Coral colony size-frequency distributions can be used to assess population responses to local environmental conditions and disturbances. In this study, we surveyed juvenile pocilloporids, herbivorous fish densities, and algal cover in the central and southern Saudi Arabian Red Sea. We sampled nine reefs with different disturbance histories along a north–south natural gradient of physicochemical conditions (higher salinity and wider temperature fluctuations in the north, and higher turbidity and productivity in the south). Since coral populations with negatively skewed size-frequency distributions have been associated with unfavorable environmental conditions, we expected to find more negative distributions in the southern Red Sea, where corals are potentially experiencing suboptimal conditions. Although juvenile coral and parrotfish densities differed significantly between the two regions, mean colony size and size-frequency distributions did not. Results suggest that pocilloporid colony size-frequency distribution may not be an accurate indicator of differences in biological or oceanographic conditions in the Red Sea.

This study reports the occurrence and distribution of synthetic musks (SMs) and organic UV filters (UVFs) in sediment samples collected in 8 riverine runoffs from the Pearl River and Pearl River estuary (PRE). Here, 6 of the 8 target compounds were detected in all sediments with concentrations ranging from 0.35ngg−1 to 456ngg−1. Higher concentrations of SMs and UVFs were evident in the eastern outlets compared to the western suggesting greater input of these contaminants from the Pearl River Delta (PRD) region. All the compounds showed a decreasing trend toward the seaward side which confirming that riverine runoff was the most important source of SMs and UVFs to the coastal environment. Notably, high levels of SMs and UVFs were detected in two fishing harbors in the PRE area. In comparison to UVFs, the SM compounds exhibited a significant correlation with TOC content in the sediments.

Concentrations of trace metals such as iron (Fe), copper (Cu), zinc (Zn), cobalt (Co), nickel (Ni), manganese (Mn), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), vanadium (V), and selenium (Se) were determined in seawater and zooplankton from the surface waters off Rushikulya estuary, north-western Bay of Bengal. During the study period, the concentration of trace metals in seawater and zooplankton showed significant spatio-temporal variation. Cu and Co levels in seawater mostly remained non-detectable. Other elements were found at higher concentrations and exhibited marked variations. The rank order distribution of trace metals in terms of their average concentration in seawater was observed as Fe>Ni>Mn>Pb>As>Zn>Cr>V>Se>Cd while in zooplankton it was Fe>Mn>Cd>As>Pb>Ni>Cr>Zn>V>Se. The bioaccumulation factor (BAF) of Fe was highest followed by Zn and the lowest value was observed with Ni. Results of correlation analysis discerned positive affinity and good relationship among the majority of the trace metals, both in seawater and zooplankton suggesting their strong affinity and coexistence.

On 5 November 2015, the Fundão tailings dam collapsed and its content first reached River Doce and then the Atlantic Ocean by 22 November. This study focuses on the oceanic time and space patterns of river discharge dispersion. By using an ocean model together with nLw(555) and RGB images from MODIS sensors, the river plume was followed for 2months after the arrival of the tailings at the ocean. The results show the huge effect of this accident and reveal that riverine waters may have dispersed hundreds of kilometres, reaching regions as far as the shelf in front of the city of Rio de Janeiro. The movement of the freshwater was essentially to the south in accordance with the seasonal wind regime. Episodic frontal systems, leading to wind reversion, and oceanic mesoscale features contribute to the offshore dispersion of the plume. The region more often in contact with the riverine waters was located at the inner shelf between the river mouth and the city of Vitória, turning to the outer shelf and shelf break at lower latitudes.

Water and sediments were collected on March 2013 and April 2014 from Khalid Khor creek area in United Arab Emirates to assess their quality parameters. The pH and alkalinity of the water samples were measured and their values were similar to those of shallow saltwater ecosystems. In addition, elemental analyses and organic compounds were done using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Gas Chromatography—Mass Spectroscopy (GC–MS), respectively. The concentration of heavy and trace metals in the water samples were within the acceptable limits except for lead which showed high values, while the concentrations of metals in the sediment samples were relatively high and ranged from 6517 to 13,768mg/kg. GC–MS analysis showed the presence of polyaromatic heterocyclic (PAHs) compounds in sediments near the shipping area and in amounts classified as highly carcinogenic; however, no polychlorinated biphenyls (PCB) were identified. Moreover, fecal bacterial contamination in water was detected in concentrations that range between 300 and 10,140 organisms/100mL.

A 96m long sediment core (S10-33) from the Mali Ston Channel (Adriatic Sea) showed large natural variation in carbonate share (between 1% and 95%) and concentration of elements. These variations indicate rather significant changes in fine-grained sediment that was deposited in this area during Younger Pleistocene and Holocene. Unaffected by anthropogenic influence, sediment in the core was used to determine background concentration of trace elements in sediment with various carbonate content. Here we propose a method of the normalization of trace elements to carbonate share, in order to assess natural/background concentration of metals in sediments consisting of carbonates and alumosilicates in various proportions. Six characteristic metals (Co, Cr, Cu, Ni, Pb, and Zn) that were normalized to carbonate share showed very good correlation, with much higher background concentrations in alumosilicate than in carbonate end member. Simple formulas were proposed to easily determine background concentration of these elements, in coastal and shelf depositional environments with mixed carbonate-alumosilicate sediments.

