Search Results (405)

In addition to their historical relevance, underwater sites of cultural heritage (e.g., shipwrecks, archeological sites) represent secondary habitats for marine life. However, despite a growing interest in their ecological role, studies focusing on these artificial environments remain limited. In this study, we performed the first systematic assessment of the marine biodiversity associated with the submerged structures of the ancient roman port of Egnazia. In particular, we conducted a seasonal (summer 2022 and winter 2023) comparative analysis of the qualitative and quantitative variations in the observed nektonic and benthic taxa between the submerged piers and two surrounding control areas. For benthopelagic and vagile benthic taxa, two seasonal samplings with four transects (of 10 m × 4 m) and three replicates per transect were conducted to analyze taxon diversity, abundance, and variability of individual size. The photo-quadrat method was employed to characterize sessile benthic taxa, using PVC frames measuring 40 cm × 40 cm, randomly placed on the study substrates with 20 replicates for each pier and the two controls. Our results highlight the occurrence of 75 taxa (67 associated with the submerged piers and 63 with the surrounding control areas), including 17 benthopelagic species, 26 vagile benthic and 32 sessile benthic taxa. Overall, our findings highlight that the submerged ancient structures of Egnazia represent a stable and functional marine habitat, promoting an increase in the local biodiversity and abundance of individuals of different species. Full article

The rich Eocene larger benthic foraminiferal (LBF) assemblages in the vicinity of Verona have long been well known. However, they are described in detail only from the Ypresian to Bartonian interval. Here, we present the results of our morphometrically based study of Priabonian LBF. The lowermost part of the succession, just above the uppermost occurrence of giant Nummulites (N. biedai), outcrops at Monte Cavro and contains Heterostegina reticulata multifida and Nummulites hormoensis as major constituents. These taxa clearly determine the earliest Priabonian Shallow Benthic Zone (SBZ) 18C. Slightly younger strata can be analyzed in the other three studied exposures on the northern side of Castel San Felice. These beds already represent the early Priabonian SBZ 19A Zone based on the first appearing Spiroclypeus sirottii and the presence of Heterostegina reticulata mossanensis and Nummulites fabianii (replacing H. r. multifida and N. hormoensis, respectively). The most abundant LBF in these beds are the very diverse and well-preserved orthophragmines represented the families Discocyclinidae (genera Discocyclina and Nemkovella) and Orbitoclypeidae (genera Orbitoclypeus and Asterocyclina). They determine the Orthophragmine Zone (OZ) 14. The distinction of six species of the genus Discocyclina (especially that of D. euaensis from D. dispansa) is discussed in detail. The exposures around Castel San Felice are considered as key localities for the SBZ 19A and OZ 14 Zones, containing their key LBF assemblages. Consistently, both orthophragmine and LBF range charts for the late Lutetian to Priabonian are updated. Full article

Coral reef ecosystems are home to diverse marine flora and fauna. However, these ecosystems are threatened by an array of environmental and anthropogenic factors. Here, we investigated coral reef diversity, structure, and health status, and identified their key environmental drivers. Coral reef data were collected from Koh Seh Island, located inside the Marine Fisheries Management Area in the Kep archipelago. We found that the reef cover largely comprised live corals (64%, mainly Porites and Tubinaria species), followed by Zoanthids (15%) and sand/rubble (15%). Based on Ward’s hierarchical cluster analysis, coral communities were grouped into three zones: East, South, and West zones. Coral diversity was slightly higher in the East zone, though not statistically significant. Zone East showed a positive association with sediment loads and water temperature. Elevated levels of salinity, dissolved oxygen, and pH were characteristic of the East and South zones, whereas the West zone was distinguished by deeper water conditions. We also found that Favites was the key indicator for coral communities in the East zone, which features shallow, high-DO, high-pH waters with more sediments, strong currents, and significant human activities like fishing and transportation. Goniastrea species were abundant in the South and East zones, making it the indicator taxon, while the West zone had no indicator, suggesting that coral species are sparse in this zone. Interestingly, only a few dead corals were found, and no signs of diseases were detected around the Koh Seh coral reefs. This may reflect the effectiveness of joint protection efforts by Marine Conservation Cambodia and the Marine Fisheries Department in Kep province. Overall, our study provides a valuable baseline for assessing future changes in benthic reefs and coral communities on Koh Seh island, throughout the Kep Archipelago and its surrounding areas. Full article

