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Coastal areas are regions of active interaction between the sea and land and are highly sensitive to changes in heavy metal contamination caused by natural and anthropogenic activities. The contents of heavy metals in 80 surface sediments in the Qizhou Island sea area in the northeast of Hainan Island were determined to assess the contamination status, spatial distribution, sources, and ecological risks. The results indicate that the main factors influencing the distribution patterns and contents of heavy metals are hydrodynamic conditions and sources of materials. The accumulation of Cd and Pb in the sediments is attributed to the combined effects of natural sources and anthropogenic input. In addition to widespread anthropogenic influence, the enrichment of Cd in the southeastern outer shelf area of the study region may be controlled by biogenic carbonate rocks or enhanced input of near-source materials during the late Pleistocene low sea level period.

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Weakfish (Cynoscion regalis) is not federally managed but feeds on species of management and ecological interest. We examined the trophic ecology of weakfish in Chesapeake Bay and the coastal and offshore waters of the eastern United States. For these areas, we determined the dominant prey of weakfish; identified how much diet variation was explained by the factors: season, size class, and year; and quantified prey biomass removed by weakfish from 2007 to 2019. In general, diet composition was mostly dominated by Engraulidae, Osteichthyes (bony fishes), and Mysidacea, and significantly varied by season and size class in Chesapeake Bay and coastal waters, although this was less dramatic in Chesapeake Bay. The total amount of variance explained by the three factors was 23.1% (Chesapeake Bay) and 14.7% (coastal waters), with year not being a significant factor in explaining weakfish diet variation for these areas. Weakfish total prey biomass removal occurred primarily in coastal waters in the fall and small size class (annual mean: approximately 41,038 t; maximum: approximately 63,793 t). Highly opportunistic feeders, weakfish cannibalism also played an essential part of their diet. These results have implications for fisheries and ecosystem management of weakfish when considering ecological interactions in regulatory approaches, such as recruitment and cannibalism, competition with federally managed fishes, and the natural mortality of their prey.

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Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year-round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote and Synechococcus communities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote, Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. Unlike Synechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates than Synechococcus. This work both produces and demonstrates the necessity of taxon- and site-specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change.

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This study aimed to understand the reproductive biology and migrative behavior of the largehead hairtail Trichiurus lepturus in a tropical area, specifically off Pernambuco coast, northeastern Brazil. Commercial catches from fish corrals provided samples for analysis, including measurements, weight recording, and examination of gonads to determine its maturation stage. Reproductive analyses were performed, such as sex ratio, gonado-somatic index, and sizes at first maturity. There was a slightly higher proportion of females among the 141 largehead hairtail specimens analysed. No significant differences were observed in length distributions between males and females. However, during the winter, significant differences were observed in length distributions for grouped sexes. The species exhibited a seasonal migratory pattern, with a higher presence on the continental shelf during the winter. The study identified strategic allocation of energy in feeding activities and temporal spacing of reproductive cycles, as indicated by the sex ratio and abundance of individuals during different seasons. Fish corrals probably do not harm largehead hairtail population off the southwestern Atlantic tropical coast, with minimal capture of individuals below the size of first maturity. The insights of the study into reproductive and migration patterns contribute to future assessments and management strategies for this species and corral fisheries.

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Eolian dust and riverine discharge are identified as two key components of terrestrial input to the oceans. They supply micronutrients to the oceans and modify marine carbon biogeochemistry and global climate through dust-land-ocean interactions. However, it is challenging to accurately constrain regional terrestrial inputs in the past, with currently available models and geochemical proxies. The present study utilizes sedimentary wtCaCO3% records to estimate lithogenic fluxes. The depth-dependance of CaCO3 preservation in the Holocene and Last Glacial Maximum (LGM) sediments in two major basins of the tropical Northeast Atlantic Ocean is described using a carbonate dissolution model. Results show that during the LGM, reduced dust deposition and slight drops of fluvial input are found in the Canary Basin and Cape Verde margins, respectively. To supplement, carbonate deposition during the LGM indicates that the deep subtropical Northeast Atlantic is seized by more sluggish deep waters relative to today.

