Benthic Marine Organisms Research Articles

Influence of different substrates on bacterial communities in coral reefs and surrounding environments of a coastal bay

Substrate types are diverse in coastal coral reefs, which can determine the distribution pattern of marine benthic organisms. Coastal coral reefs are also increasingly influenced by activities from the intertidal zone. However, the variation of bacterial communities on different substrates from the intertidal zone to coastal coral reefs have been seldom discussed. Here, we collected 12 samples of different substrate (rock, sand, live coral, and dead coral) from three environments (i.e., intertidal zone, coral distribution area, and no-coral distribution area) in Daya Bay of the South China Sea, and investigated the influence of substrates on bacterial communities. The results showed that the bacterial diversity (Shannon and Chao 1 index) in sand substrates was higher than those in stone/hard substrates. However, a more complex co-occurrence network of bacterial communities were observed in intertidal sand samples than sand samples from the coral area. Principal coordinate analysis and taxonomic analyses of bacterial composition showed that substrate type can shape the variations in bacterial communities from different environments in the Daya Bay region. Bacteroidetes and Chloroflexi were more abundant in sand substrates, while Cyanobacteria and Planctomycetes were more abundant in rock substrates. Redundancy analysis revealed that environmental factors, such as gravel, heavy metals, salinity, and pH regulated the bacterial community in the coastal region. Furthermore, the shared operational taxonomic units (OTUs) from different substrates in the coral distribution area were identified, and most of the top 20 shared OTUs (core bacteria) were identical to the bacteria associated with coral reef ecosystems in previous studies; thus, indicating that core bacteria exist in coral reefs from Daya Bay. This study broadens the understanding of the effect of substrates on bacterial distributions in coral reefs and surrounding environments from a coastal bay.

In Vitro Toxicity and Modeling Reveal Nanoplastic Effects on Marine Bivalves.

Nanoplastics (NPs) represent a growing concern for global environmental health, particularly in marine ecosystems where they predominantly accumulate. The impact of NPs on marine benthic organisms, such as bivalves, raises critical questions regarding ecological integrity and food safety. Traditional methods for assessing NP toxicity are often limited by their time-intensive nature and ethical considerations. Herein, we explore the toxicological effects of NPs on the marine bivalve Ruditapes philippinarum, employing a combination of in vitro cellular assays and advanced modeling techniques. Results indicate a range of adverse effects at the organismal level, including growth inhibition (69.5-108%), oxidative stress, lipid peroxidation, and DNA damage in bivalves, following exposure to NPs at concentrations in the range of 1.6 × 109-1.6 × 1011 particles/mL (p/mL). Interestingly, the growth inhibition predicted by models (54.7-104%), based on in vitro cellular proliferation assays, shows strong agreement with the in vivo outcomes of NP exposure. Furthermore, we establish a clear correlation between cytotoxicity observed in vitro and the toxicological responses at the organismal level. Taken together, this work suggests that the integration of computational modeling with in vitro toxicity assays can predict the detrimental effects of NPs on bivalves, offering insightful references for assessing the environmental risk assessment of NPs in marine benthic ecosystems.

Response of inner shelf benthic foraminiferal community to different concentrations of dissolved oxygen under laboratory culture experiment

