This study deals with the toxicity assessment of crude and bunker oils representative of prospective oil spill threats in Arctic and Sub-Arctic seas (NNA: Naphthenic North-Atlantic crude oil; MGO: Marine Gas Oil; IFO: Intermediate Fuel Oil 180), alone or in combination with a third-generation dispersant (Finasol OSR52®). Early life stages of sea urchin, Paracentrotus lividus, were selected for toxicity testing of oil low-energy water accommodated fractions. A multi-index approach, including larval size increase and malformation, and developmental disruption as endpoints, was sensitive to discriminate from slight to severe toxicity caused by the tested aqueous fractions. IFO (heavy bunker oil) was more toxic than NNA (light crude oil), with MGO (light bunker oil) in between. The dispersant was toxic and further on it enhanced oil toxicity. Toxic units revealed that identified PAHs were not the main cause for toxicity, most likely exerted by individual or combined toxic action of non-measured compounds.

The remote Gulf of Carpentaria (GoC) represents 10% of Australia's coastline. This large, shallow sea supports high-value fishing activities and habitat for threatened species, and is a sink for abandoned, lost and discarded fishing gear (ALDFG) ‘ghost nets’, most originating from fishing activities outside of Australia's Exclusive Economic Zone. With growing concerns about the plastic waste along the world's coastlines, we retrospectively analyzed ghost net sighting information from four aerial surveys across 15 years, to investigate whether densities of ghost nets are changing through time or in space. We found an increase in ghost nets, despite more than a decade of illegal fishing countermeasure and clean-up efforts in the broader region. This demonstrates that the input of ALDFG into the system currently overwhelms the substantial net removal activities. We make recommendations for improving monitoring and consider the underlying drivers of nets being lost to improve ghost gear management on land and at sea.

Ciliates comprise essential components of microzooplankton in diverse marine environments. However, the extent to which environmental variables shape the distribution of planktonic ciliates in complex estuarine systems remains unclear. Here, 52 samples were collected from the Pearl River Estuary, China to reveal the influence of environmental variables on planktonic ciliate communities. Distinct community compositions of ciliates were found in three identified water masses: Pearl River diluted water mass, South China Sea surface water mass, and South China Sea bottom water mass. Significant differences in abundance, biomass, cell size, and oral diameter structure of ciliates were also detected among the three water masses. The partial Mantel test showed that water mass (as represented by water temperature and salinity) surpassed other environmental variables to be the primary factor driving the dynamics of the ciliate community. This study revealed the controlling mechanisms of planktonic ciliate communities in a subtropical, hydrographically complex estuarine ecosystem.

Seabird colonies exert a strong influence on coastal ecosystems, increasing soil nitrogen bioavailability and modifying plant communities. Previous studies have evidenced that increased N in soils leads to changes in plant cell wall composition; however, this effect has not been assessed in seabird colonies. The main objective of this study was to determine the influence of seabird colonies on nitrogen, cellulose and lignin content in cell walls. For this purpose, analyses were performed on droppings, soils and three native plant species (Armeria pubigera, Armeria pungens and Corema album) growing in yellow-legged gull colonies. The results showed that N excreted by yellow-legged gull is assimilated by plants, increases N content in plant tissues and reduces cellulose and lignin synthesis, therefore potentially altering plant resistance against phytoparasites.

A comprehensive radiological survey using multivariate statistical analysis was carried out to evaluate the distribution of ⁴⁰K, ²³²Th, ²²⁶Ra, ²³⁵U, and ¹³⁷Cs, and associated radiation indices in beach sand samples of the coastal area of the Aegean Sea. The activity concentration of selected radionuclides was measured and no clue of recent migration of radiocaesium by not only precipitation but also through an indirect way, such as ocean runoff, was found. As part of radiological risk assessment, external radiation hazard index, radium equivalent activity, effective dose, and absorbed dose rate were estimated. Pearson correlation, cluster, and PCA analysis were used by processing observed radiological parameters to determine the correlation between the radiological parameters and locations. Pearson correlation shows a strong association between all parameters and activity of ²²⁶Ra and ²³²Th. A spatial distribution map was provided to a distinct visual representation of the distribution of radionuclide contents in the study area.

