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The results of long-term studies are used to present, for the first time, the structural organization of zoobenthos communities and the dynamics of their density and biomass in rivers and brooks of the the Khektsir Ridge, including the boundaries of the Bol'shekhekhtsirskii Reserve, Khektsirskii Wildlife Reserve (the southern part of the Russian Far East). The benthic organisms were found to contain 23 groups (22 groups in the spring and summer, 19 groups in the autumn, and 8 groups in the winter). Leading in the occurrence frequency (>90%) were chironomids, mayflies, and oligochaetes. The chironomids and amphipods accounted for 37.0 and 19.1% of the total benthos density, and mollusks and amphipods, for 32.1 and 29.7% of the total biomass, respectively. Dominants in terms of density and biomass were amphipods; chironomids dominated in terms of density, and mollusks, in terms of biomass. The mean density of benthic organisms was 637 ± 21 spec./m2, and the mean biomass was 1.8 ± 0.2 g/m2. The benthic communities of rift segments in the rithral zone were found to be most productive. It is shown that the seasonal and long-term dynamics of zoobenthos communities is pronounced and can be traced in the group composition, structure, and quantitative characteristics. [ABSTRACT FROM AUTHOR]

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Fine-grained organic-rich sediments (FGORS) are accumulating in estuaries worldwide, with multi-faceted negative ecosystem impacts. A pilot experiment was carried out in a residential canal of the Indian River Lagoon estuary (IRL, Florida, USA) using an aeration treatment intended to mitigate the harmful ecological effects of organic-rich sediment pollution. Planktonic and benthic communities were monitored, and environmental data collected throughout the aeration process. Results were compared against control conditions to evaluate the efficacy of aeration in the mitigation of FGORS. During the aeration process, hurricane Irma impacted the study area, bringing heavy rainfall and spawning a brown tide event (Aureoumbra lagunensis). The overall thickness and volume of FGORS, and the organic content of surface sediments did not change during the aeration treatment. Dissolved oxygen was higher and ammonium concentrations were lower in aeration canal bottom water compared to the control canal. During treatment, aeration did facilitate benthic animal life when temperatures dropped below 25°C, likely due to water column mixing and the increased capacity of water to hold dissolved gasses. In general, aeration did not significantly change the planktonic community composition relative to the control canal, but, during the post-bloom period, aeration helped to weaken the brown tide and phytoplankton densities were 35–50% lower for A. lagunensis in aeration canal surface water compared to the control canal. Aeration has important management applications and may be useful for mitigating algal blooms in flow-restricted areas and promoting benthic communities in cooler environments. [ABSTRACT FROM AUTHOR]

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]

Cold seeps are characterized by typical endemic communities with associated microorganisms that depend on sulfide, methane, reduced nitrogenous compounds, and metals as electron donors for their survival through chemosynthesis. The discovery of an active cold seep site in January 2018 in the Krishna-Godavari (K-G) basin of Bay of Bengal was followed by a transit cruise in March 2018 to investigate the distribution and diversity of macrofauna. Further, the ambient sediment and pore water biochemistry were estimated to understand its relationship with macrofauna and the microbial associates of the sediment. Samples were collected at a water depth of around 1750 m at 3 stations: SP1, SP2, and SP3, using the box corer. The benthic fauna at the sites consisted mainly of Bivalvia, shrimps of Caridea family, Gastropoda species, Malacostraca species, Polychaeta, and few species of Echinoidea, Ophiuroidea, and Echiura. A total of 2313 macrofaunal individuals belonging to 8 classes, 18 families, and 20 species were identified from all the three stations. The communities were diverse at these sites with an average Shannon diversity index of 1.64 and are closely related to the lineages previously studied in ecologically similar environments. Most of the macrofauna were found to be filter feeders preferring a low organic carbon environment. Relict vesicomyid clams at the present study site suggest the succession from vesicomyids to the present composition of bivalve mussels and siboglinid worms. The microbial associates in the sediment significantly correlated with methane and hydrogen sulfide concentrations. The study suggests that the K-G basin cold seep serves as a conducive environment for the flourishing of benthic communities and therefore can support a rich biodiversity. [ABSTRACT FROM AUTHOR]

The Aviles Canyon System (Northern Atlantic coast of Spain) is one of the ten marine regions studied in the Spanish seas by the LIFE+ INDEMARES project, which aims to identify special areas of conservation within the Natura 2000 Network. This study aims to characterize the composition and distribution of the macrobenthic fauna in order to provide baseline data to obtain a basic knowledge of the environment. Three oceanographic surveys were carried out to investigate species and habitats of this deep-sea ecosystem. The stations were sampled using a box corer, in order to evaluate the distribution and biodiversity of the macroinfauna, and to analyse the granulometric composition and the organic matter content. Sediments were mainly sandy in nature, the finest sediments with the highest organic matter content were found in the deepest areas, while coarser sediments were located in shallow stations. Polychaetes were the best represented group in total number of species and individuals, followed by crustaceans and molluscs. Five major macrobenthic assemblages were determined through multivariate analyses. Bathymetry and sedimentary composition were the main factors structuring the benthic community separating shallow and coarser stations from deeper and finer ones. [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]

In Greece, the implementation of the Water Framework Directive for rivers is based mainly on benthic macroinvertebrates and uses a semi-quantitative method with a D-frame net, which is certified by the International Organization for Standardization. Before the official adoption of this method, a quantitative shovel sampler ("Cretan shovel") was used in southern Greece (Crete), which has been implemented for almost three decades due to the specific river habitats found in Crete (e.g., seasonal flow, narrow riverbeds, and coarse substrates). In this study, we compared community metrics, diversity indices, feeding groups, locomotion types, and ecological quality derived from data collected using timed semi-quantitative kick samples and quantitative shovel samples collected from the same sites simultaneously. In total, 20 samples from the north and south of Greece were collected. The majority of community metrics, diversity indices, and traits were comparable between samplers. However, there were statistically significant differences in the relative abundance of Ephemeroptera, Plecoptera, and Trichoptera, passive filterers' and the (semi) sessil groups, and Pielou's index. Most differences in the ecological quality between the kick and shovel samples were observed in 50% of the sites in northern Greece because the shovel is less effective at capturing motile zoobenthos. The ecological quality assessment in Crete by the Cretan shovel is comparable with the D-frame net in 75% of the samples. Thus, the Cretan shovel could efficiently sample the Cretan streams, which are characterized by coarse, narrow, turbulent, and hydrologically fluctuating river habitats. Such comparisons could improve sampling effectiveness and make additional data available to assess ecological quality. [ABSTRACT FROM AUTHOR]

The Ulleung Basin of the East Sea is a biological hotspot, but studies on the macrobenthos therein are lacking. To evaluate the macrobenthos species diversity and community structure in the Ulleung Basin, we conducted a survey from 2017 to 2021. A total of 262 species of macrobenthos was detected by the survey, and the average habitat density was 243 individuals/m2. The average biomass of macrobenthos was 43.7 g/m2, and the average Shannon and Wiener's diversity index was 2.3 (0.69–3.61). The dominant species were the polychaetes Terebellides horikoshii, Chaetozone setosa, Scalibregma inflatum, and Aglaophamus sp. and the bivalvia Axinopsida subquadrata. The community structure of macrobenthos differed according to water depth, and a correlation analysis using environmental variables showed that the community was affected by water temperature, salinity, and dissolved oxygen. The macrobenthic fauna in the Ulleung Basin was greatly influenced by water depth, the sedimentary environment was different, and the dominant species were also different. In addition, there was little seasonal change compared to the East Sea coast. Our findings will facilitate further investigation of benthic ecosystems throughout the East Sea. [ABSTRACT FROM AUTHOR]

