The remote and uninhabited Northwestern Hawaiian Islands (NWHI) contain 70% of the shallow water coral reefs in the United States and are regularly exposed to derelict fishing nets. These nets snag on the shallow reefs, damaging or killing benthic communities. However, no data exist to quantify this impact. Here we use a novel application of photogrammetry, Structure-from-Motion (SfM), to calculate benthic cover from mosaic images at net-impact and control sites. Net-impact sites had significantly higher cover of bare substrate, sand, and crustose coralline algae and significantly lower coral and macroalgae cover compared to control sites. These differences were unrelated to net size and fouling. Our study demonstrates the utility of using SfM to efficiently quantify impacts of derelict fishing nets. Revisiting these sites will be essential to document how the reef recovers to further our understanding of the lasting impacts of derelict fishing nets on coral reef habitats.

This study investigates the presence of microplastics in surface seawater and zooplankton at five different locations off the Terengganu coast in Malaysia, southern South China Sea. A total of 983 microplastic particles, with an average abundance of 3.3 particles L⁻¹ were found in surface seawater. An average of one plastic particle was detected in 130 individuals from 6 groups of zooplankton. These groups include fish larvae, cyclopoid, shrimps, polychaete, calanoid and chaetognath where they ingested 0.14, 0.13, 0.01, 0.007, 0.005 and 0.003 particle per individual, respectively. Microplastics in the form of fragments are the most common type of ingested microplastics that ranged between 0.02 mm (cyclopoid) – 1.68 mm (shrimp and zoea). Contrastingly, fibers, which are identified as polyamide are the main type of microplastics that dominate in seawater.

Most monitoring studies of marine anthropogenic debris have focused on sandy beaches, so little is known about litter on rocky shorelines. We surveyed litter trapped on a rocky intertidal shore in False Bay, South Africa, between May 2015 and March 2018. An exceptional upwelling of seabed litter occurred in November 2017 (70 items∙m⁻¹). Excluding this event, monthly clean-ups at spring low tide collected 2 (1.3–3.1) items∙m⁻¹∙month⁻¹ and 31 (19.4–49.4) g∙m⁻¹∙month⁻¹ of which 74% was plastic (31% by mass). Litter loads peaked in autumn when seasonal rains washed litter into False Bay, suggesting that most litter comes from local land-based sources. Litter composition differed from that on a nearby sandy beach, with more glass and other dense items on the rocky shore, but 60% of plastic items floated in water. Sand inundation and biotic interactions helped to trap buoyant plastics in the intertidal zone.

We examined the relative importance of spatial processes (dispersal-related) and environmental processes (environmental selection-related) in community structure for macrobenthos (including juveniles and adults) and meroplanktonic larvae in the subtidal areas of Daya Bay, China. We found that both macrobenthos and meroplanktonic larvae showed similar spatial patterns, both following the distance-decay relationship. The results of variation partitioning analysis (VPA) showed the roles of both spatial and environmental factors in governing the assembly of both communities, although both explained only a small (slightly larger for spatial factor) fraction of the community variation. We also found that macrobenthos were more affected by spatial processes than meroplanktonic larvae. In addition, we highlight that the mechanisms determining community structure change according to the spatial extent considered.

Dokdo's high marine biodiversity has received worldwide attention recently. A total of 578 macrozoobenthos are recorded since the 1960s, but ecology of Dokdo's fauna is unknown. We monitored Dokdo's subtidal macrozoobenthos for 5 years in 2013–17, in the present study. Five stations representing three subtidal habitats were monitored; 1) oceanic plateau, 2) coastal terrace, and 3) island wharf. In total, 13,664 individuals belonging to 141 taxa were recorded during the survey. The number of species and density varied greatly among stations without distinct year-round variation. Faunal compositions significantly differed in time and space, reflecting varied faunal adaptations in a harsh environment. Whilst, temporal stability in faunal assemblages was evidenced for some dominant or cosmopolitan taxa. High spatial heterogeneity reflects site-specific oceanographic conditions. Meantime, sea-surface temperature and wave action were associated with year-round faunal compositions. Overall, the Dokdo's macrozoobenthos significantly contribute to marine biodiversity of the East Sea.