Dissolved oxygen, a vital parameter for a majority of marine organisms, may decline in the near future due to anthropogenic eutrophication in coastal waters. The effect of depleting dissolved oxygen on the marine benthic community is difficult to assess from field studies, as dissolved oxygen often co-varies with several other parameters, especially organic matter. The controlled laboratory culture experiments can help to assess the effect of a specific parameter on marine organisms. Foraminifera constitute a substantial fraction of the marine benthic organisms, and a few species are vulnerable to depleted oxygen. A majority of the previous culture experiments have used isolated specimens of individual benthic foraminiferal species. Although such studies helped to understand the response of individual species to a particular parameter, they have to be scaled up to understand the community-level response of benthic foraminifera. Here, we assess the community-level response of the shallow subtidal benthic foraminiferal community to five different oxygen concentrations (1.67 mL/L to 5.01 mL/L) in a laboratory culture experiment. The living benthic foraminiferal abundance was considerably high at the intermediate oxygen concentration, whereas it decreased at both the lower and higher concentrations. The decreasing dissolved oxygen caused poor preservation of dead benthic foraminifera due to a drop in pH. The relative abundance trend of the species belonging to the same genus was different, suggesting a species-specific response to the dissolved oxygen. The maximum abundance at 2.91 mL/L and the varying response of individual species clearly suggest a non-linear response of the benthic foraminiferal community to the dissolved oxygen.

Combined effects of organic and mineral UV-filters on the lugworm Arenicola marina

Pollution from personal care products, such as UV-filters like avobenzone and nano-zinc oxide (nZnO), poses a growing threat to marine ecosystems. To better understand this hazard, especially for lesser-studied sediment-dwelling marine organisms, we investigated the physiological impacts of simultaneous exposure to nZnO and avobenzone on the lugworm Arenicola marina. Lugworms were exposed to nZnO, avobenzone, or their combination for three weeks. We assessed pollutant-induced metabolic changes by measuring key metabolic intermediates in the body wall and coelomic fluid, and oxidative stress by analyzing antioxidant levels and oxidative lesions in proteins and lipids of the body wall. Exposure to UV filters resulted in shifts in the concentrations of Krebs’ cycle and urea cycle intermediates, as well as alterations in certain amino acids in the body wall and coelomic fluid of the lugworms. Pathway enrichment analyses revealed that nZnO induced more pronounced metabolic shifts compared to avobenzone or their combination. Exposure to avobenzone or nZnO alone prompted an increase in tissue antioxidant capacity, indicating a compensatory response to restore redox balance, which effectively prevented oxidative damage to proteins or lipids. However, co-exposure to nZnO and avobenzone suppressed superoxide dismutase and lead to accumulation of lipid peroxides and methionine sulfoxide, indicating oxidative stress and damage to lipids and proteins. Our findings highlight oxidative stress as a significant mechanism of toxicity for both nZnO and avobenzone, especially when combined, and underscores the importance of further investigating the fitness implications of oxidative stress induced by these common UV filters in benthic marine organisms.

More than a colour; how pigment influences colourblind microbes.

Many animals have pigments when they themselves cannot see colour. Perhaps those pigments enable the animal to avoid predators, or to attract mates. Maybe even those pigmented surfaces are hosts for microbes, even when the microbes do not see colour. Do some pigments then serve as a chemical signal for a good or bad microbial substrate? Maybe pigments attract or repel various microbe types? Echinoderms serve as an important model to test the mechanisms of pigment-based microbial interactions. Echinoderms are marine benthic organisms, ranging from intertidal habitats to depths of thousands of metres and are exposed to large varieties of microbes. They are also highly pigmented, with a diverse variety of colours between and even within species. Here we focus on one type of pigment (naphthoquinones) made by polyketide synthase, modified by flavin-dependent monoxygenases, and on one type of function, microbial interaction. Recent successes in targeted gene inactivation by CRISPR/Cas9 in sea urchins supports the contention that colour is more than it seems. Here we dissect the players, and their interactions to better understand how such host factors influence a microbial colonization. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.

Toxic effect of chromium on nonspecific immune, bioaccumulation, and tissue structure of Urechis unicinctus.