Benthic invertebrates are important trophic links in food webs and useful bioindicators of environmental conditions, but long‐term benthic organism abundance data across broad geographic areas are rare and historic datasets are often not readily accessible. This dataset provides densities of benthic macroinvertebrates collected from 1930 to 2019 during surveys in Lake Erie, a Laurentian Great Lake. The surveys were funded by the governments of the United States and Canada to investigate the status and changes in the benthic community. From the total of 21 lake‐wide and basin‐wide benthic surveys conducted in Lake Erie from 1929 to 2019, we were able to acquire data for 17 surveys, including species‐level data for 10 surveys and data by higher taxonomic groups for seven surveys. Our amassed Lake Erie dataset includes data from 11 surveys (including five with species‐level data) conducted in the western basin in 1930–2019, seven surveys (six with species‐level data) in the central basin, and eight surveys (seven with species‐level data) in the eastern basin (1973–2019). This Lake Erie dataset represents the most extensive temporal dataset of benthic invertebrates available for any of the Laurentian Great Lakes. Benthic samples were collected using Ponar or Shipek bottom dredges and taxa densities were calculated as individuals per square meter using the area of the dredge. Density data are provided for taxa in the Annelida, Arthropoda, Mollusca, Cnidaria, Nemertea, and Platyhelminthes phyla. Current taxonomy was used for most groups but, in a few cases, older taxonomic names were used for consistency with historical data. Analysis of this dataset indicates that eutrophication, water quality improvement, and dreissenid introduction were the major drivers of changes in the benthic community in the western basin, while hypoxia was a major factor in the central basin, and dreissenid introduction was the most important driver in the eastern basin. Considering the rarity of high taxonomic resolution long‐term benthic data for lake ecosystems, this dataset could be useful to explore broader aspects of ecological theory, including effects of eutrophication, hypoxia, invasive species, and other factors on community organization, phylogenetic and functional diversity, and spatial and temporal scales of variation in community structure. In addition, the dataset could be useful for studies on individual species, including abundance and distribution, species co‐occurrence, and how the patterns of dominance and rarity change over space and time. Use of this dataset for academic or educational purposes is encouraged as long as this data paper is properly cited. [ABSTRACT FROM AUTHOR]

This is a contribution in a series of taxonomic publications on benthic fauna of polymetallic nodule fields in the eastern abyssal Clarion-Clipperton Zone (CCZ). The material was collected during environmental surveys targeting exploration contract areas 'UK-1', 'OMS' and 'NORI-D', as well as an Area of Particular Environmental Interest, 'APEI-6'. The annelid families Amphinomidae and Euphrosinidae are investigated here. Taxonomic data are presented for six species from 41 CCZ-collected specimens as identified by a combination of morphological and genetic approaches; of the six species, three are here described as new, one species is likely to be new but in too poor condition to be formalised and the two others likely belong to known species. Description of three new species Euphrosinella georgievae sp. nov., Euphrosinopsis ahearni sp. nov., and Euphrosinopsis halli sp. nov. increases the number of formally described new annelid species from the targeted areas to 21 and CCZ-wide to 52. Molecular data suggest that four of the species reported here are known from CCZ only, but within CCZ they have a wide distribution. In contrast, the species identified as Bathychloeia cf. sibogae Horst, 1910 was found to have a wide distribution within the Pacific based on both morphological and molecular data, using comparative material from the abyssal South Pacific. Bathychloeia cf. balloniformis Böggemann, 2009 was found to be restricted to APEI-6 based on DNA data available from CCZ specimens only, but morphological data from other locations suggest potentially a wide abyssal distribution. The genus Euphrosinopsis was previously known only from Antarctic waters, and Euphrosinella georgievae sp. nov. was recovered as a sister taxon to the Antarctic specimens of Euphrosinella cf. cirratoformis in our molecular phylogenetic analysis, strengthening the hypothesised link between the deep-sea and Antarctic benthic fauna. [ABSTRACT FROM AUTHOR]

Antarctica is a remote place, the continent is covered by ice and its surrounding coastal areas are frozen for the majority of the year. Due to its peculiarity the observation of the underwater organisms is particularly difficult, complicated by logistic factors. We present a long-term dataset consisting of 755 images acquired by using a non-invasive, autonomous imaging device and encompassing both the Antarctic daylight and dark periods, including the corresponding transition phases. All images have the same field of view showing the benthic fauna and part of the water column above, including fishes present in the monitored period. All the images are manually annotated after a visual inspection performed by expert biologists. The extended monitoring period and the annotated images make the dataset a valuable benchmark suitable for studying the dynamics of the long-term Antarctic underwater fauna as well as for developing and testing algorithms for automated image analysis focused on the recognition and classification of the Antarctic organisms and the automated analysis of their long-term dynamics. Measurement(s) Coastal Benthic Megafauna Technology Type(s) Autonomous Imaging Device Factor Type(s) None Sample Characteristic - Organism Sterechinus neumayeri • Odontaster • Trematomus • Polynoidae • Diplasterias • Ophiuridae • Ammothea • Neobuccinum eatoni • Staurocucumis • Flabegraviera mundata Sample Characteristic - Environment coastal sea water Sample Characteristic - Location East Antarctica [ABSTRACT FROM AUTHOR]

The Cambrian Series 2–Miaolingian transition is a pivotal period during Earth history, which witnessed the decline of biodiversity and the reduction in biomass, i.e., the redlichiid–olenellid trilobite extinction. The notable δ13C excursion (RECE) near the Cambrian Series 2–Miaolingian boundary in east Gondwana and China apparently corresponds with the redlichiid trilobite extinction. To better understand the causal mechanism of this biotic crisis, we report the carbon isotope stratigraphy and facies changes from Cambrian Series 2–Miaolingian transition of the Mantou Formation on the southern North China Craton. The carbon isotope excursions at the Cambrian Series 2–Miaolingian transition in the study area are 0.7‰ in the Chishanhe section and −0.2‰ in the Luoquan section, respectively, showing a weak negative excursion or even no negative excursion. The sedimentary environments in the study area gradually changed through time from a clastic tidal flat to a carbonate platform across the transition, which indicated a gradual rise in sea level, with anoxic conditions occurring predominantly before the RECE δ13C excursion. Microbially induced sedimentary structures and oncoids occurred widely at the top of Cambrian Series 2. Abundant metazoan trace fossils were preserved in the Miaolingian Series of the study area. The evolution of biogenic structures across the Cambrian Series 2–Miaolingian transition indicates the emergence of harsh environments associated with the proliferation of MISS and oncoids at the RECE horizon and the recovery of benthic metazoan fauna after the RECE biotic crisis. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the north coasts of the Egyptian Red Sea, including Ras Gharieb, Hurghada, Safaga and Qusier, by evaluating the heavy metal pollution in seawater and benthic flora and fauna in the winter and summer of 2016. The concentrations of heavy metals (Fe, Mn, Zn, Cu, Ni, Cd and Pb) were analysed with an atomic absorption spectrophotometer. The results revealed that the Fe levels in the seawater ranged from 7.86 and 27.95 μg l−1, while the Zn concentrations fell between 1.83 and 5.63 μg l−1. In contrast, the recorded values of Mn, Cu, Ni, Pb and Cd in the seawater were minimal at the study sites. Regarding the biota samples, Porifera species were more adaptable than others to an accumulation of most metals in their tissues. Furthermore, seaweeds and seagrasses demonstrated remarkable adaptation in highly polluted regions, especially those with high turbidity, landfilling, sedimentation and high eutrophication rates – much more than the benthic fauna. Our research highlights the critical need for strict regulation of metal emissions in these coastal regions. [ABSTRACT FROM AUTHOR]

The ecological effects of seabed‐penetrating fishing gears depend, in part, on the seabed penetration (P) of the gear. We present a gear impact tool that utilizes published data to provide estimated P of globally utilized seabed‐penetrating fishing gears in different sediments and their resulting impact on biological communities. As P correlates with the depletion (d) of benthic fauna caused by fishing gears, we use P to calculate d, which can be used to estimate the relative benthic status (RBS; the community biomass of benthic fauna relative to carrying capacity) of the seabed. The tool can provide an objective appraisal of different fisheries management scenarios or interventions (e.g., gear modification, gear substitution, or fishing effort limits) on seabed status, particularly in situations of limited data or resources. For otter trawling in mud, gear modification may provide greater ecological benefits than reducing fishing effort; mean RBS increased by 29% in fished areas by removing the impact from the otter trawl sweeps; this is comparable to reducing fishing effort by approximately 70%. In contrast, modification of beam trawl gear in sand resulted in marginal improvements (6%) in RBS. Modification or removal of gear components with high seabed penetration could result in greater improvements in RBS than spatial management, dependent on gear type and sediment. We provide a quantitative method for estimating the effectiveness of different management scenarios in reducing the benthic impact of seabed‐penetrating fishing gears, enabling an objective evaluation of the trade‐off between spatial management measures (closures or effort reductions) versus technical modifications. This article met the requirements for a Gold‐Gold JIE data openness badge described at http://jie.click/badges [ABSTRACT FROM AUTHOR]