Hydrothermal vents are “oases” of biological productivity and endemicity on the seafloor. Chemosynthetic communities at deep-sea hydrothermal vents are characterized by high abundance and endemism. The distribution of species among these isolated habitats supports regional biodiversity and stability, so understanding the fundamental processes is a key target of conservation. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing the diversity and distributions of vent animals. By combining a biophysical model with biological larvae traits, we quantify potential larval dispersal of vent species via ocean circulation in the Azores Triple Junction. Here we present results from a biophysical model of larval dispersal run for the hydrothermal vent benthic mussel Bathymodiolus azoricus. Several scenarios were implemented, based on similar data sets, although changing values for one or two parameters, such as swimming behaviour and planktonic larvae duration. Results showed that larvae retention is the most common pattern from the Azores Triple Junction vent fields mussel. The Rainbow vent field is rather isolated, being the sink population of the Menez Gwen and Lucky Strike but with a very low number of larvae exchange. Results are discussed in the framework of spatial management to maintain the populations after an impact by natural or human disturbance. Full article

This paper provides a comprehensive review of sessile benthic invertebrate biodiversity across three interconnected marine areas in Western Australia’s Gascoyne and southern Pilbara regions: Ningaloo Reef (a UNESCO World Heritage site), the nearby Muiron Islands to its north, and Exmouth Gulf to its east. The study aims to identify taxonomic and spatial knowledge gaps and establish a baseline biodiversity record for the broader region. We collated specimen-based records from seven Australian museums and supplemented them with data from the Atlas of Living Australia, iNaturalist, and a Web of Science literature review. In total, we report 827 verified species of sessile benthic invertebrates in shallow waters (less than 30 m depth) across the Gascoyne and southern Pilbara regions from 4578 records. Ningaloo Reef exhibits the highest diversity, hosting 587 species, including 239 scleractinian corals and 124 sponges. Exmouth Gulf is home to a diverse and unique assemblage of at least 295 species, including 165 species of putative turbid water specialists or regionally restricted species which are not found at Ningaloo Reef or the Muiron Islands. Notably, all three sea pen species identified in this review are recorded exclusively from Exmouth Gulf. The Gulf also hosts a distinctive community of filter-feeding invertebrates, including 125 sponges, 27 tunicates, and 18 anemones that are not found in neighboring regions. The Muiron Islands, although under sampled, host 22 species of sponges, 14 octocorals, and 5 tunicates that have not so far been found at Ningaloo Reef or Exmouth Gulf, highlighting the uniqueness of the islands’ marine invertebrate fauna. The southern sector of Ningaloo Reef is under sampled, and there are gaps in the state faunal collections for many groups, including anemones, corallimorphs, zoanthids, cerianthids, and hydrozoans. Further targeted taxonomic research on existing museum collections is crucial, as only 18% of specimen records have been verified, and 41% of the verified records are only identified to morphospecies. This limits our understanding of regional diversity and distribution patterns but provides ample opportunity for further taxonomic study. Expanding monitoring programs to include Exmouth Gulf and the Muiron Islands, along with unique habitats such as the King Reef artificial reef, and conducting additional biodiversity, demographic, and ecosystem health research is essential to assess the cumulative impacts of climate change and other environmental stressors on the unique and culturally significant marine ecosystems of this region. Full article

Marine benthic organism detection (BOD) is essential for underwater robotics and seabed resource management but suffers from motion blur, perspective distortion, and background clutter in dynamic underwater environments. To address visual feature degradation and computational constraints, we, in this paper, introduce EMR-YOLO, a deep learning based multi-scale BOD method. To handle the diverse sizes and morphologies of benthic organisms, we propose an Efficient Detection Sparse Head (EDSHead), which combines a unified attention mechanism and dynamic sparse operators to enhance spatial modeling. For robust feature extraction under resource limitations, we design a lightweight Multi-Branch Fusion Downsampling (MBFDown) module that utilizes cross-stage feature fusion and multi-branch architecture to capture rich gradient information. Additionally, a Regional Two-Level Routing Attention (RTRA) mechanism is developed to mitigate background noise and sharpen focus on target regions. The experimental results demonstrate that EMR-YOLO achieves improvements of 2.33%, 1.50%, and 4.12% in AP, AP₅₀, and AP₇₅, respectively, outperforming state-of-the-art methods while maintaining efficiency. Full article