The contamination of toxic heavy metals in aquatic environments has garnered significant global attention due to its detrimental effects on marine organisms and human health. Hexavalent chromium is a typical environmental and occupational heavy metal pollutant, identified as carcinogenic heavy metal. This study aimed to assess the impact of different Cr (VI) concentrations (0.05-2.5 mg/L) on Urechis unicinctus (U. unicinctus) by investigating bioaccumulation, antioxidant defense system, expression of resistance-related genes, and histological issues. A clear concentration-effect relationship was observed in the bioaccumulation of Cr (VI) in muscle tissues of U. unicinctus. Moreover, exposure to Cr (VI) can alter the activities of lysozyme (LSZ), catalase (CAT), and superoxide dismutase (SOD) to enhance cellular defense mechanisms in U. unicinctus. Likewise, maintained the normal protein structure and functional stability by regulating protein folding. The heat shock cognitive protein (HSC70) gene showed an upward and then downward trend after Cr (VI) exposure. At 12 h, the HSC70 gene expression reached the maximum values of 4.75 and 4.61-fold in the 0.1 and 1.5 mg/L groups, respectively. The organism produced a large number of free radicals, and elevated level of metallothionein (MT) was used to scavenge free radicals and alleviate oxidative stress. Additionally, histopathological examination revealed disorganization in the midgut, atrophic changes in intestinal connective tissue, uneven distribution in respiratory tissues, and irregular shape with a significant reduction in epithelial cells within the gastric cavity. These findings can serve as a valuable reference for elucidating the toxicity mechanisms of heavy metals towards marine benthic organisms and enhancing water environment monitoring strategies.

Visean terrigenous sediments of the South Tatar Arch (Volga-Urals oil and gas bearing province) – multifacial filling of the karst surface of the Tournaisian isolated carbonate platform

The paper presents new thickness and sandiness maps of the Visean terrigenous strata (Radayevkian and Bobrikian regional stages, Lower Carboniferous) of the South Tatar Arch, constructed using the “Natural Neighbour” spatial interpolation method in ArcGIS Pro software based on the analysis of geophysical survey data for more than 30,000 boreholes. The interpretation of the maps in combination with the results of sedimentological, ichnotextural and petrophysical core studies, supplemented by the analysis of archival and published materials, provided an opportunity to update the approach to modelling the sedimentation of the terrigenous Lower Carboniferous of the South Tatar Arch. The proposed sedimentation models of terrigenous and coal-bearing sediments take into account the chronostratigraphic data, the karstification of isolated carbonate platforms, the sediment accumulation rates and the ichnotextural characteristics of the sediments. It is concluded that the accumulation and preservation of terrigenous and peat (coal-bearing) sediments differ in duration (0.1 million years vs. 1.5–2 million years) and are consequently associated with transgressive and regressive phases. The accumulation of terrigenous sediments includes: (a) transgressive eustatic episodes – short-term incursions of a marine basin onto the eroded surface of an isolated carbonate platform, during which silty and sandy, well-sorted bioturbated sediments were accumulated, often with a variety of ichnofossils of marine benthic organisms; (b) the regressive eustatic phase resulted in the predominant erosion of sediments on the arch; whereas sediments in the incisions were largely preserved. The accumulation of peat (coal-bearing) deposits includes (a) the regressive eustatic phase, during which the vast area of the eastern Volga-Urals region was covered with flourishing vegetation and stable swamp environments were forming in the incisions of the Tournaisian surface; (b) the transgressive phase – the peat was overlaid and buried by transgressive marine silt-sand sediments; then it was compacted and transformed into coal. The alternation of coal-bearing and transgressive intervals indicates the cyclicity of these processes. The proposed sedimentation models extend the concepts of previous studies and are consistent with the developed maps of thickness and sandiness of the Lower Carboniferous terrigenous sediments, explaining the complex, covering and mosaic distribution of sand bodies over the area, as well as the filling of incisions with sediments of different lithological types.