The Hiraiso Formation of northeast Japan represents an important and under-explored archive of Early Triassic marine ecosystems. Here, we present a palaeoecological analysis of its benthic faunas in order to explore the temporal and spatial variations of diversity, ecological structure and taxonomic composition. In addition, we utilise redox proxies to make inferences about the redox state of the depositional environments. We then use this data to explore the pace of recovery in the Early Triassic, and the habitable zone hypothesis, where wave aerated marine environments are thought to represent an oxygenated refuge. The age of the Hiraiso Formation is equivocal due to the lack of key biostratigraphical index fossils, but new ammonoid finds in this study support an early Spathian age. The ichnofossils from the Hiraiso Formation show an onshore-offshore trend with high diversity and relatively large faunas in offshore transition settings and a low diversity of small ichnofossils in basinal settings. The body fossils do not, however, record either spatial or temporal changes, because the shell beds represent allochthonous assemblages due to wave reworking. The dominance of small burrow sizes, presence of key taxa including Thalassinoides, Rhizocorallium and Holocrinus, presence of complex trace fossils, and both erect and deep infaunal tiering organisms suggests that the benthic fauna represents an advanced stage of ecological recovery for the Early Triassic, but not full recovery. The ecological state suggests a similar level of ecological complexity to late Griesbachian and Spathian communities elsewhere, with the Spathian marking a globally important stage of recovery following the mass extinction. The onshore-offshore distribution of the benthic faunas supports the habitable zone hypothesis. This gradient is, however, also consistent with onshore-offshore ecological gradients known to be controlled by oxygen gradients in modern tropical and subtropical settings. This suggests that the habitable zone is not an oxygenated refuge that is only restricted to anoxic events. The lack of observed full recovery is likely a consequence of a persistent oxygen-limitation (dysoxic conditions), hot Early Triassic temperatures and the lack of a steep temperature/water-depth gradient within the habitable zone. [ABSTRACT FROM AUTHOR]

Benthic fluxes of oxygen and carbon in coastal zones are poorly resolved in mechanistic models due to the lack of understanding of the diverse interactions among the physical, chemical, and biological drivers of biogeochemical fluxes. To inform modelling efforts we used ex-situ incubation experiments to identify spatial and seasonal patterns of oxygen and dissolved inorganic and organic carbon (DIC and DOC) fluxes in the coastal southern Baltic Sea. We used boosted regression trees to identify important drivers of the studied fluxes. Our results demonstrate that benthic communities, in addition to sediment parameters, played a dominant role in shaping oxygen and DIC fluxes, while neither benthic community, environment, season, nor sampling location could account for the highly variable DOC fluxes. DIC fluxes were partly decoupled from oxygen fluxes, since carbonate dissolution, anaerobic respiration, and submarine groundwater discharge affected DIC fluxes in the study region. Boosted regression trees proved to be a useful tool to study drivers of biogeochemical fluxes as it allowed to identify non-linear effects of biological and environmental variables on benthic fluxes. [ABSTRACT FROM AUTHOR]

Benthic macroinvertebrates are widely used to assess the ecological quality of fresh waters. This is because they are in direct contact with the aquatic environment and respond differently to pollutants and changes in the watershed, which are difficult to assess by toxicological or chemical monitoring alone. This study used benthic macroinvertebrate parameters to assess the quality of the nearshore waters of lake Kivu. Twenty‐six metrics covering various aspects of the community were tested using whisker plots to compare their sensitivity in discriminating between reference and disturbed stations. Nine parameters (% EPT taxa, % Diptera taxa, % Chironomid taxa, % Insect taxa; % no Insects taxa, ratio EPT/Chironomid taxa, % moderate tolerant taxa, % very moderate tolerant taxa, Family Biotic Index) were found to be sensitive and were able to discriminate between reference and disturbed stations. All sensitive metrics, with the exception of the percentage of EPT taxa, were positively and/or negatively correlated with the physico‐chemical parameters affected by the changes in the littoral zone. The combined values of the three calculated biotic indices (ASPT, BMWP, and FBI) showed that the biological water quality varies from moderate to good in the reference stations and from average to poor in the disturbed stations. It is concluded that metrics based on benthic macroinvertebrates are effective for assessing water quality in the littoral zone of Lake Kivu in the context of the lack of historical water quality databases and specific tools for toxicological assessment. It is suggested to compare the performance of this approach with others currently used in bio‐indication. [ABSTRACT FROM AUTHOR]

The high latitude scleractinian coral Alveopora japonica Eguchi, 1965 occurs in high density in the shallow rocky subtidal in Jeju Island, forming coral carpets. Despite its ecological role providing a unique habitat for other benthic organisms, the benthic fauna associated with the A. japonica coral carpet is poorly known. To identify fauna associated with the coral carpet, we explored three sites dominated by A. japonica and one control site on northwestern Jeju Island in May 2013. Using SCUBA, we collected A. japonica and the epibenthic mega-fauna associated with the colonies in 1×1 m2 and identified them to the species level. At a depth of 10 to 15 m, A. japonica colonies heavily covered the seafloor, forming a layer called a coral carpet, with a density of 94 (Keumneung-ri), 133 (Biyangdo), and 155 (Gwidok-ri) colonies/m2. Thirty-four molluscan species were identified from the four sites, including 20 bivalves and 14 gastropods. The coral carpets were enriched with sessile bivalves compared to the control site, as we identified twenty bivalve and eight gastropod species from the coral carpets. Most bivalve species associated with the coral carpets had tropical-subtropical affinities, while gastropods were mainly subtropical and subtropical-low boreal species. Leiosolenus lischkei M. Huber, 2010, in the family Mytilidae and Barbatia steamsi (Pilsbry, 1895), in the family Arcidae, were the two most abundant bivalve species in the coral carpet, L. lischkei being a borer, and B. stearnsi a nestler. The tropical to subtropical Pacific star shell Astralium haematragum (Menke, 1829)was the most abundant gastropod at the study sites. The bivalves and gastropods associated with the coral carpet were small-sized juveniles or sub-adults, suggesting that the coral carpet provides a micro-habitat for the bivalves and gastropods. [ABSTRACT FROM AUTHOR]

The preliminary consequence of pollutants in water is to reduce the quality of water although this may not be immediately noticeable because of the selfpurifying ability of some water bodies. The study on the physicochemical characteristics, bacteriological, and macrobenthic invertebrates was carried out in the Orogodo River. All the examined physicochemical characteristics of the water showed no significant difference (p > 0.05) across the stations. For the heavy metals, it was in decreasing order as follows: station 2 > station 3 > station 1. All the heavy metals except nickel had high values upstream (station 1). Bacteriological examination of the water revealed the presence of mesophilic bacteria across the stations at p < 0.01 (a highly significant difference). E. coli varied significantly (p < 0.01) across the stations. However, a further evaluation using the DMR test revealed that the population recorded at station 3 was significantly higher than that recorded at stations 1 and 2. A total of 787 macrobenthic invertebrates comprising 44 macroinvertebrates' taxa were recorded. Most of the macrobenthic faunas observed were distributed across the three stations except the chironomids, the rat-tailed maggot (Eristalis tenax), and the family Hirudinea whose occurrence was almost restricted to station 2. This revealed an ecological impact because this species is a basic indicator of an ecosystem sentinel. Sorenson's quotient of faunal similarity showed that macrobenthic fauna at these three stations was similar. The similarity was the highest between stations 1 and 3 (75.0%) and the lowest between stations 1 and 2 (50.0%). The biological monitoring working party (BMWP) score system showed that station 2 was moderately polluted, while stations 1 and 3 were only slightly affected. At stations 1, 2, and 3, the arithmetic WQI (water quality) values were 900.99, 1010.10, and 951.20, respectively. The high values of WQI obtained across the stations were attributable to the concentrations of Fe, Cu, Cr, Cd, Ni, Pb, V, and THC, thus reiterating the conclusion drawn from the physicochemical parameter analysis. Boiling the water before consumption is highly recommended to avoid possible human health problems, especially effects from microbial pathogens like coliforms and E. coli. [ABSTRACT FROM AUTHOR]

