The prevalence of microplastics in the sediments of six beaches of the Puducherry coast in India was studied and its correlation to fishing activities and recreational activities was analysed. On an average, 72.03 ± 19.16 microplastic particles/100 g dry weight of sediments is found to be the microplastic abundance in the study. A Strong positive correlation (Pearson's R = 0.92, p = 0.0103) between fishing activity and microplastic abundance and a weak correlation (Pearson's R = 0.04, p = 0.932) between microplastic abundance and recreational activities is found. Majority (65.12%) of the microplastics belongs to the size bracket of 300 μm-1 mm and only 34.88% were large microplastics (>1 mm). The Polymers of the microplastics were identified as Polypropylene, HDPE, LDPE, Polystyrene, Polyurethane etc. using Raman spectroscopy. Microplastic fragments comprise 56.32% of the total particles. In terms of colour of the microplastics, white (26.92%) is the most abundant.

Particle flux material collected in 2000 m depth in the Northeast Atlantic at 33°N and 22°W was analyzed for trace metals and persistent organic pollutants. Element enrichment factors relative to lithogenic Al were elevated indicating possible anthropogenic contributions for all trace metals except V. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls and the pesticide DDT exhibited median fluxes of 10.40 μg m⁻²d⁻¹,0.29 μg m⁻² d⁻¹, and 0.90 μg m⁻² d⁻¹, respectively. Flux composition reflected long range transport, with low molecular weight and low-chlorinated compounds dominating ∑₁₅PAH and ∑₂₃PCB. PAH isomer ratios identified fossil fuel combustion as the main ∑₁₅PAH source. The composition of ∑₄DDT suggested inputs of the fresh technical pesticide during high dust intensity periods. Pollutant fluxes showed seasonality linked to export production in the region, as well as a dependence on annual and sub-annual dust input events.

Despite the increasing interest in microplastic (MP) research, the accurate prevalence, distribution and fate of these materials in the environment is yet poorly known and, consequently, a focus of debate. Hence, to better ascertain the presence of microplastics in specific environments, samples from 35 random sites distributed across a 4200-meter long section from the area of Sidi Mansour, Sfax-Tunisia, were collected and analyzed. MPs were extracted, digested with potassium hydroxide and dyed with Eosin B, for visual microscopy counting and sorting. Polymer composition and surface morphology were identified by FTIR-ATR spectroscopy and SEM microscopy. Total abundances ranged from 252 to-5332 particles per m² where fragments and granules were the most frequent types of microplastics. These findings highlight the considerable presence of these materials in the studied harbor region and underscore the density dependence on the distribution and occurrence of MPs and how these tend to accumulate in the sandy sediments.

The prediction models of MWQI in mangrove and estuarine zones were constructed. The 2011–2015 data employed in this study entailed 13 parameters from six monitoring stations in West Malaysia. Spatial discriminant analysis (SDA) had recommended seven significant parameters to develop the MWQI which were DO, TSS, O&G, PO4, Cd, Cr and Zn. These selected parameters were then used to develop prediction models for the MWQI using artificial neural network (ANN) and multiple linear regressions (MLR). The SDA-ANN model had higher R2 value for training (0.9044) and validation (0.7113) results than SDA-MLR model and was chosen as the best model in mangrove estuarine zone. The SDA-ANN model had also demonstrated lower RMSE (5.224) than the SDA-MLR (12.7755). In summary, this work suggested that ANN was an effective tool to compute the MWQ in mangrove estuarine zone and a powerful alternative prediction model as compared to the other modelling methods.

Increased sediment loads within algal turfs, can be highly detrimental to coral reef systems. However, significant knowledge gaps remain in relation to sediment dynamics, especially linking suspended sediments, sedimentation and turf-bound sediments. To examine these links, a series of different methods for quantifying suspended sediments, sedimentation and the accumulation of turf sediments were compared, simultaneously, on an inner-shelf reef. We revealed that the amount and composition of sediment quantified using different methods varied markedly, with commonly employed measures of sedimentation failing to accurately reflect patterns of sediment accumulation in turfs. Our results highlighted the propensity for turfs to trap and retain sediments, with turfs accumulating approximately 2.6 times more sediment than traps, and 6 times more sediment than SedPods, over a seven-day period. This study highlights the major, but often overlooked, role that algal turfs can play in sediment dynamics on coral reefs.