Distribution and characteristics of microplastics in 16 benthic organisms in Haizhou Bay, China: Influence of habitat, feeding habits and trophic level

Microplastics (MPs) are widely found in the ocean and cause a serious risk to marine organisms. However, fewer studies have been conducted on benthic organisms. This study conducted a case study on the pollution characteristics of MPs on 16 marine benthic organisms in Haizhou Bay, and analyzed the effects of habitat, trophic level, and feeding mode on the MPs pollution characters. The results showed that MPs were detected in all 16 organisms with an average abundance of 8.84 ± 9.14 items/individual, which is in the middle-high level in the international scale. Among the detected MPs, the main material was cellophane. This study showed that benthic organisms can be used as indicator organisms for MPs pollution. MPs in organisms can be affected by their habitat, trophic level, and feeding mode. Comprehensive analysis of MPs in benthic organisms will contribute to fully understand the characterization and source resolution of MPs pollution.

Development ofmarine biodiversity database (BISMaL) to enable estimations past habitat conditions formarine life inthe northwestern Pacific.

Global activities involving the collection of marine biodiversity information have provided a large amount of biological observation records that cover various spatiotemporal areas. To predict biological responses or distribution changes in response to environmental changes by using these observation records, it is essential to analyze not only the current marine physicochemical environmental conditions but also the past conditions when the organisms were observed. We developed a new function to estimate the past marine environmental conditions for the observation records in our marine biodiversity database (Biological Information System for Marine Life: BISMaL) and examine whether the database can reliably estimate thermal habitats for both benthic and planktonic marine organisms. For the benthic squat lobster Shinkaia crosnieri, the estimated and observed in situ temperatures were similar to each other. For the planktonic chaetognaths Krohnitta pacifica and K. subtilis, the estimated temperatures showed clear seasonal changes specific to their distribution areas. These results indicated that BISMaL can reliably provide past habitat conditions regardless of planktonic or benthic lifestyles. BISMaL, which provides both biological observations and estimated past environmental conditions through web services, could lower the barrier to data access and use and make data-driven science available not only for data scientists but also for various marine scientists, such as taxonomists, ecologists and field scientists. Database URL: https://www.godac.jamstec.go.jp/bismal/e/.

Send nudis: An assessment of nudibranch diversity in Sodwana Bay, South Africa.

Climate change is posing unprecedented pressure onto marine ecosystems worldwide. This makes it imperative to monitor the effects that are being experienced in these environments. Nudibranchs are benthic marine organisms that possess characteristics that have the potential to act as indicators of change within ecosystems such as coral reefs. Therefore, these species have the ability to provide valuable information on fine-scale changes in environmental conditions. It is thus essential for studies, such as this, to establish baseline analyses from which changes within nudibranch populations can be examined in order to investigate their ability to act as bioindicators. Recommendations can also be made for future sampling procedures through investigating environmental and experimental parameters that influence nudibranch communities. Nudibranch populations were sampled on Two-Mile Reef in Sodwana Bay, South Africa, through SCUBA where individuals were photographed and later identified. Data were collected within a sample-based dataset, as well as by citizen scientists within an incidence-based dataset. Across both datasets, a total of 85 species were identified. Nudibranch populations showed high levels of diversity within an uneven, unstable community. Citizen scientist data provided imperative information to the baseline assessment and, therefore, the inclusion of these data increased the robustness of this study. Environmental and experimental variables investigated did not influence the outcomes of this study and should therefore not be heavily focused on in designing future experiments. Future monitoring studies should continue to record oceanic pH in order to detect any possible changes due to ocean acidification. It is recommended that sampling events should be increased in order to capture all species present in these localities. These events should also encompass an extended temporal scale in order to cover a larger temperature range. Research on bioindicators is essential within today's rapidly changing climate, mainly due to human activities, particularly within an extremely vulnerable habitats such as coral reefs.

