Mediterranean Sea is among the world's leading tourist destinations; however, the sharp increase in tourists during the high season may affect coastal seawater. The main aim of this study was to evaluate the occurrence and temporal variation of anthropogenic nutrients in coastal seawater in relation to tourist flows in three Mediterranean islands (Cyprus, Sicily and Rhodes), through short-term macroalgae deployments, coupled with δ¹⁵N analysis and GIS mapping. In all islands, an overall increase in macroalgae δ¹⁵N occurred over the deployment carried out in August in the tourist sites, suggesting the presence of anthropogenic nutrients. Decreasing δ¹⁵N values occurred at increasing distance from the coastline in two out of the three islands (Cyprus and Sicily). This study revealed the usefulness of the approach used in the assessment of tourism impact in terms of trophic enrichment and its potential to support competent authorities for the development of sustainable coastal management plans.

Marine pollution caused by plastic litter can threaten the survival and health of marine organisms. In 2019, a juvenile fin whale (Balaenoptera physalus, length: 13.02 m, weight 12,000 kg) was found dead floating on the sea near Jeju Island, Republic of Korea. During the dissection, 45 plastic particles were found in the body of the whale, including fishing lines, plastic filaments, pieces of fishing nets, and Styrofoam particles. The largest item found was a piece of fishing line (1180 mm in length and 1.15 mm in thickness). Filaments, both bundled and separated, were more frequent. Some of the filaments found were entangled with the baleen plate bristles. These observations suggest that plastic pollution is a potential risk for baleen whale species. This is the first record of plastic ingestion by a vulnerable baleen whale species in the sea off East Asia.

Areas like the Mediterranean coastlines, which have high population density, represent locations of high pollution risk for surrounding environments. Thus, this study aims to compare data on the abundance, size, and composition of buoyant plastic particles collected during two weeks in 2019 in the Ligurian and Tyrrhenian Seas with data from 2018. The results from 2019 show average meso- and microplastic particle concentrations of 255,865 ± 841,221 particles km⁻², or 394.19 ± 760.87 g km⁻²; values which differ significantly from those reported in 2018. Microplastic particles accounted for 88.7% of the sample; the majority of which had a size range being between 1 and 2.5 mm. These data are an important milestone for long-term monitoring of the highly variable plastic pollution levels within this region; showing overlaps in zones of pollutant accumulation in addition to increased overall concentrations of plastic particles compared to previous data.

A comparison study was performed on anionic surfactant and phosphate concentrations between the entrance and the exit of Turkish Straits System (TSS). Surface water samples were collected at fall season in 2016 and the spring season in 2017. According to the values obtained from the samples taken from 6 stations at the entrance and 7 at the exit, anionic surfactant values were high at the exit of the TSS, while the phosphate concentrations were relatively lower. The high phosphate values at the entrance are related to the eutrophic feature of the Black Sea. Also, the location of these stations covers one end of the Canal Istanbul Project, which is planned to be built soon, so the data of this study will constitute an important database.

A fluorescence probe was delicately designed for the detection of malachite green (MG) in water and fish samples. Through the electrostatic self-assembly of CdTe QDs on the surface of polystyrene (PS) microspheres, the fluorescence signal was amplified. After grafting molecularly imprinted film, the fluorescence probe of MIP@PS@CdTe was fabricated and applied to the detection of MG based on fluorescence quenching. The linear range of MG detection was 0.01–20 μmol L⁻¹, and the detection limit was 4.7 nmol L⁻¹ (3σ, n = 9) which was much lower than those of the previous reports. The recoveries of MG in aquaculture water and fish samples ranging from 87.6% to 105.4% illustrated that the detection by MIP@PS@CdTe probe was accurate and reliable.

The aim of the present study was to evaluate the presence of polycyclic aromatic hydrocarbons (PAHs) in oysters (Crassostrea rhizophorae) collected from Todos os Santos Bay (Bahia, Brazil). The total PAH concentration was highest in Madre de Deus (36.3 to 37.8 ng g⁻¹ in dry weight, dw), which is located near a petrochemical complex, oil refinery, and commercial port. In the Paraguaçu river estuary, PAH concentrations varied between 23.2 and 25.7 ng g⁻¹ dw. The lowest concentrations (1.55 ng g⁻¹ dw) were found in the Jaguaribe river estuary, which can be considered a relatively preserved area. The main source of PAHs in the study areas was observed to be pyrogenic. Values of benzo[a]pyrene toxic equivalent ranged from 0.28 to 4.20. The concentrations of PAHs in oysters from the Paraguaçu river estuary and in Madre de Deus indicate the possible lifetime risk of developing cancer in humans who feed on it.

Strongylocentrotus intermedius cultured in the northern Yellow Sea in China was utilized to evaluate the effects of chronic CO₂-driven ocean acidification (OA) on adult sea urchins. Based on the projection of the Intergovernmental Panel on Climate Change (IPCC), present natural seawater conditions (pHNBS = 8.10 ± 0.03) and three laboratory-controlled OA conditions (OA₁, ΔpHNBS = − 0.3 units; OA₂, ΔpHNBS = − 0.4 units; OA₃, ΔpHNBS = − 0.5 units) were employed. After 60-day incubation, our results showed that (1) OA significantly repressed the growth of adult S. intermedius; (2) food consumption tended to be decreased with pH decline; (3) intestinal morphology was changed, and activities of intestinal cellulase and lipase were decreased under acidified conditions; (4) expression levels of two immune-related genes (SiTNF14 and SiTGF-β) were altered; (5) rate-limiting enzyme activities of the glycolytic pathway and tricarboxylic acid cycle (TAC) were changed in all OA treatments compared to those of controls.

This paper investigated the long-term changes (from 1973 to 2013) of the seagrass meadows of Zostera marina, Zostera noltei and Cymodocea nodosa in the Adriatic Sea subjected to multiple pressures. We examined the changes of the meadows by means of field data collection, observations and analysis of aerial photography to identify the most important drivers of habitat loss. The major decline of seagrass extension observed from 1973 to 1989, was primarily driven by urban development, and by the increase of the blue tourism. From 1989 to 2007 seagrass habitats progressively recovered due to the decrease of urbanization, but from 2007 to 2013 a further significant loss of seagrass meadows was apparently driven by thermal anomalies coupled with an increasing anthropogenic pressure. Our long-term analysis provides evidence that the rates of seagrass loss are faster than the recovery rates (i.e., −4.5 loss rate vs +2.5% recovery rate per year).

Here, I contribute new insight into why excess seawater nutrients are an increasingly identified feature at reef locations that have low resistance to thermal stress. Specifically, I link this unfavourable synergism to the development of enlarged (suboptimal) zooxanthellae densities that paradoxically limit the capacity of the host coral to build tissue energy reserves needed to combat periods of stress. I explain how both theoretical predictions and field observations support the existence of species-specific ‘optimal’ zooxanthellae densities ~1.0–3.0×10⁶ cellscm−². For the central Great Barrier Reef (GBR), excess seawater nutrients that permit enlarged zooxanthellae densities beyond this optimum range are linked with seawater chlorophyll a>0.45μg·L⁻¹; a eutrophication threshold previously shown to correlate with a significant loss in species for hard corals and phototrophic octocorals on the central GBR, and herein shown to correlate with enhanced bleaching sensitivity during the 1998 and 2002 mass bleaching events.