A partial skeleton of a blue or fin whale, estimated to have been 16.5 m in length and thought to have been lying on the seafloor for <10 years, was observed at a depth of 1288 m off western Vancouver Island, British Columbia, Canada (48.68°N, 126.84°W). Four push cores were taken at the site, three (15-26 cm in length) directly under caudal vertebrae and one 18 cm long, considered a reference, 15 m away, in order to characterize changes in the benthic foraminiferal assemblage due to the whale-fall. A Q-mode cluster analysis identified four groupings, separating the surface and deeper samples of both the whale-fall and reference cores. The results of a metric multi-dimensional scaling plot and permutational multivariate analysis of variance test of the surface samples also suggest there was a significant difference between the whale-fall and reference core benthic foraminiferal faunas. No endemic species were recovered. Downcore samples below 6 cm in the whale-fall and reference cores were characterized by common Uvigerina peregrina, Pseudoparrella pacifica, Bolivina spissa, Bulimina striata, and Takayanagia delicata. In contrast, Cassidulinoides parkeriana, which typically is a minor component of benthic foraminiferal assemblages, dominated the upper 6 cm of the whale-fall cores, whereas the low oxygen-tolerant species T. delicata dominated the same interval in the reference core. The dramatic increase in abundance of C. parkeriana in the upper sediments below this whale-fall, as well as at the Torishima Seamount whale-fall site off Japan, indicate that it is an opportunistic species well adapted to taking advantage of unpredictable and highly localized tropic windfalls such as whale-falls. To our knowledge, this is the first benthic foraminiferal species shown to increase dramatically in abundance in the presence of awhale-fall. Additionally,modern fragments of whale bones occurring as deep as 12 to 15 cm downcore at the western Vancouver Island site demonstrate the effect of bioturbation by invertebrate scavengers that consumewhale carcasses, indicating that detailed biostratigraphic records below whale-falls should be interpreted with caution. [ABSTRACT FROM AUTHOR]

Environmental change and growing anthropogenic pressure on water resources is increasing the duration and intensity of drying events in streams in many geographical locations. Favourable sediment characteristics (e.g. high porosity and low fine sediment load within the substrate matrix) may facilitate benthic macroinvertebrate use of subsurface sediments in response to drying. However, the influence of sedimentary characteristics on the use and subsequent recovery of macroinvertebrates from initial vertical migration into, survival during unfavourable conditions within, and subsequent re‐emergence from subsurface sediments have not been directly observed.Transparent mesocosm tanks were used to directly observe the vertical movement and subsequent re‐emergence of Gammarus pulex from subsurface sediments in response to increasing dry period (1, 7, or 21 days) and fine sediment load (0.5–1 mm particle diameter used for light and heavy sediment treatment) and following rehydration and resumption of flowing conditions.Increasing volumes of fine sediment addition limited the ability of G. pulex to access subsurface sediment in response to drying and re‐emerge following rehydration. The longest dry period (21 days) reduced the ability of G. pulex to re‐emerge from the subsurface sediments following rehydration and flow resumption.Increasing fine sediment load negatively affects taxa using subsurface sediments as a refuge. Increased fine sediment deposition has the potential to reduce both access to the sub‐surface and re‐emergence once surface flow resumes.As many rivers are beginning to dry out, or are showing prolonged drying due to global warming, it is increasingly important that river management reduces the input of fine sediment into rivers and increase sediment porosity of riverbeds to facilitate access into the subsurface refuge by benthic fauna. [ABSTRACT FROM AUTHOR]

Human activities in riverine water bodies can cause loading of nutrients and other pollutants in receiving systems, affecting species interactions and population dynamics. The present study aimed to investigate the influence of anthropogenic alteration on an artificial water body, i.e., the Shahid Rajaee reservoir, in Iran that is experiencing a serious water crisis. The reservoir is subject to high anthropogenic nutrient loads from the Shirinroud and Sefidroud rivers, the effect of which needs to be evaluated considering the strategic importance of the reservoir as a source of drinking water. A field sampling campaign was carried out at seven stations (one in each of the two river mouths and five in the reservoir itself) each month from April to July 2016. The study entailed sampling of benthic macroinvertebrate fauna at the river mouths and plankton communities at the reservoir stations. In addition to macroinvertebrate and plankton, abiotic and nutrient variables were measured at all stations. Substantial loading of organic matter, mainly from the Shirinroud River, was detected throughout the sampling period, with a detrimental effect on both benthic and plankton communities. The decline in plankton diversity was particularly noticeable at stations close to the river mouths during June and July, with a bloom of Dinoflagellata and Cyanobacteria and strong dominance of larger zooplankton taxa, e.g., Copepoda. Our results suggest that river water quality, affected by human activities, alters the planktonic communities in Rajaee reservoir. Our assessment indicates that measures on both the Shirinroud River and the reservoir are required to mitigate and prevent even stronger eutrophication of the reservoir ecosystem. [ABSTRACT FROM AUTHOR]

For decades, we monitored numbers and weights of the macrozoobenthos in a vast tidal‐flat area in the Dutch Wadden Sea. We used data collected since 1992 to estimate annual secondary production. Data on chlorophyll concentrations and primary production were available for a nearby tidal inlet, showing rapid increases in the late 1970s and gradual declines since the late 1980s. The benthos responded with a doubling of biomass around 1980 and gradual declines of summer biomass, annual production as well as seasonal biomass gain for the 1992–2019 de‐eutrophication period. In nearly all years, production of bivalves (on average 25.5 gAFDM m−2 yr−1) accounted for more than half of the total zoobenthic production (averaging 42.7 gAFDM m−2 yr−1). Production values for individual years were not correlated with chlorophyll concentrations or primary production of that year, but did show a significantly positive relationship with bivalve recruitment success in the preceding year. As recruitment was governed by predation pressure on early bivalve bottom stages, it is a top‐down process. Bottom‐up processes were expressed in the gradually declining long‐term trend of bivalve growth rates and secondary production during the de‐eutrophication period and also in a few years when bivalve numbers were so high that growth rates were reduced by food competition. In by far most years, numbers of bottom animals were too low to fully exploit the carrying capacity of the system and production increased linearly with preceding recruitment. [ABSTRACT FROM AUTHOR]

In coastal systems, planktonic and benthic silicifiers compete for the pool of dissolved silicon, a nutrient required to make their skeletons. The contribution of planktonic diatoms to the silicon cycle in coastal systems is often well characterized, while that of benthic silicifiers such as sponges has rarely been quantified. Herein, silicon fluxes and stocks are quantified for the sponge fauna in the benthic communities of the Bay of Brest (France). A total of 45 siliceous sponge species living in the Bay account for a silicon standing stock of 1215 tons, while that of diatoms is only 27 tons. The silicon reservoir accumulated as sponge skeletons in the surface sediments of the Bay rises to 1775 tons, while that of diatom skeletons is only 248 tons. These comparatively large stocks of sponge silicon were estimated to cycle two orders of magnitude slower than the diatom stocks. Sponge silicon stocks need years to decades to be renewed, while diatom turnover lasts only days. Although the sponge monitoring over the last 6 yr indicates no major changes of the sponge stocks, our results do not allow us to conclude if the silicon sponge budget of the Bay is at steady state, and potential scenarios are discussed. The findings buttress the idea that sponges and diatoms play contrasting roles in the marine silicon cycle. The budgets of these two major silicon users need to be integrated and their connections revealed, if we aim to improve our understanding of the silicon cycling in coastal ecosystems. [ABSTRACT FROM AUTHOR]

Developments in animal electronic tagging and tracking have transformed the field of movement ecology, but interest is also growing in the contributions of tagged animals to oceanography. Animal-borne sensors can address data gaps, improve ocean model skill and support model validation, but previous studies in this area have focused almost exclusively on satellite-telemetered seabirds and seals. Here, for the first time, we develop the use of benthic species as animal oceanographers by combining archival (depth and temperature) data from animal-borne tags, passive acoustic telemetry and citizen-science mark-recapture records from 2016–17 for the Critically Endangered flapper skate (Dipturus intermedius) in Scotland. By comparing temperature observations to predictions from the West Scotland Coastal Ocean Modelling System, we quantify model skill and empirically validate an independent model update. The results from bottom-temperature and temperature-depth profile validation (5,324 observations) fill a key data gap in Scotland. For predictions in 2016, we identified a consistent warm bias (mean = 0.53 °C) but a subsequent model update reduced bias by an estimated 109% and improved model skill. This study uniquely demonstrates the use of benthic animal-borne sensors and citizen-science data for ocean model validation, broadening the range of animal oceanographers in aquatic environments. [ABSTRACT FROM AUTHOR]

