Growing evidences revealed the deleterious impacts of microplastics (MPs) on marine organisms. However, the effects of MPs on the movement behavior of marine crustacean is poorly understood. Therefore, this study aims to evaluate the physiological and behavioral responses of mysid shrimp (Neomysis japonica) larvae to polystyrene (PS) and carboxylated polystyrene (PS–COOH). PS-COOH presented a greater physiological toxicity to shrimp larvae compared to PS, causing significant lethal and growth inhibition effect, owing to bioaccumulation of MPs inside stomach. Both two MPs decreased the feeding efficiency of larvae, showing weakened predation competence. Moreover, reduced hunting and/or explorative ability of shrimps caused by MPs was also identified, which was evidenced by an overall decrease in swimming activity, range and frequency after exposure. Our study firstly highlighted that micron-sized polystyrene particles had the negative effects on the movement behavior of mysid shrimp larvae, thus posing potential hazard to population dynamics and ecological function of marine crustacean.

Marine litter is a world-wide problem, but the knowledge on this topic in remote areas such as the poles and the deep-sea is still limited. This paper seeks to provide the first accounts of deep-sea litter in the South-Western Caribbean Sea. The survey used 5066 still images from ROV video surveys around four hydrocarbon exploratory drilling zones. Forty-eight deep-sea litter items were found at depths between 427 and 2561 m, and analyzed by three different marine litter classifications. Plastic was the most frequent material (65%) and general litter the main category (69%). Almost half of the deep-sea litter items were found close to marine organism. This baseline is a first step to further research of human impact on the marine bottoms of the Caribbean. The paper highlights the importance of deep-sea litter as a descriptor of marine pollution, and the role of scientific cooperation between off-shore industry and the academy.

Changes in seawater pH can alter the chemical speciation of waterborne chemical elements, affecting their bioavailability and, consequently, their bioaccumulation in marine organisms. Here, controlled environmental conditions and a ²¹⁰Pb radiotracer were used to assess the effect of five distinct pH conditions (pHT ranging from 7.16 to 7.94) on the short-term (9 days) accumulation of Pb in the blue mussel, Mytilus edulis. After 9 days of exposure, higher levels of Pb were observed in the soft tissues of mussels maintained in the lower pH conditions, while Pb levels accumulated by mussel shells showed no difference across pH conditions. These results suggest that pH decreases such as those predicted by ocean acidification scenarios could enhance Pb contamination in marine organisms, with potential subsequent contamination and effect risks for human consumers.

Field investigations and incubation experiment were carried out in the Dafengjiang River (DFJR) and Sanniang Bay (SNB) surface water from September 2017 to July 2018 to study the composition and spatio-temporal distributions of different nitrogen (N) species, lability of dissolved organic N (DON), and contributions of different N species from the DFJR to the dissolved inorganic N (DIN) level in the SNB. The spatio-temporal distributions of different N species exhibited significant seasonal variation (p < 0.05). The average contribution of DIN, DON, and particulate nitrogen (PN) to TN was 31.91%, 46.57%, and 21.52%, respectively. Comparatively being the dominant form of N in the study area, the average lability of DON across the incubation sites D1, D5 and D7 ranged from 72%–79%. DIN, DON, and PN from the DFJR respectively contributed to 55.95%, 7.03%, and 5.63% of water quality in the SNB.

Seagrass longevity up to 47 years in well-restored, well-sited seagrass restorations are demonstrated from 253 trials at 83 regional sites in tropical and subtropical portions of three oceans (Atlantic, Pacific, Indian Oceans). These trials include over 3.04 million planted units into 306.3 ha. Approximately 12% of the total global tropical restored seagrass by Van Katwijk, Thorhaug et al. (2016) calculations from 1786 trials are included. Almost all projects herein reviewed persisted since date of planting except several cases with harsh anthropogenic impact or forceful natural events in first post-planting months. The oldest tropical/subtropical restoration continually observed is 47 yrs, many are 35 yrs. An array of observed and/or measured restored services accompanied these. This review may provide informational background for government resource managers, legislators, scientists, and citizens concerning tropical/subtropical seagrass longevity. This data from these trials may substantiate future seagrass restoration investments. Public outreach, national & regional government training,and outreach occurred, needing continuation.

