Search

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Continental margins usually have a high degree of environmental heterogeneity, which, in turn, promotes high benthic biodiversity. The South-Southeast regions concentrate the most well-mapped areas of the Brazilian continental margin regarding seafloor geomorphology and physical oceanography. However, the structure of the soft-sediment benthic fauna of the continental slope is still unknown. Characterization and understanding of the Brazilian continental slope biota are imperative since human activities are increasing in the last decades, especially after the discovery of the pre-salt reservoir in Santos Basin. In this study, we aimed to establish a baseline of the spatial distribution of the benthic macrofaunal communities regarding their latitudinal and bathymetric patterns in the Santos Basin to support future environmental monitoring activities in the region. As part of the Santos Project - The Santos Basin Regional Environmental Characterization (PCR-BS) - coordinated by CENPES/PETROBRAS, a benthic oceanographic cruise was carried out in 2019. Sediment samples were collected using a GOMEX-type box corer in 47 stations distributed in eight transects (4002,400 m depth range). In total, 12 additional stations (1,300-2,200 m) were defined to cover an area where oil and gas are exploited. Our results showed that macrofaunal assemblages of the Santos Basin present strong depth zonation related to changes in organic matter input, as well as to temperature, carbonate, and grain size. At local scale, the northern sector stood out for having a higher abundance of macrofauna in the upper slope (400 m) and it probably reflects the oceanographic processes and the organic enrichment caused by the upwelling events that occur at Cabo Frio region. The zonation pattern and the dominance of some polychaete, peracarid crustacean, and bivalve families were similar to other SE Brazilian continental margins. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the effect of dredging activities on the structure of the macrobenthic community of a port complex in São Luís do Maranhão (2°S, Brazil). Sampling was performed on four occasions: pre-dredging, dredging 1 (25% of the material dredged), dredging 2 (75% of the material dredged) and post-dredging. Total mean density was 430.8 ± 55.0 ind/m², with 147.76 ± 280.82 ind/m² at pre-dredging, 161.90 ± 285.67 ind/m² at dredging 1, 53.83 ± 72.15 ind/m² at dredging 2 and 67.29 ± 72.58 ind/m² after dredging, revealing a reduction during dredging 2. The most representative groups were Polychaeta, Oligochaeta, Crustacea and Mollusca. Lumbrineris sp. (Polychaeta) was present in all sampling periods and was the dominant species. Richness and Shannon diversity of the species were higher in the pre-dredging and post-dredging periods, with reductions during the dredging activities (dredging 1 and 2). Principal component analysis revealed a correlation with granulometry and heavy metals in the sediment. The dredging activities led to a reduction in the macrobenthic community. Moreover, post-dredging recovery was insufficient for the recovery of the community. [ABSTRACT FROM AUTHOR]

The subtidal soft-sediment macrobenthos of a residential coastal marina's 25 ha through-flow canal system was investigated in relation to that in the adjacent natural waterways. The marina, developed from a polluted brownfield island in a warm-temperate estuarine bay, straddles the interface between the axial estuarine channel and a smaller backwater creek separating the island from the mainland, one entrance/exit connecting the canals to each water mass. Although they shared a common pool of taxa, an epibenthic cerithioid microgastropod dominated the axial channel as a whole, a subsurface paraonid polychaete likewise the backwater creek, whilst, unusually, sediment/water interface crustaceans dominated the whole marina canal system, especially the amphipods Ampelisca and Grandidierella. In contrast, the abundance of opportunistic annelids in the marina was very low. Whilst coastal marinas have generally been considered ecological disasters, biodiversity in this one's canals was unusually high at 104 observed invertebrate taxa; 97% of those achieving >25 m−2 in the local axial estuarine channel also occurred in the marina, and additionally its canals supported a number of uncommon taxa not otherwise known from the estuarine bay. This South African marina atypically appears to constitute a biodiversity asset, the more valuable because of its brownfield-site origin; and such appropriately constructed and managed through-flow marinas could form potential refuges for threatened estuarine and coastal soft-sediment benthos. It is concluded that only new marinas with a through water flow should be permitted to be located in ecologically sensitive or conservationally important areas and that regular monitoring of soft-sediment benthos should form an essential part of marina management regimes. [Display omitted] • Subtidal soft-sediment macrobenthos of through-flow coastal marina canals studied. • 97% of common taxa in adjacent natural estuarine channel also present in marina. • Unusually, marina-canal benthos dominated by crustaceans, particularly amphipods. • The 25 ha of brownfield canals biodiverse, with >100 invertebrate macrobenthic taxa. • Such coastal marinas could provide refuges for local macrobenthic biodiversity. [ABSTRACT FROM AUTHOR]

The present study reflects the seasonal variation of macrobenthic invertebrates from Aripal and Watalara streams in Kashmir Himalaya. During the study, a significant difference (p<0.05) was observed in the density of Annelida, Mollusca, and Arthropoda on a seasonal scale. Macrobenthic invertebrates were found to be at their highest density during summer and autumn, whereas they were recorded lowest during winter and spring. The total density during summer and autumn was found to be significantly different (p<0.05) when compared to winter and spring seasons. The data also depicted the maximum density of Arthropoda followed by Mollusca and Annelida. The study reveals the seasonal stability of the stream ecosystem within the temperate region and also provides the baseline information for macrobenthic invertebrate community structure. [ABSTRACT FROM AUTHOR]

