Hypoxia and benthic community recovery in Korean coastal waters

Low dissolved oxygen (hypoxia and/or anoxia) has become a major cause of change to the benthic component of ecosystems around the world. We present the response of a benthic community to hypoxia in organically enriched environments in Korean coastal waters. Disturbances due to low dissolved oxygen (DO), and organic enrichment altered community dynamics, result in defaunation during summer hypoxia with delayed recolonization occurring in winter. As DO decreased, the number of taxa, their abundance and biomass of macrofauna dropped significantly at inner bay stations in Chinhae Bay and Youngsan River estuarine bay affected by hypoxia. With the return of normoxic conditions in Chinhae Bay, recolonization was initiated by opportunistic species, with a 1-4months lag. The polychaetes, Sigambra tentaculata, Mesochaetopterus sp., and Lumbrineris longifolia, were most persistent under hypoxia. The first recolonizers were the polychaetes Paraprionospio pinnata, S. tantaculata, Glycinde gurjanovae and Nectoneanthes multignatha and the bivalve Theora fragilis. The second group of colonizers included the polychaetes Capitella capitata, Mesochaetopterus sp. and L. longifolia, and the bivalve Raetellops pulchella. Hypoxic and near anoxic conditions resulted in mass mortality in Chinhae Bay and Youngsan River estuarine bay, but communities did partially recover after return to normoxic conditions despite delayed recolonization.     

Testing BOPA index in sewage affected soft-bottom communities in the north-western Mediterranean

The implementation of the European directive (ELD) 2000/60/EC has produced the development of several biotic indices based in benthic communities. These indices try to summarise ecological quality status of different communities. However, a universal index that works in all situations is difficult to establish, because there are several sources of variation. Therefore, there is the need for testing and validation of these indices which is required for making management decisions on different scales, and in different regions and communities. In this study we test one of these indices, BOPA index, developed by Dauvin and Ruellet [Dauvin, J.C., Ruellet, T., 2007. Polychaete/amphipod ratio revisited. Marine Pollution Bulletin 55, 215-224] in five locations affected by sewage disposal. These disposals are often released via outfall into shallow subtidal habitats, leading to a common source of pollution in coastal marine environments. BOPA index provides a valuable overview of the gradient status of a benthic environment, discriminating between stations more affected by discharge. Nevertheless, BOPA index, used to establish the ecological quality status, seemed to overestimate the status and hence there is the need to calibrate the thresholds between EcoQs classes as defined for these medium-to-fine sand communities, which are characteristics of shallow sublittoral soft-bottoms of the north-western Mediterranean Sea.     

Status of Macrobenthic Community and Its Relationships to Trace Metals and Natural Sediment Characteristics

Laizhou Bay, located in the northwest of Shandong Peninsula, has complex transitional environments between terrestrial and marine ecosystems. In the present study, a total of 122, 131, and 139 species were collected in spring, summer, and autumn 2011, respectively. Species constitutions of macrobenthos were grouped into four phyla, of which annelida were the most abundant phylum, the average biomass proportion of echinodermata was the lowest, and the proportion of important species for mollusca was the highest. The structure of the macrobenthic community showed significant differences between sites, and greater divergence was observed between the third site (S03) and other stations. The ABC plots showed that the biomass curve lay below the abundance curve, and the W‐statistic value was negative. The result of the BOPA index showed that two stations had moderate ecological status in spring and that there were two heavily polluted sites and one moderately polluted site in summer. The BIO‐ENV analyses indicated that the grain‐size fractions together with trace metals (Hg, Pb, Zn, Cu, and Cr) could be considered as the major environmental variables influencing the macrobenthic patterns. The results together demonstrated that the macrobenthic communities in Laizhou Bay were negatively affected, perhaps by the tremendous impact of heavy metals in the sediments.     

