Macrobenthic Community Composition Research Articles

Effects of variations in hydrological connectivity on the macrobenthic community structure in reclaimed wetlands

The Nanhui Dongtan Wetland is the most extensively reclaimed part of the Yangtze River Estuary wetland. In recent decades, urbanization has led to the extensive reclamation of the intertidal wetlands of Nanhui Dongtan. Macrobenthos are crucial as secondary production groups in the food web. However, there is a lack of in-depth research on the response mechanisms of macrobenthic communities to environmental disturbances in reclaimed wetlands. This study investigated the impact of hydrological connectivity changes caused by land reclamation on the macrobenthic community based on the macrobenthic community composition in preserved tidal flats and closed and open reclamation areas in Nanhui Dongtan. The results showed that the macrobenthos species richness in the closed reclamation area was significantly lower than that in the other areas. After dividing the functional groups of macrobenthos, structural equation modeling revealed a negative correlation between the salinity and the functional group composition. Analysis of the food sources revealed significant positive correlations between predatory and sediment-feeding populations and sediment organic matter content, between detritivorous group and environmental chlorophyll-a content, and between herbivorous group and suspended organic matter content in water. Therefore, variations in hydrological connectivity in different reclamation areas caused differences in food source distribution, which led to different compositions of macrobenthic functional groups. The results of this study provide a theoretical reference for the study of intertidal wetland habitat restoration.

Unraveling the functional diversity of macrobenthic community from Prydz Bay, Indian sector of the Southern Ocean

Antarctic marine ecosystems show rich macrobenthic diversity with a high level of endemism and biomass which is under the threat of global climate change. Till date, information regarding the structure of macrobenthic communities from Prydz Bay is extremely meagre. The present study investigates the spatial pattern of macrobenthic communities, and their response to environmental factors from Prydz Bay complemented with trait-based functional diversity patterns. Samples were collected from 8 stations during the 11th Indian scientific expedition to the Southern Ocean. A total of 57 species of macrobenthos belonging to 8 phyla and 33 families were identified. The macrobenthic communities were dominated by families, Lumbrineridae, Glyceridae, Ophiuridae, and Epimeriidae. Macrobenthos abundance in the study area ranged from 0 to 1592 indv.m-2, whereas biomass ranged from 0 to 1210.2 g m-2. CLUSTER analysis divided the entire macrobenthic community into four groups based on 13.5% similarity. SIMPER analysis delineated species Nacella kerguenlensis and Rossella antarctica as the main contributors for establishing similarity in macrobenthic community composition across the groups. Canonical correspondence analysis (CCA) showed environmental variables like clay %, depth, and sediment total organic carbon as the governing factors in structuring the composition of macrobenthic species. Biological trait analysis (BTA) was performed to visualize the functional diversity of the total macrobenthic population based on morphological and ecological characteristics. A total of 23 traits in 6 categories were used to assess the functional diversity of the study area. The most widespread trait categories were epifaunal environmental position, motile locomotion strategy, sexual brooder and spawner, burrowing living habitat, predatory and detritivore feeding strategies. Investigating the functional diversity of macrobenthic assemblages using BTA represents a novel step towards evaluating the ecological status of the benthic realm of Prydz Bay. RLQ approach in combination with fourth-corner analysis was used to evaluate the relationships among biological traits, macrobenthic species and environmental parameters.The RLQ analysis revealed the positive association of tube dwelling and burrowing polychaetes with silty substratum, and the sessile organisms were found to be negatively correlated with the presence of carnivores/predators. The present study gives a comprehensive understanding about the macrobenthic community structure along with biological trait categories from Prydz Bay.

The effects of flow field on the succession of the microbial community on artificial reefs

The flow field is one of the most important external conditions affecting the development of biofouling community on artificial reefs (ARs), especially the microbial community. In this article, we investigated the temporal dynamics of microbial communities between the stoss side and the lee side of ARs. The results showed that the composition and structure of microbial and macrobenthic communities between the stoss side and the lee side both presented obvious temporal variations. Microbial diversity and richness were higher on the stoss side than that on the lee side. There was a greater impact on bacterial and archaeal communities on temporal scale compared to that on micro-spatial scale, which was not suitable for the fungal community. The organism biomass, abundance and coverage of macrobenthic community on the lee side were higher than those on the stoss side, and the microbial diversity on the stoss side increased significantly with the organism coverage.