Detecting the distribution and density of marine zoobenthos is crucial for monitoring healthy coastal ecosystems and for growth reference tracking in precision aquaculture. However, current detection algorithms for marine zoobenthos have high computational complexity and cannot guarantee a balance between accuracy and speed, limiting their deployment in fishery equipment. This study used a portion of the Augmented Underwater Detection Dataset, a large underwater biological dataset containing marine zoobenthos data. A marine zoobenthos recognition algorithm was proposed for sea cucumbers, sea urchins, and scallops based on an improved lightweight YOLOv5, which can recognize the three types of marine zoobenthos. In the image enhancement module, an underwater image enhancement algorithm based on color balance and multi-input fusion is used, which turns the blurred image into a natural appearance of the seabed image. The lightweight backbone network EfficientnetV2-S was chosen to replace the original YOLOv5 backbone network, reducing network parameter calculations and improving recognition speed. A Bottleneck Transformer was introduced into the backbone network, and an attention mechanism based on the convolution module was introduced to construct the embedded Convolutional Block Attention Module in the Neck structure of YOLOv5, thereby improving the recognition accuracy of the lightweight YOLOv5 model. The experimental results showed that the mAP of the proposed algorithm reached 0.941, which is an improvement of 0.002 compared with the original YOLOv5l algorithm. The computation of this algorithm is 37.0 FLOPs (G), the model size is 54 MB, and the inference time is 5.9 ms. Compared to the original YOLOv5l algorithm, the reductions are 66.1%, 40.5%, and 39.2%. The proposed algorithm efficiently identified and classified marine zoobenthos. • The paper proposes a new high-precision method for marine zoobenthos detection. • A lightweight high-precision Backbone fusing EfficientnetV2 and BotNet is proposed. • Introducing an underwater image enhancement module to improve underwater image quality. • Introducing CBAM in the Neck structure enhances the feature fusion capability. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sandstone reefs play an important role in sheltering a great diversity of organisms. In the north sector of the state of Espírito Santo, southeastern Brazil, the beaches are characterized by ferruginous sandstone reefs in the intertidal zones. These structures have unconsolidated sediment deposited over the reefs, mainly composed of bioclastic fragments of shells and seaweed, like the rhodolith. Rhodoliths are free-living calcareous algae with three-dimensional structures. By modifying the environment's physical characteristics, they create new microhabitats capable of being inhabited by several organisms, such as meio- and macrobenthonic invertebrates. This study sought to investigate the diversity of benthic fauna (macro- and meiofauna) on different substrates (rhodoliths vs. unconsolidated sediment) in the sandstone reef and investigate whether there are differences in benthic community structure between reef zones on Gramuté Beach in the Costa das Algas Environmental Protection Area in Aracruz, Espírito Santo, Brazil. Uni and multifactor analyses showed significant differences in the composition of the benthic fauna between the substrates (p < 0.05). Meiofauna and macrofauna had higher numbers of taxa and diversity associated with rhodoliths compared to with sediments. A multivariate analysis corroborates the results of the univariate, showing variations between substrates and beach zones. The presence of rhodoliths at Gramuté Beach contributes to the heterogeneity of the ecosystem and increases the richness and diversity of the benthos. The character of the benthic community and its dynamic aspects are discussed herein and are extremely important for conservation actions. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The anthropogenic construction activities on the coasts, such as pile-driving, generate vibrations that propagate through the substrate. Such substrate-borne vibrations could potentially affect marine organisms inhabiting the benthic environments. However, there is a lack of documented studies on the effects of vibrations on benthic animals. To investigate whether anthropogenic substrate-borne vibrations such as pile-driving operation influence the fiddler crab, Austruca lactea , we measured their locomotion response under vibrations of 35, 120, 250, 500, and 750 Hz generated by a vibrator. We compared the locomotion of crabs between control and vibration-treatment groups using videography. The duration of movements was significantly lower under 120 Hz vibrations compared to the control. Moreover, crab velocity was significantly higher under vibrations of 120 Hz and 250 Hz compared to the control group. Our result suggests that A. lactea can detect low-frequency substrate-borne vibrations and experience stress, leading to increased energy consumption. [Display omitted] • Fiddler crabs can detect low-frequency (120–250 Hz) substrate-borne vibrations. • Austruca lactea reduced movement duration or increased velocity to such vibrations. • The locomotion of them suggests that such vibrations could pose a stressor. • Vibrational disturbances should be considered for coastal construction. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is one of the environmental endocrine disruptors, due to its chemical stability it exists in abundant concentrations in water and soil consequently accumulating in the food chain and causing many endocrine-related health problems. So far, studies on the effects of BPA on marine invertebrates have focused on acute toxicity, endocrine regulation, reproduction, and development. However, fewer studies have been conducted on marine benthos. The current study aimed to detect the accumulation of BPA and its impact on tissue structure, antioxidant capacity, and immune indexes in marine worm, Urechis unicinctus. U. unicinctus , as a common marine benthic animal, were exposed to different concentrations of BPA. Blood cells and intestinal tract were taken for tissue structure inspection, and supernatant of the coelomic fluid was collected for oxidative and antioxidant biomarkers. Results showed that the accumulation of BPA in muscles of U. unicinctus tended to increase with exposure time. BPA induced a rise in H 2 O 2 and MDA content, and altered the activities of CAT, T-SOD, GST, LSZ and ACP, weaken the immune system functions. Moreover, pathological observation showed that BPA caused severe histopathology in the respiratory intestine, stomach, and midgut. These results will be helpful to understand the response mechanism of U. unicinctus under BPA exposure and provide a reference for controlling the aquaculture conditions and marine water quality of U. unicinctus. • BPA induced different damage to the stomach, midgut, and respiratory intestine of Urechis unicinctus. • BPA caused some negative effects on Urechis unicinctus immune indexes and oxidative stress indexes. • BPA affected the expression of MT and HSC70 genes. • BPA accumulated significantly in muscle. [ABSTRACT FROM AUTHOR]

The Nanhai No. 1 Shipwreck is a wooden ship sunk 800 years ago during the Southern Song Dynasty of China. The zoobenthic shellfish communities in the sediments covering the wreck came from 296 species from 5 phylums, of which 290 were molluscs. These molluscs were mainly composed of local marine fauna based on the literature. By comparing the structural parameters of the zoobenthic debris communities and their changes among the different sediment layers, it is notable that the seabed environment was influenced by the wreck within a short period of time, and corroded metal objects from the ship could impact the mollusc communities. Because of the relatively continuous and stable particle deposition in the sea, the wreck was quickly covered in sediment. During this deposition process, the seabed level of the shipwreck site gradually returned to similar conditions prevalent in the surrounding area. Sedimentation sealed the wooden objects of the hull from the sea water and relatively anaerobic conditions between the sediment and the wood structures were formed. This anaerobic environment inhibited the eroding effect of aerobic bacteria and wood boring animals, thereby preserving the shipwrecked hull. [ABSTRACT FROM AUTHOR]

The rocky shores in Chile have a wide invertebrate species diversity, that include species with marked abundances in determined regions. The aim of the present study is to analyse the spatial distribution pattern in different marine invertebrate species in rocky shore of Araucania region, considering if these species have random, uniform or associated patterns, and extrapolate if these patterns have Poisson, binomial or negative binomial distribution respectively. The results revealed the presence mainly of gastropods molluscs that would graze on benthic algae, these species have mainly aggregated pattern that has a robust negative binomial distribution pattern. The obtained results agree with observations for marine benthic fauna that mentioned the presence of aggregated pattern, has negative binomial distribution. Other ecological topics about spatial distribution were discussed. As costas rochosas no Chile têm uma ampla diversidade de espécies de invertebrados, que incluem espécies com abundância marcada em determinadas regiões. O objetivo do presente estudo é analisar o padrão de distribuição espacial em diferentes espécies de invertebrados marinhos na costa rochosa da região de Araucanía, considerando se essas espécies possuem padrões aleatórios, uniformes ou associados, e extrapolar se esses padrões possuem distribuição binomial de Poisson, binomial ou negativa. respectivamente. Os resultados revelaram a presença principalmente de moluscos gastrópodes que pastam em algas bentônicas, estas espécies têm principalmente agregado padrão que tem um padrão robusto de distribuição binomial negativa, padrão agregado de grupos, e a fauna de água doce que apresenta distribuição binomial negativa. Outros tópicos ecológicos sobre distribuição espacial foram discutidos. [ABSTRACT FROM AUTHOR]