Long-term trends in the macrobenthos and water quality of the lower Chesapeake Bay (1985–1991)

Long-term trends in macrobenthic communities of the lower Chesapeake Bay, USA, were examined using data collected quarterly (March, June, September and December) from 1985 to 1991 at 16 stations along a salinity gradient from tidal freshwater regions of the major tributaries (James, York and Rappahannock rivers) to the polyhaline region of the main-stem of Chesapeake Bay. A non-parametric trend analysis procedure was applied to five parameters characterizing macrobenthic community structure: community biomass, species richness, abundance of individuals, proportion of biomass composed of opportunistic species (opportunistic biomass composition) and proportion of biomass composed of equilibrium species (equilibrium biomass composition). For the parameters tested 36 trends were detected. For community biomass, five trends were significant; all had positive slopes and occurred in the James and York rivers. For species richness, six trends were significant; all had positive slopes with three trends in the James River, two trends in the York River and one trend in the main-stem of Chesapeake Bay. For abundance of individuals, 17 trends were detected; all abundance trends were seasonally dependent, had positive slopes and occurred at 12 of the 16 stations. For opportunistic biomass composition, four trends were significant; all had positive slopes with one trend in the lower Rappahannock River and three trends in the main-stem of Chesapeake Bay. For equilibrium biomass composition four trends were significant; two trends had positive slopes (one in the James River and one in the York River) and two trends had negative slopes (one in the Rappahannock River and one in the main-stem of Chesapeake Bay). Trends in the James and York rivers were considered to indicate improving conditions for the benthos, while trends in the lower Rappahannock River and the main-stem of the Chesapeake Bay were considered to indicate deteriorating conditions. Deteriorating conditions for the benthos were associated with regions exposed to summer, low dissolved oxygen events. The trends in the indicators of benthic biological community health were inferentially related to trends observed in water quality conditions in the tributaries and main-stem of Chesapeake Bay. All major water quality and biotic trends appeared to correspond in an ecologically meaningful manner.     

Macrobenthic community structure in the northern Saudi waters of the Gulf, 14 years after the 1991 oil spill

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.     

Status of macrobenthic community of Manifa-Tanajib Bay System of Saudi Arabia based on a once-off sampling event

Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions. Some of these bays, including Manifa-Tanajib Bay System (MTBS), were also exposed to the 1991 oil pollution event. This study investigates the status of the macrobenthos in MTBS during 2006. This bay system is characterized by very shallow inner bays with elevated salinity and temperature compared to the rest of the bay area. As a result mainly of the hyper salinity, the inner bay communities are distinct from the outer bay communities. Overall, fairly high species richness with several rare species was observed. High Shannon-Wiener diversity values and ABC plots indicated the healthy status of the polychaete communities, while BOPA index indicated slightly polluted status in 20% of the stations. The oil sensitive amphipods were not completely re-colonized in 20% of the stations, even after 15 years of recovery from the 1991 oil spill.     

Impact of Mussel Culture on Macrobenthic Community Structure in Saldanha Bay, South Africa

The impact of raft mussel-culture in Saldanha Bay, South Africa on macrobenthic community structure (abundance and biomass) was studied. Sampling was conducted in January between 1993 and 1996 to assess: (1) the composition of macrobenthos below rafts relative to outside the farm; (2) effects of raft position and age within the farm; and (3) recovery rate of benthos after raft removal. Analyses included ABC plots, hierarchical clustering and species diversity indices. Disturbed communities were found under 78% of raft sites sampled. The level of disturbance (Warwick Statistics) and the dominant opportunistic species (Bray–Curtis Similarities) changed from year to year, polychaetes and scavenging gastropods being most common. The degree of disturbance appeared related to raft sites positioned in the middle of the farm rather than raft age. Whereas ABC plots and hierarchical cluster analyses best identified the disturbance of benthic communities, diversity indices detected marginal recovery four years after raft removal. Although deposit feeders dominated all sites, suspension feeders increased in number and biomass at reference sites. This study presented a “yes/no” scenario that will be addressed in subsequent research in the modelling of culture ecosystems.     