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The machairodontine felid Homotherium achieved a global geographic distribution throughout much of the Pleistocene. Accordingly, that large carnivore is important for understanding patterns of community composition. We report on a new record of Homotherium based on a fragmentary premaxilla-maxilla discovered on McFaddin Beach, Texas, along the Gulf of Mexico. Skeletal remains of extinct, Pleistocene vertebrates accumulate on McFaddin Beach. Those fossils appear to originate from submerged deposits on the continental shelf in the Gulf of Mexico, an area that was subaerially exposed in the Late Pleistocene during glacial intervals. Marine erosion and transport altered the externally visible morphology of the current specimen, obscuring and/or damaging taxonomically informative details of the preserved dentition. However, high-resolution X-ray computed tomography revealed diagnostic portions of the unerupted crown of an upper canine within its alveolus. The serrated edges of the canine combined with the position of the incisors demonstrate that the specimen from McFaddin Beach represents a species of Homotherium. That specimen is the latest in a larger sample of Homotherium in Texas that spans most of the Pliocene-Pleistocene. This is the first occurrence of Homotherium from the continental shelf of the Gulf Coast. That landscape may have formed a broad subtropical Gulf Coast corridor that facilitated the dispersal of Neotropical taxa along the coast between Texas and Florida. The associated fauna from McFaddin Beach contains Neotropical mammals common to southern Texas and Florida and indicates that Homotherium was a member of the fauna inhabiting the Gulf Coast corridor during the Late Pleistocene.

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The Western Indian Continental Shelf (WICS) experiences upwelling during the Southwest Monsoon (SWM), leading to deoxygenation and acidification of subsurface waters. The region has patchy growth of corals, e.g. in the Grande Island and Angria Bank. Measurements made during the late SWM of 2022 reveal that the shelf waters around the Grande Island were subject to varying environmental conditions, viz. lower temperature (21.3-26.1°C), oxygen (0-4.9 mL L-1) and pHT (7.506-7.927). Complete anoxia was associated with sulphide build-up to a maximum of 5.9 µmol L-1 at 17 m depth. An additional episodic condition (high temperature, low oxygen and pH) also occurred associated presumably with a plankton bloom in April 2017. Hence, unlike the offshore coral site Angria Bank, waters around the Grande Island experiences extreme changes in physico-chemical conditions (e.g. Ωarg ∼1.2-1.8 during October 2022) seasonally as reported here. The biogeochemical conditions are however not as intense (Ωarg = 0.6) as observed along the eastern boundary upwelling system of the Pacific Ocean.

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Rights and interests concerning the continental shelf beyond 200 nautical miles (extended continental shelf, ECS) are related to important aspects of a nation's marine utilization such as marine resource development, marine technological innovation, and the construction of marine ecological civilization. China is a country with a long coastline and has the right to delineate large areas of ECS according to the United Nations Convention on the Law of the Sea (UNCLOS). However, the process of confirming China's ECS rights under international law is particularly complicated owing to the complex maritime delineation disputes between China and its neighboring countries. From the perspective of international law, this study uses the method of historical analysis and case analysis to retrospectively explore the evolution of the international legal frameworks governing ECS and analyze its current characteristics and trends in practice. On this basis, the paper evaluates the major challenges of China's national practice in ECS delineation and puts forward suggested countermeasures for safeguarding its legitimate rights and interests related to ECS.