Copyright of Iheringia. Série Zoologia is the property of Fundacao Zoobotanica do Rio Grande do Sul and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anthropogenic activities including coastal industries, urbanization, extensive agriculture and aquaculture as well as their cumulative impacts represent major sources of perturbation of marine coastal systems. Macrobenthic communities are useful ecological indicators for monitoring the health status of marine environments (or polluted environments). The present study reports, for the first time, the response of benthic macrofauna sampled during two years survey (2015–2016) to multiple anthropogenic pressures on the coastal zone south of Sfax (Tunisia). A total of 12 stations were monitored seasonally at locations downstream from the main potential sources of disturbance. 106 macrobenthos taxa, belonging to six animal phyla and 70 families, were identified with a dominance of polychaetes (42%), crustaceans (35%) and molluscs (18%). We used an ANOVA test and cluster analysis to identify spatial gradient linked to environmental and anthropogenic factors, including depth, sedimentary texture and anthropogenic activities (i.e. phosphogypsum discharges).The macrofauna present lowest species number and abundance on stations undergoing anthropogenic inputs, which are extremely polluted by heavy metals (Cd, Cu, F and N) and excess of organic matter. Univariate parameters reveal a general trend of increasing species diversity with increasing distance from the pollution source. The polluted stations are strongly dominated by carnivores, and selective deposit feeders, and more closely linked to the availability of trophic resources than to anthropogenic constraints. The seasonal changes in macrobenthic abundance, diversity indices and community structure are mainly linked to the biological cycle (e.g. recruitment events) of the dominant species. Biotic indices (AMBI and BO2A) classified the coastal zone south of Sfax as moderate and good ecological status. This study suggests that initiating a long-term monitoring programme would improve our understanding of the temporal changes of macrobenthic communities of this ecosystem, contributing to the assessment of effective management and conservation measures in this disturbed area. Image 1 • Coastal zone south of Sfax (Tunisia) is subject to intensive anthropogenic pressures. • Macrofauna community is poorly diversified at shallowest stations undergoing to anthropogenic pressures. • Three macrobenthic assemblages are identified in the coastal zone linked to environmental and anthropogenic factors. • Using the biotic indices, the coastal zone of Sfax can be classified as moderate to good ecological status. [ABSTRACT FROM AUTHOR]

The article presents data on the activity of the radionuclide 137Cs in seawater, sediment, macroalgae, and zoobenthos from different locations in Admiralty Bay, King George Island, maritime Antarctica. The activity of 137Cs in the macrophytobenthos remained relatively stable across species, oscillating at the level of 1 Bq kg−1dw. However, a few individuals exhibited higher activity, particularly at stations closer to the glacier front. This result could have been caused by specific conditions resulting from melting glaciers and meltwater inflow and mixing with oceanic water. The activities of 137Cs in zoobenthic were in the range from 0.12 Bq kg−1dw (Asteroidea) to 24.2 Bq kg−1dw (Porifera) and the total doses in marine species were several orders of magnitude lower than reference levels. Stable isotopes of δ13C and δ15N suggest that the main factor influencing 137Cs activity may be the source of carbon (marine vs. terrestrial/glacial), rather than feeding strategy or trophic niches. [Display omitted] • 137Cs in Antarctic biota were still detected. • Low activity of 137 Cs is observed in most cases of the Antarctic ecosystem. • Carbon cycling may affect radionuclides activity in zoobenthos. • Total dose from 137Cs in Antarctic species was negligible. [ABSTRACT FROM AUTHOR]

The Rio Doce estuary was critically impacted in 2015 by the world's largest mining tailing spill, with still unclear long-term effects on the aquatic biota. Here we present a long-term (2015 to 2020) assessment of estuarine benthic assemblages, where we demonstrate that despite a decline in the absolute concentrations of potentially toxic elements; sediment contamination is still above pre-impact conditions. The presence of these contaminants is likely responsible for a continued low habitat quality for the benthic fauna, characterized by a reduction of 96 % of the macroinvertebrate density and persistent change in the benthic assemblage composition. Our study supports previous work indicating the long-term nature of pollution impacts in estuaries, and demonstrate that although water quality levels were quickly adequate under regulatory terms, they largely lack significance to the overall ecosystem health assessment, as they are not related to the recovery of bottom- dwelling assemblages in estuarine ecosystems. • Mine tailing spill altered benthic macrofauna composition for over 4 years. • Heteromascus similis , Pholoe sp., and Sthenelais sp. were persistently eliminated. • Benthic assemblages' weak recovery was correlated with sedimentary contamination. [ABSTRACT FROM AUTHOR]

The anthropogenic marine debris, especially abandoned, lost or otherwise discarded Fishing Gear (ALDFG), represents a rising concern, because of its potential harmful impact on the marine animal forests. We carried out 13 km of video recordings, by means of a remotely operated vehicle, from 10 to 210 m depth, in an anthropised area of the Tyrrhenian Sea (Mediterranean Sea). This site, for its high ecological importance and biodiversity value, has been identified for the establishment of a new marine protected area (MPA). The aim of this paper was to assess marine litter abundance and its effects on the benthic fauna. The debris density, in the study area, ranged from 0.24 to 8.01 items/100 m2, with an average of 3.49 (±0.59) items/100 m2. The derelict fishing gear, mainly fishing lines, were the main source of marine debris, contributing 77.9% to the overall litter. The impacts of debris on the benthic fauna were frequently recorded, with 28.5% of the litter entangling corals and impacting habitats of conservation concern. These impacts were exclusively caused by the derelict fishing gear (91.2% by longlines), and the highest percentage (49.1%) of ALDFG causing impacts was observed from 41 to 80 m depth, in the coralligenous biocenosis. The results of the present study will help the fulfilment of "harm" monitoring, as recommended by the Marine Strategy Framework Directive (MSFD) and the UN Environment/MAP Regional Plan on the marine litter management in the Mediterranean Sea. Regarding the actions to reduce the derelict fishing gear, preventive measures are usually preferred instead of the extensive removals based on cost-effectiveness and sustainability. The establishment of a new MPA in the area could be a good solution to reduce ALDFG, resulting in the improvement of the ecological status of this coastal area. Image 1 • Marine litter was quantified within a new Marine Protected Area. • Litter density ranged from 0.24 to 8.01 items/100 m2 (mean = 3.49 items/100 m2). • Derelict fishing gear represented 77.9% of the total litter items. • Fishing lines have been recognized as a cause of coral damage. The derelict fishing gear, mostly fishing lines, were the main source of marine debris, contributing 77.9% to the overall litter observed in the Milazzo Marine Protected Area. [ABSTRACT FROM AUTHOR]

