Marine litter, in particular plastic debris, poses a serious threat to marine life, human health and the economy. In order to reduce its impact, marine litter collections such as beach clean-ups are frequently conducted. This paper presents a systematic review of temporal developments, geographical distribution, quantities and waste treatment pathways of collected marine litter. Results from over 130 studies and projects highlight the worldwide increase in collection efforts. Many of these are in wealthy countries that do not primarily contribute to the problem. Over 250 thousand tonnes, have already been removed, but there is little or no information available regarding how this waste is treated or used post collection. This paper highlights the need for a whole-system quantitative assessment for the collection and waste treatment of marine litter, and identifies the challenges associated with utilising this waste in the future.

PURPOSE OF REVIEW: This article reviews the literature and presents the current status of the use of socio-acoustic surveys in soundscape studies, through the indication of appropriate question formats, types, and topics for each data collection method (soundwalks, interviews, listening tests, and focus group) for the involved public and acoustic stimuli. RECENT FINDINGS: The ISO 12913-2 establishes ways of data collection and reporting requirements for soundscape studies (International Organization for Standartization 2017), including the triangulation technique. This standard recommends some data collection methods, like soundwalks and interviews. Even so, some authors are using different methods to collect data, such as focus group and listening tests. This study investigated through 52 peer-reviewed papers published on the last 20 years the current status of socio-acoustic studies regarding question topics and types, used stimuli, and characteristics about the participants, using the four major adopted data collection methods in soundscape studies: soundwalks, interviews, listening tests, and focus group. Some topics like “soundscape quality” and “sound sources identification and evaluation” are common in the recent studies, as well as the adoption of some question types such as semantic differential scale, the staple scale, and ranking order scale.

The response of oyster (Crassostrea virginica) hemocytes was studied following exposure to anatase nanoparticles (ca. 7.4nm), surface-coated rutile nanocomposites (UV–Titan M212, ca. 86nm) and bulk titanium dioxide (TiO₂) particles (anatase and rutile crystalline forms; 0.4-0.5μm). Hemocytes were collected from oysters and exposed to one of the four particle types at concentrations of 0.1, 0.5, and 1.0mg/L under dark and environmentally-relevant light conditions for periods of two and four hours. Hemocyte mortality, phagocytosis, and reactive oxygen species (ROS) production were then evaluated using flow-cytometric assays. Bulk and nanoparticulate TiO₂ had little effect on viability of oyster hemocytes or on production of ROS. Significant changes in phagocytosis occurred after exposure to anatase nanoparticles for 4h under dark conditions, and UV–Titan for 2h under light conditions. Results demonstrate that TiO₂ particles (bulk or nanoscale) produce minimal effects on hemocyte biomarkers examined following acute, in vitro exposures.

Hydroid assemblage's responses to organic contamination were evaluated using sedimentary sterols as explanatory variables. At seven coral reef sites in the Havana west coast, hydroids were collected along three 10 m × 1 m, 10 m deep transects. Five sterols were analysed, i.e., coprostanol, an indicator of faecal contamination, and cholestanol, cholesterol, stigmasterol and brassicasterol, indicators of biogenic organic matter inputs. The sampling sites were classified by level of contamination. A total of 65 species comprised the hydroid assemblages. Hydroids community abundance and richness decreased in the contaminated sites. Coprostanol had the highest relative importance for these variables and also for Plumularia floridana and Clytia gracilis abundances. Obelia dichotoma and Halecium bermudense were relatively abundant in the contaminated sites. The results indicate that faecal contamination negatively affected the hydroid assemblages, highlighting the importance of integrated biological and chemical indicators to evaluate the environmental conditions of the Havana coral reef.

Coastal ecosystems are under significant human pressure, partly due to the proximity of pollution sources. In this study, a total of 20 samples were taken in summer around the coastal waters of the Balearic Islands (Spain) using a manta trawl net to examine the concentrations of floating plastic debris through the NIXE III project campaign. Although plastic concentrations showed high variability along the coast, the higher particle concentration (max: 4,576,115 items ⋅ km⁻²) and weight (max: 8,102.94 g(DW) ⋅ km⁻²) values were located at the north of the Balearic Promontory. The particle size analysis showed the high prevalence of microplastics (< 5 mm) in these waters, where particles of approximately 0.7 mm and 1 mm² were the most frequent in the range analyzed. The high plastic concentration values in the N-NW coast of Ibiza and Mallorca in sparsely populated locations suggest that the plastic particle distribution was mostly conditioned by the hydrodynamic surface conditions.

Microplastic contamination in surface waters of the South Funen Archipelago in Denmark was assessed. Therefore, ten manta trawls were conducted in June 2015. Moreover, 31 low-volume bulk samples were taken to evaluate, whether consistent results in comparison to the net-based approach can be obtained. Microplastic contamination in the South Funen Archipelago (0.07 ± 0.02 particles/m3) is slightly below values reported before. The sheltered position of the study area, low population pressure on adjacent islands and the absence of any major potential point sources were identified as major factors explaining the low concentration of microplastics. Within the Archipelago, harbors or marinas and the associated vessel traffic are the most probable sources of microplastics. The concentration of microplastics in low-volume bulk samples is not comparable to manta trawl results. This is mainly due to insufficient representativeness of the bulk sample volumes.

Marine litter has been considered a potential transport vector of non-indigenous species. In this study developed in Tjärnö (Sweden), at the entry of the Baltic Sea, the communities inhabiting coastal litter and natural substrates (N = 5448 macroorganisms) were monitored from eight sites of different ecological conditions. The results showed that litter can support high densities of marine organisms and represent a new habitat in the studied coast. The taxonomic profile of the communities supported by marine litter and hard natural substrate were significantly different. Moreover, opposite to the expectations of reduced diversity in artificial structures, more diverse communities were found on litter. Non-indigenous species were attached mainly to non-plastic artificial materials. From these results it can be concluded that marine litter can significantly alter the biotic composition of coastal ecosystem, representing a shelter for invasive species and diverse natives.

Sesuvium portulacastrum was treated with mixture of copper, zinc, and cadmium for 60 days, with the concentration of each metal ranging from 0 to 20 mg/L. The tolerance of plants and bioaccumulation of heavy metals were then investigated. The height of S. portulacastrum decreased significantly with increasing heavy metal concentrations from 1 to 20 mg/L. The biomass was adversely impacted when the concentration exceeded 5 mg/L. There were no significant differences in malondialdehyde (MDA) concentration among different treatment groups, while the soluble protein content and superoxide dismutase (SOD) activity decreased with increasing heavy metal concentration. However, the BCF values of the three metals were all higher than 10 and the tolerance in root was up to 1000 mg/kg without causing significant growth inhibition, suggesting that S. portulacastrum should be a potential candidate for phytostabilization for the phytoremediation of polymetallic contaminations in coastal environments.