Establishing biologically relevant sediment organic matter thresholds for estuaries and embayments of the Southern California Bight, USA

• Thresholds for sediment TOC and TN were predictive of healthy, intact macrobenthic communities. • Decline in macrobenthos condition with increasing gradients of sediment organic matter. • Thresholds were consistent with other coastal ocean sites in Northern Hemisphere. • First study to put forth sediment TN thresholds protective of benthic community condition. • Thresholds could be used as a guideline in the management of eutrophication stressors. Estuaries, lagoons, and embayments are key components of the coastal ecosystem and they are pervasively exposed to a variety of stressors – the most common of which is eutrophication. In shallow water coastal systems, eutrophication typically manifests as shifts in sediment oxygen horizons and accumulation of toxic reduced compounds in the porewater, which have direct, negative effects on the benthic fauna that live in these sediments. To catalog, prevent, and remediate these stressors, the coastal zone management community has expressed a need to identify targets for biostimulatory compounds and products in the environment that are protective of biological integrity of coastal waters. In response to this need, the present study identified and validated a series of sediment total organic carbon (TOC) and total nitrogen (TN) concentrations associated with changes in macrobenthic community composition across the estuaries and embayments of the Southern California Bight (SCB). Using data from a regional monitoring program, benthic community condition, quantified using the M-AMBI condition assessment index, was modelled as a function of TOC or TN concentration using logistic regression. Then, we evaluated eutrophication thresholds at concentrations corresponding to several relative probabilities (from 0.6 to 0.8), reflecting a range of policy makers’ potential tolerance for risk of failing to meet biointegrity goals. Organic matter thresholds were extracted from the regressions that were predictive of healthy macrobenthic community condition at a 0.8 probability (1.23 mg g −1 TN, 15.51 mg g −1 TOC), 0.7 probability (2.58 mg g -1 TN, 22.9 mg g −1 TOC), or 0.6 probability (3.68 mg g −1 TN, 28.96 mg g −1 TOC) – as an illustration of how these types of stressor response models could be used to set targets for management of these ecosystems. These thresholds were subsequently validated by applying them to data held back from the model creation and by comparing them to taxon-specific inflection points identified from TITAN changepoint analysis of the macrobenthic/TOC/TN calibration data. The different TOC and TN thresholds correctly classified between 67 and 86% of the validation samples, with most of the misclassifications being instances of low organic matter concentration but poor community condition (i.e., false positives). The TOC thresholds identified from our Southern California dataset fell within a similar range (10–35 mg g −1 ) that has been linked to benthic community impacts from a variety of coastal ocean sites across the Northern Hemisphere. The consistency in thresholds across multiple habitats and different types of biota is suggestive of a general, quantitative threshold for organic matter accumulation in near shore sediment habitats and could be useful for informing the management of coastal ecosystems and setting targets biostimulatory stressors in these systems.

SOME FEATURES OF THE SPECIES, SPATIAL AND TROPHIC STRUCTURE OF SUBLITTORAL AND LOWER LITTORAL MACROBENTHOS COMMUNITIES IN COASTAL LAGOON ECOSYSTEMS (KANDALAKSHA BAY, WHITE SEA)

The species composition, diversity, spatial and trophic structure of macrobenthic communities of the sublitoral and lower littoral zones were studied in several lagoon ecosystems (Kandalaksha Bay, White Sea). Surveys detected 52 species of benthic invertebrates and 6 species of seaweeds and algae in the investigated ecosystems. In the sublittoral zone, the greatest species diversity, total density and biomass of species populations were found in the lagoon least closed off from the sea, located at the exit from Kislaya Inlets’ head, where marine less euryhaline species were found more. The smallest species diversity was found in the most fenced and silted lagoons of the Nikolskaya Inlet and Zelyoniy Cape, where brackish water and marine euryhaline species prevailed. An intermediate position was occupied by the lagoon of Yermolinskaya Inlet and the lagoon near Lake Yershovskoe. In the littoral zone, as opposed to the sublittoral, common indicators of the macrobenthos community structure (total density, biomass, and less so the species diversity) increased from less regulated and open ecosystems to more enclosed ones. The exception was the lagoon of Nikolskaya Inlet, where significant overregulation and siltation led to a significant reduction in species diversity, total density and, especially, biomass of the macrobentos community. The trophic structure of macrobenthic communities of the studied lagoon ecosystems is characterized by a similar structure – the group of collector detritivores prevailed in the sublittoral zone, with an upward tendency from more open lagoons to lagoons sheltered off from the sea. In the lower littoral zone, which is more exposed to tidal impact, there was a greater amount of immobile sestonivores (Mytilus edulis), as well as scraper grazers (Littorina littorea) with the group of immobile sestonivores (M. edulis) tending to increase towards lagoons that are moderately sheltered off from the sea (the lagoon near Lake Yershovskoe lake and the lagoon of Yermolinskaya Inlet).