Abstract We conducted a broad-scale ecological effect assessment of agricultural chemicals where we combined biomonitoring databases of riverine invertebrate communities with predictions of environmental concentrations of chemicals, based on an exposure evaluation model for Japanese rivers. One of the difficulties of broad-scale assessment arises from the use of biomonitoring databases for which the monitoring sites are often spread across different geographic regions, with varying species compositions and heterogeneous environmental factors. This problem was circumvented using a trait-based approach, which extracts patterns of ecological properties of species response to changes in either chemical concentration or environmental factors. We identified groups of species that had particular trait categories that were negatively correlated with herbicide pollutants (the predicted concentration divided by the acute toxic concentration). Numerical abundances of species groups classified by trait categories had more sensitive responses to herbicide pollutants than total species abundance. However, a finding that trait diversity and species diversity indexes in the communities examined did not change with herbicide pollutants means that the two indexes showed resistance to chemical stresses. We inferred that the reason for the greater resistance in terms of trait and species diversity was that compositional changes of species caused by increasing herbicide pollutions were simply a shift from communities composed of susceptible species to those composed only of tolerant species. Graphical abstract fx1 Highlights • We assessed herbicide effects on invertebrate communities. • We used biomonitoring databases of riverine invertebrate communities (River Environmental Database) and the exposure evaluation of Japanese rivers (PeCHREM/G-CIEMS models) for this assessment. • Species abundance of particular trait categories significantly decreased with increased herbicide pollutants. • Species number, total abundance and wet biomass non-significantly decreased with increased herbicide pollutants. • Trait diversity was unaffected by herbicide pollutants. [ABSTRACT FROM AUTHOR]

Abstract Interest in the presence of pharmaceutically active compounds in the aquatic environment has been growing for over 20 years, yet very few studies deal with the metabolism of pharmaceuticals in marine organisms. In this study, the bioaccumulation under short-term conditions and metabolism of diclofenac were investigated. Mytilus trossulus was used as a representative of the Baltic benthic fauna. The mussels were exposed to diclofenac at a concentration of 133.33 μg/L for five days, following a five-day depuration phase. The highest concentration of diclofenac (7.79 μg/g dw) in tissues was determined on day 3. Subsequently, the concentration of diclofenac in tissues decreased rapidly to 0.86 μg/g dw on day 5. After five days of depuration, the concentration of diclofenac was 0.21 μg/g dw. Hydroxylated diclofenac metabolites were found both in tissues of mussels and water. This study shows that M. trossulus has the potential to accumulate diclofenac and metabolize it to 4-OH and 5-OH diclofenac. Highlights • Diclofenac is absorbed and accumulated in soft tissues by M. trossulus • M. trossulus metabolize diclofenac to 4-OH diclofenac and 5-OH diclofenac • Absorption and accumulation of diclofenac by M. trossulus depends on exposure time • Diclofenac undergoes partial degradation in artificial seawater [ABSTRACT FROM AUTHOR]

Abstract The bioturbation potential of macrobenthos communities (BPc) is an important parameter in marine ecology. Based on macrobenthos field surveys, BPc values were estimated in Bohai Bay, China. The horizontal distribution of BPc values changed across seasons while showing a certain level of continuity over time. The maximum BPc value was recorded in summer while the minimum occurred in winter. Although only a few environmental variables showed a statistically significant (p < 0.05) correlation with BPc, about 20 environmental variables exhibited a moderate correlation with BPc (0.3 < r < 0.5). The depth of the redox potential discontinuity (RPD) measured in situ changed across seasons, and the biogenic mixing depth values derived from the BPc index exhibited a relationship with the lowest RPD depth measurements. Our results suggest that the RPD depth can be predicted from BPc values, thereby showcasing a useful application of the BPc index in marine benthic pollution and environmental management research. Highlights • Estimation of bioturbation potential in Bohai Bay, China • Macrobenthic bioturbation potential has spatial and seasonal variations. • Correlation between BPc and environmental variables • BMD derived from BPc shows potential of estimating sediment status. [ABSTRACT FROM AUTHOR]

Abstract The bioavailability of trace elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Zn) in lowly to moderately contaminated coastal sediments from the Berre lagoon, France, was assessed by comparing their potentially bioavailable concentrations and bioaccumulated concentrations in the polychaete Alitta succinea. No linear correlations were observed contrarily to what is generally observed in similar works in areas with highly contaminated sediment. Correlations between trace and major elements (Fe, Ca, S, Mg, P, Al) in Alitta succinea tissues and their distribution in organism tissues show that, in such lowly to moderately contaminated sediments, biological variabilities should be considered. Normalization procedures allow to take into account these variabilities and to identify that sediment contamination is partly involved in the benthic ecosystem degradation of the Berre lagoon. Alitta succinea cannot be used as relevant bioindicator for Zn and Co bioavailability in sediment, since these elements are regulated by this organism. Highlights • In moderately contaminated sediments bioaccumulation is not correlated with the bioavailable form of contaminants in sediment • Biological variabilities of the target organism, such as the polychaeta Alitta succinea, must be considered • Geochemical measurement of major elements in organism tissues may allow normalization procedures • Sediment contamination in the Berre lagoon is partly involved in the benthic ecosystem degradation • Such method cannot be applied for biologically regulated trace elements (i.e., Co and Zn in this study) [ABSTRACT FROM AUTHOR]