Marine urbanization promotes the addition of hard substrata that barely resembles natural substrate nearby. We manipulated habitat topography in five marinas across one of the most populated regions from the Southwestern Atlantic Ocean to describe the effect of habitat complexity on the diversity of benthic communities across sites with distinct conditions and biotas. The highest biomass was found in the two marinas under high pollution and freshwater disturbances, regardless of habitat complexity. Habitat topography did not affect species richness but determined the structure of sessile communities in all marinas. The structure of mobile communities was affected only in the most diverse site, increasing the abundance of isopods. In general, fragile ascidians, hydrozoans, and non‐calcified polychaetes dominated complex habitats, while structurally defended animals such as barnacles, serpulids, and encrusting bryozoans dominated simple habitats, suggesting that dominant species are selected by habitat complexity based on their morphological traits. However, the final community structure was also determined by differences across marinas, suggesting that the effect of increasing habitat topography is mostly site‐specific. Therefore, strategies to minimize the disparity between natural and artificial habitats must consider historic local community and a multiple stressors scenario. [ABSTRACT FROM AUTHOR]

The article describes the features and results of using the autonomous underwater vehicle (AUV) MMT-3000 for research of Antarctic ecosystems and deep-sea biological resources of the South Seas. The methodology for working with an AUV in the extreme conditions of Antarctica and the technical solutions used to visually assess the distribution of bottom animals are discussed. The results of processing the data obtained by AUV during deep-sea missions in the Atlantic sector of the Antarctic during the expedition of the RV Akademik Mstislav Keldysh (cruise 79) in 2020 are presented. At the same time, the data of image analysis and trawl catch were compared. Based on the experience gained, the requirements to be implemented in the new AUV MMT-3500, which is designed and manufactured to effectively carry out deep-sea research in subsequent expeditions in the Southern Ocean, are determined. [ABSTRACT FROM AUTHOR]

A survey of the macrozoobenthos communities in the Maritsa River (South Bulgaria) was carried out in the summer of 2021. Benthic samples were collected and physicochemical parameters (water temperature, pH, conductivity, dissolved oxygen and nutrients) were measured at 15 sites located on the main river and its tributary system. The studied sites belonged to different river types and characterised the diversity of the ecological conditions—from unaffected to anthropogenically influenced river stretches. In addition, data from a study conducted in the summer of 2020 were used to analyse species–factor interactions in the river ecosystems and to assess the bio-indicative potential of the aquatic invertebrates. The dynamics of the taxonomic composition and abundance of the macrozoobenthos were analysed in relation to environmental factors. The physicochemical conditions of the water environment changed during the period of high water, which led to a reduction in the composition of the macrozoobenthos. Plecoptera and Trichoptera decreased in richness and abundance downstream and under human impacts. Ephemeroptera and Chironomidae were permanently present along the whole river. Oligochaeta increased in the lower river reaches and at sites with a greater amount of organic matter. The ecological status determined by the macrozoobenthos varied from high (site 1) to good, moderate and bad (site 13) at the studied sites. [ABSTRACT FROM AUTHOR]

Despite the high number of fish species described for the Amazon region, the ichthyofauna that inhabits the depths of the main channels of large tropical rivers is one of the least known. In order to know the diversity patterns of these fish in whitewater rivers of the Central Amazon, we used data from the main channel benthic fish assemblage of the Japurá, Purus and Madeira rivers and tested the hypothesis that there are marked spatial and seasonal differences in the composition of the fish community among them. For this, we used a multivariate dispersion test, total β diversity and its decomposition into local (LCBD) and species contribution to β diversity (SCBD). Additionally, we tested for relationships between LCBD values and richness, total abundance, and environmental variables. We categorized species with higher SCBD values into resident or migratory to investigate the potential importance of floodplains to benthic fish assemblage of the main channel of whitewater rivers. Our results corroborate the proposed hypothesis, showing that there are seasonal and inter-river differences in benthic ichthyofauna, being more evident for the Purus River. LCBD showed strong negative relationships with species richness and total abundance, particularly in the Japurá and Madeira rivers in rising season, indicating that rivers and season with high uniqueness in their composition also had low richness and abundance. LCBD was negatively correlated with conductivity and pH, which increased with declining these environmental variables, as observed mainly in Japurá River in both seasons. Approximately one third of the species had higher than average SCBD values and were considered major contributors to β diversity, as well as classified as migratory. This demonstrates the importance of conducting studies that use spatial and seasonal variables, in addition to including the background fish fauna in conservation studies, expanding the protected area and taking into account the different patterns of diversity between rivers. Furthermore, these differences in assemblage composition might be explained by the asymmetrical spatial use of habitats during different seasons, strongly suggesting the importance of the flood-pulse cycle for maintaining diversity in this environment. [ABSTRACT FROM AUTHOR]

Coralligenous bioconstructions are one of the Mediterranean's most distinctive and biodiverse marine habitats. This research aimed to provide a preliminary characterization of macrobenthic coralligenous assemblages at four sites located in the Marine National Park of Karaburun-Sazan in Albania. We analyzed images obtained from videos recorded along underwater transects at two different depths. Over a total of 61 taxa (3 Rhodophyta, 2 Ochrophyta, 6 Chlorophyta, 30 Porifera, 5 Cnidaria, 3 Mollusca, 2 Annelida, 1 Arthropoda, 4 Bryozoa, 4 Echinodermata, and 1 Chordata), 53 were identified at the species level using taxonomic and semi-quantitative video image analysis, thus allowing an update to the Albanian coralligenous species list with 34 new species. This study revealed differences in species richness and composition among the investigated sites and between depths, with a high number of taxa exclusive to one site and a few taxa common to all sites. Seven taxa are protected by law, among which are the echinoderm Centrostephanus longispinus, included in the Bern (Annex II) and Barcelona (Annex II) Conventions and Habitat Directive (92/43 EEC) (Annex IV), and the sponges Spongia (Spongia) officinalis and S. (S.) lamella, included in Annex III of the Bern Convention. Only the alga Caulerpa cylindracea can be considered an alien species. Although preliminary, the present research indicated the occurrence of rich and diversified macrobenthic assemblages in the study area. Moreover, it has been demonstrated that video analysis can provide a biodiversity baseline within MPAs, where traditional methods involving invasive sampling cannot be applied, particularly in areas such as the Albanian coasts, where anthropogenic impacts have been historically significant. Finally, this work provides a first estimate of the structural biodiversity in a recently established marine protected area, thus representing the basis for subsequent monitoring. [ABSTRACT FROM AUTHOR]

Oceanic anoxia is regarded as the immediate cause of the Late Devonian Frasnian–Famennian (F–F) bio-crisis and Annulata bio-event. The oceanic anoxia has been linked to continental weathering and input. However, some previous findings indicate oxic marine environments during the F–F bio-crisis. Moreover, the relative impact of terrestrial input on the Late Devonian oceanic redox conditions, when comparing a bio-crisis and a bio-event, remains unknown. Here, we present a decoupled oceanic redox model suggesting the redox conditions were different between shallow and deep water columns during the F–F bio-crisis, i.e., intensified euxinia in the photic zone and a more oxygenated condition at the seafloor. Geochemical (biomarker and trace metal) and sedimentologic evidence from the Late Devonian Seaway, eastern U.S., indicate that the shallow-deep decoupled oceanic redox conditions were regulated by terrestrial weathering and input. During the F–F bio-crisis, land nutrient input intensified photic zone euxinia through eutrophication, while hyperpycnal flows oxygenated seafloors. After the F–F bio-crisis, the seafloor redox conditions shifted from oxygenation to silled euxinia, and the watermass became hydrographically restricted. During this post-F–F interval, the euxinia at the seafloor intensified due to land nutrient runoff during the Annulata bio-event. Importantly, the land weathering and input during the F–F bio-crisis were more prominent than during the Annulata bio-event. This resulted in widespread and intense photic zone euxinia during the F–F bio-crisis, relative to the seafloor euxinia that developed in restricted areas during the Annulata bio-event. Our decoupled oceanic redox model may explain the preferential decimation of shallow-water organisms during the F–F bio-crisis. The seafloor euxinia during the Annulata bio-event may provide a niche for the turnover of benthic faunas adapting to low oxygen levels. This study suggests that continental weathering and influxes played an important role in regulating oceanic oxygen evolution and impacting life evolution and bio-diversity. • PZE intensified but seafloor became more oxygenated in the Late Devonian Seaway during the F–F bio-crisis. • Seafloor oxygenation may be caused by hyperpycnal flows. • Land input caused redox changes during the F–F bio-crisis and Annulata bio-event. • Seafloor shifted from oxygenation to silled euxinia after the F–F bio-crisis. • The redox model may explain the preferential decimation of shallow-water organisms in the Late Devonian Seaway during the F–F bio-crisis. [ABSTRACT FROM AUTHOR]