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Magnetic spherules originate from anthropogenic and natural sources and can be differentiated based on morphology and composition. Using magnetic measurement, diameter measurement, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) analysis of a 10 m sediment core in the mud area of the South Yellow Sea, we found that magnetic spherules occur at all observed depths of the core. The magnetic spherule concentrations vary from 10 spherules/0.5 g to 62 spherules/0.5 g. Here, concentrations generally less than 10 spherules/0.5 g are considered as the background value in the core. The peak value of magnetic spherules appeared at the 0.02, 0.3, 2 and 8 m, and their concentrations are 62, 52, 36, 48 spherules/0.5 g, respectively. According to the deposition age, concentration, diameter, morphology and chemical characteristics of the spherules, it is found that the spherules at 0.02 m are produced by industrial coal burning. A volcanic eruption event was the main responsible for the accumulation of spherules at 0.3 and 8 m, while the spherules located at 2 m are related to a wildfire event. Magnetic spherules are common in continental shelf regions and can well document the human activities and natural environment events.

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Inland and offshore sediments from Southern Italy were studied in order to evaluate the occurrence and nature of microplastics (MPs). Inland sediments were collected in the Bradano and Basento rivers (Apulo-Lucanian region, Southern Italy), while offshore sediments were collected on the continental shelf near Bari (Adriatic Sea) and Metaponto (Ionian Sea). MPs were detected and characterized using optical microscopy, micro-Fourier-Transform Infrared spectroscopy (µ-FTIR) and micro-Raman analyses. The number of MPs present varied between 144 and 1246 kg-1 of dry sediment (468.8 ± 410,7 MPs kg-1) with a predominance of black fibers; no correlation emerged between MPs and sediment grain size. In river sediments, the occurrence of MPs is associated with local pollution, whereas the offshore occurrence of MPs depends on seasonal river flow and submarine canyons. Compositional analyses suggest that the main source of MPs in the studied sediments is sewage discharge from residential areas.

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Background: This dataset contributes to the knowledge of macro- and megafaunal Mollusca associated with a range of benthic habitat types in the South Orkney Islands, Antarctica, an exceptionally diverse region of the Southern Ocean. The information presented is derived from Agassiz trawl samples collected on the archipelago's shelf plateau and slope, within and outside of the South Orkney Islands Southern Shelf Marine Protected Area (SOISS MPA). Sampling was conducted in the framework of the British Antarctic Survey/SCAR "South Orkneys - State of the Antarctic Ecosystem" (SO-AntEco) project aboard RRS James Clark Ross during expedition JR15005 in Austral summer 2016. This dataset is published by the British Antarctic Survey under the licence CC-BY 4.0. We would appreciate it if you could follow the guidelines from the SCAR Data Policy (SCAR 2023) when using the data. If you have any questions regarding this dataset, do not hesitate to contact us via the contact information provided in the metadata or via data-biodiversity-aq@naturalsciences.be. Issues with the dataset can be reported at https://github.com/biodiversity-aq/data-publication/. This dataset is part of the Biodiversity, Evolution and Adaptation Project of the Environmental Change and Evolution Program of the British Antarctic Survey. The cruise report of the expedition is available at https://www.bodc.ac.uk/resources/inventories/cruise_inventory/reports/jr15005.pdf. New information: We report occurrences of Mollusca from individual samples taken with a 2 m-wide Agassiz trawl (AGT) in the framework of the February - March 2016 research expedition JR15005 of RRS James Clark Ross to the SOISS MPA and adjacent shelf and slope areas. Of 78 successful AGT deployments, 44 trawls at depths ranging from 235-2194 m yielded living Mollusca, totalling 2276 individuals, 67 morphospecies and 163 distributional records. One hundred and fifteen empty shells were also collected and recorded in the dataset. Three morphospecies (one Bivalvia and two Gastropoda) were sampled exclusively as empty shells, yielding a total of 70 morphospecies and 2391 specimens represented in the dataset. All specimens were preserved in 96% undenatured ethanol and are stored as vouchers in the collections of the British Antarctic Survey (BAS), Cambridge, United Kingdom. The publication of this dataset aims at increasing the knowledge on the biodiversity, abundance and geographical and bathymetric distribution of larger-sized epi- and shallow infaunal Mollusca of the South Orkney Islands.