Here, we collected 16 species (n = 298) from Laizhou Bay, China to investigate the trophodynamics, bioaccumulation and cancer risks of polycyclic aromatic hydrocarbons (PAHs). Results demonstrated that naphthalene was the most abundant PAH, followed by phenanthrene and fluorene in the marine organisms. The sum of 16 PAHs concentrations (Ʃ 16 PAHs) ranked with algae (19,435 ng·g−1 lipid weight, lw) > benthonic animals (6599 ng·g−1 lw) > fish (1760 ng·g−1 lw). Combustion and oil spill are two primary sources, contributing 60.3 % and 39.7 % of Ʃ 16 PAHs, respectively. High values of log BAF were found for 4–6 rings PAHs. Algae and benthonic animals showed a high ability to accumulate 2–4 rings PAHs and 5–6 rings PAHs, respectively. A biodilution pattern for PAHs was found in the marine food web. The carcinogenic risks of some benthos and fish were higher than 1 × 10−6, threatening resident health by consumption of these seafoods. [Display omitted] • High concentrations of 2–3 rings PAHs are found in marine organisms. • Combustion and ship emissions contribute 60.3 % and 39.7 % of Ʃ 16 PAHs. • Algae and benthos strongly accumulate 2–3 and 5–6 rings PAHs, respectively. • A biodilution pattern is observed for 16 PAHs in marine food web. • Consumption of some benthos and fish may lead to a potential cancer risk. [ABSTRACT FROM AUTHOR]

Here, we collected 16 species (n = 298) from Laizhou Bay, China to investigate the trophodynamics, bioaccumulation and cancer risks of polycyclic aromatic hydrocarbons (PAHs). Results demonstrated that naphthalene was the most abundant PAH, followed by phenanthrene and fluorene in the marine organisms. The sum of 16 PAHs concentrations (Ʃ 16 PAHs) ranked with algae (19,435 ng·g−1 lipid weight, lw) > benthonic animals (6599 ng·g−1 lw) > fish (1760 ng·g−1 lw). Combustion and oil spill are two primary sources, contributing 60.3 % and 39.7 % of Ʃ 16 PAHs, respectively. High values of log BAF were found for 4–6 rings PAHs. Algae and benthonic animals showed a high ability to accumulate 2–4 rings PAHs and 5–6 rings PAHs, respectively. A biodilution pattern for PAHs was found in the marine food web. The carcinogenic risks of some benthos and fish were higher than 1 × 10−6, threatening resident health by consumption of these seafoods. [Display omitted] • High concentrations of 2–3 rings PAHs are found in marine organisms. • Combustion and ship emissions contribute 60.3 % and 39.7 % of Ʃ 16 PAHs. • Algae and benthos strongly accumulate 2–3 and 5–6 rings PAHs, respectively. • A biodilution pattern is observed for 16 PAHs in marine food web. • Consumption of some benthos and fish may lead to a potential cancer risk. [ABSTRACT FROM AUTHOR]

The effects of acidification related to the CO 2 enrichment in the coastal environments on marine macrobenthic abundance, diversity and richness were analyzed in a medium- term (21 days) using mesocosm experiments. Two sampling sites located in the Bay of Cadiz – SW, Spain were selected and tested at pH values ranged from 7.9 to 6.0 (± 0.1). Moreover, variations in the concentrations of metals in the sediment samples were analyzed at the end of each experiment. The results showed low variation in the concentrations of metals in the sediment among the pH treatments. A significant decrease (p < 0.05) in the abundance, diversity and richness of assemblages were measured between the control and the lowest pH level in both sampling sites tested in this study (Rio San Pedro and El Trocadero). The majority of species were found in all samples except in pH 6.0 which only two species were found ( Hydrobia ulvae and Scrobicularia plana ,) in Rio San Pedro sediment fauna. In general, the results of cluster analysis showed 60% and 40% similarity in all replicated tests in El Trocadero and Rio San Pedro of sediment fauna, respectively. The results of the Principal Component Analysis (PCA) showed that both sediment parameters and pH reduction can interfere in the benthic assemblage indices. Although the assemblages’ indices have shown decreases only in the lower pHs, the organisms also could be impacted by chronic effects. Therefore, the extension of this study is important in order to improve the knowledge about the risks associated with CO 2 enrichment in on marine organisms. [ABSTRACT FROM AUTHOR]

Abstract: Bottom fishing such as trawling and dredging may pose serious risks to the seabed and benthic habitats, calling for a quantitative assessment method to evaluate the impact and guide management to develop mitigation measures. We provide a method to estimate the sensitivity of benthic habitats based on the longevity composition of the invertebrate community. We hypothesize that long‐lived species are more sensitive to trawling mortality due to their lower pace of life (i.e., slower growth, late maturation). We analyze data from box‐core and grab samples taken from 401 stations in the English Channel and southern North Sea to estimate the habitat‐specific longevity composition of the benthic invertebrate community and of specific functional groups (i.e., suspension feeders and bioturbators), and examine how bottom trawling affects the longevity biomass composition. The longevity biomass composition differed between habitats governed by differences in sediment composition (gravel and mud content) and tidal bed‐shear stress. The biomass proportion of long‐lived species increased with gravel content and decreased with mud content and shear stress. Bioturbators had a higher median longevity than suspension feeders. Trawling, in particular by gears that penetrate the seabed >2 cm, shifted the community toward shorter‐lived species. Changes from bottom trawling were highest in habitats with many long‐lived species (hence increasing with gravel content, decreasing with mud content). Benthic communities in high shear stress habitats were less affected by bottom trawling. Using these relationships, we predicted the sensitivity of the benthic community from bottom trawling impact at large spatial scale (the North Sea). We derived different benthic sensitivity metrics that provide a basis to estimate indicators of trawling impact on a continuous scale for the total community and specific functional groups. In combination with high resolution data of trawling pressure, our approach can be used to monitor and assess trawling impact and seabed status at the scale of the region or broadscale habitat and to compare the environmental impact of bottom‐contacting fishing gears across fisheries. [ABSTRACT FROM AUTHOR]

Dikerogammarus villosus , one of the most successful invaders in European river systems, is commonly regarded as a threat to native biodiversity and a main factor structuring the benthic community of invaded systems. The impact of D. villosus has been intensively studied in small-scale experiments and field observations, but its impact on natural communities on a larger scale remains unclear. Here, we investigated the benthic community structure at ten sites covering a broad range of habitats along the River Rhine (Central Europe) and its tributaries, to determine whether D. villosus is one of the main factors structuring the benthic community. Community composition was analysed using non-metric multidimensional scaling, distance-based redundancy analysis, and correlation analyses. D. villosus was one of nine relevant taxa present that altogether reflected a large part of the variation in the benthic samples, but further analyses indicated that the species might be less important for the community structure than other relevant taxa. Moreover, all nine relevant taxa together can explain only a similar amount of variation in our samples than the five relevant non-faunal environmental factors (water temperature, pH, conductivity, percentage of medium-sized gravel and macrophytes). Overall, our results suggested that rather a combination of non-faunal environmental factors than D. villosus mainly structure the benthic community composition on this larger spatial scale. [ABSTRACT FROM AUTHOR]

