Numerical modelling is a key tool in understanding and determining the sources, trajectories and fates of micro-plastic debris (MPD). In this study, we introduce TrackMPD, a new modelling framework for the 3D transport of marine debris. TrackMPD fills the gaps in previous models by: (1) using a three-dimensional approach; (2) providing compatibility with a variety of ocean models; and (3) including a wide range of physical processes (advection, dispersion, windage, sinking, settling, beaching and re-floating) and MPD behaviours that depend on particle dynamical properties, and the fouling and degradation states. We implement a sensitivity analysis based on 44 scenarios to assess the relative importance of the different processes and behaviours on the MPD trajectories and fates. Results show that the MPD dynamical properties that impact their sinking, in particular plastic density and biofilm thickness and density, have the biggest effect on the MPD transport, followed by turbulent dispersion and washing-off.

The present study aimed to develop monitoring methods for shallow water sessile and mobile epifauna with the main focus on enhancing the chance of early detection for new non-indigenous species (NIS) invasions. The field sampling was conducted between June and September in 2012, in the Archipelago Sea (Finland). The tested monitoring methods included baited traps that capture organisms and habitat collectors that provide habitat and refuges for organisms, as well as fouling plates. Catch efficiency of a trap/collector was defined as the number of NIS and all species caught, including their abundances. The American collector with oyster shells (habitat collector) caught the highest number of NIS, and their use is recommended in all places, where oyster shells are easily accessible. Sampling of all habitats of interest between 1 and 2 m depth is recommended with at least three habitat collectors per site.

Port baseline surveys (PBS) provide species inventories in and around ports, with a focus on non-indigenous species that may have been introduced by vessels, primarily via ballast water. PBS are an essential tool to support effective management strategies for non-indigenous as well as native harmful aquatic organisms and pathogens (HAOP). This paper describes the methodology of PBS that were conducted in 12 Adriatic ports. The PBS employed existing protocols that were adapted to meet the characteristics of the Adriatic sites. Their results are reported in several papers included in this special issue, each of which is devoted to a specific community. An overview of existing surveys protocols – which provide valuable support to decision-making and to design effective monitoring of non-indigenous species – is also supplied.

Concentrations and enrichment of major (Na, Al and Cl) and trace (V, Mn, Fe, Ni, Cu, Zn, As, Br, Mo, Hg, Pb and U) elements were evaluated in ²¹⁰Pb-dated sediment cores from saltmarsh areas surrounding an anthropized lagoon at southeastern Gulf of California. A chemometric approach was used to identify the sedimentary processes that control the variability of elements among the cores; and the elemental fluxes were compared among coring sites on the basis of historical urbanization and industrial development in the area. The highest fluxes and excess concentrations of V, Ni, Hg and Pb were observed after 1960 in cores EUI and EUIII, and in 1980 at EUII. In general, the historical trends of metal enrichment coincide with the growth of urban and industrial developments around the lagoon, and particularly with the beginning and full operation of a thermoelectric power plant in 1980s.

The interaction of microplastic (MP) with marine organisms is crucial for understanding the significant effect that MP and its additives may have on marine environments. However, knowledge regarding the magnitude of these pollutants in the Eastern Mediterranean Sea and the tropical Red Sea is still scarce. Here we examined the levels of phthalate acid esters (PAEs) and MP in Herdmania momus and Microcosmus exasperatus sampled along the Mediterranean and Red Sea coasts of Israel. High levels of dibutyl phthalate (DBP) and bis (2‑ethylhexyl) phthalate (DEHP) were found in ascidians at the majority of sampling sites, and MP particles were found in ascidians at all sites. As efficient filter-feeders and being widely-distributed, invasive ascidians present fundamental opportunities for the environmental monitoring of microplastic and its additives worldwide. The high levels of pollutants revealed emphasize the need for further research into the magnitude and effects of MP and PAEs in these regions.

Native generalist grazers can control the populations of non-indigenous invasive algae (NIIA). Here, it was found that the simultaneous consumption of two co-occurring NIIA, Caulerpa cylindracea and C. taxifolia var. distichophylla, hinders the grazing ability of the main Mediterranean herbivorous, the native sea urchin Paracentrotus lividus. The ingestion of any of the two NIIA alone did not produce any difference in sea urchin righting time with respect to usual algal diet. In contrast, the simultaneous consumption of both NIIA, which grow intermingled in nature and are consumed by P. lividus, retarded its righting behavior. Such result reveals substantial physiological stress in the sea urchin, which resulted in reduced motility and coordination. The reported findings reveal the potential of NIIA co-occurrence to escape the supposed control exerted by the main native generalist grazer in Mediterranean sublittoral communities, which in turn can be locked in an “invaded” state.