Along the northern Mid-Atlantic Ridge (nMAR), in habitats under moderate (<10 °C) hydrothermal influence on the Snake Pit vent field (SP), large assemblages dominated by Bathymodiolin mussels remain poorly characterised, contrary to those in warmer habitats dominated by gastropods and alvinocaridid shrimps that were recently described. In this study, we assessed and compared the population structure, biomass, diversity and trophic interactions of two Bathymodiolus puteoserpentis assemblages and their associated fauna at SP. Three sampling units distanced by 30 cm were sampled in 2014 during the BICOSE cruise at the top of the Moose site (''Elan'' site), while few meters further down three others, distanced by ∼1 m were obtained in 2018 during the BICOSE 2 cruise at the edifice's base. We observed a micro-scale heterogeneity between these six sampling units partially explained by temperature variations, proximity to hydrothermal fluids and position on the edifice. Meiofauna dominate or co-dominate most of the sampling units, with higher densities at the base of the edifice. In terms of macrofauna, high abundance of Pseudorimula midatlantica gastropods was observed at the top of the vent edifice, while numerous Ophioctenella acies ophiuroids were found at the base. Contrary to what was expected, the apparent health and abundance of mussels seems to indicate a current climax stage of the community. However, the modification of B. puteoserpentis isotopic signatures, low number of juveniles decreasing over the two years and observations made during several French cruises in the study area raise questions about the fate of the B. puteoserpentis population over time, which remains to be verified in a future sampling campaign. • Assemblage heterogeneity at different scales linked to fluid proximity & location. • Meiofaunal groups dominated. Macrofaunal disparity between top and base of edifice. • Low number of mussel juveniles over time questions the future of the population. [ABSTRACT FROM AUTHOR]

A 4000 m2 steel slag (SS) bed was constructed in the brackish water area for water quality remediation in 2017. This study demonstrates the ability of SS to stimulate carbon sequestration based on one-year pilot and in situ SS beds. The pilot SS bed increased the soil organic matter (SOM) content by 5.1 wt %, sequestering sewage-derived organic carbon (C org) as SOM. Notably, recalcitrant SOM increased by over 40 %, indicating long-term retention of C org in the sediment. SS increased the C org density in the sediment by approximately two times, exceeding that of the dense carbon ecosystems found in global seagrass meadows and peatlands. The complexation of the low-molecular-weight C org with iron in SS was the main pathway for C org fixation. Benthic animal investigations showed that SS capping fostered an anaerobic fauna ecosystem, aiding biotic C org sequestration. Algae proliferation on the SS bed suggested complex benthic ecosystems with photosynthetic carbon fixation. Overall, SS beds offer a new abiotic carbon sequestration pathway with environmental restoration benefits; in situ capping with metal-containing material is potentially more economical and sustainable compared to traditional landfilling. • Steel slag (SS) bed enhanced carbon sequestration in coastal sediments. • SS increased the organic carbon (C org) density in sediments by two times. • SS slowed down the degradation of C org by polymerization. • SS bed functioned for benthic fauna settlement and algal proliferation. [ABSTRACT FROM AUTHOR]

The significant changes in seafloor conditions during the Ediacaran-Cambrian transition presumably bear on the autecology of the benthic animals living in this time interval. However, little evidence shows morphological modifications and life strategy transitions in early animals in response to this substrate revolution. Dinomischidae is a family of diploblastic-grade with a sessile, suspension-feeding lifestyle, which includes Xianguangia , Daihua and Dinomischus. Here, we redescribe Calathites spinalis , a poorly known taxon from the early Cambrian (Epoch 2, Age 3, ∼518 Ma), as a new member of this family. Our new material reveals that the body of C. spinalis consists of a stalked calyx and 18 tentacle-sheath complexes, which is a typical trait of dinomischids. Our phylogenetic analyses recover Calathites as a sister group of Xianguangia and Daihua and support dinomischids being a monophyletic group. Members of dinomischids possess unique attachment structures that vary in shape and size, presenting a unique example of morphological adaptations of early sessile animals during the Cambrian substrate revolution. Comparison with early metazoan fossils reveals that dinomischids and other early basal metazoans lagged behind sessile bilaterians in terms of adaptations to substrate changes; the former tends to persist with attachment strategies adapted to Proterozoic-style seafloor conditions that were relatively firm. [Display omitted] • Exquisite fossils of Calathites exhibit traits typical of dinomischids. • Dinomischids have diverse types of attachment structures. • Dinomischids are categorized as shallow sediment stickers adapted to firm Proterozoic-style seafloor conditions. • Insights into adaptations of Chengjiang sessile metazoans to the Cambrian substrate revolution. [ABSTRACT FROM AUTHOR]

During the Devonian, the Gondwana occupied areas close to the South Pole and hosted many epicontinental seas, with a benthic fauna dominated by brachiopods. Due to the limited preservation of chronostratigraphic markers (e.g. conodonts and graptolites) on this paleocontinent, the study of ichnology and palynology has helped to track Devonian events in the South American and African continents. In the Paraná Basin, there are records of several transgressive and regressive cycles that occurred throughout the Devonian. Thus, this study considers changes in the size and shape of the brachiopod (Australocoelia palmata Morris and Sharpe, 1846) in the Lower-Middle Devonian Chapada Group (Early Pragian-Eifelian) in the state of Mato Grosso, Brazil as a proxy for paleoenvironmental change. Morphometric analysis (length, width and length x width) shows that fossils collected in transgressive strata (Lower Unit 2, Chapada Group) had the most diverse sizes. However, fossils from a regressive context (Upper 2 Unit, Chapada Group) tend to be 25% smaller in length and width. This case of dwarfism in Australocoelia palmata may be related to changes in the composition of marine waters, resulting from an anoxic moment, driven by sea-level fluctuations. • Transgressive and regressive cycles impacted the brachiopod fauna of the Paraná Basin. • Anoxic conditions in the Devonian of the Paraná basin hampered the growth of brachiopods. • The morphometric reduction of brachiopods indicates paleoecological stresses during the Emsian. [ABSTRACT FROM AUTHOR]

Biomass is a fundamental ecological measure used to quantify ecosystem structure and function. It is costly to measure but can be estimated using conversion factors based on established relationships between different biomass measures, however such conversion factors may not be applicable across broad geographic regions. For temperate benthic fauna, currently available mass-to-mass conversion factors were largely established in Northern Hemisphere ecosystems. Here, we present conversion factors for temperate Australian benthic fauna typically found in microtidal coastal bays and estuaries (14 taxa encompassing five classes: Polychaeta; Bivalvia; Gastropoda; Crustacea; Insecta). We derived 126 conversion factors using two statistical techniques between several mass measures (e.g. wet mass, dry mass, ash-free dry mass, shell-free masses) with specimens from three preservation methods (ethanol, formalin, frozen). Our conversion factors were generally not congruent with those obtained from the literature. We also found that the choice of prediction method used to derive conversion factors can be a substantial source of error in biomass estimation that has largely been overlooked in mass-to-mass conversion. Log-linear ordinary least squares regression models provided substantially more accurate predictions than simple mean ratios. We outline an analytical approach for future use to derive more globally comparable conversion factors for estuarine benthic fauna. • First biomass conversion factors for benthic fauna in southern temperate estuaries. • Choice of prediction method is a substantial source of error in biomass estimation. • Log-linear ordinary least squares regression models gave most accurate predictions. • Propose analytical approach for developing conversion factors. [ABSTRACT FROM AUTHOR]

Studies on the bathyal fauna of northern Pacific waters suggested that a transition or boundary between the North Pacific Province and Central Pacific Provinces would be found somewhere along the Emperor Seamount Chain. Strong currents flow west to east across the seamount chain in a region known as the Main Gap and it was proposed that any larvae produced either north or south of the Main Gap would not be capable of crossing the gap. An expedition to test the hypothesis that a faunal change would be found in the vicinity of the Main Gap was conducted in 2019. Eleven ROV dives were conducted, one on an unnamed seamount at the southern edge of Hess Rise, and 10 dives on seven seamounts along the Emperor Seamount Chain. Six dives were on seamounts north of the Main Gap, while four (including the dive on Hess Rise) were on the southern side. Of the six northern dives, three were at deeper depths (∼2000–1800 m) and three were shallower (∼1500–1100 m); of the southern dives two were at the deeper depths and two were shallower. One shallower dive occurred on Jingu Seamount, situated on the southern edge of the Main Gap. Analysis of the fauna from both collected specimens and annotations of the dive video produced four clusters: a , the four dives south of the Main Gap; b , the three deeper dives north of the Main Gap; c , the shallower dive at Jingu Seamount; and d , the four shallower bathyal dives north of the Main Gap. It was concluded that the bathyal fauna underwent a significant change from north to south across the area of the Main Gap and the adjacent Small Gap, in the area of 37–39 °N, covering distances as small as 75 km or as much as 400 km. [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]