Marine litter is commonly observed everywhere in the ocean. In this study, we analyzed 17 km of video footage, collected by a Remotely Operated Vehicle (ROV) at depths ranging between 20 and 220 m, during 19 transects performed on the rocky banks of the Straits of Sicily. Recently, the Contracting Parties of the Convention on Biological Diversity (CBD) recognized this site as an Ecologically or Biologically Significant Area (EBSA). The research aim was to quantify the abundance of marine litter and its impact on benthic fauna. Litter density ranged from 0 items/100 m 2 to 14.02 items/100 m 2 with a mean (±standard error) of 2.13 (±0.84) items/100 m 2 . The observed average density was higher (5.2 items/100 m 2 ) at depths >100 m than at shallower depths (<100 m, 0.71 items/100 m 2 ). Lost or abandoned fishing lines contributed to 98.07% of the overall litter density, then representing the dominant source of marine debris. Litter interactions with fauna were frequently observed, with 30% of litter causing “entanglement/coverage” and 15% causing damage to sessile fauna. A total of 16 species showed interaction (entanglement/coverage or damage) with litter items and 12 of these are species of conservation concern according to international directives and agreements (CITES, Berne Convention, Habitat Directive, SPA/BD Protocol, IUCN Red List); we also observed 7 priority habitats of the SPA/BD Protocol. This research will support the implementation of monitoring “Harm” as recommended by the UN Environment/MAP Regional Plan on Marine Litter Management in the Mediterranean, and the Marine Strategy Framework Directive (MSFD). The institution of a SPAMI in the investigated area could represent a good management action for the protection of this hotspot of biodiversity and to achieve a Good Environmental Status (GES) for the marine environment by 2020, under the MSFD. [ABSTRACT FROM AUTHOR]

Lagoons in the southeast coast of Brazil have experienced eutrophication due to the exponential increase of human population and sewage discharges. Living benthic foraminifera have demonstrated to be good bioindicators of such impacts. This study aims to evaluate the organic matter accumulation effects on the foraminiferal distribution in the Itaipu lagoon (Brazil). On the basis of the biotic and abiotic analyses, three sectors are identified. The Sector I, an inner area, is characterized by high dissolved oxygen values and foraminiferal species with preference for marine conditions, demonstrating the sea influence. The Sector II, in the mangrove margins, is associated to sandy sediment and biopolymers and mainly represented by euryhaline species. The Sector III is marked by low density or absence of living foraminifera and corresponds to a low quality organic matter enriched area (North, Southwest and Centre). [ABSTRACT FROM AUTHOR]

Background. The beam trawl fisheries of veined rapa whelk, Rapana venosa (Valenciennes, 1846), cause small benthic organisms to be captured and also damage the other species living on the seafloor. To solve this problem, a proper modification that minimise the by-catch should be designed and put into practice. This study aims to compare 72 mm commercial diamond-mesh codend with 72 mm square-mesh codend to reduce the benthic bycatch in this fishery. Materials and methods. Totally 15 hauls were carried out in south-eastern Black Sea Region within 10-14 August 2017. A commercial diamond-mesh and square-mesh beam trawls were towed simultaneously behind a commercial fishing vessel to compare the by-catch compositions. Paired t-test was used to compare the catch amount of two codends based on species. GLMM (Generalised Linear Mixed Models) was used to compare the length of captured veined rapa whelk, mussel, and crab species. Results. There was a 77-percentage-point reduction in the mean number of the captured individuals as by-catch in square-mesh codend when compared with commercial diamond-mesh codend and this difference was found statistically significant (P < 0.05). A total of 17 species was captured as by-catch in both codends. Comparing to diamond-mesh codend, the catch amount of the 13 by-catch species had decreased in square-mesh codend. Conclusions. In conclusion, the square-mesh codend was found successful in decreasing the by-catch amount of many benthic species except for flatfish species and large crabs. In addition to this, the veined rapa whelk amount fell by half and this means a 25-percentage-point profit decrease for fishermen. [ABSTRACT FROM AUTHOR]

Beach nourishment is a widely utilized solution to counteract the erosion of shorelines, and there is an active discussion on its possible consequences on coastal marine assemblages. We investigated the impact caused by a small-scale beach nourishment carried out in the Western Adriatic Sea on macrofaunal recruitment and post-settlement events. Artificial substrates were deployed in proximity of nourished and non-manipulated beaches and turbidity and sedimentation rates were measured. Our results indicate that sedimentation rates in the impacted site showed a different temporal change compared to the control sites, suggesting potential modifications due to the beach nourishment. The impact site was characterized by subtle changes in terms of polychaete abundance and community structure when compared to controls, possibly due to beach nourishment, although the role of other factors cannot be ruled out. We conclude that small-scale beach nourishments appear to be an eco-sustainable approach to contrast coastal erosion. [ABSTRACT FROM AUTHOR]

Quantitative analyses of soft bottom invertebrate fauna from four Norwegian sill fjords show increased macrofaunal abundance, species richness, and a considerably changed benthic deep water macrofaunal composition in the inner parts of the fjord system. In retrospect, the analyses show significantly altered benthic macrofaunal community structure that was not reflected by the changes in the Shannon-Wiener diversity indices during regular monitoring. The observed changes are mainly due to an increased abundance of opportunistic species, especially of the polychaete Polydora sp. during the last 10–15 years which is correlated significantly to declining dissolved oxygen, rising temperature in the bottom water and increasing total organic matter in the sediment. Possible anthropogenic and climatic impact factors related to the observed macrofaunal changes and environmental consequences of the changes are discussed. [ABSTRACT FROM AUTHOR]

Sub-Seabed CCS is regarded as a key technology for the reduction of CO 2 emissions, but little is known about the mechanisms through which leakages from storage sites impact benthic species. In this study, the biological responses of the infaunal bivalve Limecola balthica to CO 2 -induced seawater acidification (pH 7.7, 7.0, and 6.3) were quantified in 56-day mesocosm experiments. Increased water acidity caused changes in behavioral and physiological traits, but even the most acidic conditions did not prove to be fatal. In response to hypercapnia, the bivalves approached the sediment surface and increased respiration rates. Lower seawater pH reduced shell weight and growth, while it simultaneously increased soft tissue weight; this places L . balthica in a somewhat unique position among marine invertebrates. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Effects of water-based drill cuttings on sediment reworking activity were studied on two important benthic bioturbators (the bivalve Abra segmentum and the brittle star Amphiura filiformis ) using thin aquaria, fluorescent-dyed sediment particles (luminophores), time lapse photography and image analysis. In the present context, sediment reworking activity was measured as maximum mixing depth and total amount of luminophores transported below the sediment-water interface. There was a significant reduction in the amount of downward transported luminophores in drill cuttings treatments compared to controls with added natural sediments for both species, which also was true regarding maximum mixing depth for A. segmentum . Further, A. filiformis showed a clearly delayed burrowing of luminophores in the drill cuttings treatment compared to control. To conclude, the study showed that water-based drill cuttings have the potential to reduce sediment reworking. Further, it is evidenced that water-based drill cuttings not only cause burial effects. [ABSTRACT FROM AUTHOR]