Heavy metals (HMs) in aquaculture-influenced sediments pose a threat to both aquatic ecosystems and human health via aquatic product intake. Based on a long-term (from 2011 to 2018) study, the concentrations of five HMs in oyster-cultured sediments in the Maowei Estuary, China, were ranked as follows: Pb (17.58 ± 10.82 mg/kg) > Cu (17.15 ± 8.61 mg/kg) > As (10.27 ± 5.24 mg/kg) > Cd (0.16 ± 0.14 mg/kg) > Hg (0.067 ± 0.033 mg/kg). These concentrations were all close to the guide values in China and those reported in other studies. However, through the Mann-Kendall test, Cu showed obvious increasing interannual trends, and according to ecological risk assessment, the sediments were highly contaminated with Cu and Hg. The health risks to local residents via oyster intake showed that both noncarcinogenic and carcinogenic risk did not exceed the safety criteria (THQ = 1, TCR = 10⁻⁶). The current study suggests that ecological and human health risks be integrated to control HMs in the Maowei Estuary.

Sediment cores from Staten Island's salt marsh contain multiple historical oil spill events that impact ecological health. Microtox solid phase bioassay indicated moderate to high toxicity. Multiple spikes of TPH (6524 to 9586 mg/kg) and Σ16 PAH (15.5 to 18.9 mg/kg) were co-incident with known oil spills. A high TPH background of 400–700 mg/kg was attributed to diffuse sources. Depth-profiled metals Cu (1243 mg/kg), Zn (1814 mg/kg), Pb (1140 mg/kg), Ni (109 mg/kg), Hg (7 mg/kg), Cd 15 (mg/kg) exceeded sediment quality guidelines confirming adverse biological effects. Changes in Pb²⁰⁶/²⁰⁷ suggested three metal contaminant sources and diatom assemblages responded to two contamination events. Organic and metal contamination in Saw Mill Creek Marsh may harm sensitive biota, we recommend caution in the management of the 20–50 cm sediment interval because disturbance could lead to remobilisation of pre-existing legacy contamination into the waterway.

Due to strong regulation of phthalates, non-phthalate plasticizers (NPPs) have been introduced to the industrial market. In this study, concentrations of 16 phthalates and five NPPs in sediment were measured to investigate the occurrence, potential source, and ecotoxicological implications of these contaminants. Phthalates and NPPs were detected in all sediment samples, indicating ubiquitous contaminants. Di(2-ethylhexyl)phthalate (DEHP) and trioctyl trimellitate (TOTM) were the dominant for phthalates and NPPs, respectively, implying emerging contamination by TOTM. Spatial distribution of these contaminants showed decreasing gradients from inner to outer bays. Clear declining trends in phthalate and NPP concentrations were found in sediment near a wastewater treatment plant outfall, suggesting a potential source of contamination. Approximately 95% of sediment samples exceeded sediment quality guidelines for DEHP suggested by previous studies, implying that benthic organisms are suffering from adverse biological effects. This is the first report on the occurrence of NPPs in the coastal environment.

In this study, the concentrations of 28 polychlorinated biphenyl (PCB) congeners, including 12 dioxin-like PCBs and 7 indicator PCBs, were determined in sediments around oil production facilities in the Escravos River Basin of the Niger Delta in Nigeria. The aim was to describe the spatial patterns, sources, and ecosystem risks associated with exposure to PCBs in sediments of this river basin. Gas chromatography-mass spectrometry (GC–MS) was used to determine the concentrations of PCBs in the sediments. The Ʃ28 PCB concentrations in sediments from the Escravos River Basin ranged between 226 and 31,900 ng g⁻¹ with a median concentration of 2300 ng g⁻¹. The results indicated that sediments around crude oil production facilities, such as, wellheads, flow stations, and truck lines, had significantly higher levels of Ʃ28 PCBs (p < 0.05) than those collected near residential communities within the river basin. The median concentrations of PCB homologues in sediments from this river basin followed the sequence: hexaPCBs > penta-PCBs > tetra-PCBs > hepta-PCBs > tri-PCBs > di-PCBs > deca-PCBs > octa-PCBs > nona-PCBs. The risk assessment of PCBs in sediments from this river basin suggest very high potential risks for both organisms and humans.

This note reports data about a heterogeneous assemblage of anthropogenic litter recorded in 307 nesting and roosting sites of Yellow-legged Gull (Larus michahellis) from a small Mediterranean island. I obtained items of anthropogenic litter on > 30% on the total, with plastic, glass and paper the significantly more abundant litter categories. Litter items were found in the nests mainly as a dry remnant in the regurgitated pellets. Fragments of expanded polystyrene (EPS) with peck marks were also recorded, these last transported to the nests because of their resemblance to the cuttlebones of the Sepia cuttlefish. Ingestion of this litter and the pecking on EPS can negatively impact on seabirds. Moreover, the presence of this litter highlights a transport of polluting material even at considerable distance from anthropized areas. Finally, the presence of scavenger species (an endemic lizard and terrestrial molluscs) feeding on food remains could suggest an assimilation of litter into the trophic webs.