The ferrous iron (Fe²⁺) facilitates the formation of root Fe plaque of wetland plants, but its effect on the tolerance of wetland plants to artificial sewage stress has been seldom reported. In this study, the influences of Fe²⁺ on the formation of Fe plaque and its effects on the tolerance of Spartina alterniflora to artificial sewage stress were investigated. The artificial sewage stress decreased the plant height and chlorophyll content and significantly increased the MDA content in leaves. The symptoms of these stresses were alleviated with increasing Fe²⁺ concentration accompanied by significant increase in leaf alcohol dehydrogenase activity. The increase of Fe²⁺ concentration significantly increased the root Fe plaque content and reduced the accumulation of toxic metals in leaves of S. alterniflora. These results support our hypothesis that the exogenous Fe²⁺ supply may enhance the stress resistance of S. alterniflora to artificial sewage containing heavy metals.

Around the coastline of the UK, macro-debris has been observed in average densities of over 700 items per metre. Systematic beach-cleans were conducted at 35 sites around the Scottish Orkney Islands, in order to quantify and categorise the level of marine debris found there. Litter was collected from 100 m transects and categorised by its material, broad source (terrestrial or marine) and potential sector source. Variation between sites, and the relative contribution of pre-determined environmental variables in influencing said variation, were analysed using the “capscale” function for a canonical analysis of principle coordinates (CAP). 513 items/m were observed, (77% plastic), with “String/cord (<1cm diameter)” being the most abundant and widely distributed litter type. 47% of macro-debris was attributed to the fishing sector and < 10% to leisure, living and tourism-associated activities. Conversely, the unique regional hydrodynamics must be examined further, before the source of any given item can be categorically assigned.

Acoustic data was collected across 15 sites distributed through the coastal area of Rio de Janeiro, Brazil, encompassing regions of different natural characteristics. Noise levels and the acoustic complexity index were calculated. Quantity and composition of anthropogenic sound sources varied across recording sites, with at least one type of sound source being registered in each location. A cluster analysis using third-octave levels from eight frequency bands divided recording sites into two groups, one considered as impacted by anthropogenic noise and the other as less-impacted. The noisiest recording locations were those with higher numbers of anthropogenic sound sources, specifically large ships. It was evidenced that anthropogenic noise affects not only noise levels, but also low-frequency acoustic complexity, which decreased in the presence of vessel traffic. The constant noise input of human activities tended to mask natural variability in the soundscape at lower frequencies.

This study separates marine carrying capacity into four key dimensions, i.e., social, economic, resource, and ecological, and uses the entropy method to evaluate the carrying capacity of China's 11 coastal regions during the period 2007–2016. We then predict the values of marine carrying capacity in the subsequent five years (2017–2021) using the grey Verhulst model. Results reveal a significant disparity in marine carrying capacity among the 11 coastal regions of China, and social and ecological carrying capacities illustrate among the four subcategories. Pearl River Delta in the south has the highest marine carrying capacity value and shows an increasing trend, while Yangtze River Delta and Bohai Rim Region in the north are stable. With regard to the predicted values for 2017–2021, forecasting results illustrate that the industrial structure of China's coastal areas is gradually turning towards the mode of diversified and comprehensive utilization of marine resources.

Seagrass are an important marine ecosystem of the Fiji Islands. We confirm six seagrass species from the archipelago and defined five broad categories of seagrass habitat. We report, with high confidence, seagrass meadows covering 59.19 km² of Fiji's shallow water habitats from literature and this study. Long-term monitoring of seagrass abundance, species composition, and seed banks at eight sentinel sites, found no long-term trends. Examination of key attributes that affect seagrass resilience identified meadows as predominately enduring and dominated by opportunistic species which had moderate physiological resistance, and high recovery capacity. We examined threats to Fiji's seagrass meadows from extreme climatic events and anthropogenic activities using a suite of indicators, identifying water quality as a major pressure. Based on these findings, we assessed existing protections in Fiji afforded to seagrass and their services. This understanding will help to better manage for seagrass resilience and focus future seagrass research in Fiji.