Radionuclides in the Arctic echinoderms have seldom been studied despite their considerable environmental importance. This manuscript covers the results of 90 Sr and 137 Cs measurements in common echinoderm taxa collected from the Svalbard Bank in the Barents Sea and from two High-Arctic fjords (Isfjorden and Magdalenefjorden). We focused on the echinoid, Strongylocentrotus droebachiensis , the asteroid, Henricia sanguinolenta , and the ophiuroid, Ophiopolis aculeata . For all echinoderms, the analysis revealed a negative correlation between 90 Sr activity and the mass. Thus, we concluded that metals are accumulated faster at a young age when the growth is most rapid. The highest average activities of 137 Cs followed the order O . aculeata > H . sanguinolenta > S . droebachiensis . This suggests that bioaccumulation was highly taxon-dependent and could reflect differences in the isotope exposures associated with the diet of echinoderms. The study provides a baseline for understanding radionuclide processes in the High-Arctic benthic echinoderm communities. [ABSTRACT FROM AUTHOR]

The organic enrichment of surficial sediments has a known effect on benthic faunal communities due largely to oxygen depletion and sulfide toxicity. Total dissolved sulfide (free S − 2 = H 2 S + HS − + S 2 − ) concentrations in sediments are widely measured as a practical indicator of community effects. However, the standard ion selective electrode (ISE) method for free S − 2 analysis can provide biased results owing to the inclusion of non-toxic mineral sulfides and the oxidation and volatilization of free S − 2 . A rapid field protocol was developed that alleviates these problems while also providing data on dissolved oxygen concentrations. Sediments collected near salmon aquaculture pens over cohesive and permeable substrates were analysed using the standard and new protocols. The results confirm previous conclusions of artifacts with the standard ISE method, while the dual indicator approach more accurately describes the stages, spatial extent and magnitude of sediment geochemical alterations affecting benthic communities. [ABSTRACT FROM AUTHOR]

This study reports on the development and application of a chronic sediment toxicity test using the benthic ostracod Heterocypris incongruens. H. incongruens reproduction parameters such as egg production, first day of brooding, egg-laying ratio, and hatching ratio were examined in this study. The test was first validated by determining the repeatability of the test method under seven control performances. The results showed good test repeatability of most endpoints, with coefficient of variation (CV) results below 15%. However, lifetime egg production, hatching ratio, and the reproductive rate were highly variable, with CVs ranging from 29.5% to 51.9%. Next, an application example of the proposed chronic method was performed using a series of urban road dust (URD) samples diluted with a reference sediment and compared to a 6 d H. incongruens toxicity test. The results of the proposed chronic test showed a statistically significant difference in the first day of brooding at 6.25% URD which did not exhibit significant mortality and growth inhibition in 6 d toxicity test. [ABSTRACT FROM AUTHOR]

A sediment quality assessment was performed near to the main industrial source of metal contamination in Sepetiba Bay, Brazil, which represents one of the worst cases of trace metal contamination reported for coastal areas. Acute and chronic toxicity tests, benthic fauna community analysis and metal bioavailability evaluations were applied to identify risks to the benthic community. Significant amphipod mortality was observed close to the major pollution source and lower copepod fertility was observed for all stations. Equilibrium-partitioning and biotic-ligand models to predict pore water metal toxicity, which were based on acid-volatile sulfide (AVS) and organic carbon fraction ( f OC ) normalization approaches, suggested that metals are not likely to be available in sediment pore water. However, Cd, Pb and Zn concentrations were mainly (>50%) weakly bound to sediments, suggesting high potential bioavailability. Linking the chemical results with ecotoxicological responses, we observed that sediment-feeding organisms presented acute and chronic toxicities that were positively correlated to the metal concentrations in the sediments. Additionally, benthic fauna composition was dominated by tolerant species, revealing a trophic structure response to environmental contamination. These results reinforce the necessity of a multiple lines of evidence approach to establish sediment quality and to support environmental management decisions that are based on observed effects and potential extrapolation scenarios into the future. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Oceanography is the property of Instituto Oceanografico da Universidade de Sao Paulo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reef Check Australia (RCA) has collected data on benthic composition and cover at > 70 sites along > 1000 km of Australia's Queensland coast from 2002 to 2015. This paper quantifies the accuracy, precision and power of RCA benthic composition data, to guide its application and interpretation. A simulation study established that the inherent accuracy of the Reef Check point sampling protocol is high (<± 7% error absolute), in the range of estimates of benthic cover from 1% to 50%. A field study at three reef sites indicated that, despite minor observer- and deployment-related biases, the protocol does reliably document moderate ecological changes in coral communities. The error analyses were then used to guide the interpretation of inter-annual variability and long term trends at three study sites in RCA's major 2002–2015 data series for the Queensland coast. [ABSTRACT FROM AUTHOR]

We sampled different substrates (sand, gravel, leaf litter and stones) in the rainy and dry season to study the distribution and composition of benthic macroinvertebrates in tropical streams (northeastern Brazil). Benthic macroinvertebrates were distributed according to the substrates, with stones showing a higher richness and abundance of species and abundance of collector-gatherers and filter-collectors. The results of the PCoA showed a separation of stones from the other substrates and similarities between sand and gravel. [ABSTRACT FROM AUTHOR]

The authors investigated the impact of the extension of the El Kantra Channel on the composition and structure of macrobenthic assemblages in Boughrara Lagoon (Gulf of Gabes, Tunisia along with the use of 4 biotic indices (AMBI, BENTIX, M-AMBI and TUBI). Thirteen stations were sampled seasonally in 2012–2013. Forty-one species were found in 2012–2013 not recorded in 2009–2010, including 20 species of polychaetes belonging to the trophic groups of deposit-feeders and carnivores which are expected to increase in areas disturbed by organic pollution. During the survey, we recorded a high fish mortality, essentially caused by the development of harmful algal blooms (HAB) which increased organic matter deposition, thus inducing polychaete development. This seems to weaken the bio-indicating power of biotic indices used here which, paradoxically, classified all sampled stations at a high ecological status. A review of these indices and their applicability to all marine environments is recommended. [ABSTRACT FROM AUTHOR]

