To understand the impact of seasonal variability on plankton food web composition in tropical coastal waters, samples were collected from three locations along Tuticorin coastal waters during postmonsoon, summer, and northeast (NE) monsoon seasons. During the NE monsoon, the total suspended matter (TSM) and nutrient concentrations were relatively higher, whereas salinity and plankton (phytoplankton and zooplankton) abundances were lower. Cluster analysis also revealed that the NE monsoon formed into a separate cluster because of the lower phytoplankton abundance caused by higher loads of TSM; this arrests light penetration, thereby resulting in a decrease in plankton abundance. The increase in zooplankton biomass coincided with the decrease in diatoms (p < 0.05), and the increase in cyanobacteria may reflect that grazers food choice has a significant impact on the base of the food web composition. The present study states that the phytoplankton biomass was greatly influenced by seasonality and associated changes rather than the huge supply of nutrient loads.

This study developed a novel probabilistic agent-based approach for modeling of marine oily wastewater treatment processes. It begins first by constructing a probability-based agent simulation model, followed by a global sensitivity analysis and a genetic algorithm-based calibration. The proposed modeling approach was tested through a case study of the removal of naphthalene from marine oily wastewater using UV irradiation. The removal of naphthalene was described by an agent-based simulation model using 8 types of agents and 11 reactions. Each reaction was governed by a probability parameter to determine its occurrence. The modeling results showed that the root mean square errors between modeled and observed removal rates were 8.73 and 11.03% for calibration and validation runs, respectively. Reaction competition was analyzed by comparing agent-based reaction probabilities, while agents' heterogeneity was visualized by plotting their real-time spatial distribution, showing a strong potential for reactor design and process optimization.

Surface sediments from three zones (fresh water, estuarine, and riverine/industrial zones) of the Cochin estuary, Southwest coast of India, were seasonally analyzed to understand the nature and degradation status of organic matter. Amino acid-based indices such as total hydrolyzable amino acids (THAAs), percentage contributions of amino acid carbon to total organic carbon (THAA-C%) and those of amino acid nitrogen to total nitrogen (THAA-N%), and degradation index (DI) were calculated. Elevated levels of amino acids in the sediments of the estuary were attributed to river runoff, autochthonous production, allochthonous inputs, and industrial and domestic effluent discharges. Higher levels of THAA-C%, THAA-N%, THAA, and positive DI found in most of the stations suggest the fresh deposition of organic matter. Multivariate statistical analyses revealed that the dispersal pattern of amino acids depends on the sediment texture, organic matter, redox state, and microbial processes in the study region.

Microplastic ingestion by mesozooplankton may be an important pathway for the microplastics to enter the food web. To determine microplastic abundance in Guanabara Bay, samples were collected by neustonic haul with a 64-μm-net and oblique hauls using 64- and 200-μm nets. Microplastic size and abundance as well as copepod, fish-larvae, and chaetognath sizes, densities, and preferential prey sizes were determined. Microplastic abundance was higher in samples collected with fine nets (average 4.8 microplastics m−3, maximum 11 microplastics m−3) than in those collected with coarse net. Microplastic abundance in Guanabara Bay was higher than that in other marine ecosystems. Microplastics >100 μm were too large to be ingested by copepods. However, for fish larvae and chaetognaths, the abundance of microplastics, at the corresponding prey size range, were, respectively, ~9000- and 14,400-folds lower than the preferential copepod prey, in the same size range. Thus, in Guanabara Bay, microplastics were available, but too diluted to be frequently ingested by fish larvae and chaetognaths.

The use of macroalgae transplants is a recent technique used in pollution biomonitoring studies in marine ecosystems. Only 60 articles published between 1978 and 2017 reported the use of this environmental tool for the active biomonitoring of inorganic pollutants and nutrients worldwide. In this review paper, we evaluated studies on this topic in relation to the development of methodological aspects of the technique and the degree of standardization of the protocols used. On the basis of findings of this review, we conclude that the technique is not yet standardized and that uniformisation of protocols is required to enable comparison of the results of different studies. We propose a new protocol for applying the technique, in which each suggestion has been carefully and rigorously compared with the relevant findings reported in the available literature.