Benthic habitats are highly complex and diverse ecosystems that are increasingly threatened by human-induced stressors and the impacts of climate change. Therefore, accurate classification and mapping of these marine habitats are essential for effective monitoring and management. In recent years, Unmanned Aerial Vehicles (UAVs) have been increasingly used to expand the spatial coverage of surveys and to produce high-resolution imagery. These images can be processed using photogrammetry-based techniques to generate high-resolution digital elevation models (DEMs) and orthomosaics. In this study, we demonstrate that integrating descriptors extracted from pre-trained Convolutional Neural Networks (CNNs) with geomorphometric attributes derived from DEMs significantly enhances the accuracy of automatic benthic habitat classification. To assess this integration, we analyzed orthomosaics and DEMs generated from UAV imagery across three shallow reef zones along the Red Sea coast of Saudi Arabia. Furthermore, we tested various combinations of feature layers from pre-trained CNNs—including ResNet-50, VGG16, and AlexNet—together with several geomorphometric variables to evaluate classification accuracy. The results showed that features extracted from the ResNet-50 FC1000 layer, when combined with twelve geomorphometric attributes based on curvature, slope, the Topographic Ruggedness Index (TRI), and DEM-derived heights, achieved the highest overall accuracies. Moreover, training a Support Vector Machine (SVM) classifier using both pre-trained ResNet-50 features and geomorphometric variables led to an improvement in overall accuracy of up to 5%, compared to using ResNet-50 features alone. The proposed integration effectively improves the automation and accuracy of benthic habitat mapping processes. Full article

Cytochrome P450 monooxygenases (P450s) are one of the most widespread enzyme superfamilies in the biological world. In insects, P450 proteins play a crucial role in the synthesis of endogenous substances and the metabolism of xenobiotics. To date, extensive research has been conducted on P450 gene-mediated detoxification and metabolism across multiple insect species. While Chironomidae species—dominant benthic organisms inhabiting diverse ecological niches and playing critical ecological roles—remain largely uncharacterized in terms of P450 protein annotation, with the exception of a single study on Propsilocerus akamusi. In this study, we expanded the annotation scope by identifying the P450 protein genes in eight additional Chironomidae species. A total of 577 P450 protein genes were annotated across the eight species, which could be classified into the following four distinct clans: 50 belonging to the CYP2 clan, 258 to the CYP3 clan, 198 to the CYP4 clan, and 71 to the Mito clan. Phylogenetic analysis using Drosophila melanogaster as an outgroup revealed that the CYP2 clan and the Mito clan are highly conserved during evolution, while the CYP3 clan and the CYP4 clan have undergone significant expansion. Most P450 proteins in Chironomidae species exhibit clear orthologous relationships with their D. melanogaster counterparts. Our research contributes to a better understanding of the evolutionary processes and the physiological functions of P450 proteins in Chironomidae species and lays the foundation for elucidating the role of P450 in environmental adaptability among the Chironomidae species inhabiting diverse habitats. Full article

Amphidinols (AM) are a diverse group of bioactive polyketides produced by dinoflagellates of the genus Amphidinium, known for their hemolytic, antifungal, and cytotoxic activities. This work presents the assessment of AM profiles in a comprehensive number of strains, whose species boundaries were previously established through detailed taxonomic analysis. Using UHPLC-MS/MS, we characterized the spectrum of AM analogs in 54 Amphidinium strains isolated from diverse geographical locations. In addition, toxicity was assessed using brine shrimp assays, which revealed significant inter- and intraspecific variability. Despite the broad diversity in AM content, no clear correlation was observed between total AM levels and toxicity across all strains. Multivariate analysis grouped the strains into clusters distinguished by distinct AM profiles and toxicity levels, suggesting that AM production alone does not predict toxicity. Our findings highlight the complexity of Amphidinium bioactivity, emphasizing the influence of strain-specific factors and other bioactive compounds. This work highlights the importance of integrating chemical, genetic, and biological assessments to understand better the factors that govern toxicity in this genus, with implications for ecological studies and the monitoring of harmful dinoflagellates. Full article