This study aims at constructing an efficient bacterial consortium to biodegrade crude oil spilled in China's Bohai Sea. In this study, TCOB-1 (Ochrobactrum), TCOB-2 (Brevundimonas), TCOB-3 (Brevundimonas), TCOB-4 (Bacillus) and TCOB-5 (Castellaniella) were isolated from Bohai Bay. Through the analysis of hydrocarbon biodegradation, TCOB-4 was found to biodegrade more middle-chain n-alkanes (from C17 to C23) and long-chain n-alkanes (C31–C36). TCOB-5 capable to degrade more n-alkanes including C24–C30 and aromatics. On the basis of complementary advantages, TCOB-4 and TCOB-5 were chosen to construct a consortium which was capable of degrading about 51.87% of crude oil (2% w/v) after 1week of incubation in saline MSM (3% NaCl). It is more efficient compared with single strain. In order to biodegrade crude oil, the construction of bacterial consortia is essential and the principle of complementary advantages could reduce competition between microbes.

The bioavailability and risk assessment of As were studied in sediments of the Yangtze River estuary (YRE). Results showed that residual fractions dominated the As partition (>85%), which attenuated overall bioavailability. After the residual fraction, As mainly partitioned into the Fe-Mn oxides fraction (3.16–4.22%). Arsenic bound to Fe-Mn oxides was higher in wet seasons. The carbonate fraction was minimal, which may result from the negative state presence of As in sediments. According to the risk assessment code, the YRE was classified as low risk. Additionally, the reduction of As(V) to As(III) may occur due to the reducing condition in wet seasons. Considering As(III) is more toxic and mobile, As bound to the exchangeable and Fe-Mn oxides fractions may have more potential ecological risk. Thus, the speciation and fraction should be both considered on the ecological risk of As in sediments of the YRE.

Researchers have utilized chemical fingerprints in the determination of habitat utilization and movements of the aquatic animals. In the present effort, we analyzed polychlorinated biphenyl (PCB) congeners and organochlorine pesticides in the samples of juvenile bluefin tuna caught offshore of Virginia, and in larger bluefin tuna from the Gulf of Maine and near Nova Scotia. For a given specimen, or a given location, PCB concentrations were highest, followed by DDTs, and chlordanes. Average contaminant concentrations from fish captured from the three locations were not significantly different; and PCBs, DDTs, and chlordanes correlated well with each other. Trans-nonachlor/PCB 153 ratios in bluefin tuna of eastern Atlantic (i.e., Mediterranean) origin are low compared to the corresponding ratios in fish in the western Atlantic. As the former migrate to the western Atlantic, these ratios gradually turnover due to the accumulation of biomass from forage contaminated with higher trans-nonachlor/PCB 153 ratio reflecting dissimilar use of chlordane pesticides on two sides of the Atlantic Ocean. The trans-nonachlor/PCB 153 ratio indicated that one juvenile bluefin tuna from offshore of Virginia and one large bluefin tuna from Gulf of Maine in the present study originated from foraging grounds in the Mediterranean Sea, and that they have made the trans-Atlantic migrations. The remaining individuals were determined to be either spawned in the Gulf of Mexico or the trans-nonachlor/PCB 153 ratio for the putative Mediterranean bluefin tuna was completely turned over to resemble the ratio characteristic to the western Atlantic. Based on the turnover time for trans-nonachlor/PCB 153 ratio previously determined, the residence time of juvenile bluefin tuna offshore Virginia was estimated to be at least 0.8 to 1.6years. A discriminant function analysis (DFA) plot of total PCB normalized signatures of PCB congeners showed three separate clusters, which suggested that bluefin tuna from offshore Virginia, Gulf of Maine, and Nova Scotia could have had extended residences and foraging within the areas of capture to be able to sustain the stable signatures of PCB congeners. The DFA cluster results supported the concept of metapopulation theory of spatial ecology comprising discrete aggregates of local populations of bluefin tuna where the desired prey species are likely to be abundant. Despite their highly migratory trait and endothermic advantage of foraging in broader and colder habitats, the movements and mixing across the aggregation ranges related to feeding did not appear to be extensive. Advancement in the understanding of bluefin tuna population dynamics beyond the coarse concept of trans-Atlantic migrations to the metapopulation hypothesis provides a novel exploratory tool in the stock assessment and resource management. As the chemical tracer tags are fortified naturally and document the time- and space-integrated foraging history, they promise to serve as the low-cost alternatives to the high-cost electronic data recording tags employed for addressing the migratory movements of bluefin tuna. Between the different potential chemical tracer tags, a distinct advantage of PCB/pesticide analysis over the otolith micro-constituent analysis is that the muscle tissue of a given individual bluefin tuna can be sampled repeatedly for PCB/pesticide analysis over different spatial and temporal scales in a non-lethal manner.

This paper presents a study on the impact of underwater gas blowouts near the ocean surface, which has a greater relevance to assess Health, Safety, and Environmental risks. In this analysis the gas flux near the surface, reduction of bulk density, and gas surfacing area are studied for different scenarios. The simulations include a matrix of scenarios for different release depths, release rates, and initial bubble size distributions. The simulations are carried out using the MEGADEEP model, for a location in East China Sea. Significant changes in bulk density and gas surface flux near the surface are observed under different release conditions, which can pose a potential threat for cleanup and rescue operations. Furthermore, the effect of hydrate formation on gas surfacing is studied for much greater release depths. The type of outcomes of this study is important to conduct prior risk assessments and contingency planning for underwater gas blowouts.