The direct evidences for the ingestion of microplastics by cetaceans, especially the cetaceans in Asian marine areas are limited. In this study, residue of microplastics in the intestinal tracts of East Asian finless porpoises (Neophocaena asiaeorientalis sunameri) was investigated. Microplastics were detected in all specimens, with mean abundance of 19.1 ± 7.2 items/individual. With respect to microplastics properties, fibers, blue items, and polypropylene were predominant in shapes, colors, and plastic materials, respectively. Trophic transfer and unintentional ingestion might be the potential pathways for microplastics ingested by finless porpoise. The specific intestinal structure might account for the predominance of fibers and the accumulation of microplastics at the beginning portion of intestines. This study indicates that cetaceans in Chinese marine areas also suffer from microplastics pollution. Further studies on the fate and ecological effects of microplastics should be conducted to reveal their potential risks to cetaceans.

Oil-related aggregates (ORAs) may contribute to the fate of oil spilled offshore. However, our understanding about the impact of diatoms and associated bacteria involved in the formation of ORAs and the fate of oil compounds in these aggregates is still limited. We investigated these processes in microcosm experiments with defined oil dispersions in seawater at 5 °C, employing the Arctic diatom Fragilariopsis cylindrus and its associated bacterial assemblage to promote ORA formation. Accumulation of oil compounds, as well as biodegradation of naphthalenes in ORAs and corresponding water phases, was enhanced in the presence of diatoms. Interestingly, the genus Nonlabens was predominating the bacterial communities in diatom-supplemented microcosms, while this genus was not abundant in other samples. This work elucidates the relevance of diatom biomass for the formation of ORAs, microbial community structures and biodegradation processes in chemically dispersed oil at low temperatures relevant for Arctic conditions.

Lagoon Burullus is located in the North West quadrant of the Nile Delta. It receives drainage water through several drains around the lagoon. Understanding the mobility and bioavailability of zinc metal in bottom sediments of Lagoon Burullus is essential for the design of remediation processes and the institution of environmental recommendation for zinc pollution.Single extractions used to fractionate zinc into five fractions. The chemical analyses preceded using atomic absorption spectrometry after using the digestion technique. Zinc concentrates in the residual fraction (167.5μg/g) followed by the organic (14.6μg/g), exchangeable (3.2μg/g), carbonate (2.4μg/g) and then the Fe-Mn hydroxides (1μg/g) fractions. The average content of zinc (189μg/g) is about three fold the average earth's crust.Ecological pollution index show that the metal has a low-risk assessment to surrounding ecosystem. The anthropogenic activities considered as the main source of pollution.

Our study evaluated heavy metal concentrations in soft tissues of sea hare, Aplysia fasciata, from the Lower Laguna Madre, Texas. Heavy metals in tissues followed Se>As>Pb>Cd. Concentrations ranged As (BDL-28.08), Cd (BDL-5.50), Pb (BDL-12.85) and Se (4.25–93.43ppm). Median As, Cd, Pb, and Se tissue levels exceeded exposure levels. Significant relationships occurred in metal-metal (AsCd, AsPb, CdPb, CdSe, and PbSe), metal-tissue (significant Se uptake by inhalant and exhalant siphons and As in the hepatopancreas), and metal-metal within tissue (AsPb in the hepatopancreas and CdPb in the digestive cecum) analyses (p<0.05). Bioaccumulation factors (BAF) suggested the inhalant siphon, hepatopancreas, and digestive cecum function as macroconcentrators of Cd, hepatopancreas and digestive cecum as macroconcentrators of Pb, and all tissues were deconcentrators for As and Se. As a bioaccumulator of heavy metals, Aplysia was evaluated as a bioindicator of marine pollution in harbors and bays.

China's rapid economic and social development has led to an acceleration in nutrient inputs to coastal waters, which, in turn, has resulted in severe coastal eutrophication. On the occasion of the 40th anniversary of China's reform and opening up, the evolution of the causative factors and the state as well as future prospects for coastal eutrophication in the China Seas are analyzed and summarized. Results showed that the coastal eutrophication situation was not so serious at the beginning of reform and opening up, but it worsened rapidly from the end of the 1980s to the mid-2000s. In the last decade, the worsening trend has been curbed but the status of coastal eutrophication has not been substantially improved. Much work is still needed to be able control the total amount of nutrients entering coastal waters and enable comprehensive treatment of coastal eutrophication in the China Seas.