Data on the occurrence and abundance of meso and microplastics for the South Pacific are limited and there is urgent need to fill this knowledge gap. The main aim of the study was to apply a rapid screening method, based on the fluorescence tagging of polymers using Nile red, to determine the concentration of meso and microplastics in biota, sediment and surface waters near the capital cities of Vanuatu and Solomon Islands. A spatial investigation was carried out for sediment, biota and water as well as a temporal assessment for sediment for two consecutive years (2017 and 2018). Accumulation zones for microplastics were identified supported by previous hydrodynamic models. Microplastics were detected for all environmental compartments investigated indicating their widespread presence for Vanuatu and Solomons Islands. This method was in alignment with previous recommendations that the Nile red method is a promising approach for the largescale mapping of microplastics in a monitoring context.

The explosive growth of phytoplankton under favorable conditions in subtropical coastal waters can lead to water discolouration and massive fish kills. Traditional water quality monitoring relies on manual field sampling and laboratory analysis of chlorophyll-a (Chl-a) concentration, which is resources intensive and time consuming. The cloudy weather of Hong Kong also precludes using satellite images for algal blooms monitoring. This study for the first time demonstrates the use of an Unmanned Aerial Vehicle (UAVs) to quantitatively map surface water Chl-a distribution in coastal waters from a low altitude. An estimation model for Chl-a concentration from visible images taken by a digital camera on a UAV has been developed and validated against one-year field data. The cost-effective and robust technology is able to map the spatial and temporal variations of Chl-a concentration during an algal bloom. The proposed method offers a useful complement to traditional field monitoring for fisheries management.

The development of the Grijalva-Usumacinta river basin exerts modifications on its discharge area. A sediment core was studied to reconstruct environmental changes and trace element contamination status during the past 45 years. ²¹⁰Pb-derived mass accumulation rates indicate higher sediment input to the area since 1995, related to increased precipitation and floodings in the catchment area. Sediments show finer particles from the late 1970s on, likely related to dams construction upriver and/or land use changes. Heavy metal enrichment factors (EF < 2) suggest minimum contamination. Benthic foraminifera and redox-sensitive - elements (As, Ba, Co, Cr, Cu, Ni, Pb, V and Zn) indicate the sediments before 2000 were deposited under oxygenated conditions. Afterwards, environmental conditions changed and benthic foraminifera and dinocysts assemblages changed suggesting eutrophication and lower oxygen conditions during the last 20 years. Monitoring should be continued to assess eutrophication/hypoxic/pollution trends that could become deleterious to the marine biota.

This study presents the first report on the concentration of trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) in the blood and egg fractions of green turtles from Rocas Atoll, a pristine nesting site in NE Brazil. The highest concentrations of all elements were in the blood or shell samples. In order, iron, Zn, Cu, Al and As presented the highest concentrations in all tissues. The nonessential trace elements were below the limit of detection for more than 50% of the yolk (Al, Cd and Pb) and albumen samples (Al, As, Ba, Cd and Pb). This study will serve as a baseline reference for future monitoring of the ecotoxicology of breeding green turtles in the southwestern Atlantic Ocean.

The Yellow River Delta (YRD) is an important spawning and nursery area for numerous fishes. The concentrations of Fe, Al, Mn, Zn, Ni, Cr, Cu, Co, Pb and Cd in muscle, liver, gills and skin of two broadly distributed commercial fish in the YRD were analyzed. The results demonstrated that liver and gills displayed higher accumulation ability of metals than other tissues, while muscle always accumulated the lowest concentrations of metals. Generally, significant opposite relationships (p < 0.05) were observed between fish size and metals in fish tissues especially in muscles of both fish species which may be explained by the lower feeding rate, stronger detoxification and elimination mechanisms in the bigger individuals. All metals in muscles were well below the proposed toxic limit. Besides, the toxic effects were not expected to occur for the consumption of muscles of studied fish according to the results of human health risk assessment.