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This study examines the simultaneous water-atmosphere exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) on the continental shelf of the Gulf of Cadiz, as well as the effect it has in terms of the radiative balance in the atmosphere, between 2014 and 2016. The experimental database consists of new measurements of the spatial and seasonal distribution of CO2 partial pressure (pCO2) and N2O concentration in 2016. pCO2 shows a wide range of variation influenced mainly by seasonal thermal variations (8.0 µatm 0C-1), as well as with the relative intensity of biological activity. There is experimental evidence of a progressive increase of pCO2 over the last 2 decades, with an estimated gradient of 4.2 ± 0.7 µatm y-1. During 2016, the Gulf of Cadiz acted as a slight source of CO2 to the atmosphere, with a mean flux of 0.4 ± 2.2 mmol m-2 d-1. The analysis of concentration variations in the water column shows that nitrification is the main N2O production process in the study area, although in the more coastal zone there are signs of inputs related to continental and sediment contributions, most probably induced by denitrification processes. In 2016, the Gulf of Cadiz acted as a weak sink of atmospheric N2O, with a mean flux of -0.1 ± 0.9 µmol m-2 d-1. From previous studies, performed with a similar methodology, an interannual database (2014-2016) of water-atmosphere fluxes of CO2, CH4 and N2O, normalized to the mean wind speed in the area, has been generated. Considering their respective Global Warming Potential (GWP) a joint greenhouse gasses (GHG) flux, expressed in CO2 equivalents of 0.6 ± 2.0 mmol m-2 d-1, has been estimated, which extended to the area of study indicates an approximate emission of 67.9 Gg CO2 y-1. However, although there is a high uncertainty associated with the spatial, temporal and interannual variations of CO2, CH4 and N2O fluxes in the Gulf of Cadiz, the exchange of greenhouse gasses could be influencing a radiative forcing increase in the atmosphere. When considering the available information on local and global estimates, the uncertainty about the effect of the joint exchange of GHGs to the atmosphere from the coastal seas increases significantly.

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The range of the butterfly genus Pseudocoladenia includes several biodiversity hotspots, such as the Himalayas, mountains of southwestern China, and Sundaland. However, the taxonomic status of some of its species/subspecies remain controversial, and no previous phylogenetic or biogeographic analyses have been conducted. Herein, we determined the systematic relationships and biogeographic history of this genus by reconstructing its phylogeny based on six genes and 69 specimens as representatives of all known species/subspecies. Two species delimitation methods (Bayes Poisson Tree Processes and Bayesian Phylogenetics and Phylogeography) were also employed to assess the status of each taxon. Based on these results and morphological evidence, we identified 12 species and three subspecies in the genus and subsequently classified these into three species groups: P. fatih, P. dea, and P. dan. Five taxa, P. sadakoe (Sonan and Mitono, 1936) stat. nov., P. celebica (Fruhstorfer, 1909) stat. nov., P. fulvescens (Elwes and Edwarda, 1897) stat. nov., P. eacus (Latreille, 1823) stat. nov., and P. fabia (Evans, 1949) stat. nov. were all recognized as independent species. Additionally, two taxa, P. eacus sumatrana (Fruhstorfer, 1909) comb. nov. and P. eacus dhyana (Fruhstorfer, 1909) comb. nov., were placed under P. eacus (Latreille, 1823) stat. nov. as subspecies. Another new species distributed in N. Yunnan, Pseudocoladenia yunnana Fan, Cao & Hou sp. nov., was discovered and described. Divergence time and ancestral range estimation indicated that the most recent common ancestor of Pseudocoladenia was distributed in the Himalayas-Hengduan Mountain region and Indochina and diverged approximately 14.00 Ma. Continuous and episodic dispersal, vicariance, and extinction were used to determine the current geographic distribution of the genus. The P. fatih group had a prominently disjunct distribution between the Himalaya-Hengduan Mountain and Taiwan. Meanwhile, the P. dan group was first derived in Indochina and subsequently dispersed into the southeastern Asian archipelagoes. This study provides a reference for the evolutionary route of transoceanic distributed species in Asia and elaborates on the causes of biodiversity.