Beta Diversity of Antarctic and Sub-Antarctic Benthic Communities Reveals a Major Role of Stochastic Assembly Processes

Community assembly is the result of both, deterministic and stochastic processes. The former encompasses niche-based local-scale mechanisms such as environmental filtering and biotic interactions; the latter includes ecological drift, probabilistic colonisation, and random extinctions. Using standardised sampling protocols, we show that the spatial variation in species composition (beta diversity) of shallow subtidal macrobenthic communities of sub-Antarctic (Strait of Magellan and Yendegaia Fjord [Beagle Channel]) and Antarctic (Fildes Bay [King George Island, West Antarctic Peninsula]) localities reflects a high contribution of stochastic processes to community assembly. Null model analyses indicated that random sampling from species pools of different sizes drove the observed among-locality differences in incidence- and abundance-based beta diversity. We analysed a normalised stochasticity ratio (NST), which delimits between more deterministic (<50%) and more stochastic (>50%) assembly. NST was notably larger than 50%, with mean values of 69.5% (95% CI = 69.2–69.8%), 62.5% (62.1–62.9%), and 72.8% (72.5–73.2%) in Strait of Magellan, Yendegaia Fjord, and Fildes Bay, respectively. Accordingly, environmental factors, such as depth, seawater temperature, salinity, and underwater light penetration, accounted for a small fraction of the spatial variation in community composition across the three localities. In this region, therefore, stochastic processes could have stronger effects on community assembly than deterministic niche-based factors. As anthropogenic biotic homogenisation continues apace, our study can give useful insights into the major ecological processes in Southern Ocean’ coastal marine communities.

Soft-Sediment Communities of the Northern Indian River Lagoon, FL, United States

Understanding the structure and function of infaunal communities is useful in determining the biodiversity and ecosystem function of shallow estuaries. We conducted a survey of infaunal communities within three separate water basins [Mosquito Lagoon (ML), Indian River (IR), and Banana River (BR)] in the larger Northern Indian River Lagoon, FL, United States to establish a database of infaunal community structure and function. Twenty-seven sites were sampled quarterly from 2014 to 2016. Analysis of all samples determined that basin, season, and sediment composition were the primary drivers of macrobenthic community composition. Diversity was highest in the ML, and lower in spring compared to other seasons. The occurrence of a brown tide (Aureoumbra lagunensis) in 2016 allowed a comparison of winter and spring communities before (2015) and during (2016) a bloom event. Community composition and diversity at the BR sites were the most affected by the bloom event with the lowest diversity and abundances during the bloom. Diversity in the IR was also lower during the bloom, while the ML was unaffected by the bloom. Species of all feeding groups were affected by the bloom, with lower abundances found in all groups. In addition, to determine the overall trophic diversity of infaunal communities, we collected infaunal organisms from two of the quarterly sampled sites for isotope analyses. Values of δ13C and δ15N from infaunal tissue were compared to those of potential food sources at each site. Substantial interspecific variation in isotope values of infaunal organisms within a site suggests the presence of diverse nutritional modes that include suspension and deposit feeding and predation. Together, these data suggest that infaunal communities contribute to benthic pelagic coupling and nutrient cycling within the estuarine communities, but the overall function of these communities may be tightly linked to their species composition.

Macrobenthos‐based RBP II (Rapid Bioassessment Protocol II) as a tool to assess the sediment and water quality in a treated textile effluent receiving stream ecosystem associated with a wetland marsh: A case study from Sri Lanka

AbstractMacrobenthos are important bioindicators of organic and nutrient pollution. The present study used the macrobenthos‐based rapid bioassessment protocol (RBP II) to study the effects of treated textile effluent inputs into a natural stream ecosystem connected to a wetland marsh. Three reference sites and three sites receiving point source inputs from a textile effluent treatment plant were selected. The physical and chemical parameters, and the abundance and diversity of macrobenthos at each site, were assessed during the rainy and dry seasons of 2020. Although the water quality parameters at the sites representing the point source inputs did not exceed the standard textile effluent discharge limits, a significant influence on the macrobenthic community composition was observed at the effluent discharge receiving sites. The dominant macrobenthos in the ecosystem (Baetis sp., Leptophlebia sp; Tubifex sp.) exhibited significant correlations with lead, copper, chromium and cadmium concentrations of the water and sediments. The Shannon–Weiner Diversity Index, Family Biotic Index, EPT Index and EPT/C ratio used in the rapid bioassessment protocol indicated significantly strong correlations with the water and sediment quality parameters, demonstrating their suitability to be used as a tool for biological measurements in aquatic ecosystems receiving textile effluents.

