Laboratory experiments investigated oxygen dynamics in buried oiled sands sampled from areas impacted by the Macondo spill. Measured oxygen fluxes in oil deposits that were permeable to tidal water ranged from 10⁻³ to 10⁻⁴ μmol/cm²-sec, orders of magnitude higher than fluxes in non-permeable deposits (10⁻⁶ to 10⁻⁷ μmol/cm²-sec). Oxygen dynamics were well described by 1-d models that represent increased oxygen consumption in oiled sands. Experiments demonstrated that when oxygen is present and the oil deposit is permeable to tidal water, biodegradation of alkylated phenanthrenes and dibenzothiophenes proceeded over time scales (i.e., weeks) to have a significant impact on the mass and quality of buried oil. For this biodegradation process to proceed, two independent conditions must be met, a source of oxygenated water has to be present (e.g., tidal flushing in the intertidal zone) and the oiled deposit has to be permeable to water (i.e., pores cannot be completely saturated with oil).

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.

The 2010 Deepwater Horizon (DwH) oil spill in the Gulf of Mexico discharged ~3.19 million barrels of oil into Gulf waters, making it one of the largest marine disasters in history in terms of volume. We report on the results of a study to assess oil impacts to coastal fishes and invertebrates. Using two-decades of fisheries-independent data in coastal Alabama and Mississippi, we document variability following both natural and anthropogenic disturbances from two periods pre-DwH (1997–2001 and 2007–2009), one intra-spill period for acute DwH effects (2010–2012) and one period post-spill for chronic, longer-term impacts (2014–2017). Results indicated significant changes to community structure, relative abundance, and diversity in the intra-spill period. Causation for changes is confounded by variables such as behavioral emigration, altered freshwater inflow, death of consumers, and the mandated fishery closure. Results highlight the need for long-term, comprehensive monitoring/observing systems to provide adequate background for assessing future disturbances.

In order to determine the practicability of developing a protocol for bioassessing polar marine environment based on network analysis, microplankton communities and co-occurrence patterns at Ardley Cove and Great Wall Cove (King George Island, Antarctica) were studied in January 2016 through high-through sequencing. The spatial patterns and significant differences between community structures in two coves clearly reflect those in environmental heterogeneity. Moreover, both coves had their discriminated network structure and keystones. Then multivariate analyses to quantify the relationship between environmental variation and planktonic microbes response, give further evidence that nitrate and temperature, alone or in combination with other several parameters, structuring the communities respectively indeed. This study presents the first detailed description on co-occurrence networks between microbes and local environmental parameters in Antarctic coastal water. These findings suggest that co-occurrence networks based on planktonic microbes have the robust potential to assess environmental heterogeneity in polar marine ecosystem.

Anthropogenic nutrient enrichment results in hypoxia, ocean acidification and elevated nutrients (HOAN) in coastal environments throughout the world. Here, we examined the composition of biofilm bacterial communities from a nutrient-excessive fish farm with low dissolved oxygen (DO) and pH levels using 16S rRNA gene sequencing. HOAN was accompanied by higher bacterial diversity and richness, and resulted in an altered community composition than the control site. HOAN resulted in more Flavobacteriales, Rhizobiales, Epsilonproteobacteria and Vibrionales, but less Oceanospirillales and Alteromonadales. Photobacterium sp. and Vibrio sp. were mostly found to be exclusive to HOAN conditions, suggesting that HOAN could possibly proliferate the presence of these potential pathogens. Our study suggests the complexity of bacterial communities to hypoxia and acidification in response to increased nutrient loads, along with identities of nutrient, oxygen and pH-susceptible bacterial groups that are most likely affected under this ocean trend.