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The Indian Ocean (IO) continental shelf characterized by unique oceanographic and meteorological features and extreme habitat is a biodiversity hotspot region. Marine biodiversity provides valuable resources and services, in terms of economy, cultural, science, and education. Unsustainable exploitation and habitat degradation represent the greatest threat to biodiversity. Understanding how these services will change in the future requires knowledge of marine biodiversity. Although macrofaunal biodiversity is critical for the functioning of shelf systems, it has received much less attention, particularly in the IO, mainly due to logistics reasons precluding our ability to predict future changes. Here, we discuss the state of knowledge of macrofaunal ecology, to identify the knowledge gaps, which will allow for setting research priorities. The new framework in research synthesis, research weaving, that combines systematic mapping with bibliometric analysis was applied. The research weaving approach helps illustrate the evolution of research over time and identifies areas of current research interests and the performance of institutions and collaboration patterns. Data retrieved from the Web of Science were analyzed in the R and VOS Viewer software. The results highlight how macrofaunal research in IO is constrained by spatial and temporal scales, with the majority of studies focused on structural patterns. Moreover, most studies were conducted in a few countries (India, Australia, Saudi Arabia, Iran, and South Africa) using different sampling techniques hindering comparison within the IO habitats. Future studies investigating the macrofaunal community using a multidisciplinary approach and scientific collaboration (regional and international) can advance our efforts to close the marine biodiversity knowledge gaps.

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Microplastics are ubiquitous emerging contaminants found in every habitat surveyed, building upon international databases globally. Costs and accessibility often correlate to few deep sea sediment surveys, restricting the number of stations within a given sampling area. An extensive survey of the Porcupine Seabight, Porcupine Bank, the Goban Spur, and south-western canyons resulted in identifying microplastics in deep sea sediment surface layers from 33 of the 44 stations sampled (75%), with a total of 83 particles (74 synthetic and 9 natural) recorded. No microplastic hotspots were identified, and abundances (kg d.w.-1) were not correlated with distance from land, depth, or the presence of macrolitter on the seafloor. Understanding the sources of deep sea microplastics, such as marine traffic, is crucial to developing effective mitigation strategies as well as further monitoring campaigns targeting microplastic pollution in areas with significant deep sea biodiversity such as the Porcupine Seabright.

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Ice shelves cover ~1.6 million km2 of the Antarctic continental shelf and are sensitive indicators of climate change. With ice-shelf retreat, aphotic marine environments transform into new open-water spaces of photo-induced primary production and associated organic matter export to the benthos. Predicting how Antarctic seafloor assemblages may develop following ice-shelf loss requires knowledge of assemblages bordering the ice-shelf margins, which are relatively undocumented. This study investigated seafloor assemblages, by taxa and functional groups, in a coastal polynya adjacent to the Larsen C Ice Shelf front, western Weddell Sea. The study area is rarely accessed, at the frontline of climate change, and located within a CCAMLR-proposed international marine protected area. Four sites, ~1 to 16 km from the ice-shelf front, were explored for megabenthic assemblages, and potential environmental drivers of assemblage structures were assessed. Faunal density increased with distance from the ice shelf, with epifaunal deposit-feeders a surrogate for overall density trends. Faunal richness did not exhibit a significant pattern with distance from the ice shelf and was most variable at sites closest to the ice-shelf front. Faunal assemblages significantly differed in composition among sites, and those nearest to the ice shelf were the most dissimilar; however, ice-shelf proximity did not emerge as a significant driver of assemblage structure. Overall, the study found a biologically-diverse and complex seafloor environment close to an ice-shelf front and provides ecological baselines for monitoring benthic ecosystem responses to environmental change, supporting marine management.