Transcriptomic analysis reveals the immune response mechanisms of sea cucumber Apostichopus japonicus under noise stress from offshore wind turbine

As an important form of renewable energy, offshore wind power can effectively reduce dependence on traditional energy sources and decrease carbon emissions. However, operation of wind turbines can generate underwater noise that may have negative impacts on marine benthic organisms in the surrounding area. Sea cucumbers are slow-moving invertebrates that inhabit the ocean, relying on their immune system to adapt to their environment. To evaluate the frequency range of characteristic noise produced by offshore wind turbines, we conducted a field survey. Additionally, we utilized sea cucumbers in simulated experiments to assess their response to the noise produced by offshore wind turbines. We established a control group, a low-frequency noise group simulating offshore wind turbine noise at 125 Hz and 250 Hz, and a high-frequency noise group at 2500 Hz, each lasting for 7 days. Results from measuring immune enzyme activity in the coelomic fluid suggest that noise can reduce the activity of superoxide dismutase enzymes, which may make sea cucumbers more susceptible to oxidative damage caused by free radicals. Exposure to low-frequency noise can have the effect of diminishing the activity of catalase, and this decrease in catalase activity could potentially increase the susceptibility of the sea cucumber's coelom to inflammation. In order to elucidate the hypothetical mechanism of immune response, intestinal tissue was extracted for transcriptome sequencing. The results showed that under 125 Hz low-frequency noise stress, the number of differentially expressed genes was the highest, reaching 1764. Under noise stress, sea cucumber's cell apoptosis and cell motility are reduced, interfering with lipid metabolism process and membrane synthesis. This research provides theoretical support for the environmental safety assessment of offshore wind power construction.

Cerianthus lloydii (Ceriantharia: Anthozoa: Cnidaria): New Status and New Perspectives.

Subclass Ceriantharia is a well-defined and probably ancient group of marine benthic organisms renowned for their bilateral symmetry, which is reflected in the arrangement of tentacles and mesenteries. Four species of Ceriantharia have been reported in the Arctic, including Cerianthus lloydii Gosse, 1859, also known from the Northern Atlantic and Northern Pacific. The integrity of this species was questioned in the literature, so we performed a molecular study of C. lloydii from several geographically distant locations using 18S and COI genes. The phylogenetic reconstructions show that specimens of C. lloydii form a single group with high support (>0.98), subdivided into distinctive clades: (1) specimens from Northern Europe, the Black and Barents seas, and (2) specimens from the White, Kara, Laptev, and Bering seas and also the Canadian Arctic and the Labrador Sea available via the BOLD database. There are several BOLD COI sequences of Pachycerianthus borealis (Verrill, 1873), which form a third clade of the C. lloydii group, sister to the European and Arctic clades. Based on low similarity (COI 86-87%) between C. lloydii and the type species of the genus Cerianthus Delle Chiaje, 1841-C. membranaceus (Gmelin, 1791), we propose a new status for the genus Synarachnactis Carlgren, 1924, and a new family Synarachnactidae to accommodate C. lloydii.

Sediment and bottom water eDNA metabarcoding to support coastal management

Ocean sprawl and climate change exacerbate coastal erosion and flooding, resulting in habitat loss and decreasing biodiversity. To counteract these threats, different coastal defence tools have been developed, with an increasing emphasis on nature-based solutions. However, tracking the impacts of these interventions on marine benthic organisms requires appropriate sampling designs and timely investigation methods due to the dynamic nature of coastal environments. Environmental DNA metabarcoding is a promising, non-invasive, and quick technique to monitor community changes. Here, environmental DNA COI-based metabarcoding data from sediment and bottom water samples were used to characterize benthic communities at three sites along the Emilia-Romagna coast differing in the topology of coastal defence actions (from no defences to groynes and low-crested barriers) and to evaluate the effectiveness of the two sampling matrices in detecting local biodiversity. The findings revealed significant differences in the structure of the benthic communities depending on site, sample type (i.e., sediment versus bottom water), and their interaction. The three sites differ in abiotic characteristic affecting the community composition. Lido di Dante and Riccione showed higher species diversity due to the new type of substrata provided by the hard defence structure, while Foce del Bevano showed the presence of species typical of low impacted areas. Bottom water, hosting more traces of pelagic and nektonic species, showed significantly different species composition compared to sediment samples, suggesting the need to consider both matrices in coastal monitoring.