Vibrio species are widely distributed in the estuarine and coastal waters that possess the greatest threat to human health worldwide. In this study it is aimed to isolate and observe the abundance of Vibrio sp. and prevalence of biomarker genes and antibiotic resistance profile of V. cholerae isolated from the Port Blair bays of South Andaman. A total of 56 water samples were collected from the seven sampling stations of Port Blair bays in which maximum number of Vibrio sp. population density (1.78 × 10⁴) was recorded in Phoenix Bay. Among the 786 isolates 57.38% of the isolates were confirmed as Vibrio sp., Vibrio cholerae and Vibrio parahaemolyticus. PCR results revealed that the prevalence of biomarker genes was recorded maximum in the isolates from Phoenix Bay and Junglighat Bay samples. Upon further analysis, it was observed that the prevalence of hlyA gene (215 bp), was found to be the most widespread biomarker determinant in 84.17% of isolates. Major virulence determinants; ctxA, ompU and toxR genes were not detected in V. cholerae isolates from Port Blair bays. Maximum antibiotic resistance pattern was observed in Phoenix Bay isolates and maximum number of V. cholerae isolates was resistance to tetracycline (60.76%). Cluster and Principal Component Analysis were employed to understand the diversity and distribution of Vibrio isolates and its biomarker genes. Upon PCA analysis seasonal influence was not much perceived in Vibrio species diversity in Port Blair bays and the lack of significant difference in the detection of species diversity in this study is due to resemblance in geographical conditions and sources of pollution.

Heavy metal concentrations were investigated in water and sediments of Shadegan Wetland southwest of Iran to assess the fate, partitioning, and risk assessment and also to quantify the sources of heavy metals using MLR-APCS (multiple linear regression of absolute principal component scores) receptor model. The relatively high values of Kd (partition coefficient) for Pb, Zn, Ni, As, and V revealed their affinity for being enriched in sediments while Sb, Mo, and Se exhibited greater partitioning towards water. Enrichment factors of Se, Cd, Pb, Mo, Co, Zn, and Cu revealed significant to moderate contamination and should be of some concern. Application of the modified ecological risk index (MRI) revealed sediments moderate to high risk. Hazard index values for Hg were found less than the safe level. MLR-APCS model indicated that anthropogenic sources in sediments were responsible for 80.9%, 73.2%, 73.1%, 88.6% and 74.2% of Se, Mo, Hg, Pb, and Zn, respectively.

In oil spill models, vertical mixing due to turbulence is commonly modelled by random walk. If the eddy diffusivity varies with depth, failing to take the derivative of the diffusivity into account in the random walk scheme will lead to incorrect results. Depending on the diffusivity profile, the result may be either over- or underprediction of the amount of surfaced oil. The importance of using consistent random walk schemes has been known for decades in, e.g., the plankton modelling community. However, it appears not to be common knowledge in the oil spill community, with inconsistent random walk schemes appearing even in recent publications. We demonstrate and quantify the error due to inconsistent random walk, using a simplified oil spill model, and two different diffusivity profiles. In the two cases considered, a commonly used inconsistent scheme predicts respectively 58% and 176% the amount of surface oil, compared to a consistent scheme.

Along the Upper Gulf of Thailand, coastal fences and breakwaters have been constructed using bamboo since 2005. Despite their potential benefits, bamboo structures disintegrate within seven years releasing floating debris which severely damages mangrove tree stems. The aim of the study was to investigate whether such stem damage resulted in the decline of Avicennia spp. stands along the Upper Gulf of Thailand. Tree health assessments were conducted to assess the probability of crown dieback in damaged and undamaged trees. Satellite-derived time-series of vegetation indices were used to detect long-term forest decline. In contrast to the unaffected landward mangroves, seaward mangroves were unable to recover from insect-induced defoliation events after the collapse of a nearby fence. Furthermore, there was a significantly higher probability that damaged trees showed signs of moderate-to-severe crown dieback. It is recommended that bamboo fences be secured by replacing individual stems before they become detached.