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Soft corals (Anthozoa: Octocorallia) are discreet components in the Southwestern Atlantic reef communities. In Brazil, the native octocoral shallow-reef fauna is mostly represented by gorgonians. Consequently, except for the nephtheid Neospongodes atlantica, most of the known soft corals from this region are considered non-indigenous. Hitherto, the monotypic genus Neospongodes, which was proposed in the early 1900s, has been considered to be endemic to the Northeastern Brazilian coast. Herein, based on in situ records, we show that N. atlantica is a substrate generalist that has been probably expanding its distribution by dominating extensive shallow and mesophotic sandy and reef bottoms, generally outcompeting other reef benthic organisms, including Brazilian endemic species. Based on previously unidentified museum specimens, new records, and a broad literature review, we provide the most comprehensive modelling of the potential distribution of this species in the Southwestern Atlantic. Based on molecular inference supported by in-depth morphological analysis, the probable non-indigenous and, therefore, ancient introduction of N. atlantica in Brazilian waters is discussed. Finally, these results support that Neospongodes and the Indo-Pacific Stereonephthya are synonyms, which led us to propose the latter as taxonomically invalid.

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As a consequence of anthropogenic climate change, marine species on continental shelves around the world are rapidly shifting deeper and poleward. However, whether these shifts deeper and poleward will allow species to access more, less, or equivalent amounts of continental shelf area and associated critical habitats remains unclear. By examining the proportion of seabed area at a range of depths for each large marine ecosystem (LME), we found that shelf area declined monotonically for 19% of LMEs examined. However, the majority exhibited a greater proportion of shelf area in mid-depths or across several depth ranges. By comparing continental shelf area across 2° latitudinal bands, we found that all coastlines exhibit multiple instances of shelf area expansion and contraction, which have the potential to promote or restrict poleward movement of marine species. Along most coastlines, overall shelf habitat increases or exhibits no significant change moving towards the poles. The exception is the Southern West Pacific, which experiences an overall loss of area with increasing latitude. Changes in continental shelf area availability across latitudes and depths are likely to affect the number of species local ecosystems can support. These geometric analyses help identify regions of conservation priority and ecological communities most likely to face attrition or expansion due to variations in available area.

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Concentrations of 13 phase-partitioned polycyclic aromatic hydrocarbons (PAHs) in seawater were monitored monthly off Oki Island, Japan, during 2015-2019 to elucidate seasonal variations, main source, and transport pathways of PAHs in the southwestern Sea of Japan. Total PAH (dissolved plus particulate) concentrations in surface seawater at 36°09.0'N, 133°17.3'E (site OK) were in the range 0.49-9.36 ng L-1 (mean 2.77, SD 2.05 ng L-1) with higher levels in summer-autumn, an order of magnitude lower than those in the East China Sea during 2005 and 2009-2011 and about one-third of those recorded in the Sea of Japan in 2008 and 2010. The main sources of dissolved and particulate PAHs were combustion products. Increasing dissolved PAH levels during July-October indicate that the area around southern Oki Island is impacted by PAH-rich summer continental-shelf water transported by the Tsushima Warm Current flowing from the East China Sea.

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We aimed to describe how debris originated from coastal cities and fisheries circulates and accumulates along the Argentine continental shelf and its potential interaction with southern giant petrels (SGP, Macronectes giganteus). We used tracking data of 31 SGPs (adults and juveniles) from Patagonian colonies. Lagrangian simulations of particles were released from coastal cities and fisheries. Oceanographic features together with plastic input generated a corridor of debris through the Argentine shelf with areas of high debris accumulation, exposing SGP to plastic consumption. During chick provisioning trips 93.9% of petrel's locations overlapped with areas of plastic accumulation. Although early developmental stages were more exposed to particles from cities, the exposure of petrels (all classes) to debris from fisheries was 10% higher than from cities. Measures to reduce debris from fisheries, would reduce plastic ingestion by giant petrels. Proper management of open sky dumpsters would reduce plastic consumption by chicks and juveniles.

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