A hypoxia event occurred in the nearshore of the northern Yellow Sea in summer 2016, and a bloom of small jellyfish occurred in June of this year. As a key copepod species in the Yellow Sea, Calanus sinicus exhibits early recruitment mainly in this nearshore area. Therefore, this study assessed the effects of these two phenomena on C. sinicus especially on their early recruitment. Sampling in nearshore waters was performed every month from May to December, except for October 2016. The numerical abundance of eggs and nauplii (E + N), copepodites and adults (C + A) of C. sinicus was determined in relation to environmental factors. Results showed that dissolved oxygen (DO) concentrations decreased from June on, attaining a minimum in August, and showed a significant positive relationship with C. sinicus E + N abundance. This suggested that decreasing DO had potential negative effects on early recruitment of C. sinicus. The abundance of small jellyfish, dominated by Sugiura chengshanense (Hydromedusa), also showed a significant positive relationship with C. sinicus E + N abundance, indicating a potential predator-prey relationship between them. Spatial relationships were also examined between E + N abundance and DO concentration in July and with small jellyfish abundance in June. Both bottom DO (B-DO) and E + N abundance in inshore waters were significantly lower than those in offshore water in July, indicating a potential negative effect of low B-DO (<6 mg L⁻¹) in nearshore water. Spatial variation of small jellyfish abundance showed no correlation with C. sinicus abundance in June, but the non-overlapping patchy distribution also suggested their potential predator-prey relationship. Together, both the seasonal and spatial results indicated that low DO and a small jellyfish bloom in nearshore waters had detrimental effects on early recruitment of C. sinicus. These negative effects thus have the potential to indirectly impact the trophodynamics of fishery resources in the northern Yellow Sea.

The Deepwater Horizon oil spill released millions of barrels of crude oil into the Gulf of Mexico, and saw widespread use of the chemical dispersant Corexit. We assessed the role of traits, such as cell size, cell wall, motility, and mixotrophy on the growth and photosynthetic response of 15 phytoplankton taxa to oil and Corexit. We collected growth and photosynthetic data on five algal cultures. These responses could be separated into resistant (Tetraselmis astigmatica, Ochromonas sp., Heterocapsa pygmaea) and sensitive (Micromonas pusilla, Prorocentrum minimum). We combined this data with 10 species previously studied and found that cell size is most important in determining the biomass response to oil, whereas motility/mixotrophy is more important in the dispersed oil. Our analysis accounted for a third of the variance observed, so further work is needed to identify other factors that contribute to oil resistance.

During drier periods estuarine salinization can stimulate the colonization of marine organisms and further bioinvasion, therefore, may cause future ecological change. In this sense, we applied the Rapid Assessment Surveys (RAS) on natural and artificial hard substrates during the most intense drought period (between 2014 and 2016) since 1950, in a tropical estuary in Eastern Brazil. Through the estuary salinization the ascidian Didemnum psammatodes overgrow the dominant native taxa; this dominance taxa shift provided suitable habitat favorable for invasion of Ophiothela mirabilis across the estuary. Even the invasion starts on artificial substrates, the higher resilience of natural substrates were not enough to enable the establishment of invasive species. This baseline is the first evidence of bioinvasion influenced by climate change drought periods in tropical estuaries in South America, which is a great advance for the development of management strategies to mitigate this and future climate change scenarios.

A preliminary report on the abundance of microplastic in the coastal waters in the depth zone 5 to 20 m in the surface waters, sediment and in selected fishes occurring off Kochi, India is presented. Spatial and temporal variation in microplastic abundance was observed with higher abundance in surface water indicating threats to pelagic ecosystem. The relative concentration of microplastic was highest during monsoon season. The major microplastics were fragments of 1-5 mm in white and blue colours. Gut content analysis of 16 species (653 individuals) comprising pelagic (8 species) and demersal (8 species) indicated occurrence (4.6%) of microplastics (fragment>filament>pellet) of size 0.27mm to 3.2 mm in Sardinella longiceps, S. gibbosa, Stolephorus indicus Rastrelliger kanagurta and Cyanoglossus macrostomus. Raman spectroscopy indicated that Polyethylene (PE) and Polypropylene (PP) were the polymer types of microplastics from the fish gut.

To assess potential dispersion of pollutants around Honiara, Solomon Islands, and Port Vila, Vanuatu, 3D ocean circulation models were developed using Telemac-3D. A series of scenarios then explore the vulnerability of the system and test potential control measures. Results show that high coastal concentrations are most likely during the wet season, with increased volumes of discharge as well as favourable wind speed and direction. Buoyant plumes flow along the coastline, and high concentrations build up in enclosed bays. Control measures tested focus on consolidating existing outflows at depth off-shore. This results in an overall reduction of surface concentrations along the coastline. However, the reduction is dependent on the depth, off-shore positioning, and volume of outflow. With increased concentrations then found at depth, the subsequent impact on off-shore and benthic ecosystems would also need to be considered.

French Polynesia exhibits a wide diversity of islands and coral-reef habitats, from urbanized high islands to remote atolls. Here, we present a geographically extensive baseline survey that examine the concentrations of nine metals (Ag, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) and one metalloid (As) in superficial sediments from 28 sites spread over three islands of French Polynesia. We used Principal Component Analysis, Pearson's correlation, hierarchical cluster analysis and generalized linear mixed-effect models on Pollution Load Index to investigate site contamination and metal(loid) associations. At most sites, metal(loid) concentrations were below commonly applied sediment quality guidelines. However, a few sites located near farming activities, river discharges and urbanized areas showed concentrations above these guidelines. This study provides critical baseline values for metal(loid) contaminants in this region and in coral-reef areas in general, and spur decreased discharge of metal(loid) contaminants in the anthropogenised areas of French Polynesia.

Risk screening tools are being increasingly used to identify the potential invasiveness and associated risks of non-native species. In this study, the Aquatic Species Invasiveness Screening Kit was used to evaluate the invasiveness risks of extant and horizon non-native marine fish species for the coastal waters of South Korea. In total, 57 marine fish species were screened and the threshold scores for the Basic Risk Assessment (BRA) and the BRA + Climate Change Assessment (BRA+CCA) (5.5 and 1.5, respectively) reliably distinguished those species carrying a high risk of invasiveness from those carrying a low to medium risk. For both the BRA and BRA+CCA, common lionfish Pterois miles was the highest-scoring species, followed by white perch Morone americana, red drum Sciaenops ocellatus, marbled spinefoot Siganus rivulatus and redcoat Sargocentron rubrum. The outcomes of this study will contribute to the management of non-native marine fish species for the conservation of the native ecosystems in the coastal waters of South Korea.