Alpine streams are particularly vulnerable to climate change and in many parts of the world are poorly studied, which is true of western North America. We sampled the invertebrate communities and measured the physico-chemical parameters of nine small streams in a single alpine meadow. There was a wide variation in the physico-chemical variables in this single, small catchment. Three variables were selected based on their high loadings from principal component analysis, and these were slope, width and pH. There were relations between densities of some of the benthic organisms and the three main environmental gradients. We found large variation in densities (595 to 7340 individuals m⁻²) and diversity of benthic communities across a small gradient of physico-chemical variation in these nine streams in a single alpine meadow. High beta diversity (most > 0.8) between streams indicated substantial differences in community structure and diversity in a small area of about 1 km. These results suggest strong environmental filters on communities in these alpine stream systems and the potential for high regional biodiversity far beyond what individual streams support. Full article

Global climate changes have led to dramatic increases in drought durations in previously permanent streams, impacting the biodiversity and functioning of river ecosystems. However, the response of benthic diatom communities to hydrological intermittency remains poorly understood. In this study, we compared the taxonomic and functional compositions of the diatom communities between permanent and intermittent sections in two hilly stream systems in southwestern Hungary. Our results showed that both the taxonomic and functional compositions of diatom communities were significantly affected by changes in the hydrological regime, leading to a decline in species richness and diversity and functional richness in intermittent sections. Functional richness and dispersion decreased significantly with declining taxonomic richness, likely as a consequence of species loss driven by flow intermittency. Aquatic–subaerial diatoms with moderate oxygen requirements were indicative of intermittent sections, while large, occasionally aerophilic and oxybiontic diatoms characterized permanent sections. The relative abundance of low-profile diatoms increased in intermittent sections, indicating that the natural successional process of communities was disrupted due to streambed drying. Furthermore, intermittent sections were marked by elevated abundances of α-mesosaprobous and α-meso-polysaprobous diatoms, indicating a reduced self-purification capacity under intermittent-flow conditions. These findings provide detailed insight into the responses of diatom communities to drought and water scarcity in intermittent streams, which are becoming increasingly common in warm temperate regions. Full article

Twenty-nine sediment samples were collected from Hurghada Bay, a highly impacted coastal area along the Northern Red Sea of Egypt, to evaluate environmental quality and human-induced effects on benthic ostracods. As potential bioindicators, benthic ostracods are highly responsive to environmental disturbances, with pollution leading to reduced abundance, lower diversity, and increased opportunistic taxa. To investigate the link between ostracod assemblages and sediment contamination, we measured the concentrations of eight heavy metals (Cu, Cd, Zn, Pb, As, Cr, Ni, and Mn) using inductively coupled plasma–atomic emission spectrometry (ICP-AES). Multivariate statistical analyses identified three distinct ostracod assemblages distributed across three station groups with varying pollution levels. Group I, associated with offshore stations, exhibited low to moderate heavy metal (HM) concentrations and high ostracod abundance and was dominated by Moosella striata, Hiltermannicythere rubrimaris, Ruggieria danielopoli, Neonesidea schulzi, and Paranesidea fracticorallcola, where the water depth and sand content are the main controlling factors. In contrast, Group II, corresponding to stations with the highest HMs and total organic matter (TOM), was dominated by pollution-tolerant species Jugosocythereis borchersi, Cyprideis torosa, Alocopocythere reticulata, and, to a lesser extent, Ghardaglaia triebeli, with reduced ostracod density and diversity. Group III, characterized by stations influenced by the mud-controlling factor, had the lowest HMs and was dominated by pollution-sensitive species Xestoleberis rhomboidei, Paranesidea fortificata, and Loxocorniculum ghardaquensis. These findings highlight the ecological risks posed by HM pollution and emphasize the urgent need for pollution mitigation strategies and continued monitoring to preserve the Red Sea’s benthic biodiversity. Full article

