Microplastic (<5 mm) ingestion has been recorded in Galeus melastomus, the blackmouth catshark, around the Balearic Islands. In total 125 individuals were analyzed for microplastic ingestion. Results ...have shown that 16.80% of the specimens had ingested a mean value of 0.34 ± 0.07 microplastics/individual. Stomach fullness index ranged from 0.86 to 38.89% and regression analyses showed that fuller stomachs contained more microplastics. A higher quantity of filament type microplastics were identified compared to granular or hard plastic type. No significant differences were given between ingestion values of two locations over the continental shelf providing further evidence of the ubiquitous distribution of microplastics. The findings in this study reflect the availability of this man made contaminant to marine species in seafloor habitats. Based on results from this study, data on microplastic ingestion could be used to study trends in the amount and composition of litter ingested by marine animals in accordance with descriptor 10 of the Marine Strategy Framework Directive.
Display omitted
•16.80% of the analyzed sharks ingest 0.34 ± 0.07 microplastics per individual.•G. melastomus with more replenished stomachs had higher quantities of microplastics.•Higher presence of microplastics filament in stomach contents of G. melastomus.•G. melastomus could be used as a common indicator species for microplastic ingestion.
Galeus melastomus inhabiting the continental shelf off the western Mediterranean Sea ingest 0.34 ± 0.07 microplastics/individual.
Marine litter loads in sea compartments are an emergent issue due to their ecological and biological consequences. This study addresses microplastic quantification and morphological description to ...test spatial differences along an anthropogenic gradient of coastal shallow sediments and further on to evaluate the preferential deposition of microplastics in a given sediment grain fraction. Sediments from Marine Protected Areas (MPAs) contained the highest concentrations of microplastics (MPs): up to 0.90 ± 0.10 MPs/g suggesting the transfer of microplastics from source areas to endpoint areas. In addition, a high proportion of microplastic filaments were found close to populated areas whereas fragment type microplastics were more common in MPAs. There was no clear trend between sediment grain size and microplastic deposition in sediments, although microplastics were always present in two grain size fractions: 2 mm > x > 1 mm and 1 mm > x 0.5 mm.
•MPs loads are greater in marine protected areas than in the urbanized coastal zone.•Filaments are found in areas close to urbanization.•MPs are present in all sediment grain sizes of 2 mm > × > 1 mm and 1 mm > × 0.5 mm.•There is spatial variability in MP deposition in shallow coastal sediments.
This bibliographic review provides an overview of techniques used to detect marine litter using remote sensing. The review classified studies in terms of platform (satellite, aircrafts, drones), ...sensors (passive or active), spectral (visible, infrared, microwaves), spatial resolution (<1 to >30 m), type and size (macroplastics, microplastics), or classification methodology (sighting, photointerpretation, supervised). Most studies applied satellite information to address marine litter using multi- and hyper- spectral optical sensors. The correspondence analysis on analyzed variables exhibited that aircrafts with high spatial resolution (<3 m) with optical sensors (λ = 400 to 2500 nm) seem to be the most optimum combination to target marine litter, while satellites carrying Synthetic Aperture Radar (SAR) sensors (λ = 3.1 to 5.6 cm) may detect sea-slicks associated to surfactants that might contain high concentration of microplastics. Gaps indicate that future goals in marine litter detection should be addressed with platforms including optical and SAR sensors.
•Combinations of platform, sensors, spectral resolution are addressing marine litter.•Optical sensors onboard aircrafts target marine litter at precise spatial resolution.•Sea-slicks might be inferred by SAR sensors.•Marine litter detection requires optical and SAR sensors for future advances.
The Mediterranean Sea has been described as one of the most affected areas by marine litter in the world. Although effects on organisms from marine plastic litter ingestion have been investigated in ...several oceanic areas, there is still a lack of information from the Mediterranean Sea. The main objectives of this paper are to review current knowledge on the impact of marine litter on Mediterranean biodiversity, to define selection criteria for choosing marine organisms suitable for use as bioindicator species, and to propose a methodological approach to assessing the harm related to marine litter ingestion in several Mediterranean habitats and sub-regions. A new integrated monitoring tool that would provide the information necessary to design and implement future mitigation actions in the Mediterranean basin is proposed.
According to bibliographic research and statistical analysis on current knowledge of marine litter ingestion, the area of the Mediterranean most studied, in terms of number of species and papers in the Mediterranean Sea is the western sub-area as well as demersal (32.9%) and pelagic (27.7%) amongst habitats.
