The soft-bottom macrobenthos of Gray's Reef National Marine Sanctuary and nearby shelf waters off the coast of Georgia, USA

As part of an ongoing ecological assessment of the Gray's Reef National Marine Sanctuary (GRNMS), a 58-km² marine protected area 32 km off the coast of Georgia, USA, surveys of benthic macroinfaunal communities, contaminant levels in sediments and biota, and general habitat conditions were conducted during 2000-2002 at 20 stations within the sanctuary and along three cross-shelf transects in nearby shelf waters. Macroinfaunal community structure and composition exhibited distinct cross-shelf patterns associated with sediment granulometry, depth and possibly other factors related to shoreline proximity (e.g., erosional effects, recruitment of estuarine species). Finer-scale spatial patterns of benthic fauna among stations within the sanctuary appear to be related to proximity to live-bottom habitat and other features of seafloor structure (e.g., rippled vs. flat sand). Population densities of dominant fauna within the sanctuary also varied considerably among years, resulting in shifts in the ranking of dominants at most stations. Chemical contaminants generally were at low background concentrations below probable bioeffect levels and thus are not a likely cause of the observed spatial patterns of benthic fauna. However, trace concentrations of pesticides, PCBs, and PAHs were detectable in sediments and biota throughout the study area, demonstrating that chemicals originating from human activities are capable of reaching the offshore sanctuary environment, possibly from atmospheric deposition or cross-shelf transport of materials outwelled through coastal sounds. Highly diverse infaunal assemblages also were observed within the sanctuary and nearby sites of similar depth, suggesting that the sanctuary is an important reservoir of marine biodiversity. Results of this study should be useful in addressing long-term science and management needs of the GRNMS and in furthering our understanding of broader ecological patterns and dynamics of the surrounding South Atlantic Bight (SAB) ecosystem.     

Macrobenthic Communities of the Lower Chesapeake Bay. III. Southern Branch of the Elizabeth River

Macrobenthic invertebrates of an industrialized seaport ecosystem were studied seasonally from October, 1977 through July, 1978. Five stations were selected along the Southern Branch of the Elizabeth River, Virginia. The benthic community was dominated by eurytopic species that were not affected by minor to moderate stresses induced by man's activities in the seaport. Caution is required when benthic communities of the lower polyhaline to mesohaline zones of an estuary are used to indicate the effects of anthropomorphic alterations.     

Deep-sea meiobenthic communities underneath the marginal ice zone off Eastern Greenland

Marginal ice zones (MIZ) are known to be the most highly productive systems in the Arctic Ocean with large amounts of primary production reaching the deep seafloor. This study characterizes the effect of the ice-edge related primary production and subsequent phytodetritus sedimentation on deep-sea meiobenthic communities, particularly nematodes, along the Eastern Greenland continental margin in July 2000. Results were based on data from six stations along a depth transect crossing the MIZ with the shallowest stations under the ice-cover (656 and 1,198 m), intermediate stations at the ice-edge (1,560 and 2,129 m), and deepest stations in ice-free areas (2,735 and 3,033 m). The presence of the ice-cover significantly affected the availability of organic matter on the deep seafloor. The present results confirm a close bentho-pelagic coupling in the area of investigation. Enhanced flux of phytodetritus from primary production to the benthic system appears at stations underneath or close to the ice-edge and at the sampling sites in ice-free areas. The availability of phytodetritus at these stations enhanced bacterial activities, meiofauna abundances, and the number of nematodes species. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Variable Importance of Macrofaunal Functional Biodiversity for Biogeochemical Cycling in Temperate Coastal Sediments