The western Iberian marine Pliocene represents a key transitional zone between tropical and boreal molluscan faunas. Recent studies at the rediscovered fossil locality of Vale Farpado have yielded 34 bivalve species, distributed among 18 families. The most diverse families identified are Veneridae and Pectinidae. The assemblage is predominantly composed of suspension- and deposit-feeding taxa, with no evidence of carnivorous feeding strategies. Most taxa exhibit an infaunal life habitat. Initial colonising bivalve communities inhabited mobile, gravel-dominated substrates, where coarse clasts and disarticulated bioclasts provided stable microhabitats for epifaunal species. Over time, later assemblages became established, primarily on sandy substrates. Palaeoenvironmental indicators, including molluscs and foraminifera, suggest that these benthic communities occupied the infralittoral zone, at depths generally shallower than 30 metres, and the sea surface temperatures were broadly subtropical. However, periodic incursions of cooler, nutrient-rich waters driven by upwelling systems influenced local conditions, enhancing primary productivity and supporting a taxonomically rich and ecologically complex benthic ecosystem. The bivalve assemblages of Vale Farpado thus contribute valuable insights into the palaeoecology and biogeographical dynamics of the Pliocene North Atlantic, particularly in the context of sea surface temperature gradients and bivalve faunal interchange between temperate and tropical marine realms. Full article

Pharmaceuticals are increasingly being detected in coastal ecosystems globally, but contamination and bioaccumulation levels are understudied in temporarily closed estuaries. In these systems, limited freshwater inputs and periodic closure may predispose them to pharmaceutical accumulation. We quantified in situ water column pharmaceutical levels at five sites in a temporarily closed model urban estuary (Zandvlei Estuary) in Cape Town, South Africa, that has been heavily anthropogenically modified. The results indicate an almost 100-fold greater concentration of pharmaceuticals in the estuary relative to False Bay, into which the estuary discharges, with acetaminophen (max: 2.531 µg/L) and sulfamethoxazole (max: 0.138 µg/L) being the primary pollutants. Acetaminophen was potentially bioaccumulative, while nevirapine, carbamazepine and sulfamethoxazole were bioaccumulated (BAF > 5000 L/kg) by sandprawns (Kraussillichirus kraussi), which are key coastal endobenthic ecosystem engineers in southern Africa. The assimilative capacity of temporarily closed estuarine environments may be adversely impacted by wastewater discharges that contain diverse pharmaceuticals, based upon the high bioaccumulation detected in key benthic engineers. Full article

This study provides the first comprehensive characterization of benthic macrofaunal communities in the Loukkos estuary, highlighting their spatial and seasonal variability and the environmental factors shaping their structure. A total of 47 species were identified across 12 site–season combinations, dominated by molluscs (47%), polychaetes (23%), and crustaceans (21%). Species richness varied considerably along the estuarine gradient, ranging from fewer than five species in the upstream sector to up to 30 species downstream. Overall, higher diversity was observed in the downstream areas and during the dry season. Macrofaunal density also exhibited substantial variability, ranging from 95 ind.m⁻² to 14,852 ind.m⁻², with a mean density of 2535 ± 4058 ind.m⁻². Multivariate analyses identified four distinct benthic assemblages structured primarily by spatial factors (ANOSIM R = 0.86, p = 0.002), with negligible seasonal effect (R = −0.03, p = 0.6). Assemblages ranged from marine-influenced communities at the estuary mouth dominated by Cerastoderma edule, through rich and diverse seagrass-associated communities in the lower estuary dominated by Bittium reticulatum, and moderately enriched mid-estuary communities characterized by Scrobicularia plana and Hediste diversicolor, to species-poor upstream communities dominated by the tolerant species H. diversicolor. Canonical analysis showed that salinity and vegetation explain nearly 40% of the variation in benthic assemblages, highlighting the key role of Zostera seagrass beds as structuring habitats. Moreover, upstream anthropogenic pressures alter environmental conditions, reducing benthic diversity and favoring tolerant species. Full article