Offshore oil platforms and fouling communities in the southern Arabian Gulf (Abu Dhabi)

This study examined the fouling organisms on the legs of offshore oil platforms at two sites in the southern Arabian Gulf (offshore Abu Dhabi, United Arab Emirates). 100% of the metal structures was colonized by encrusting organisms. Both the number of individuals and the total biomass tended to decrease with depth. The total weight of dead shells always exceeded that of living organisms. Sessile filter feeders dominated the biomass, whereas small mobile forms had the largest number of individuals. The biomass at the deeper platform (22 m) was dominated by bivalves, barnacles and bryozoans, while polychaetes and amphipods had the greatest number of individuals. Biomass values here ranged from 1 g/0.1 m2 at 20 m to 147 g/0.1 m2 at 5 m; the corresponding individual numbers were 266 (20 m) and 11,814 indiv./0.1 m2 (5 m). The results at the shallower platform (11 m) differed in several respects: barnacles clearly dominated over bivalves, and sponges exceeded byrozoans, while total individual numbers fell due to a decline in polychaete dominance. Biomass values here ranged from 84 g/0.1 m2 at 10 m to 153 g/0.1 m2 at 0 m; the corresponding individual numbers were 695 (10 m) and 3,125 indiv./0.1 m2 (0 m). The potential role of such fouling communities on artificial structures in the Gulf is discussed.     

太湖浮游细菌种群基因多样性及其季节变化规律

为认识湖泊中浮游细菌的多样性及其变化规律,本研究采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)的方法,研究了太湖梅梁湾和湖心区浮游细菌种群16S rRNA基因多样性以及种群基因组成的季节变化特征.研究结果表明,太湖浮游细菌种群具有丰富的基因多样性.浮游细菌的丰度、DGGE条带数、种群的Shannon-Wiener指数、Simpson 指数和Pielou指数均呈现显著的季节变化规律:夏季及秋季浮游细菌的丰度、基因多样性及种群的均匀度较高,而冬季和春季则较低.浮游细菌种群的基因组成随时间变化.梅梁湾浮游细菌的丰度显著高于湖心.梅梁湾与湖心浮游细菌主要建群种的基因型存在显著差异.     

Benthos abundance pattern and species composition in conditions of pollution in Amursky Bay (the Peter the Great Bay,the Sea of Japan)

Multivariate statistical analysis of data on environmental variables and benthic macrofauna, of 30 sites from four surveys done between 1986 and 1989 in Amursky Bay, is presented. The purpose of this study is to investigate a contamination gradient, assess effects on benthic fauna and evaluate quantitative and qualitative benthic parameters.Contamination was assessed using chemical data from PCA-ordination analysis. Clear patterns were found using three categories, moderate, severe and gross. Significant changes in the number of taxa, density and ecological indices are observed between severe and moderate levels. Changes in these parameters, excluding the number of species, were also detected between gross and moderate levels. Only biomass differs non-significantly. However results of cluster analysis and MDS ordination indicate that two benthic communities exist in Amursky Bay.The most "contaminant insensitive" species polychaetes are Tharyx pacifica, Dorvillea (Schistomeringos) japonica, Dipolydora cardalia, Capitella capitata, phoronid Phoronopsis harmeri. Contaminant sensitive species include Maldane sarsi, Lumbrineris sp. and Scoloplos armiger.     

Effects of organic pollution on the initial development of fouling communities in a tropical bay, Brazil

Transplantation of artificial panels between a polluted and an unpolluted site was used to evaluate eutrophication effects on the development of fouling communities in Ilha Grande Bay, SE Brazil. Organic pollution changed the relative dominance of species in the fouling communities of transplanted panels, although, their richness, evenness, and specific composition did not change. The chlorophyte Ulva sp. occurred only in the polluted site and in panels transplanted to it, whereas the bryozoan Aetea lingulata was found only in the unpolluted site and in panels transplanted to this site. These species are therefore good pollution indicators. The best pollution indicators, however, were amphipods and Spionidae polychaetes which formed mucous tubes. These groups had significantly higher values of percent cover (p<0.0001) in the polluted site and in panels transferred to it. The dominance shift is the first evidence that more meaningful changes can occur in the structure of fouling communities on a long-term scale.     

Effects of the closure of a major sewage outfall on sublittoral, soft sediment benthic communities

The present study examines the benthos within western inner Swansea Bay (Wales, UK), for the period before, during and immediately after the cessation of a major, sewage discharge from Mumbles Head. There have been significant improvements in seawater quality and changes in the species composition of the benthic communities following the cessation of the sewage discharge. There has been an increase in the diversity of deposit feeders, especially the amphipods, and a decrease in the diversity of the filter feeders, especially the polychaetes. Changes are not attributable either to sediment organic matter content or to gross changes in sediment type, but are related to the significant reduction in suspended particulate organic material and sewage contaminants discharged to the Bay. A recovery model has been proposed to describe how soft sediment benthic communities in a shallow, sublittoral, high tidal energy environment respond to the abrupt cessation of a major sewage discharge.     