Biomonitoring of Benthic Organisms for Coastal Protection: A Checklist Study from Pantai Remis and Blue Lagoon on the West Coast of Peninsular Malaysia

The objective of the study was to provide an updated checklist of benthic marine organisms in Pantai Remis (Selangor) and Blue Lagoon (Negeri Sembilan) in November 2022. The research areas comprised a total of 26 species of marine benthic organisms, which were divided into 12 orders, 18 families, and 22 genera. Benthic macrophytes formed the largest group (11 species), followed by other benthic macrofauna (molluscs, with eight species). In addition, three coral species, two gastropods, and two crabs were also recorded. The findings revealed that both sites are fertile and suitable habitats for marine benthic organisms. The established checklist of benthic organisms can serve as an ongoing basis for future reference as part of our efforts to develop coastal marine ecosystem management and conservation on the west coast of Peninsular Malaysia. In summary, the checklist of benthic organisms provides the basic information that is much needed for the protection of coastal ecosystems.

EFP-YOLO: A quantitative detection algorithm for marine benthic organisms

Underwater object detection technologies are widely applied in the field of marine scientific research. In real underwater environments, a large number of dense, blurred, and small-sized objects appear. It is difficult for current general-purpose object detectors to detect these samples. To solve these problems, this paper proposes a quantitative detection algorithm EFP-YOLO (Enhance the Ability of Feature Extraction and Perception Ability of YOLOX) for marine benthic organisms that improved on YOLOX. Firstly, IGACSP (Cross Stage Partial Module with Interactive Global Attention) is embedded in the backbone to enhance the ability for extracting features of small-sized and blurred objects, which fuses local and global information in a parallel interactive way. To improve the capacity for detecting multiscale objects, EPPM (Efficient Pyramid Pooling Module) fuses feature maps from different scales that provide sufficient contextual information. Secondly, FSM (Feature Selection Module) and FAM (Feature Alignment Module) are introduced into the feature fusion part for spatial feature extraction and feature alignment, respectively. The modules provide accurate boundary localization information for the detection of dense objects. Finally, ATFhead (Asymmetric Task Focused head) is proposed to increase the scale perception, spatial perception, and task perception of the detection head. It improves the classification and localization abilities of the model, thus achieving accurate counting of marine benthic organisms. The experimental results show that compared with YOLOX-S, mAP0.5:0.95 is improved from 59.7% to 64.6% on the DUO dataset. EFP-YOLO demonstrates superior performance in the quantitative detection of marine benthos compared to other object detection algorithms. This can effectively advance marine scientific research and promote biological conservation efforts. To show the generality of EFP-YOLO, we use a generic object detection dataset for experiments. You can access the code for EFP-YOLO publicly on https://github.com/llllllvv/EFP-YOLO.

Bioconcentration of pharmaceuticals in benthic marine organisms (Holothuria tubulosa, Anemonia sulcata and Actinia equina) exposed to environmental contamination by atenolol and carbamazepine

The present work assess the bioconcentration kinetics of atenolol (ATN) and carbamazepine (CBZ) in common marine organisms including Holothuria tubulosa, Anemonia sulcata and Actinia equina under controlled laboratory conditions. CBZ exhibited higher uptake and excretion rates resulting higher bioconcentration factor (BCF) (41–537 L/kg for CBZ vs 7–50 L/kg for ATN) although both are below the limits established by the European Union (EU). The measured BCF using kinetic data showed some differences with those predicted using the concentrations measured at the steady-state, probably explained because the steady state was not ready reached. The animal-specific BCF followed the order of Holothuria tubulosa >Actinia equina >Anemonia sulcata for ATN while was the opposite for CBZ. The study highlighted between-tissues differences in the digestive tract and the body wall of the Holothuria tubulosa. The work presented is the first to model bioconcentration of ATN and CBZ in holothurian and anemone animal models.