Data‐driven bioregionalization: A seascape‐scale study of macrobenthic communities in the Eurasian Arctic

AbstractAimWe conduct the first model‐based assessment of the biogeographical subdivision of Eurasian Arctic seas to (1) delineate spatial distribution and boundaries of macrobenthic communities on a seascape level; (2) assess the significance of environmental drivers of macrobenthic community structures; (3) compare our modelling results to historical biogeographical classifications; and (4) couple the model to climate scenarios of environmental changes to project potential shifts in the distribution and composition of macrobenthic communities by 2100.LocationEurasian Arctic seas, in particular Barents, Kara and Laptev Seas.Taxon169 species of macrobenthic fauna; most common taxa are Polychaeta (85 species), Malacostraca (30 species), Bivalvia (26 species) and Gastropoda (10 species).MethodsWe employed the Region of Common Profile (RCP) approach to assess the bioregionalization patterns of Eurasian Arctic seafloor communities. The RCP approach allows the identification of seascape‐scale distribution patterns by simultaneously considering biotic and environmental data within one modelling step.ResultsFour RCPs were identified within the Eurasian Arctic. The results showed that water depth, sea‐ice cover, bottom‐water temperature and salinity, proportion of fine sediments, particulate organic carbon (POC) and depth of the euphotic zone were among the most important driving variables of macrobenthos communities. The projections, driven by the climate‐change scenarios, suggested a general north‐eastward shift of the RCPs over the 21st century, mainly correlated with retreating sea‐ice and increasing sea‐bottom temperature.Main conclusionsThe identified RCPs largely match the previously reported large‐scale distribution patterns of macrobenthic communities in Eurasian Arctic seas. The spatio‐temporal dynamics of RCPs are in agreement with local long‐term observation data on macrobenthic resilience/vulnerability in the studied region. The representation of the ecoregions and biotas in a probabilistic form, together with quantitative assessment of potential climate‐driven changes, will help to adequately consider macrobenthic biodiversity dynamics in the development of science‐based conservation measures.

Jellyfish degradation in a shallow coastal Mediterranean lagoon

Recurrent jellyfish blooms in the coastal zone call for understanding the impacts of jelly-falls on the functioning of benthic communities, especially in shallow enclosed ecosystems where their biomass can affect local carbon cycling and productivity. Each year, blooms of the jellyfish Aurelia coerulea appear and collapse in a semi-enclosed coastal Mediterranean lagoon (the Thau lagoon, south of France). Although the lagoon is shallow, large accumulations of dead jellyfish are never observed on its bottom, so it was hypothesized that decaying jellyfish were rapidly consumed by local macrobenthic organisms. The current work aimed to test this hypothesis, by estimating the impact of the presence of dead A. aurelia medusae on local macrobenthic community composition and assessing their biomass loss rates under different scenarios of accessibility by the macrobenthos. Unexpectedly, our results revealed a limited role of macrobenthic scavengers in the disappearance of dead medusae, although this later was particularly fast (19–78h). Only one taxon (Tritia sp., Nassariidae family) showed a significant response to the presence of dead A. coerulea medusae on the seabed. Thus, our results suggest that the fast disappearance of dead jellyfish biomass in Thau results from its rapid degradation and consumption by local microorganisms, likely due to the combined effects of high local temperatures and the small size of A. coerulea medusae. Thus, the important biomass produced during A. aurelia blooms in Thau might essentially boost its microbial food web. The potential role of jellyfish blooms in controlling biogeochemical cycles and food web functioning in shallow lagoons is discussed, underlying the need to include this process in ecosystem-based models.