Seamounts can have strong influence on the dynamics and production of waters surrounding them, sometimes creating a kind of oasis effect. To assess to what depths and under what conditions this effect may persist on seamounts, we analysed the fauna and recent history of the Valencia Seamount (VS), a deep, small seamount (summit depth: 1056 m) from an oligotrophic zone of the Mediterranean Sea. The (living) epibenthic fauna of the VS summit (up to 1300 m) was composed of filter feeders, surface deposit feeders and carnivores (63 species), structured in a trophic chain as indicated by the high positive relationship (r2 0.502) between the δN15and δC13 of the fauna analysed. This trophic linearisation (compared with Catalan and NW Mallorca slope sites at similar depths) may optimise the energy flux reaching the seamount, with rather high %TOC (0.93–1.19%) and C/N (5.0–5.5) in July. The Valencia Seamount can also act as a reservoir zone for fish (grenadiers: Nezumia aequalis , and Hymenocephalus italicus) and shrimps (Plesionika martia), which are distributed at shallower depths on adjacent slopes, where they are exploited. The specimens caught were mainly juveniles, suggesting that these species may rather form pseudopopulations. Tuna and cetaceans were regularly sighted on the surface of VS during a specific period of the year (June–July). Reconstructing the recent history of Valencia Seamount (MC2 sediment core taken at 1151 m in 2021) we evidenced a decline of zooplankton pteropods (primary consumers) since ca. the 1960s (MC2 dating after 210Pb, metals and microplastic analyses), linked to a decline of Si in sediments suggesting a decrease in primary production due to a decrease in rainfall and river runoff. An increase of vorticity (ω + values), i.e. of cyclonic gyres, and currents after the 1970s over the summit probably increased resuspension of organic matter, which in turn may enhance zooplankton aggegations at VS summit. We hypothesise that this would explain the parallel increase in mesopelagic myctophids in MC2 (from otolith records). Sediments of the Valencia seamount recorded several historical changes. Reconstruction studies carried out in oceanic areas can therefore help to understand the history and improve the management of fragile systems such as seamounts. • Valencia Seamount (VS) fauna composed mainly by filter and surface deposit feeders. • VS webs structured as chains (high correlation δN15 vs δC13) optimizing energy flux. • The VS acts aggregating mobile fauna, distributed shallower at adjacent slopes. • Pteropods decline (primary consumers) suggests an historic fall of primary production. • Decrease of primary production attributable to a decline of rainfall and river runoff. [ABSTRACT FROM AUTHOR]

The aquatic ecological health status was focused on the Huai River Basin (HRB) from the aspects of water quantity, water quality, water ecology, river connectivity, and riparian habitat environment. Ten monitoring sections were set up in the middle and upper reaches of HRB, and 5 experiments of each section were conducted in July and December from 2012 to 2014. Thus, relevant data on the species, the density of phytoplankton, zooplankton and benthic animals, the concentration of water physicochemical variables, and riparian habitat quality were obtained. Eleven key impact factors were chosen using frequency statistics, theoretical analysis, and correlation analysis methods, forming the evaluation index system of aquatic ecological health. Then, the indicator weight value was determined by the combined weight method, and the health degree was evaluated by the comprehensive index method. On the whole, the aquatic ecological health degree of the upper sections (D1 ~ D3) of the Shaying River ranges from 0.334 to 0.927, which is generally in a "sub-healthy" state. The aquatic ecological health degree of the main section of the Huai River (D8 ~ D10) ranges from 0.362 to 0.777, which is in the "critical" or "sub-healthy" state. The Huaidian Sluice (D5) and Fuyang Sluice (D6) in the middle and lower reaches of the Shaying River had the worst aquatic ecological health. Its water ecological health range is 0.283–0.523, and most of them are under "sub-pathologic." The research results have important theoretical and practical significance. They can enrich the evaluation theories and methods of river aquatic ecological health, help to grasp the aquatic ecological health status in HRB, and provide basic support for aquatic ecological protection and water pollution control in sluice-controlled rivers. [ABSTRACT FROM AUTHOR]

Sympatric adaptive phenotypic divergence should be underlain by genomic differentiation between subpopulations. When divergence drives similar patterns of phenotypic and ecological variation within species we expect evolution to draw on common allelic variation. We investigated divergence histories and genomic signatures of adaptive divergence between benthic and pelagic morphs of Icelandic Arctic charr. Divergence histories for each of four populations were reconstructed using coalescent modelling and 14,187 single nucleotide polymorphisms. Sympatric divergence with continuous gene flow was supported in two populations while allopatric divergence with secondary contact was supported in one population; we could not differentiate between demographic models in the fourth population. We detected parallel patterns of phenotypic divergence along benthic‐pelagic evolutionary trajectories among populations. Patterns of genomic differentiation between benthic and pelagic morphs were characterized by outlier loci in many narrow peaks of differentiation throughout the genome, which may reflect the eroding effects of gene flow on nearby neutral loci. We then used genome‐wide association analyses to relate both phenotypic (body shape and size) and ecological (carbon and nitrogen stable isotopes) variation to patterns of genomic differentiation. Many peaks of genomic differentiation were associated with phenotypic and ecological variation in the three highly divergent populations, suggesting a genomic basis for adaptive divergence. We detected little evidence for a parallel genomic basis of differentiation as most regions and outlier loci were not shared among populations. Our results show that adaptive divergence can have varied genomic consequences in populations with relatively recent common origins, similar divergence histories, and parallel phenotypic divergence. [ABSTRACT FROM AUTHOR]

In this study, Holocene paleoenvironmental changes were interpreted based on benthic foraminifers from a core (39°20′S-61°27′W) extracted from the Argentine Continental Shelf close to the Bahia Blanca Estuary, in the south of Buenos Aires Province. Foraminiferal fauna was determined, and found to include 44 species of 22 genera. From micropaleontological and sedimentological analysis, paleoenvironmental changes during the middle-late Holocene were recognized. Two stages were determined: from 8319–8045 to 7836-7623 Cal. yrs BP, the sediments reflected a shallow environment with estuarine conditions and low energy, enabling determination of a coastal depositional environment. As from ca. 7836–7623 up to ca. 651-557 Cal. yrs BP, the sediments indicated a passage towards to a shallow shelf environment with great marine influence, displaying a high degree of energy and oxygenation, which may have been related to a rise in sea level ca. 7836 -7623 Cal. yrs BP. The detailed study of the benthic foraminiferal fauna presented herein and the sedimentological and chronological analysis performed on the continental shelf next to the Bahía Blanca Estuary provide further proof of the relative location of the mean sea level during the middle Holocene transgressive hemicycle in Argentina. [ABSTRACT FROM AUTHOR]

The influence of hydrodynamic factors on the formation of zoobenthos communities in the coastal zone exposed to active wind-wave mixing, as well as in the deep part of water bodies characterized by the silt accumulation is considered for the Curonian Lagoon. The features of the qualitative and quantitative distribution of zoobenthos and their effect on determining the water quality using zoobenthos parameters are analyzed. Recommendations are given for the placement of hydrobiological monitoring stations based on zoobenthos parameters. [ABSTRACT FROM AUTHOR]

An autonomous lander equipped with a video camera (dropcam) was used for in situ observations of the bento-demersal macrofauna on the upper continental slope off Punta Pichalo in northern Chile, an area of permanent coastal upwelling processes, located ~70 km north of Iquique. The lander was deployed at nine stations and between 227 and 798 m of depth. According to morphological characteristics, 34 operational taxonomic units (OTUs) were identified to the lowest taxonomic level; 24 belonged to macroinvertebrates and 10 to fishes. Macroinvertebrates comprised 9 OTUs of crustaceans, seven cnidarians, and six echinoderms. Fishes included 3 OTUs of the order Chondrichthyes, 3 belonging to macrourid. Perciformes, Anguilliformes, and Alepocephaliformes were represented by one OTU each. Also, we observed one species of lanternfish (Myctophidae). Apart from the brachyuran decapod Lophorochinia parabranchia Garth, 1969 and euphausiids, all species were observed at depths greater than 560 m. The presence of one individual identified as the granulate dogfish Centroscyllium granulatum Günther, 1887 extended the known distribution range of this species about 1000 km to the north. Images taken at 795 m showed Bathyraja peruana McEachran & Miyake, 1984. Our study suggests that the upper continental slope of northern Chile harbors nearly undiscovered biodiversity, worth to be studied more intensively to complete the comparable sparse knowledge about marine biodiversity and species distribution at the continental margin in front of Chile. [ABSTRACT FROM AUTHOR]