Differential response of Bruguiera cylindrica to individual (CuSO₄) and combined (CuSO₄ NaCl) effect was evaluated. The plantlets were treated with control, 0.15 mM CuSO₄, 400 mM NaCl and 0.15 mM CuSO₄ + 400 mM NaCl. Under combined stress, higher accumulation of Cu in the roots indicate that the roots are the primary site of Cu accumulation and thus the plant perform as an excluder and photosynthetic efficiency reduced drastically and significant enhancement in the superoxide and hydroxyl free radicals which increase membrane lipid peroxidation, leading to cellular damage and destruction. As evidenced from SEM-EDXMA, increase in Cu and Na⁺ levels in xylem and pith regions of leaf and stem and the presence of deeply stained structures, denoting the probable formation of complex containing the metal. Increased CaOx crystal forming cells (crystal idioblasts) reveals the regulation of bioaccumulated Cu and Na⁺ by complexing with CaOx. Thus the study suggested that, 400 mM NaCl and 0.15 mM CuSO₄ treatments does not have negative impact on plant growth, the NaCl tolerance potential compromised in the presence of mild CuSO₄ concentration during combined stress.

Spatial and temporal variations and trends of SST and Chl-a in the Persian Gulf were evaluated using MODIS data from 2002 to 2018. Trend indicator and key features were built up based on Mann-Kendall test, Hurst exponents and Wavelet Transform (WT) techniques to investigated the volatilities, trend estimation and persistence of original and WT signals. The key features revealed that the Chl-a pattern is heterogeneous in both time and spatial scale, whereas SST pattern is more homogenous. Trend analysis of the study area showed identifiable and sustainable trend with maximum tendency to decrease of Chl-a, and increase of SST. More than 48% of the study area is under slight decrease, and about 20% area mostly located at the northern parts show slight increase of Chl-a values. The presented methodology is applicable to the data signals that keep the range of inter-annual approximation components of DWT not less than scale level-4.

Along the Viña del Mar - Concón coastal strip 11,894 litter items were collected, and grouped into 48 different categories (11 litter typologies). The average litter abundance was 0.25 items/m², plastic items, and cigarette butts being the most common. Hazardous litter can be found along the entire study area, reaching 28.9% (3438 items of 11,894 total items collected distributed in 14 different categories), and an average of 0.071 items/m². The application of environmental evaluation indices based on litter data, allows categorizing the study area as a clean-moderate coastal strip with some presence of hazardous litter items, and unsatisfactory environmental conditions. Studied sectors were statistically grouped into three specific types that ranged from sectors in optimal environmental conditions (Group A) to sectors in adverse environmental conditions (Group C). The typology and magnitudes of litter found along the study area suggest a combination of sources that mainly include direct activities on the beach (recreational and smoking-related) as well dumping. In the same way, sanitary waste, ocean/waterway items, and items related to surfing activities were observed. Strategies for litter management and environmental quality improvement need to be developed and enforced.

Plastics and synthetic materials are polluting the world's oceans. In this study we exposed juvenile mussels, Mytilus edulis, to glass reinforced plastic (GRP) dust, under laboratory conditions. The study ran for a period of 7 days, to test for the morphological and potential physiological impacts of GRP. Infrared spectroscopy has revealed that the GRP resin material is poly diallyl phthalate. In mussels, particulate glass and plastics were detected in the digestive tubules and gills, with a suite of inflammatory features observed in all examined organs. In parallel, we observed the effect of powdered GRP on swimming behaviour and survival of water fleas, Daphnia magna. Polymer particles and fibreglass adhered to the filament hairs on appendages, including the caudal spine, in exposed organisms. Most importantly, swimming impairment and sinking of the animals were recorded shortly after exposure. The potential implications for severe localized impact of GRP on aquatic environment are discussed.

Identifying the transformations of heavy metal in different media is a scientific issue, and geographical detector is applied to evaluate the spatiotemporal stratified heterogeneity mechanisms for heavy metals in the Yangtze River Estuary. Heavy metal concentrations in water and sediment were consistent with lognormal distributions. Their concentrations were organized into four classes. Class 1 included concentrations that were less than or equal to 25%, Class 2 included those between 25%–50%, Class 3 concentrations were between 50%–75% and Class 4 were >75%, which were based on their lognormal distributions. In water and sediment, the mean heavy metal concentrations yearly decreased from 2012 to 2016. The Chongming area was significantly lower than those found in the other areas, which is the least affected area by anthropogenic activities. The explanatory power of sediment to spatiotemporal stratified heterogeneity of heavy metals in shellfish organisms was much greater than that of water.