Polycyclic aromatic hydrocarbons and changes in the trophic structure of polychaete assemblages in sediments of Todos os Santos Bay, Northeastern, Brazil

Polycyclic aromatic hydrocarbons (PAHs) and the trophic structure of polychaete assemblages were studied in sediments at 28 stations in Todos os Santos Bay. Total PAH concentrations varied from 8 to 4163 ng g(-1) dry weight. The indexes used for the determination of PAH origin suggested both pyrolytic and petrogenic sources. A total of 397 individuals of polychaetes was recorded which were classified in three trophic groups. The PCA ordination resulted in the formation of three groups of stations, Group I characterised by sandy sediments, low organic content, low total PAH concentration and percentage of potentially harmful PAH was dominated by subsurface deposit-feeders. The other two groups (IIa and IIb), showed similar percentages of silt and clay, however, Group IIb formed by those stations with high total organic carbon, total nitrogen, sulphur contents, high total PAH concentration and percentage of potentially harmful PAH was dominated by carnivores. Trophic changes could be explained by the level of exposure to PAH effects relative to differences in the life style and feeding strategies between deposit-feeders and carnivores.     

Benthic infauna variability in relation to environmental factors and organic pollutants in tropical coastal lagoons from the northern Yucatan Peninsula

We examine the abundance and species composition variability of benthic infauna from tropical coastal lagoons in relation to environmental factors and organic pollutants. Sediment samples were collected at 40 sites in four lagoons in the northern Yucatan Peninsula. A total of 7985 individuals belonging to 173 species were sampled. While the eastern lagoons were dominated by polychaetes, the western ones were dominated by crustaceans. Overall, polychaetes had the highest abundance (48%), followed by crustaceans (42%). According to canonical correspondence analysis, species attributes were correlated with water salinity, pH and temperature, but also with sediment pentachlorobenzene, trichlorobenzene, and low molecular weight polycyclic aromatic hydrocarbons. Some pollutants exceeded sediment quality guidelines, representing a potential environmental risk to benthic infauna. Together, environmental factors and pollutants explained 52% of the variance in abundance and species composition among sites.     

The response of benthic macrofauna to anthropogenic stress in Narragansett Bay, Rhode Island: a review of human stressors and assessment of community conditions

The present state of knowledge regarding the input of anthropogenic pollutants into Narragansett Bay, Rhode Island was reviewed and benthic infaunal communities present at four depositional environments within the upper Bay were characterized. Inter-station differences in species composition and abundance of these assemblages were examined in relation to established pollution gradients.Using diversity curves and multivariate statistics, evidence of significant anthropogenic impact on the structure of benthic macrofaunal communities in Narragansett Bay was identified. The magnitude of this impact was greatest at stations closest to the Bay’s urban centers, where exposure to multiple stressors had resulted in communities of opportunistic taxa which persisted in a state of low faunal diversity characteristic of early stages of species succession. As was expected based on historic models of faunal succession; the apparent maturity of benthic assemblages in Narragansett Bay increased along the north-south gradient of decreasing anthropogenic stress.     

松嫩平原湖泊鱼类群聚结构

根据2008-2009年的湖泊渔业资源调查,分析松嫩平原20个湖泊鱼类群聚结构特征.结果表明,20个湖泊鱼类群聚由44种鱼类组成,隶属于4目9科34属.21种鱼类的优势度指数在10000以上,17种鱼类为优势种.群聚Margalef指数(dMa值)为0.908-3.096(1.615±0.615),Simpson指数(λ值)为0.090-0.568(0.222±0.110),Gini指数(D值)为0.432-0.910(0.778±0.107),Shannon-Wiener指数(H值)为1.012-2.690(1.878±0.431),Pielou指数(J值)为0.407-0.915(0.777±0.107).dMa值与λ值、D值、H值和J值的相关系数分别为-0.670、0.665、0.867和0.340;λ值与D值、H值和J值的相关系数分别为-0.631、-0.924和-0.896;D值与H值和J值的相关系数分别为0.924和0.896;H值和J值的相关系数为-0.639.总体上,20个湖泊鱼类群聚结构处在不稳定中.     