The prevalence of microplastic pollution in the ocean has caused widespread concern. Many studies have focused on the occurrence of microplastics in the marine environment and organisms, but the fate of microplastics in the ocean is still unclear, and the factors affecting the distribution of microplastics have not yet been consistently concluded. The aims of this study were to estimate the load of microplastics in benthic organisms as a temporary storage and to analyze the factors affecting microplastic ingestion by benthic organisms. For the purpose of this study, the benthic organisms in Jiaozhou Bay, China, were collected quarterly and were divided into the following six groups: polychaetes, mollusks, crustaceans, echinoderms, fish, and others. We concluded that the microplastic abundance in the benthos in Jiaozhou Bay was 1.00 ± 0.11 items/ind. (15.5 ± 3.5 items/g). The total load of microplastics in the benthic fauna in the bay with an area of 374 km2 was estimated to be 36.4 kg. On an individual basis, the fish contained significantly more microplastics than the other taxa. Furthermore, the characteristics of the microplastics in the benthic organisms were mainly fibrous, black, polyethylene, and <500 μm in size. In addition, the microplastic ingestion by benthic organisms was regulated by multiple factors, including biological characteristics and the environment. The masses of the organisms, the ambient seawater and sediment, and the spatial variations all influenced the microplastic ingestion by the organisms. The results of this study demonstrate that benthic organisms are an important storage for microplastics as they transferred through the ocean, and they provide an unbiased comparison of microplastic pollution among multiple organisms and the relevant pollution factors. [Display omitted] • Benthic taxon-based microplastic pollution was studied. • Benthos is a storage for microplastics, which cannot be overlooked. • The benthos microplastic load in a 374 km2 bay area was estimated to be 36.4 kg. • Microplastic abundance in benthos was inverse to population size. [ABSTRACT FROM AUTHOR]

Stream ecosystems are affected by multiple abiotic stressors, and species responses to simultaneous stressors may differ from those predicted based on single-stressor responses. Using 12 semi-natural stream channels, we examined the individual and interactive effects of flow level (low or high flow) and addition of fine sediments (grain size <2 mm) on key ecosystem processes (leaf breakdown, algal biomass accrual) and benthic macroinvertebrate and fungal communities. Both stressors had mostly independent effects on biological responses, with sand addition being the more influential of the two. Sand addition decreased algal biomass and microbe-mediated leaf breakdown significantly, whereas invertebrate shredder-mediated breakdown only responded to flow level. Macroinvertebrate community composition responded significantly to both stressors. Fungal biomass decreased and shredder abundance increased when sand was added; thus, organisms at different trophic levels can exhibit highly variable responses to the same stressor. Terrestrial endophytic fungi were abundant in low-flow flumes where leaf mass loss was also highest, indicating that terrestrial endophytes may contribute importantly to leaf decomposition in the aquatic environment. Leaf breakdown rates depended on the identity and abundance of the dominant decomposer species, suggesting that the effects of anthropogenic activities on ecosystem processes may be driven by changes in the abundance of a few key species. The few observed interactive effects were all antagonistic (i.e., less than the sum of the individual effects); for example, increased flow stimulated algal biomass accumulation but this effect was largely cancelled by sand. While our finding that sand and stream flow did not have strong synergistic effects can be considered reassuring for management, future experiments should manipulate these and other human stressors in experiments that run for much longer periods, thus focusing on the long-term impacts of multiple simultaneously operating stressors. [ABSTRACT FROM AUTHOR]

After their release into the aquatic environment, contaminants may – depending on the physicochemical properties – adsorb to sediments. From there these contaminants can either be buried or remobilised by abiotic factors (e.g., resuspension) as well as by the bioturbating activity of sediment dwelling invertebrates. Little is, however, know about the effects of bioturbation on the fate of pesticides. Therefore, the present study quantified the impact of the bioturbation mode of benthic invertebrate species (bio-diffusor vs. bio-irrigation), the invertebrate density (i.e. 0–8 individuals per replicate), and the substance-inherent properties (i.e. hydrophobicity, water solubility) on the remobilization of sediment-associated pesticides in a laboratory-based set-up over 13 days. We found that both the bioturbation mode (i.e., species identity) and species density, as well as pesticide properties (i.e., hydrophobicity) affected the direction and magnitude of remobilisation of sediment-bound pesticides. The oligochaeta Lumbriculus variegatus showed a density-dependent effect on the remobilization of lindane to the water phase, whereas those with the amphipod Monoporeia affinis and larvae of the midge Chironomus riparius did not. Although these findings show that sediments not per definition are a sink for pesticides, the rates of pesticide remobilization are limited. This observation, thus, suggests that the risk for aquatic communities posed by the remobilization of pesticides from the sediment due to bioturbation is low. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological communities in shallow lakes are often subject to the combined effects of eutrophication and wind-wave disturbance. However, their relative importance in regulating macrozoobenthic community assembly has not been well addressed. In the present study, a monthly sampling of macrozoobenthos and environmental parameters was conducted at ten sites from December 2012 to November 2013 in Lake Hongze, the fourth largest freshwater lake in China, which has undergone serious water quality deterioration over the past few decades. A total of 30 taxa were recorded during the 12 sampling occasions, including 6 chironomids, 6 bivalves, 4 gastropods, 4 oligochaetes, 4 polychaetes, 4 crustaceans and 2 other aquatic insects. The mean abundance and biomass of total macrozoobenthos varied greatly among the ten sites and presented distinctive taxonomic composition between the protected bays and the offshore zone. Three eutrophication parameters (including permanganate index (COD Mn ), chlorophyll a, and total phosphorus in surficial sediments) and three wind-wave variables (including Secchi depth, turbidity, and mean effective fetch) were highly related to spatial variation of macrozoobenthic assemblages. When eutrophication variables were controlled, there was a significant correlation between community similarity and wind-wave disturbance condition, and vice versa . Variation partitioning showed that wind wave disturbance explained 15.9% of the variation in benthic community composition, slightly lower than that explained by eutrophication (17.9%). These results indicate that wind-wave disturbance is as important as eutrophication in regulating benthic community structure in this large shallow lake. Wind-wave disturbance imposed opposite effects on benthic community relative to eutrophication, and were more prominent in the offshore zone weakening the role of eutrophication. [ABSTRACT FROM AUTHOR]