Coastal marine systems are currently subject to a variety of anthropogenic and climate-change-induced pressures. An important challenge is to predict how marine sediment communities and benthic biogeochemical cycling will be affected by these ongoing changes. To this end, it is of paramount importance to first better understand the natural variability in coastal benthic biogeochemical cycling and how this is influenced by local environmental conditions and faunal biodiversity. Here, we studied sedimentary biogeochemical cycling at ten coastal stations in the Southern North Sea on a monthly basis from February to October 2011. We explored the spatio-temporal variability in oxygen consumption, dissolved inorganic nitrogen and alkalinity fluxes, and estimated rates of nitrification and denitrification from a mass budget. In a next step, we statistically modeled their relation with environmental variables and structural and functional macrobenthic community characteristics. Our results show that the cohesive, muddy sediments were poor in functional macrobenthic diversity and displayed intermediate oxygen consumption rates, but the highest ammonium effluxes. These muddy sites also showed an elevated alkalinity release from the sediment, which can be explained by the elevated rate of anaerobic processes taking place. Fine sandy sediments were rich in functional macrobenthic diversity and had the maximum oxygen consumption and estimated denitrification rates. Permeable sediments were also poor in macrobenthic functional diversity and showed the lowest oxygen consumption rates and only small fluxes of ammonium and alkalinity. Macrobenthic functional biodiversity as estimated from bioturbation potential appeared a better variable than macrobenthic density in explaining oxygen consumption, ammonium and alkalinity fluxes, and estimated denitrification. However, this importance of functional biodiversity was manifested particularly in fine sandy sediments, to a lesser account in permeable sediments, but not in muddy sediments. The strong relationship between macrobenthic functional biodiversity and biogeochemical cycling in fine sandy sediments implies that a future loss of macrobenthic functional diversity will have important repercussions for benthic ecosystem functioning.     

Effects of pollution on benthic invertebrate communities of the St. Marys River, 1985

A survey was undertaken in 1985 to assess spatial and temporal trends in the benthic community structure in relation to sediment contamination and wastewater sources at 70 stations between Whitefish Bay and lower Lake George in the St. Marys River. Cluster analysis identified seven benthic communities. Three were identified as pollution impacted, based on a preponderance of tubificids and nematodes, usually at high densities (up to 259 000 m^-2), but sometimes at low densities (< 100 m^-2) at individual stations. Impacted communities occurred downstream of industrial and municipal sources and in depositional areas, and were confined mainly to Canadian waters. Unimpacted communities had greater numbers of taxa, and occurred upstream of point sources, along the U.S. shoreline, and in most areas of downstream lakes. Impacted and unimpacted communities were separated along particle size and contaminant gradients in river sediments. Despite recent reductions in pollutant loadings and improvements in sediment quality, no major changes were apparent in the status of the benthic community from earlier surveys.     

Metabolism and enzyme activities of hagfish from shallow and deep water of the Pacific Ocean

Although hagfishes are ecologically important members of benthic communities there has been little data available on their metabolism. The oxygen consumption, enzyme activities, and muscle proximate composition of shallow living Eptatretus stoutii and deeper living E. deani were measured to investigate hagfish metabolism. Very low rates of oxygen consumption and both aerobic and anaerobic enzyme activities in the body musculature confirmed the low metabolism of hagfishes. However, significant variation in oxygen consumption existed. E. stoutii had significantly lower rates compared to those of the deeper living E. deani and two other shallow living species for which literature data was used. Both species could regulate their oxygen consumption to very low oxygen concentrations. Epatretus deani, which lives in an oxygen minimum zone, had a significantly lower critical oxygen tension (0.83 kPa) compared to E. stoutii (1.47 kPa). The deeper E. deani had greater lipid stores than E. stoutii which may reflect its deeper habitat and more sporadic food supply.     

Aquatic biodiversity under anthropogenic stress: an insight from the Archipelago Sea (SW Finland)

The Archipelago Sea in the northern Baltic has been subjected to large-scale cultural, economic and ecological changes, especially during the last three decades. Environmental threats originate from both basin-wide sources, affecting the whole Baltic Sea, and from local sources, such as nutrient loading from nearby river outflows, intense agriculture, fish farming, ships' traffic, boating, and man's physical impacts on the landscape and seascape. Both the Åland archipelago and the Archipelago Sea have been listed as hot-spots by HELCOM, Baltic Marine Environment Protection Commission, eutrophication being the main threat to the aquatic environment. In this study we review how biological communities have reacted to an increase in man-induced multisource stresses. Changes in plankton, benthic animals, macroalgal assemblages and fish communities have been documented in most parts of the Baltic Sea since the 1970s. What remains to be understood is the importance of these structural changes for the functioning of the Archipelago Sea ecosystem under various levels of human impact.     