Response of macrobenthic communities to heavy metal pollution in Laoshan Bay, China: A trait-based method

The effects of multiple natural and anthropogenic stressors on the functional trait composition and diversity of marine macrobenthic communities in Laoshan Bay were investigated using biological trait analysis (BTA). Seven traits, including 27 trait modalities and four functional diversity indices (functional richness, functional evenness, functional divergence, and Rao's quadratic entropy), were considered. The results of RLQ (environmental variables (R), species taxa (L), and traits (Q)) and variance partitioning analysis (VPA) showed that the trait compositions and functional diversity of macrobenthic communities were influenced by a combination of stressors, among which heavy metals were the major factors. At the sites with high heavy metal pollution, the prevalent traits were infauna, burrower, and deposit feeder, whereas epifauna, carnivores and crawlers were dominant at the sites of low heavy metal contamination. The impact of natural environmental gradients on macrobenthic communities is also worthy of attention.

Strong macrobenthic community differentiation among sub-Arctic deep fjords on small spatial scales

Fjords play an important role in carbon cycling and sequestration, but the burial of organic matter in sediments strongly depends on the composition of macrobenthic communities. We studied three deep, sub-Arctic fjords located in northern Norway to assess the community differentiation of neighbouring fjords and the underlying environmental drivers. The fjords have relatively deep depositional basins (370–570 m), but they differ in sill depth and water exchange. In all fjords studied, the silty sediments were characterised by organic matter of mostly marine origin. We found that each basin was inhabited by a distinct benthic community, with pronounced differences in total abundance, biomass and species diversity. Only in one fjord (Skjerstadfjord), with a shallow sill, a slight mouth-to-head pattern of the community was found. The strong differentiation of macrobenthos among different fjords seems not to be directly associated with environmental drivers such as organic matter input, water masses or depth.

Long-term changes in contamination and macrobenthic communities adjacent to McMurdo Station, Antarctica

Improved waste management at McMurdo Station, Antarctica beginning in the 1980s has been followed by decreases in polycyclic aromatic hydrocarbon (PAH) and metal contamination in the adjacent marine sediments. However, determining the effect of the decreased contamination on marine ecological indicators (macrobenthic fauna) is confounded by concurrent changes in climate cycles and other physical forces. Between 2000 and 2013, there was a decrease in concentrations of some contaminants including mercury, copper, organochlorines, and PAHs in marine sediments adjacent to McMurdo Station. PAH concentrations in Winter Quarters Bay decreased an order of magnitude from 2000/2003 to 2012/2013 and were within an order of magnitude of reference area concentrations by 2013. Macrobenthic communities did not indicate any sign of recovery and have not become more similar to reference communities over this same period of time. Temporal changes in macrobenthic community composition during the study period had higher correlations with climatic and sea ice dynamics than with changes in contaminant concentrations. The Interdecadal Pacific Oscillation climatic index had the highest correlation with macrobenthic community composition. The Antarctic Oscillation climatic index, maximum ice extent and other natural environmental factors also appear to influence macrobenthic community composition. Despite large improvements in environmental management at McMurdo Station, continuing environmental vigilance is necessary before any noticeable improvement in ecological systems is likely to occur. The effects of climate must be considered when determining temporal changes in anthropogenic effects in Antarctica. Maintaining long-term monitoring of both contaminants and ecological indicators is important for determining the localized and global influences of humans on Antarctica, which will have implications for the whole planet.

Response of macrobenthic communities to changes in water quality in a subtropical, microtidal estuary (Oso Bay, Texas)

AbstractThe influence of nutrient loading and other anthropogenic stressors is thought to be greater in low inflow, microtidal estuaries, where there is limited water exchange. This 11-month study compared spatial changes in macrofaunal communities adjacent to regions that varied in land cover in Oso Bay, Texas, an estuarine secondary bay with inflow dominated by hypersaline discharge, in addition to discharge from multiple municipal wastewater treatment plants. Macrofauna communities changed in composition with distance away from a wastewater treatment plant in Oso Bay, with the western region of the bay containing different communities than the head and the inlet of the bay. Ostracods were numerically dominant close to the wastewater discharge point. Macrobenthic community composition is most highly correlated with silicate concentrations in the water column. Silicate is negatively correlated with salinity and dissolved oxygen, and positively correlated with nutrients within the bay. Results are relevant for environmental management purposes by demonstrating that point-source discharges can still have ecological effects in hydrologically altered estuaries.

Climate-driven changes in macrobenthic communities in the Mediterranean Sea: A 10-year study in the Bay of Banyuls-sur-Mer.