Foreshore litter data from a UK citizen-science programme, combined with OSPAR data, were analysed for possible spatial patterns around Scottish and North Sea coastlines. Loading distributions were positively skewed, and statistics commensurate with such distributions were used. When considering coast type, litter loadings on Scottish harbour and river foreshores were influenced by local litter sources. When considering exposure to the predominant westerly winds over Scotland, litter loadings on the west coast (i.e. predominant onshore winds) were greater on foreshores on open coasts compared to those within embayments. The opposite was true for the Scottish east coast (i.e. predominantly offshore winds). The north east coast of the UK appeared to have an organised pattern of plastic litter loading, increasing in magnitude (median) and spread (inter quartile range) in the direction of the coastal flow. Four other coastal segments with similar patterns were suggested from the west of Scotland to Denmark.

Estimates of marine debris are often based on beach surveys. Few studies have documented the veracity of these observations and the factors that may affect accuracy. Our laboratory-scale experiment identified potential sources of error associated with visual identification of marine debris (1–2 cm long) during shoreline surveys of sand beaches. Characteristics of the survey site (beach characteristics), observer (personal characteristics), and debris (color and size) may be important factors to consider when analyzing data from shoreline surveys. The results of this study show that the ability of individuals to accurately identify plastic fragments depends on the plastic and sand color, and density of shell fragments. Most suggestively, the high accuracy of blue plastic counts (95%) and the under-counting of white (50%) and clear plastic counts (55%) confirmed the hypothesis that a significant amount of clear and white plastic fragments may be missed during shoreline surveys. These results highlight the need for further research and possible modifications of visual shoreline survey methodologies in order to optimize this cost-effective method of marine debris monitoring.

The diversity of free-living dinoflagellates in the coastal areas of the central Red Sea, Saudi Arabia, was studied from April 2016 to March 2017. A total of 106 dinoflagellates belonging to 36 genera, 20 families and 7 orders were identified and characterized using light microscopy. Of these, 47 taxa were potentially harmful, and 60 taxa were recorded for the first time from the Red Sea. The unexpectedly high species diversity, including new records, was due to the benthic species. The monthly variability of planktonic species records exhibited negative correlations with temperature and salinity, although in most cases, the links between them were insignificant. Subsequently, the dinoflagellates checklist for the entire Red Sea was updated and showed that there were currently 395 taxa and 66 genera. The results of this study provide a solid foundation for future studies of dinoflagellate biodiversity in the Red Sea, particularly for benthic and harmful species.

As the main fluorescent substances in oils, polycyclic aromatic hydrocarbons (PAHs) are the basis of ultraviolet (UV)-induced fluorescence spectroscopy methods to detect oil films on the sea surface. The relative contents of PAHs in six crude oil samples and their effects on ultraviolet fluorescence spectra were studied. The PAHs were divided into four categories according to their fluorescence characteristics. Naphthalene series dominated the fluorescence spectra, which led to a main peak at 320–350 nm, but this showed no relationship with PAH content. The six oil samples could not be distinguished by differences in the fluorescence spectra in this range, but could be distinguished by the fluorescence spectra in the 350–380 nm band. The relative contents of dibenzothiophene and phenanthrene series showed significant positive correlations (R² = 0.96) with fluorescence intensity. Fluorescence spectroscopy combined with GC–MS can be used to distinguish and identify crude oils.

Plastics constitute an important part of our life for many decades. All the wastes produced from human activities finally enters into the aquatic ecosystem. Microbial degradation of plastic is a promising eco-friendly strategy which represents a great opportunity to manage waste plastic materials with minimum adverse impacts. In this present study, totally 248 bacterial isolates were isolated from the plastic waste dumped sites in the coastal region districts of Tamil Nadu, India and screened for HDPE degradation. Based on the results obtained from the weight loss, viability and FT-IR, 10 bacterial isolates were considered to be potent HDPE degraders. The identification of efficient HDPE degrading isolates confirms that most of the bacterial isolates belong to the genus Bacillus spp. and Pseudomonas spp. The present study suggests that the isolated efficient bacterial strains can be used as cost-effective, eco-friendly and safe approach for the elimination of plastic wastes from the environment.