Capping represents an efficient and well-established remediation practice to contain pollutants in sediments. Coupling capping amendments with biodegradation is an emerging technology with great potential to promote simultaneous sequestration and oxidation of contaminants in situ. Capping materials alter the native sediment environment and affect the biodegradation potential of benthic microbial communities. The placement of materials specifically influences (i) porewater pH and composition, (ii) nutrient fluxes, (iii) electron accepting processes, (iv) bioavailability of contaminants, and (v) biofilm formation. This review summarizes current literature documenting the impact of these alterations on microbial ecology and biodegradation activity, describes recent advances in bioactive sediment caps, and identifies areas where additional research is warranted.

Dissolved inorganic nitrogen (DIN) enrichment accompanied by silicate deficiency in seawater can promote dinoflagellate growth over diatom growth and induce further negative ecological consequences. Here, we propose an easily exercisable method for silicate fertilization as a remedy of eutrophication. In the laboratory, rice husk ash (RHA) released silicate and phosphate in an atomic ratio range of 38–113 without a significant influence on DIN. During incubations of silicate-limited waters, low-dose fertilization increased the diatom/dinoflagellate ratio by 1–5 times. With the high-dose fertilizer addition, DIN, with an initial concentration of 7.63 ± 0.95 μmol l⁻¹, was exhausted in three days, and the diatom abundance increased by 19 times on the 5th day. The silicate fertilization method presented here can be applied independently in eutrophicated waters for dinoflagellate suppression and dissolved nitrogen removal; this method could also work as a supplementary measure to existing nutrient (N, P) reduction and biomanipulation efforts.

This study evaluated the toxicity of benzene, toluene, and xylenes (BTX), isolated and in binary mixtures to Mysidopsis juniae. The organisms were exposed to BTX, and combined effect patterns were predicted by applying the theoretical models of Concentration Addition and Independent Action. According to the LC50 of the isolated compounds, xylene (16.1 ± 2.4 mg L⁻¹) was considered the most toxic, followed by toluene (38.0 ± 5.3 mg L⁻¹) and, lastly, benzene (78.0 ± 2.9 mg L⁻¹). The binary combinations showed deviations from additivity, with exposure to the xylene–benzene mixture presenting as antagonistic, while the xylene–toluene and toluene–benzene mixtures were better explained by a dose ratio deviation, with toluene being responsible for the antagonistic pattern. This study provides new insights into toxicity prediction of a BTX mixture, which adds value to the risk assessment procedure over evaluation of chemical hazards on a case-by-case basis.

Demersal trawls provide an index of seafloor macrolitter abundance, but there are no published data from sub-Saharan Africa. We collected litter items from 235 trawls conducted to assess fish abundance off South Africa. Only 17% of trawls contained litter (3.4 items·km⁻², 2.1 kg·km⁻² but only 0.2 kg·km⁻² excluding four megalitter items). Plastic items predominated (88%), of which 77% floated once cleaned of epibionts. One LDPE bag manufactured three months before being caught carried pelagic goose barnacles Lepas anserifera, confirming that biofouling leads to rapid sinking of floating plastics. Fishery/shipping wastes comprised 22% of litter items (98% by mass; 73% excluding megalitter items); the remainder was general waste – mostly packaging or other single-use items – that could come from land- or ship-based sources. Litter was more abundant in deep water close to Cape Town. The annual demersal trawl survey is a useful way to monitor seafloor litter off South Africa.

The concentrations of total mercury (THg) and methylmercury (MeHg) were assessed in water, sediment and biota (54 species) samples from the coast of Laizhou Bay, to evaluate MeHg biomagnification in Laizhou Bay food web. The trophic web structure was determined with stable isotope ratios. The MeHg concentrations were highly variable among species ranged from 4.8 ng g⁻¹ in primary producers to 411.2 ng g⁻¹ in spotted sea bass. Weight and ecotype were the principal parameters related to the mercury concentrations for most species. The trophic magnification factors (TMFs) for MeHg and THg were 2.09 and 1.69, respectively, indicating that mercury biomagnification is occurring in this marine food web. The estimated weekly intake (EWI) and target hazard quotient (THQ) values demonstrated that consuming predatory fishes from the bay could cause potential health risks to humans.