Marine ecosystems worldwide are affected by both natural variation and human activities; to disentangle and understand their individual role in influencing the macrobenthic community composition is challenging. The relationship between interannual variability in atmospheric circulation, dictated by the climatic oscillation indices, and the benthic macrofauna composition was assessed at four sampling sites located in the Bay of Banyuls‐sur‐Mer (NW Mediterranean Sea). Between 2004 and 2013, these sites were sampled annually during autumn/winter and analyzed for sediment grain‐size and benthic macrofauna composition (species richness, abundance, and biomass). Temporal changes in these descriptors were correlated with two climatic indices (NAO and WeMO indices) and a set of environmental parameters integrated over three different time periods (i.e., whole year, springtime, and wintertime). Our results confirm the occurrence of major temporal changes in the composition of macrobenthic communities within the Gulf of Lions. More specifically, the results indicate that (a) the WeMO appears to be more closely related to benthic macrofauna composition in the Bay of Banyuls‐sur‐Mer than the NAO, (b) winter is a better integration period than spring or the whole year as a proxy for community composition changes, and (c) Rhône River water flow is likely involved in the control of benthic macrofauna composition in the whole Gulf of Lions. The present study highlights the importance of WeMO as a regional proxy, which can be used to evaluate changes in benthic macrofauna linked to climatic variability.

Effects of fish cage culture and suspended oyster culture on macrobenthic communities in Xiangshan Bay, a semi-enclosed subtropical bay in eastern China

The impacts of fish cage culture and suspended oyster culture on macrobenthic communities were investigated in Xiangshan Bay, China, on a seasonal basis from January to October of 2015. Samples were collected from a fish cage farm, a suspended oyster farm, and two corresponding reference sites. Two-way ANOVA results showed that species richness, abundance, biomass, and Shannon–Wiener diversity differed significantly between the four different investigated areas, and different seasons as well. Cluster analysis showed that macrobenthic community composition in the fish and oyster culture areas significantly differed from that in the reference sites, respectively. Trophic structure of macrobenthos in the fish and oyster culture areas mostly clustered together owing to higher abundance and biomass of surface-deposit feeders and carnivores. The macrobenthic communities and feeding guilds correlated highly with environmental factors, such as bottom water chlorophyll a and nutrients, as well as sediment total organic carbon. Although integrated multi-trophic aquaculture is regarded as a suitable approach to coordinate desirable economic, social, and environmentally sustainable outcomes, coastal ecosystems may suffer from large-scale nutrient enrichment due to aquaculture and other human activities, which should not be considered in isolation.

Distribution of soft bottom macrobenthic communities in tropical marinas of Singapore

The establishment of marinas alters physico-chemical conditions and affects distribution of resident epibiotic and pelagic communities along coastal areas. However, information on the soft bottom macrobenthos within and around these boating facilities in the tropics is limited. Here, we investigated if macrobenthic communities differed among three representative tropical marinas, and whether the communities inhabiting the marinas differed from those outside the marinas. Ekman grab sampling of the soft bottom sediment at three Singapore marinas – Raffles Marina (RM), ONEo15 Marina (OMC), Marina at Keppel Bay (MKB) – yielded a total of 73 taxa from eight phyla. Accounting for temporal variations, taxonomic richness did not differ among marinas, while Shannon index (MKB > RM = OMC) and abundance (RM > OMC > MKB) did. Macrobenthic community composition differed among the marinas, with RM dominated by a high proportion of opportunistic species and OMC supporting species that were sensitive to pollution. The surveys also revealed that communities within and outside marinas differed. Unlike RM which is more enclosed, diversity was higher within MKB than outside it, likely because the latter marina had a layout that encouraged flushing which maintained good water quality. The study showed that while Singapore’s tropical marinas can support diverse groups of macrobenthic taxa, the presence of high proportions of opportunistic species suggested that pollution within the marinas was still significant. Macrofaunal diversity in tropical marinas, such as those in Singapore, may be promoted by designs that improve water exchange.