Consequences of Increasing Hypoxic Disturbance on Benthic Communities and Ecosystem Functioning

Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota) effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface) by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days) in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential), gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH₄ ⁺ and dissolved Si. Although effluxes of PO₄ ³⁻ were not altered significantly, changes were observed in sediment PO₄ ³⁻ sorption capability. The duration of hypoxia (i.e. number of days of stress) explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the benthic habitat matters, and that the link between biodiversity and ecosystem function is likely to be affected by a range of factors in complex, natural environments.     

Assessing the suitability of genetic diversity of Chironomus riparius (Meigen) as an indicator of environmental pollution

Reliable and cost-effective indicators are needed to reduce uncertainty in ecological risk assessments of chemicals so that their long-term and evolutionary impacts in the dynamics of stressed biological communities can be accounted for.In the present study we investigate the suitability of genetic diversity as an indicator of ecological disturbance of freshwater ecosystems. For that, we selected three freshwater systems with well-known histories of metal contamination and three nearby reference sites located in Northern Portugal and the effects of metal contamination were assessed both in the levels of genetic diversity of the non-biting midge Chironomus riparius Meigen (at microsatellite markers) and in the diversity and composition of the benthic macroinvertebrate communities.Results showed a remarkable impoverishment in the abundance and diversity of macroinvertebrate communities of metal polluted sites in which most sensitive taxa were eliminated and replaced by more opportunistic ones belonging mainly to Oligochaeta and Diptera. In contrast, no evidence for pollution-induced genetic erosion was found in C. riparius populations in the studied area, with genetic diversity of the species being indeed higher in sites with impoverished macroinvertebrate communities and poor habitat quality.Our findings suggest that there are important limitations to the use of measures of genetic diversity of C. riparius per se to unravel ecological disturbance. Field studies aiming at quantifying pollutant-driven genetic erosion need to carefully consider the ecological and demographic aspects of potential target species.     

Influence of the mode of macrofauna-mediated bioturbation on the vertical distribution of living benthic foraminifera: First insight from axial tomodensitometry

We investigated the influence of bioturbation by macrofauna on the vertical distribution of living (stained) benthic foraminifera in marine intertidal sediments. We investigated the links between macrofaunal bioturbation and foraminiferal distribution, by sampling from stations situated on a gradient of perturbation by oyster-farming, which has a major effect on benthic faunal assemblages. Sediment cores were collected on the French Atlantic coast, from three intertidal stations: an oyster farm, an area without oysters but affected by oyster biodeposits, and a control station. Axial tomodensitometry (CT-scan) was used for three-dimensional visualization and two-dimensional analysis of the cores. Biogenic structure volumes were quantified and compared between cores. We collected the macrofauna, living foraminifera, shells and gravel from the cores after scanning, to validate image analysis. We did not investigate differences in the biogenic structure volume between cores. However, biogenic structure volume is not necessarily proportional to the extent of bioturbation in a core, given that many biodiffusive activities cannot be detected on CT-scans. Biodiffusors and larger gallery-diffusors were abundant in macrofaunal assemblage at the control station. By contrast, macrofaunal assemblages consisted principally of downward-conveyors at the two stations affected by oyster farming. At the control station, the vertical distribution of biogenic structures mainly built by the biodiffusor Scorbicularia plana and the large gallery-diffusor Hediste diversicolor was significantly correlated with the vertical profiles of living foraminifera in the sediment, whereas vertical distributions of foraminifera and downward-conveyors were not correlated at the station affected by oyster farming. This relationship was probably responsible for the collection of foraminifera in deep sediment layers (> 6 cm below the sediment surface) at the control station. As previously suggested for other species, oxygen diffusion may occur via the burrows built by S. plana and H. diversicolor, potentially increasing oxygen penetration and providing a favorable microhabitat for foraminifera in terms of oxygen levels. By contrast, the absence of living foraminifera below 6 cm at the stations affected by oyster farming was probably associated with a lack of biodiffusor and large gallery-diffusor bioturbation. Our findings suggest that the effect of macrofaunal bioturbation on the vertical distribution of foraminiferal assemblages in sediments depends on the effects of the macrofauna on bioirrigation and sediment oxidation, as deduced by Eh values, rather than on the biogenic structure volume produced by macrofauna. The loss of bioturbator functional diversity due to oyster farming may thus indirectly affect infaunal communities by suppressing favorable microhabitats produced by bioturbation.     

