properties on macrobenthos in the northwest Indian shelf

The paper deals with the standing stock of macrobenthic infauna and associated environmental factors influencing the benthic community in the shelf region of the northwest Indian coast. The data were collected onboard FORV Sagar Sampada during the winter monsoon (January–February, 2003) to understand the community structure and the factors influencing the benthic distribution. The environmental parameters, sediment characteristics and macrobenthic infauna were collected at 26 stations distributed in the depths between 30 and 200 m extending from nobreak{Mormugao} to Porbander. Total benthic abundance was high in lower depths (50–75 m), and low values noticed at 30 m depth contour was peculiar. Polychaetes were the dominant group and were more abundant in shallow and middle depths with moderate organic matter, clay and relatively high dissolved oxygen. On the other hand crustaceans and molluscs were more abundant in deeper areas having sandy sediment and low temperature. High richness and diversity of whole benthic groups observed in deeper depths counter balanced the opposite trend shown by polychaete species. Generally benthos preferred medium grain sized texture with low organic matter and high organic matter had an adverse effect especially on filter feeders. Deposit feeding polychaetes dominated in shallow depths while carnivore species in the middle depths. Ecologically, benthos were controlled by a combination of factors such as temperature, salinity, dissolved oxygen, sand and organic matter and no single factor could be considered as an ecological master factor.     

Bacterial community structure analysis of sediment in the Sagami River, Japan using a rapid approach based on two-dimensional DNA gel electrophoresis mapping with selective primer pairs

A rapid approach based on two-dimensional DNA gel electrophroesis (2-DGE) mapping with selective primer pairs was employed to analyze bacterial community structure in sediments from upstream, midstream and downstream of Sagami River in Japan. The 2-DGE maps indicated that Alpha- and Delta-proteobacteria were major bacterial populations in the upstream and midstream sediments. Further bacterial community structure analysis showed that richness proportion of Alpha- and Delta-proteobacterial groups reflected a trend toward decreasing from the upstream to downstream sediments. The biomass proportion of bacterial populations in the midstream sediment showed a significantly difference from that in the other sediments, suggesting that there may be an environmental pressure on the midstream bacterial community. Lorenz curves, together with Gini coefficients were successfully applied to the 2-DGE mapping data for resolving evenness of bacterial populations, and showed that the plotted curve from high-resolution 2-DGE mapping became less linear and more an exponential function than that of the 1-DGE methods such as chain length analysis and denaturing gradient gel electrophoresis, suggesting that the 2-DGE mapping may achieve a more detailed evaluation of bacterial community. In conclusion, the 2-DGE mapping combined with the selective primer pairs enables bacterial community structure analysis in river sediment and thus it can also monitor sediment pollution based on the change of bacterial community structure.     

Are Toronto’s streams sick? A look at the fish and benthic invertebrate communities in the Toronto region in relation to the urban stream syndrome

Impacts of urbanization on aquatic ecosystems are intensifying as urban sprawl spreads across the global land base. The urban stream syndrome (USS) identifies “symptoms” associated with urban development including changes in biotic communities, hydrology, water chemistry, and channel morphology. Direct relationships between road density (as surrogate of urbanization) and indicators of the USS were identified for streams in the Toronto region. Significant negative relationships were revealed between road density and biological (fish and benthic macroinvertebrate) richness, diversity, and fish Index of Biotic Integrity scores. Significant positive relationships were found between road density and tolerant fish/benthic macroinvertbrates, benthos Family Biotic Index scores, mean summer stream temperature, stream flashiness, and several water quality variables. Analysis of biological data showed that only four fish species and a reduced number of benthic macroinvertebrate families remained at the most urbanized sites. Road density was found to be a major determinant in both the fish and benthic macroinvertebrate community structure.     

Multivariate Analysis of the Hong Kong Victoria Harbour Water Quality Data

Two multivariate techniques (principal components analysis and cluster analysis) are used to analyse Hong Kong Victoria Harbour water quality data. Results show that the sampling stations can be divided into four main groups, which is consistent with the tripartite structure obtained from an environmental approach. Moreover, it is found that the groups produced can be interpreted based on two main features of the data: nutrient level and the algae-faecal pollution.