Disturbance from underwater noise is one of the primary threats to the critically endangered southern resident killer whales (SRKWs). Previous studies have demonstrated that SRKWs spend less time feeding when vessels are present. In 2018, we measured the effects of a voluntary vessel slowdown action in SRKW critical habitat to assess whether ship speed (and related source level) affects foraging behaviour. Observations of SRKWs and ships were collected from land-based sites on San Juan Island, WA, USA, overlooking the Haro Strait slow-down area. Exploratory analyses found little support for a linear relationship between ship speed and SRKW behaviour, but strong support between received noise level from ships and the probability of SRKWs engaging in foraging activity. Reducing ship speed, and therefore ship noise amplitude will help decrease the probability of ship noise disrupting SRKW foraging activity and may help to increase the proportion of accessible salmon.

Microplastics as a new class of environmental contaminants have become the hot issue of global concern. We conducted quantitative and qualitative experiments to investigate microplastics in oyster, seawater and sediment along the Zhuhai coastline. The soft tissues of oysters were digested with potassium hydroxide (10%) and hydrogen peroxide (30%), seawaters and sediments with hydrogen peroxide (30%) to degrade organic matter, and analyzed using a digital camera, optical microscopy and micro-ATR-FTIR. The abundance of microplastics were in the range of 0.14–7.90 n/g in oysters (wet weight), 10.00–27.50 n/L in seawaters and 0.053–0.26 n/g in sediments. The fiber and fragment shape, black color, 101–500 μm of size and polyethylene composition were all classified as the major constituents of microplastics. The level of contaminants in oysters was correlated to those in their surrounding environments. Therefore, oysters may serve as a promising sentinel species for the indication of microplastic pollution in the coastal zone of Zhuhai.

For the first time, the qualitative and quantitative characteristics of marine debris ingested by six hawksbill (Eretmochelys imbricata) and seven olive ridley (Lepidochelys olivacea) sea turtles from the Gulf of Oman coast of the United Arab Emirates were investigated. The numeric and gravimetric proportions of ingested marine debris obtained from the esophagus, stomach and intestines were quantified following categories of presumed sources, Marine Strategy Framework Directive (MSFD), rigidity, color and plastic polymer types. Marine debris was observed in 28.6% of olive ridley (x̅: 2.00 items; 4.83 g) and 83.3% of hawksbill specimens (x̅: 6.00 ± 2.32 items; 0.32 ± 0.24 g). Overall, the results of this preliminary study suggest that hawksbill sea turtles were ingesting marine debris at higher frequencies and that plastics were observed to be the most predominant debris ingested. However, non-plastic rubbish, particularly metallic fishing gear (fish hooks and fish traps), were observed to present lethal hazards for both species.

Sharks are fished for human consumption in Colombia, and fins are exported illegally to international markets. The goal was to identify differences in total mercury (THg) concentrations in fins and muscles of shark species seized in the Buenaventura port (Colombian Pacific), and to assess potential human health risks related to shark consumption. Seven species were considered in this study: Pelagic Thresher (Alopias pelagicus), Pacific Smalltail Shark (Carcharhinus cerdale), Brown Smoothhound (Mustelus henlei), Sicklefin Smoothhound (Mustelus lunulatus), Scalloped Bonnethead (Sphyrna corona), Scalloped Hammerhead (Sphyrna lewini), and Bonnethead Shark (Sphyrna tiburo), and THg was analyzed in shark tissues. 24% muscle samples concentrations were above international recommended limits for human consumption, especially for A. pelagicus and S. lewini. Stable isotopes (δ¹³C and δ¹⁵N) analysis showed a foraging overlapping in coastal habitats, where overfishing usually occurs. This study provides useful scientific information to develop management plans for sharks in Colombia and neighboring countries.

Litter are ubiquitous and increasing in the coastal and marine environments. Entanglement with litter is one of the principal causes of mortality in seabirds, but the population-level consequences are unknown. Currently, all seabirds collect litter for nesting material. Northern Gannets are not the exception and there are several cases where elevated percentages of polymers are part of the life cycle of gannets, especially during breeding. This baseline paper presents an analysis of litter content and its related impacts on the two gannet nests located in South France (Carry-Le-Rouet) and Northwest Italy (Portovenere) from 2017 to 2019. 654 items from both gannet nests were collected with 277 items (42%) being of natural origin, while 377 items (58%) were litter. Most of the nesting material was nautical cordage, which appears to be used preferentially. A more restrictive litter management regulation must be adopted to reduce litter generation from fishing/aquaculture-related activities.