Preliminary Results on the Composition and Structure of Soft-Bottom Macrobenthic Communities of a Seamount: the Galicia Bank (NE Atlantic Ocean)

The Galicia Bank (Atlantic Ocean, NW Iberian Peninsula) is a flat-topped seamount located about 200 km from the northwest coast of Spain. This bank is included in the LIFE+ “INDEMARES” project, who aims to identify priority areas of conservation in the Spanish seas. In 2010 and 2011 two oceanographic surveys were carried out to investigate species and habitats of this deep ecosystem. A total of 28 stations were sampled using a box corer with a sampling area of 0.09 m2, in order to evaluate the distribution and biodiversity of the macroinfauna of the Galicia Bank. An additional sediment sample was taken at each station to analyse the granulometric composition and the organic matter content. Sediments were mainly sandy in nature (medium, fine and very fine sands), with low levels of organic matter content. The samples analysed yielded a total of 1189 individuals, belonging to 89 families. Polychaetes were the best represented group in total number of individuals (67%), followed by molluscs (14%). Echinoderms (9.7%), crustaceans (6%), and the Others group (Nemertea and Sipuncula) (3.9%) were less abundant. Two major macrobenthic assemblages were determined through multivariate analyses. Sedimentary composition was the main factor structuring the benthic community, separating medium sand stations from those that had finer sediments.

Seasonal and spatial alterations in macrofaunal communities and in Nephtys cirrosa (Polychaeta) oxidative stress under a salinity gradient: A comparative field monitoring approach

Sustainability of estuaries and lagoons is vital for coastal regions both in ecological and economic terms. These ecosystems are highly vulnerable to both natural and anthropogenic disturbances, with environmental risk assessment becoming increasingly challenging, and requiring the application of more adequate and accurate approaches that allow to distinguish between the effects induced by anthropogenic factors from those related to organisms characteristics and/or ecosystem’s natural features. In this context and as a case study, the present study compared the responses to different salinities analyzed through macrobenthic community composition (namely, species richness, abundance, alpha diversity, margalef richness and rarefaction index) inhabiting the Ria de Aveiro and on Nephtys cirrosa (polychaete species present in the studied community) oxidative stress markers (including, protein content, antioxidant enzymes activity and cellular damage). Overall, results confirmed that macrofauna’s descriptors of community composition are highly suitable to assess the effects of environmental salinity at both spatial and seasonal levels. Comparatively, biomarkers provided valuable information on the effects of environmental changes at the sub-cellular level in N. cirrosa, despite showed to be less specific to spatial and seasonal salinity variation, being influenced by a multitude of different abiotic factors. The present study emphasizes the importance of identifying the potential interfering factors and their impacts on the biomarker signals observed in wild populations and reinforce that in biomonitoring programs, biomarkers should be used as complementary tools.

Macrobenthic Diversity and Community Composition in the Pahang Estuary, Malaysia

Mohamamad, A. and Jalal, K.-C.A., 2018. Macrobenthic diversity and community composition in the Pahang estuary, Malaysia. In: Ashraf, M.A. and Chowdhury, A.J.K. (eds.), Coastal Ecosystem Responses to Human and Climatic Changes throughout Asia.The Pahang estuary is known to be one of the most productive natural ecosystems in Malaysia and provides food for a variety of organisms. Unfortunately, many species are increasingly threatened there because of declining conditions in natural aquatic ecosystems. Macrobenthic community composition has been extensively used to determine the quality of the aquatic environment for a long time. The Pahang estuary is undergoing poor conditions in water quality and riverbank vegetation because of sand dredging and other human activities. These activities prove the greatest threats to habitat loss, degradation of water quality, and declining indigenous fish population. Based on the above perspectives, a study was conducted on microbenthic diversity and community along with benthic organisms in the Pahang estuary, Malaysia. The study was divided into three zones. Zone 1 was identified as low in diversity of the microbenthic community in Pahang estuary with the diversity index (H′) of 0.35; only polychaete worms and bivalves were identified from this area. Polychaete represented by Neries sp. bivalve class was represented by Yoldia sp. in this zone. For Zone 2, the number and types of benthic communities were low because of human disturbance, but they still exist because of detritus that acts as food and habitat provided by the mangrove. This area was identified as a lowest diversity index of macrobenthos (polychaete, bivalves, and gastropods) with the value of 0.31. The diversity index for Zone 3 was highest among all three zones, with the diversity index of 0.38 along with three classes of macrobenthos, which were polychaete, bivalves, and gastropods. Polychaete was represented by Neries sp., bivalves by Yoldia sp., and gastropods by Nassarius sp., respectively. The lower diversity of the macrobenthic community reveals the alarming conditions of the Kuala Pahang because of massive human disturbances along the Pahang estuary. Long-term monitoring for species diversity is necessary for the sustainable development of aquatic resources in this fascinating tropical estuary.