The present study evaluates an optical bioassay based on green photosynthetic microalgae as a promising alternative for monitoring of relevant seawater pollutants. Photosystem II fluorescence parameters from several microalgae species were examined in the presence of three common marine pesticides that act as photosynthesis inhibitors. The three pollutants were detected within 10 min in concentrations between ng/L-μg/L. The different algae species showed slightly diverse pesticide sensitivities, being Chlorella mirabilis the most sensitive one. Potential interferences due to oil-spill pollutants were discarded. The lipid content was characterized to identify microorganisms with suitable mechanisms that could facilitate stress acclimatization. C. mirabilis presented elevated content of unsaturated lipids, showing a promising potential for biosensing in saline stress conditions.The optimized microalgae-based bioassay was preliminarily incorporated into a marine buoy for autonomous pre-screening of pesticides in coastal areas, demonstrating its suitability for real-time monitoring of marine water and quantitative evaluation of total biotoxicity.

The increasing global contamination of plastics in marine environments is raising public concerns about the potential hazards of microplastics to environmental and human health. Microplastics formed by the breakdown of larger plastics are typically irregular in shape. The objective of this study was to compare the effects of spherical or irregular shapes of microplastics on changes in organ distribution, swimming behaviors, gene expression, and enzyme activities in sheepshead minnow (Cyprinodon variegatus). Both types of microplastics accumulated in the digestive system, causing intestinal distention. However, when compared to spherical microplastics, irregular microplastics decreased swimming behavior (i.e., total distance travelled and maximum velocity) of sheepshead minnow. Both microplastics generated cellular reactive oxygen species (ROS), while ROS-related molecular changes (i.e., transcriptional and enzymatic characteristics) differed. This study provides toxicological insights into the impacts of environmentally relevant (fragmented) microplastics on fish and improves our understanding of the environmental effects of microplastics in the ecosystem.

Use of nanotechnology-based products is growing at large scale globally; consequently, releasing nanoparticles are entering into aquatic ecosystems. The higher surface area versus volume ratio in comparison with bulk materials makes the nanoparticles biologically more reactive. Therefore, investigating the potential aquatic toxicity of nanoparticles has become an important issue. Algae are an ideal group to study responses of different engineered nanoparticles. Present review aims to analyse the nanoecotoxicological impact of engineered metal oxide nanoparticles on algal physiology. Impacts of nanoparticles of titanium dioxide, zinc oxide, copper oxide, silica oxides, cerium oxides, iron oxide, aluminium oxide and nickel oxide are covered in details. Different factors like size, shape, pH, dose, exposure time, photo-catalytic activity, etc. that affect the toxicity of nanoparticles to test organisms are discussed in this review. Further, a host of responses shown by algae like an increase in reactive oxygen species, lipid peroxidation and a decrease in chlorophyll content and photosynthetic efficiency are highlighted. Future scope of research is also discussed in brief.

Subsea dispersant injection (SSDI) was a new oil spill response (OSR) technology deployed during the Deepwater Horizon accident. To integrate SSDI into future OSR decisions, a hypothetical deepwater oil spill to the Gulf of Mexico was simulated and a comparative risk assessment (CRA) tool applied to contrast three response strategies: (1) no intervention; (2) mechanical recovery, in-situ burning, and surface dispersants; and, (3) SSDI in addition to responses in (2). A comparative ecological risk assessment (CRA) was applied to multiple valued ecosystem components (VECs) inhabiting different environmental compartments (ECs) using EC-specific exposure and relative VEC population density and recovery time indices. Results demonstrated the added benefit of SSDI since relative risks to shoreline, surface wildlife and most aquatic life VECs were reduced. Sensitivity of results to different assumptions was also tested to illustrate flexibility of the CRA tool in addressing different stakeholder priorities for mitigating the impacts of a deepwater blowout.

Urban structures like marinas are dominant features of our coasts, often hotspots for invasive species. The processes that govern the distribution of invasive species within and between marinas are not well understood. We therefore investigated the impacts of local-scale variability within and between marinas, analysing fouling communities at two zones (inner and outer) within three close marinas in accordance with pollutants recorded in the water and sediment. Communities varied between zones, however no significant differences in abundances of invasive species was recorded. The inner zones contained higher levels of copper and other pollutants and were correlated with lower biodiversity and abundances of many species in comparison to the outer zones. Only the native Ascidiella aspersa was found in greater abundances in the inner zones. This local-scale variability and how it impacts biodiversity is important for consideration for coastal managers in mitigating the build-up of pollutants and spread of invasive species.