This research was aimed at evaluating the seasonal partitioning of Zn, Se, As, Cu, and Co in the tissues of Mytilus galloprovincialis sampled at two industrial sites along the Algerian coast.Adult mussels were seasonally collected from two sites over the course of a whole year. The gills, digestive glands, gonads, and remaining soft tissues were analyzed through ICP-MS.The observations led to identifying metals ranges (μg g⁻¹Dᵣy Wₑᵢgₕₜ) of 67.17–395.51 (Zn), 2.18–12.74 (Se), 7.81–28.61 (As), 3.32–155.91 (Cu), and 0.10–3.59 (Co) in the various tissues.The highest concentrations were found in the digestive glands and gills as compared to the gonads and remaining soft tissues. Distinct patterns of metals partitioning were found: indeed, As and Co concentrations were higher in the digestive glands, while Se and Zn concentrations were higher in the gills. Many of the mussels samples resulted contaminated, therefore potentially posing a considerable health risk to consumers.

This study aimed to develop a first diagnostic of marine litter presence over four sandy beaches located on the southern coast of Sergipe, a Brazilian state, by means of four samplings, from December 2017 to September 2018. There was no distinction between village, semi-rural, and rural areas regarding litter presence. Plastic was the most abundant litter (> 70%), mainly represented by the items such as food packaging, cups, straws, cigarette butts, lids/seals, as well as fragments and monofilaments. The abundance of items collected ranged from 0.1 and 9.2 items.m⁻¹, and the beaches were characterized from very clean to dirty. The main sources were from tourism/recreation (42.7 ± 4.8%), followed by Unidentified (34.1 ± 6.7%), and Fishing/Marine activities (16.1 ± 6.3%). In addition, we highlight the importance of the correct litter management, environmental education activities, and marine litter monitoring program in order to reduce marine litter contamination.

Good water quality is essential to the health of marine ecosystems, yet current metrics used to track water quality in the Great Barrier Reef are not strongly tied to ecological outcomes. There is a need for a better water quality index (WQI). Benthic irradiance, the amount of light reaching the seafloor, is critical for coral and seagrass health and is strongly affected by water quality. It therefore represents a strong candidate for use as a water quality indicator. Here, we introduce a new index based on remote sensing benthic light (bPAR) from ocean color. Resulting bPAR index timeseries, based on the extent to which the observed bPAR fell short of the locally- and seasonally-specific optimum, showed strong spatial and temporal variability, which was consistent with the dynamics that govern changes in water clarity in the Great Barrier Reef. Our new index is ecologically relevant, responsive to changes in light availability and provides a robust metric that may complement current Great Barrier Reef water quality metrics.

Moín, on the Caribbean coast of Costa Rica, is a multi-use coastal zone with a variety of human activities that can cause metal pollution. With the purpose of assessing the current environmental burden due to heavy metal presence in the marine environment of Moín, and their bioaccumulation in organisms of the nearby coral reef, we determined seven metals in samples of bottom sediments, macroalgae (Cryptonemia crenulata) and sponge (Cinachyrella kuekenthali). The results were compared with samples from the southern Caribbean, an area with little human activity. Using ICP-MS, results showed a concentration range for sediments Mn > Cu > Zn > Cr > Ni > Pb > Cd, algae Mn > Cu > Zn > Ni > Cr > Pb > Cd and sponge Mn > Cu > Zn > Ni > Cr > Cd > Pb, relatively low concentrations overall and no differences observed between sites. Bioconcentration factor > 1 was determined for Cd, Cu, Ni and Zn, while concentrations in sediments were below the SQG thresholds. Our study provides the first data on metal concentrations in a macroalgae and a sponge from the Costa Rican Caribbean.

We use a multi-tracer approach to identify catchment sources of nitrogen (N) in the skeletons of nearshore Porites corals within the Great Barrier Reef. We measured δ¹⁵N, δ¹³C and C:N ratios of particulate organic matter (POM) sampled from the Pioneer River catchment and identified five distinct end-members: (1) marine planktonic and algal-dominated matter with higher δ¹⁵N values from the river mouth and coastal waters; (2) estuarine planktonic and algal matter with lower δ¹⁵N values associated with estuarine mixing; (3) lower river freshwater phytoplankton and algal-dominated matter in stratified reservoirs adjacent to catchment weirs, with the ¹⁵N-enriched source likely caused by microbial remineralization and denitrification; (4) upper river low δ¹⁵N terrigenous soil matter eroded from cane fields bordering waterways; and (5) terrestrial plant detrital matter in forest streams, representing a low δ¹⁵N fixed atmospheric nitrogen source. The δ¹⁵N values of adjacent, nearshore Porites coral skeletons is reflective of POM composition in coastal waters, with ¹⁵N-enriched values reflective of transformed N during flood pulses from the Pioneer River.