This study aims at assessing the fate of MV Wakashio oil spill, and the driving forces responsible for possible environmental consequences of polluted coastal region. GNOME simulations were performed, considering various meteo-oceanographic forcings such as (i) winds and currents, (ii) only winds, and (iii) only winds with different diffusion coefficients, and validated with the satellite images. The results revealed that the simulations performed with ‘only winds’ reasonably match with the satellite observations, indicating that winds are the primary driving forces. The conducive stokes drift is an added contribution to the predominant northwestward drift of the spill. The oil budget analysis suggests that beaching and evaporation together accounted for a significant portion of the spilled oil (1000 tons), in which ~60% of the oil was accounted only for beaching. Our results depict that the diffusion coefficient of 100,000 cm²/s and 3% windages are optimal for oil-spill simulations off the southeastern Mauritius coast.

In the present study, the combined effects of pH, dissolved oxygen (DO) and temperature levels on the antioxidant responses of the mussel Mytilus coruscus were evaluated. Mussels were exposed to two pH (8.1, 7.7-acidification), two DO (6 mg L⁻¹, 2 mg L⁻¹-hypoxia) and two temperature levels (20 °C, 30 °C-warming) for 30 days. SOD, CAT, MDA, GPx, GSH, GST, TAOC, AKP, ACP, GPT, AST levels were measured in the gills of mussels. All tested biochemical parameters were altered by these three environmental stressors. Values for all the test parameters except GSH first increased and then decreased at various experimental treatments during days 15 and 30 as a result of acidification, hypoxia and warming. GSH content always increased with decreased pH, decreased DO and increased temperature. PCA showed a positive correlation among all the measured biochemical indexes. IBR results showed that M. coruscus were adversely affected by reduced pH, low DO and elevated temperature.

Benthic marine food webs, which recycle organic matter and sustain unique biodiversity, are an important component of estuarine Patagonian fjords; however, these may be heavily influenced by salmon farming activities. Under the above conditions, this study collected several food sources (sediment organic matter, suspended particulate organic matter, macroalgae) and 26 benthic invertebrate species, and analyzed them using a Bayesian mixing model. Briefly, carbon and nitrogen stable isotopes analyses revealed that the highly variable isotopic niche widths respond to food supplies from marine and terrestrial organic matter. In addition, particulate and dissolved waste from salmon farming activities were found to modify isotopic composition ratios in many suspension feeders. Particularly, our results indicate high δ¹⁵N values in the sponge Cliona chilensis and the encrusting coral Incrustatus comauensis, which appear to be potential ecological indicators for evaluating stoichiometry imbalances and trace organic pollution sources in fjord environments.

Zn, Pb, Cr, Cu, Ni, Cd concentration and ecological risk were studied in three bays to evaluate the heavy metal (HM) contamination of seagrasses. Seasonal HM accumulation varied according to locations, seagrass species and tissues. Halophila beccarii had much higher HM concentrations except for Cr in Zhelin Bay, however, bioconcentration factors (BCF) of Cu, Ni, Pb, Zn were higher in Liusha than Zhelin Bay. Cr was much enriched in Thalassia hemperichii and Enhalus acoroides than Halophila beccarii and Halophila ovalis. Cr, Cu, Ni, Pb were easy to accumulate in belowground tissues in Halophila ovalis. In contrast, almost all HM were more enriched in aboveground tissues in other species. Generally, BCF exceeding 1 and high metal pollution index suggested HM had potential ecological risk on seagrasses. The results provide the reference for managing and protecting seagrass ecosystem in South China, and are significant to expand the global seagrass detection network.

The fluctuating asymmetry values of the two otolith parameters: length and width of Engraulis australis, recovered from the food of gannet, which inhabit colonies in islands at Hauraki Gulf, New Zealand was calculated in this study. The dissimilarity value of the otolith width was higher than that of the otolith length. An inclination of upsurge in the dissimilarity values with the fish length was noted for the otolith sizes studied. The dissimilarity value in the two otolith sizes was the lowest for fish having total length of 115–154 mm, and the highest for fish with length of 151–160 mm. The conceivable reason of the dissimilarity obtained could be related to diverse contaminants and their presence in the study location.