Cold winter effects on benthic macrofauna communities in near- and offshore regions of the North Sea

In order to investigate the effect of severe winters on the long-term variability of benthic macrofauna communities four stations from the inner German Bight towards the Dogger Bank (North Sea) were sampled in March 1990 and from May 1995 to 2002. The stations were chosen to reflect a gradient in the hydrographic regime, temperature and organic matter supply. We initially hypothesized that the effect of severe winters on benthic communities will be more pronounced in the offshore more stable environment than in the nearshore regions. Our results clearly showed the opposite pattern. The benthic communities at the nearshore stations in the German Bight changed dramatically in species abundance and community structure after the severe winter 1995/1996. But the community structure in the German Bight returned to the previous stage within 2 years. In contrast, the offshore stations in the Oyster Ground and at the Dogger Bank remained rather unaffected by the severe winter and changed gradually during the study period. The results are discussed concerning the ecological importance of severe winters for benthic communities and the utility of our results for interpreting long-term changes.     

Seasonal Dynamics of Soft Bottom Macrobenthic Communities of the Sublittoral in Peter the Great Bay, Sea of Japan

Seasonal dynamics of macrobenthos were studied at five stations located at depths of 10–60 min in the Far East State Marine Reserve (southern Peter the Great Bay) during 1984–1987. Sampling was conducted at stations once per season. Stable seasonal fluctuations of the population density and the biomass in basic taxonomic groups were found. As a rule, the quantitative parameters were augmented in spring and summer, and decreased in fall and winter. This was caused, first of all, by summer fluctuations of the number of small and short-lived species of polychaetes and bivalve molluscs. The amplitude of fluctuations decreased with increasing depth. Variation in the quantitative parameters was significant at the community level only at the most shallow-water stations. It was assumed that this phenomenon might be caused by the seasonal consumption of macrobenthos by bottom fish and by the periodicity of detritus supply to the bottom from the water column with a background of varying environmental temperature parameters and of mass settling of benthic larvae. The seasonal changes in parameters began and ceased earlier in 1986–1987 than 1984–1985, which was related to an appreciable decrease in water temperature in 1986. During the period of study, an increasing trend of parameters, apparently part of a long-term cycle, was recorded both for individual groups and for entire communities, and was the most appreciable at greater depths (47–60 m).     

Benthic response to ammonium pulses in a tropical lagoon: implications for coastal environmental processes

In New Caledonia, the benthic communities living in the coral reef lagoon around Noumea city are subjected to regular shifts from oligotrophic conditions typical of lagoon waters to nutrient enrichment due to waste water inputs. The influence of ammonium pulses on microphytobenthos production was experimentally tested under varying light intensities in the vicinity of Noumea. Benthic oxygen, ammonium and silicon fluxes at the sediment-water interface were measured in situ using benthic enclosures. Three ammonium concentrations were tested. Gross primary production was doubled with a 13.8 μmol l⁻¹ ammonium concentration increase. Fitted PI curves showed that maximum production (F_max) was linearly related to ammonium concentration, but not the optimal irradiance (I_k). Silicon fluxes were characterized by dissolution in the absence of light, a process that declined with increasing illumination. These results were attributed to microphytobenthos activity, mainly diatoms that are nutrient-limited and strongly reactive to ammonium inputs. Production may result from a multiplication of cells, but migration up to the water sediment interface may also be involved. Oxygen consumption was also significantly influenced by ammonium concentration as a positive linear relationship with added ammonium concentration was established. Even during short-term experiments, ammonium enrichment stimulated photoautotrophic production, increasing the energy available to heterotrophs. Furthermore, microbenthic activities as well as nitrate production were increased by ammonia-oxidizing bacteria able to grow chemolithotrophically at the expense of oxygen. Therefore, in the study area, pulses of urban waste waters resulted in a decrease of plant-related autotrophy in benthic communities.     