Fascinating strategies of marine benthic organisms to cope with emerging pollutant: Titanium dioxide nanoparticles

Titanium dioxide nanoparticles (NPs) have numerous applications, and their demands have increased as an alternative for banned sunscreen filters. However, the underlying mechanisms of their toxicity, remain largely unknown. Here, we investigate the mechanism of TiO2 NP cytotoxicity and detoxification through time-course experiments (1, 6, and 24 h) based on cellular observations and single-cell transcriptome analyses in a marine benthic foraminifer strain, derived from a common unicellular eukaryotic organism worldwide. After exposure for 1 h, cells enhanced the production of reactive oxygen species (ROS) in acidic endosomes containing TiO2 NPs as well as in mitochondria. In acidic endosomes, ROS were produced through the Fenton reaction on the surface of charged TiO2 NPs. In mitochondria, ROS were associated with porphyrin synthesis that chelated metal ions. Glutathione peroxide and neutral lipids acted as a sink for free radicals, whereas lipid peroxides were excreted to prevent further radical chain reactions. By 24 h, aggregated TiO2 NPs were encapsulated in organic compounds, possibly ceramide, and excreted as mucus, thereby preventing their further uptake. Thus, we reveal that foraminifers can tolerate the toxicity of TiO2 NPs and even prevent their further phagocytosis and uptake by trapping TiO2 NPs inside mucus. This previously unknown strategy could be applied in bioremediation to sequester NPs from the marine environment and can guide management of TiO2 pollution.

Editorial: Local hydrodynamics of benthic marine organisms

Editorial: Local hydrodynamics of benthic marine organisms

LSH-DETR: object detection algorithm for marine benthic organisms based on improved DETR

A recent area of study focus is object detecting technologies for marine benthic organisms. A marine benthic object detection algorithm, LSH-DETR, based on DETR, is proposed to address the detection issue in the case of dense distribution of marine benthic small objects. The locality-sensitive hashing attention is used instead of self attention in the transformer to enhance the learning ability of context information. The multilevel feature pyramid networks fusion is introduced to improve the detection performance of small targets. At the same time, repulsion loss is used to optimize the prediction loss of the bounding box to improve the missing detection phenomenon caused by the target stack. According to the findings, LSH-DETR enhanced the mAP of marine benthos to 62.8% and obtained a performance of 13.8% MR when compared to the original DETR. This improvement demonstrates that LSH-DETR is more effective at locating small, dense marine benthic organisms.

Trophic ecology of three stingrays (Myliobatoidei: Dasyatidae) off the Brazilian north-eastern coast: Habitat use and resource partitioning.

Understanding the ecological role of species with overlapping distributions is central to inform ecosystem management. Here we describe the diet, trophic level and habitat use of three sympatric stingrays, Hypanus guttatus, H. marianae and H. berthalutzae, through combined stomach content and stable isotope (δ13 C and δ15 N) analyses. Our integrated approach revealed that H. guttatus is a mesopredator that feeds on a diverse diet of benthic and epibenthic marine and estuarine organisms, principally bivalve molluscs, Alpheus shrimp and teleost fishes. Isotopic data supported movement of this species between marine and estuarine environments. H. berthalutzae is also a marine generalist feeder, but feeds primarily on teleost fishes and cephalopods, and consequently occupies a higher trophic level. In contrast, H. marianae is a mesopredator specialized on shrimps and polychaetas occurring only in the marine environment and occupying a low niche breadth. While niche overlap occurred, the three stingrays utilized the same prey resources at different rates and occupied distinct trophic niches, potentially limiting competition for resources and promoting coexistence. These combined data demonstrate that these three mesopredators perform different ecological roles in the ecosystems they occupy, limiting functional redundancy.