Microplastic (MP) ingestion has been reported in a wide variety of organisms, however, its spatial occurrence and effects on wild populations remain quite unknown. The present study targets an economically and ecologically key species in the Mediterranean Sea, the shrimp Aristeus antennatus. 39.2% of the individuals sampled had MP in their stomachs, albeit in areas close to Barcelona city the percentage reached values of 100%. Overall, MP ingestion was confirmed in a wide spatial and depth (630–1870 m) range, pointing out the great dispersion of this pollutant. The benthophagous diet and close relationship with the sea bottom of A. antennatus might enhance MP exposure and ultimately lead to accidental ingestion. Detailed analysis of shrimps' diet revealed that individuals with MP had a higher presence of endobenthic prey. Microplastic fibers are probably retained for long periods due to stomach's morphology, but no negative effects on shrimp's biological condition were observed.

Microplastics (<5 mm) have often been studied under in-vitro conditions where plastics have been investigated in isolation. However, in the natural environment microplastics readily form agglomerates conferring the particles with properties different to their pristine counterparts. Here, we examined the interaction of exopolymers with polystyrene nanoplastics and microplastics. Formation of plastic agglomerates was examined using simulated sea surface conditions. Flow cytometry coupled with microscopy revealed that nano- and microplastic particle spheres form agglomerates in seawater with a mucilagenous material and an associated microbial community. To characterise this material, differential staining methods revealed it to be glycoprotein in composition. Exposing increasing concentrations of a marine bacterial glycoprotein EPS to nano- or microplastics revealed that these types of polymers contribute to the formation and abundance of plastic agglomerates. This work highlights the importance of EPS on the fate of plastic and future research should take this into account when evaluating the impact of plastics.

High spatial resolution WorldView-2 (WV2) satellite imagery coupled with field observations have been utilized for mapping the coral reefs around Hendorabi Island in the northern Persian Gulf. In doing so, three standard multispectral bands (red, green, and blue) were selected to produce a classified map for benthic habitats. The in-situ observations were included photo-transects taken by snorkeling in water surface and manta tow technique. The satellite image has been classified using support vector machine (SVM) classifier by considering the information obtained from field measurements as both training and control points data. The results obtained from manta tow demonstrated that the mean total live hard coral coverage was 29.04% ± 2.44% around the island. Massive corals poritiids (20.70%) and branching corals acroporiids (20.33%) showed higher live coral coverage compared to other corals. Moreover, the map produced from satellite image illustrated the distribution of habitats with 78.1% of overall accuracy.

Most anthropogenic marine debris shoreline studies are conducted on sandy shores, rather than rocky coastlines. We amended a standardized protocol for monitoring marine debris on a high-loading beach composed of small rocks and cobbles in Newfoundland, Canada. Our protocol had two parts: we conducted stratified sampling to a depth of ~20cm below the surface of the rocks (standing survey), and surveyed accumulation of items on the surface of rocks every other day (loading survey). We found the vast majority of smaller items were below the surface. Only 17.2% of debris were microplastics (<5mm). Types of anthropogenic debris differed significantly between the standing survey and the loading survey. We found no relationship between either wind direction or wind speed, and distributions of debris. This study allows for a better understanding of marine debris detection along rocky coasts, and the limitations of protocols for studying them.

The effects of ocean warming and ocean acidification on developmental and reproductive traits of Lessonia trabeculata were evaluated. Meiospores were cultured for 35 days in an experimental mesocosm where temperature (~15 and 19 °C) and partial CO2 pressure (pCO2, ~400 and 1300 μatm) were controlled. The results indicate that germination was reduced at 19 °C, whereas the increase of pCO2 only had effects at 15 °C. Likewise, the increase in temperature significantly affected the vegetative growth of female gametophytes. Sex ratio was not affected significantly by any of the variables studied. Fertility and reproductive success decreased by about 50% at 19 °C. The pCO2 levels had no significant effects on most early developmental traits. The results suggest that ocean warming or periodic warming events (e.g. an El Niño event) might affect the recruiting capacity of this or other similar species by affecting their early developmental stages.