Assessing the ecological health status using macrobenthic communities of tropical coastal water

The relative contributions of natural and anthropogenic fluctuations are different in shaping habitat health status and natural benthic communities in tropical coastal water. Understanding responses of coastal benthic communities to these fluctuations are still equivocal and thus available data are inadequate. Here, multiple analytical approaches were used to address the significant risk factors and their impacts on coastal benthic habitat health through space and time. A total abundance of 1436 ± 612 individuals of 33 benthic species were counted and identified from 22 sampling stations across eight sampling periods over the two years of study. Bioassay results showed that the benthic community is moderately exposed to anthropogenic pollutants in Klang Strait coastal water. The results showed that there were no significant temporal changes of habitat health status and macrobenthic community structure; however, spatial changes were significant and synchronized with anthropogenic and natural fluctuations. This study demonstrates that Cd and Hg levels and sediment characteristics played the primary role in shaping the habitat health and macrobenthic assemblages, whereas the influence of other factors were insignificant.     

Benthic infaunal community variability on the northern Svalbard shelf

Marine benthic communities are effective indicators of environmental change. Yet in the Arctic, there are few empirical tests of how sustained climatic change may influence community structure. Northern Svalbard is influenced by both warm Atlantic and cold Arctic water masses, providing an opportunity to assess potential effects of long-term environmental changes by examining spatial variation in community structure. We examined benthic macroinfaunal communities and sediment pigments under Atlantic and Arctic water masses on the northern shelf and fjords of Svalbard. We report on infaunal biomass, abundance, species composition, and diversity at 10 stations spanning 79°–81°N and ranging in depth from 200 to 500?m. Benthic biomass averaged 128?g?WW?m^?2 (48–253?g?WW?m^?2), mean density was 3,635?ind.?m^?2 (780–7,660?ind.?m^?2), and species richness varied from 45 to 136?taxa?stn.^?1. Abundance-based community structure clustered stations in groups related to water mass characteristics, with Atlantic and Arctic shelf stations being well distinguished from each other. Dominant taxa were different in Atlantic- and Arctic-influenced locations. Faunal biomass was highest in the Atlantic-influenced fjords, followed by Arctic fjords and Arctic shelf stations, with Atlantic shelf stations having the lowest biomass. Species richness and diversity were inversely related to biomass. Patterns in faunal biomass were strongly correlated with sedimentary pigments (R ²?=?0.74 for chl a and R ²?=?0.77 for phaeopigments), with large differences in sedimentary pigment concentration among stations. These relationships suggest that benthic fauna on the northern Svalbard shelf are food limited and dependent on predictable, albeit episodic, delivery of organic matter from the water column.     

海洋微型底栖生物的多样性与地理分布

海洋微型底栖生物是指生活于海洋沉积物中及表面的所有单细胞原核和真核微型生物,包括原核微生物、真核微藻及原生动物等光合自养和异养的类群.与水体相比,海洋底栖生境孕育了形态和功能多样性更高的微型生物,在陆架浅海单位体积沉积物中其丰度较之水体中同类生物高一至几个数量级,而深海则孕育着特殊进化环境下新奇多样且数量庞大的微型底栖生物,是维持海洋生物多样性、海洋生态系统结构和功能不可或缺的部分.迄今对于微型生物是全球性还是限定性分布一直存在争议,对其解答受到分类研究欠缺及采样不足的制约.分子生物学从正反两方面提供了理论依据,但无法得出一个普遍接受的观点.海洋微型底栖生物的多样性研究侧重于物种多样性及群落结构与分子多样性,较为显著的进展体现在原核微生物的分子多样性及底栖真核微藻的物种多样性研究,对于海洋底栖原生动物的多样性研究则相较滞后.本文综述了国内外对海洋微型底栖生物各主要类群的分类学和多样性研究进展,探讨了各类群在全球的潜在物种多样性,并就我国未来加强海洋微型底栖生物多样性构成、分布与变动及驱动变化的因子以及底栖微食物网的研究提出了建议.     