This paper aims to provide a theoretical reference for studies on the paleoecology of benthic marine fauna to better understand the terms used in recent studies, or not, on the subject. Through a literature search listing the most relevant works on the subject, it was concluded that the authors use the terms paleocommunities and guilds for the classification of fauna, but nowadays concepts such as functional groups and ecological niches have been used as synonyms. Thus, many older papers can finally be reviewed from a different point of view, providing more detail, and answering open questions. Furthermore, it was observed that there is little discussion on the use of paleoecological concepts to elucidate the life history of fossil assemblages, especially from the Paraná Basin. [ABSTRACT FROM AUTHOR]

Studies addressing the macrobenthic diversity and their potential as bioindicators in water quality assessment programs are sparse for Sri Lanka. The present study investigated the macrobenthic diversity in relation to water quality parameters in some urban reservoirs in the Western Province of Sri Lanka, assessing their potential as bio‐indicators in water quality assessment programs. The six study reservoirs included the Ihalagama Tank, Peralanda Tank, Kesbewa Tank, Boralesgamuwa Tank, Bolgoda Lake and Beira Lake. The microbenthic fauna abundance at randomly selected locations (n = 9) in each reservoir and selected water quality parameters (temperature; pH; electrical conductivity; total dissolved solids; BOD5; dissolved nitrates; total dissolved phosphate and alkalinity of the overlying water at each location were measured between July 2020 and January 2021, using standard data collection methods). The species richness (SR), species heterogeneity (H′) and species evenness (J) of the macrobenthic fauna in each reservoir were calculated, and the abundance and water quality data analysed using ANOVA and PCA as appropriate. A total of 13 macrobenthic taxa (Glyphidrilus sp., Limnodrilus socialis, Dero sp., Stratiomyd larva, Chironomid larva, Bellamya sp., Melanoides tuberculata, Gyraulus sp., Lymnaea sp., Paludomus sp., Thiara sp., Ancylus sp. and Mesostoma sp.) were observed from the six study reservoirs. The oligochaete tubificid worm L. socialis dominated the sediment samples, accounting for more than 94.7% of the total macrobenthic abundance, with the highest relative abundance of this species observed in Beira Lake (99.3%). The species richness of the macrobenthic community was highest in the Ihalagama and Kesbewa tanks (SR = 5), while it was the lowest in the Peralanda Tank (SR = 2). Since the benthic community was mainly dominated by L. socialis, the lowest species heterogeneity and species evenness values were observed in Beira Lake (H′ = 0.05; J = 0.03). The values of the water quality parameters among the study reservoirs varied, with Beira Lake exhibiting significantly high BOD5, dissolved nitrate, and total dissolved phosphate values (p <.05) than the other reservoirs, indicating a higher degree of eutrophication. Furthermore, the SR, J and H′ values for the study reservoirs decreased with increasing BOD5, dissolved nitrate and total dissolved phosphate levels. Thus, it was concluded that the abundance and diversity of macrobenthic fauna are primarily governed by water quality parameters. Furthermore, L. socialis can be used as a potential bioindicator organism in water quality assessment programs in urban reservoirs. [ABSTRACT FROM AUTHOR]

The Capitanian (Middle Permian) mass extinction event, prior to and separate from the end-Permian mass extinction, has been suggested as a severe biotic crisis comparable to the big five mass extinctions of the Phanerozoic. However, there is still controversy about its global significance. In particular, this purportedly disastrous event in the Capitanian was mostly documented in the eastern Tethys, especially South China and Japan, whereas its extent in higher latitudinal regions remains unclear. A few recent studies have reported biostratigraphic and chemostratigraphic evidence for the Capitanian extinction at the northwestern marginal shelf of Pangea, including in the Kapp Starostin Formation in Spitsbergen. However, we here report a different result from these previous studies based on a study of abundant brachiopod fossils collected from eight geological sections that represent the same formation in western and central Spitsbergen, Arctic Norway. Our biostratigraphic investigation recognizes a total of five brachiopod assemblages from the type section of the Kapp Starostin Formation at Festningen in Spitsbergen. The most striking biotic change in species composition is observed at the interval between the lowermost Vøringen Member (late Artinskian) and its overlying member (Kungurian) of the Kapp Starostin Formation in Spitsbergen, which makes it much earlier than the Capitanian. A similar faunal shift at the same stratigraphic interval is also observed from bryozoan-based biostratigraphic data. This faunal turnover could be linked to a significant climatic shift (cooling) along the northwestern margin of Pangea during the Artinskian-Kungurian. Specifically, it is inferred that a climatic perturbation (cooling) likely drove the extirpation (emigration) of marine faunas out of Spitsbergen and dispersal eastward into some lower latitudinal and climatically more habitable areas. Our result indicates that the Capitanian interval in Spitsbergen does not record a catastrophic event that corresponds to the Capitanian mass extinction in Tethyan regions but rather marks gradual faunal transitions throughout the Middle to Late Permian. This faunal transition, driven by continuous cooling, was accompanied by major changes in regional lithology, which suggest a degree of local environmental control, especially in the changes of substrate and water depth, on the composition of the benthic faunas. The Wegener Halvø and Schuchert Dal Formations (Lopingian) in central East Greenland contain a diverse brachiopod fauna that is comparable to that of the post-Vøringen Member in Spitsbergen. This implies that the brachiopods in the northwestern marginal shelf of Pangea did not suffer a severe mass extinction in the Capitanian; instead, many of them migrated southward with the development of the Zechstein seaway. [ABSTRACT FROM AUTHOR]

The waters adjacent to the northeastern coast of Sakhalin Island, Russia, are an important feeding ground for the endangered western gray whale. Data on the energy available to foraging whales from their prey resources is required for researchers interested in modeling the bioenergetics of whale foraging, but little energy content information is available for the benthic prey communities of gray whales in this region. In this study, we describe the energy density (ED), biomass, and total energy availability (ED × biomass) of benthic prey sampled from two gray whale foraging areas adjacent to Sakhalin Island: the nearshore and offshore feeding areas. ED varied almost seven-fold among benthic taxa, ranging from 1.11 to 7.62 kJ/g wet mass. Although there was considerable variation within most prey groups, amphipods had the highest mean ED of all of groups examined (5.58 ± 1.44 kJ/g wet mass). Small sample sizes precluded us from detecting any seasonal or spatial differences in mean ED within or among taxa; however, mean biomass in the offshore feeding area was, in some cases, an order of magnitude higher than mean estimates in the nearshore feeding area, resulting in higher mean total energy available to foraging gray whales offshore (958–3313 kJ/m2) compared to nearshore (223–495 kJ/m2). While the proportion of total energy accounted for by amphipods was variable, this prey group generally made up a higher proportion of the total energy available in the benthos of the offshore feeding area than in the benthos of the nearshore feeding area. Data presented here will be used to inform bioenergetics modeling of the vital rates of mature females in an effort to improve understanding of population growth limits for western gray whales. [ABSTRACT FROM AUTHOR]

The objectives of this study were to test an artificial substrate sampler method for aquaculture ponds and assess the water quality based on the benthic macroinvertebrate community living in fishpond sediment at four farms with tilapia production in the Baixa Mogiana region of São Paulo State, Brazil. Benthic macroinvertebrates were monitored every 15 days for 3 months. Approximately 500,000 organisms distributed in 47 taxa were collected. Chironomidae, Glossiphonidae, Hirudinidae, Libelullidae, Oligochaeta, and Polycentropodidae were present in all collected samples, with the dominance of Chironomidae in the benthic community. Polycentropodidae, a sensitive family to organic pollution, had a greater abundance in fish farms with better environmental conditions. Significant differences in dissolved oxygen and pH were observed among fishponds at different fish farms. Biomonitoring with artificial substrate is a simple and low-cost alternative to monitoring water quality of tilapia culture in fishponds. The artificial substrate sampling method was effective, but the evaluation of more critical conditions of water quality would improve the method and enhance the knowledge of taxa and ecology of macrobenthic organisms in fishponds. [ABSTRACT FROM AUTHOR]