Applying ecological and biological criteria to the most threatened species obtained by statistical analysis, bioindicator species for different habitats and monitoring scale were selected. A threefold approach, simultaneously measuring the presence and effects of plastic, can provide the actual harm and sub-lethal effects to organisms caused by marine litter ingestion. The research revealed gaps in knowledge, and this paper suggests measures to close the gap. This and the selection of appropriate bioindicator species would represent a step forward for marine litter risk assessment, and the implementation of future actions and mitigation measures for specific Mediterranean areas, habitats and species affected by marine litter ingestion.
Display omitted
•Marine litter ingestion represents a serious harm to Mediterranean biodiversity.•A bibliographic research and statistics identified the most affected habitat/species by marine litter ingestion in the Med.•The identification of suitable bioindicators is necessary to address the effects of marine litter on marine fauna and habitat.•To assess the harm by marine litter ingestion is necessary to quantify its presence and ecotoxicological effects.
Selection of suitable bioindicators of marine litter ingestion and the simultaneous quantification of its presence and ecotoxicological effects is recommended in order to monitor the impact on Mediterranean fauna and habitats.
•Review of available quantitative data on marine litter in the Mediterranean basin.•Reviewing main litter types according to groups of interactions with species and feeding strategies.•Several taxa ...and species are affected by marine litter, both at water column and seafloor.•Biodiversity is under threat with key species under protection particularly influenced by marine litter.
The Mediterranean Sea is one of the most polluted seas worldwide, especially with regard to plastics. The presence of this emerging man made contaminant in marine environments precludes large effects and interactions with species exposed to massive litter quantities. In this review, available data of floating and seafloor litter around Mediterranean sub-basins are reported. A review of scientific literature on the interaction of plastic with marine biota resulted in the identification of 134 species, several taxa and feeding strategies affected from 1986 to 2014. Data from 17,334 individuals showed different levels of ingestion and effects on catalogued IUCN species (marine mammals and sea turtles) in addition to several pelagic fish and elasmobranchs. Biodiversity is certainly under threat, and knowledge of the extent of taxa affected is of concern considering the increasing plastic loads in the Mediterranean Sea and worldwide.
Plastic debris is a growing environmental problem on a global scale, as plastics and microplastics (MPs) can be ingested by marine organisms, inducing toxic effects. The aim of this study was to ...assess MP intake and antioxidant responses in three bioindicator species: red mullet, bogue, and anchovy (Mullus surmuletus, Boops boops, and Engraulis encrasicolus, respectively) for plastic contamination in the Mediterranean Sea. MP intake was assessed in the gastrointestinal tract of the fish. Further, several enzymes from both the liver and brain were analysed. The antioxidant defences, catalase (CAT) and superoxide dismutase (SOD), as well as the detoxifying enzyme glutathione-S-transferase (GST), were measured in both tissues. The acetylcholine esterase (AchE), as an indicator of neuronal damage, was measured in the brain. Malondialdehyde (MDA) was analysed as a marker of oxidative damage in the brain and liver samples. Total MP intake and MP typology differed between the three species, with M. surmuletus showing the lowest intake of MPs, while B. boops showed the highest intake of MPs. An increase in both antioxidant enzymes was evidenced in E. encrasicolus liver activity with respect to MP intake. In brain samples, an increase in CAT activity was found in M. surmuletus and B. boops as a consequence of MP ingestion. SOD activity in the brain increased in B. boops and E. encrasicolus that had ingested MPs. GST activity increased in the liver of M. surmuletus’ and in brains of B. boops that had ingested MPs. The intake of MPs is species related, as well as being inherently linked to the habitat they live in and being able to induce a light activation of species-specific detoxifying and antioxidant mechanisms.
We have applied a multispecies ecosystem approach to analyse the ingestion of anthropogenic particles (AP) in the gastrointestinal tract of 313 individuals (17 fish species and 8 invertebrate ...species) from pelagic, demersal and benthic habitats in a marine protected area off the Western Mediterranean (Cabrera National Park). We have quantified and characterized the ingestion at several taxonomic levels of fish, sea urchins, sea cucumbers, bivalves, and jellyfish in relation to biotic/abiotic factors based on taxonomic groups, trophic guilds (functional groups) and habitats. AP ingestion occurrence ranged from 26 to 100% with no significant differences among taxonomic groups. The fish within the MPA showed an overall ingestion occurrence ranging from 0 to 100%, the echinoderms from 29 to 100%, the bivalves from 72 to 96% and the jellyfish 36% ingestion. The ecosystem approach applied to evaluate overall AP ingestion within the species reported that for trophic guilds, the omnivorous species ingested the highest amounts of anthropogenic items, while herbivores ingested significantly fewer items than all other trophic guilds. Moreover, no significant differences were found amongst habitats, indicating a homogeneous spatial distribution of APs at all studied habitats. The multispecies approach provided insight into the high APs exposure to species within Cabrera MPA, highlighting the potential harm linked with marine litter that threatens marine biodiversity.