The food web in the lower part of the Seine estuary: a synthesis of existing knowledge

The Seine estuary illustrates the alterations to estuaries due to human activities heavy releases of pollutants of various origins and significant morphological changes beginning in the middle of the 19th century. The intertidal mudflat surface has been seriously reduced (< 30km²) since the channels of the Seine River came under management. While the role of the Seine estuary in the dynamics of the eastern English Channel ecosystem is recognized as important, the biological characteristics of the estuary remained relatively unknown until the 1990s. Biological diversity was progressively impoverished from the polyhaline zone to the oligohaline zone. In spite of a heavily contaminated environment, the macrobenthic and planktonic fauna of the Seine estuary remains similar to those of other northeastern Atlantic estuaries. The fauna exhibit clear contrasts between areas with very high abundance and others with very low abundance. The pelagic fauna, especially the copepod Eurytemora affinisand the shrimp Palaemon longirostris, are more abundant in the Seine estuary than in other estuaries. Diversified and abundant, Abra alba-Pectinaria koreni and Macoma balthica benthic communities occur, respectively, in the outer and inner parts of the estuary. In subtidal flats, benthic fauna is especially poor in terms of specific richness, abundance and biomass. Paradoxically, considering the high abundance of prey, fish are particularly scarce. Two food webs have been identified. In the oligohaline zone, where turbidity is maximum, the food web is exclusively planktonic, due to dredging that prevented benthic fauna from settling. In the polyhaline zone, fish populations that feed particularly on benthic fauna benefit from low turbidity and high oxygen concentrations. So, in spite of heavy organic and metallic contamination and human activities, the Seine estuary remains a highly productive ecosystem, which provides a nursery for marine fish and feeding grounds for migratory birds. A global management plan appears to be necessary in order to guarantee that the Seine estuary continues to function as it currently does.     

Carbon cycling by seafloor communities on the eastern Beaufort Sea shelf

Tight pelagic-benthic coupling on Arctic shelves suggests that resident benthic communities may be particularly important in the cycling of carbon and regeneration of nutrients. We sampled 16 stations in the eastern Beaufort Sea during Autumn 2003 and Summer 2004 to determine spatial patterns in sediment community carbon demand, and the manner in which that demand was partitioned among epifauna, macroinfauna, and meio-/microfauna. Sediment carbon demand in this relatively oligotrophic area was similar to that measured in more productive Arctic shelf sites, and was largely related to the distribution of phytodetritus in surface sediments. Epibenthic megafaunal communities were dominated by echinoderms and exhibited peak abundance (up to 240 ind. m^− 2) and biomass at stations in the 60-90 m depth range. Partitioning of the carbon demand revealed the local importance of megafauna, accounting for up to 41% of the community demand. Macrofauna accounted for on average between 25 and 69% of the carbon demand, while meio-/microfauna were responsible for 31-75% of the demand. Total community carbon demand by the benthos is estimated to account for approximately 60% of the annual new production in the region, suggesting the great ecosystem importance of benthic communities on the Beaufort shelf, and potentially across the Arctic. Our study region is strongly influenced by the Mackenzie River, and ongoing climate change is likely to result in altered productivity regimes, changes in quality and quantity of available food, and higher levels of sediment deposition. Impacts of these events on benthic community structure and function will likely have repercussions throughout the ecosystem.     

The Red King Crab Paralithodes camchaticus (Tilesius, 1815) (DECAPODA: ANOMURA): The Use of Species Equality Indicators to Assess the Influence on the Benthos of the Barents Sea

Russian Journal of Marine Biology - The “Difference of Evenness” (DE) index, based on the ratio of r- and K-strategists in benthic communities was proposed for a quick assessment of the...