The performance of benthic indicators of ecological change in Adriatic coastal lagoons: throwing the baby with the water?

The ecological quality of 127 stations from six Adriatic coastal lagoons was assessed using a suite of biotic indices: H', d, 1-lambda', Delta(*), Delta(+), W, AMBI, BOPA and FINE. The analysis indicated the difficulties in deriving and using the existing indices from benthic communities in highly variable environmental conditions in coastal lagoons. Different metrics rendered different results: the use of H' resulted in the classification of all stations as "Moderate/Poor/Bad", whereas BOPA classified the majority of the stations as "Good/High". Using Delta(+), most of the stations resulted as "Not anthropogenically impacted", while the W-statistics gave 82 stations as "Undisturbed" and 45 as "Moderately/Grossly disturbed". AMBI classified 55 stations as "High/Good" and 72 as "Moderate/Poor/Bad", whereas those were 32 and 95 with FINE, respectively. The latter, which was developed just for Italian coastal lagoons, was the most conservative among the indices studied. Yet, it showed the highest correlation with the species/abundance matrix. Using indices developed for coastal waters in lagoons can give the distorted indication that the water body is degraded, when it might be just a natural, low diversity, high abundance community, i.e. a lagoonal community. Moreover, the outcome of the use of a certain index has a financial dimension such that lagoons misclassified as being "poor status" will then require expensive remediation measures. For the lagoons studied, there is probably an adequate quality and quantity of benthic data available for making management decisions, but this study highlights the limits of the existing indices for lagoonal ecosystems. The challenge for the next future is to couple long term conservation of the natural environment with the highly productive activities carried out in lagoonal ecosystems.     

夏季短期调水对太湖贡湖湾湖区水质及藻类的影响

贡湖湾作为"引江济太"工程长江来水进入太湖的第一站,湖湾水体生态环境的变化是对调水工程净水效果的最好响应,因此本文针对贡湖湾一次夏季短期调水展开调查研究,分别取2013年7月24日(调水前)和2013年8月18日(短期调水后)两次监测水样的水体理化指标和浮游藻类群落数据进行了对比分析,并对浮游藻类群落与环境因子做了相关性分析.结果表明:受来水影响,短期调水后监测区水体的p H略有下降,溶解氧、浊度、硝态氮、总氮、总磷以及高锰酸盐指数等水体理化指标浓度均较调水前有所升高;其中受调水影响最为显著的区域为望虞河的入湖口区、湾心区.两次监测调水前后湖区水体优势藻种属未发生变化,仍以微囊藻为主,但蓝藻种属比例有所下降,绿藻和硅藻等种属比例则有所上升.望虞河入湖口区和贡湖湾湾心区的Shannon-Wiener多样性指数和Pielou均匀度指数受调水的影响升高.同时,浮游藻类群落结构与受水水体理化参数的冗余分析结果表明,此次监测的短期调水后,太湖贡湖湾监测湖区水体p H、溶解氧、硝态氮、总氮、总磷、高锰酸盐指数等环境因子与浮游藻类的群落分布呈显著相关,是影响受水水体中藻类群落的主要环境因子.     

Polychaetes as indicators of environmental disturbance on subarctic tidal flats, Iqaluit, Baffin Island, Nunavut Territory

The polychaetes of the tidal flats near the town of Iqaluit, Baffin Island were analysed along gradients of environmental disturbance resulting from human activity. Sources of environmental disturbance include a sewage lagoon, garbage sites; and an area of the tidal flat that is cleared by bulldozer. Sampling of the tidal flats included 300 biological sediment cores taken from 75 sites along seven transects. Environmental disturbance has resulted in four zones of polychaete communities with increasing distance. The heavily disturbed zone is closest to the disturbances and is devoid of polychaetes. The disturbed zone follows and is characterized by low diversity the result of increased densities of a few opportunistic species such as, Capitella 'capitata' sp. The moderately disturbed zone is characterized by increased species diversity due to organic enrichment from the disturbances. The undisturbed zone, located the furthest from the sources of disturbance, is characterized by moderate levels of diversity compared to the other three zones.