The Mediterranean Sea is adversely affected by human activities, of which the release of mismanaged waste into the marine environment, primarily plastic pollution, is one of the most omnipresent. The ...primary goal of this study is to link microplastic ingestion in several bioindicator species and creating hazard maps from microplastics sampled along the seafloor, in the hyperbenthos and along the sea surface layer in a Marine Protected Area (MPA). Considering the connectivity between these layers, the findings of this study identify areas of concern, especially within bay areas, where marine diversity is exposed to microplastic debris ingestion. In terms of exposure to plastic debris, our findings indicate that areas with high species diversity are particularly vulnerable to plastic exposure. The best model integrated the mean exposure of each species to plastic debris across each layer and the nektobenthic species inhabiting the hyperbenthos layer were found to be the most at risk. Furthermore, the cumulative model's scenario indicated a higher risk to plastic ingestion when all habitats were considered jointly. Overall, the findings of this research highlight marine diversity in a Mediterranean MPA are vulnerable to microplastic pollution, and this study's proposed exposure methodology is applicable to other MPAs.
Display omitted
•Bathymetry as a proxy for suitable habitat for bioindicator species•Connectivity between seafloor, hyperbenthos and sea surface layers increases exposure risk.•Species in the hyperbenthos layer are more exposed to plastic ingestion.
The marine environment has numerous impacts related to anthropogenic activities including pollution. Abundances of microplastics (MPs) and other pollutants are continuously increasing in the marine ...environment, resulting in a complex mixture of contaminants affecting biota. In order to understand the consequences, a review of studies analyzing combined effects of MPs and other types of pollutants in bivalves has been conducted as species in this group have been considered as sentinel and bioindicators. Regarding studies reviewed, histological analyses give evidence that MPs can be located in the haemolymph, gills and gonads, as well as in digestive glands in the intestinal lumen, epithelium and tubules, demonstrating that the entire body of bivalves is affected by MPs. Moreover, DNA strand breaks represent the most relevant form of damage caused by the enhanced production of reactive oxygen species in response to MPs exposure. The role of MPs as vectors of pollutants and the ability of polymers to adsorb different compounds have also been considered in this review highlighting a high variability of results. In this sense, toxic impacts associated to MPs exposure were found to significantly increase with the co-presence of antibiotics or petroleum hydrocarbons amongst other pollutants. In addition, bioaccumulation processes of pollutants (PAHs, metals and others) have been affected by the co-presence with MPs. Histological, genetic and physiological alterations are the most reported damages, and the degree of harm seems to be correlated with the concentration and size of MP and with the type of pollutant.
Plastic marine pollution is an increasing threat to global marine diversity. Quantifying this threat is particularly difficult and complex, especially when evaluating multiple species with different ...ecological requirements. Here, we examine the semi-enclosed basin of the Mediterranean Sea where the inputs of plastic pollution and its impact on marine diversity are still widely unknown. Eighty-four species from six taxonomic classes were evaluated to assess the risk of ingesting plastic marine debris, integrating inter-specific factors such as plastic exposure rates and life history traits (e.g., motility, habitat, and body size). Species were modelled within a spatial context to identify and estimate their exposure to plastic ingestion across the Mediterranean Sea using literature data, species distribution maps and plastic dispersion models. Our approach identified hotspots for the risk of plastic ingestion across multiple taxa in the Mediterranean Sea, highlighting that coastal species are at higher risk of ingesting plastic in the marine environment than open-sea species. The plastic exposure analysis indicated that species with larger home ranges were more at risk of exposure with increased distances while local species were more likely to be exposed to plastic closer to the centre of their home range location. The approach used in this study can be applied to support management and mitigation efforts throughout the Mediterranean Sea and in other geographic regions to minimize the impact of plastic pollution on marine diversity.
Display omitted
•Mediterranean marine diversity is at high risk of plastic exposure.•A signal regression improves modelling exposure to plastic debris.•Species' homerange and life history traits predicted plastic ingestion.•Coastal areas are hotspots for plastic ingestion.
PDF