What Are Lake Beaches Made of? An Assessment of Plastic Beach Litter on the Shores of Como Bay (Italy)

Plastic waste dispersion is a well-recognized environmental threat, despite continuous efforts towards improving waste disposal management over the last few decades. Plastic litter is known to strongly impact upon water bodies and shorelines, affecting the health of ecosystems and impacting upon the aesthetic value of sites. Moreover, plastic waste that is abandoned on beaches contributes towards different degradation processes that potentially lead to the formation of secondary microplastics (MPs), with likely cascade effects upon the whole ecosystem. In this view, this study aims to characterize the plastic beach litter found on the shores of the western basin of Como Lake (Italy) to better understand the origin of MPs in littoral sediments, including the recognition of object typologies and the chemical characterization of polymers using Fourier-transformed infrared analysis (FTIR). The results highlighted that the most abundant polymers on beaches are polypropylene (PP) and polyethylene (PE), representing 73% of the collected polymers. This confirms that floating, low-density polymers are more likely to accumulate on beaches. Moreover, almost 66% of litter is represented by commonly used manufactured items (disposable objects, packaging, and everyday items). This evidence, combined with the analysis of the main environmental features of the sampling sites (the main winds, distance to urban areas, and the presence of tributaries) indicate that abundance of beached litter is mainly linked to beach accessibility and the local winds. These results highlight that multiple factors affect the environmental fate of plastic litter and give insights into the assessment of secondary microplastics in beach sediments.publishedVersio

Freshwater Lacustrine Zooplankton and Microplastic: An Issue to Be Still Explored

Lakes are essentially interlinked to humans as they provide water for drinking, agriculture, industrial and domestic purposes. The upsurge of plastic usage, its persistence, and potential detrimental effects on organisms cause impacts on the trophic food web of freshwater ecosystems; this issue, however, still needs to be explored. Zooplankton worldwide is commonly studied as an indicator of environmental risk in aquatic ecosystems for several pollutants. The aim of the review is to link the existing knowledge of microplastic pollution in zooplankton to assess the potential risks linked to these organisms which are at the first level of the lacustrine trophic web. A database search was conducted through the main databases to gather the relevant literature over the course of time. The sensitivity of zooplankton organisms is evident from laboratory studies, whereas several knowledge gaps exist in the understanding of mechanisms causing toxicity. This review also highlights insufficient data on field studies hampering the understanding of the pollution extent in lakes, as well as unclear trends on ecosystem–level cascading effects of microplastics (MPs) and mechanisms of toxicity (especially in combination with other pollutants). Therefore, this review provides insight into understanding the overlooked issues of microplastic in lake ecosystems to gain an accurate ecological risk assessment.publishedVersio

Physicochemical and biological ageing processes of (micro)plastics in the environment: a multi-tiered study on polyethylene

Pollution by plastic and microplastic impacts the environment globally. Knowledge on the ageing mechanisms of plastics in natural settings is needed to understand their environmental fate and their reactivity in the ecosystems. Accordingly, the study of ageing processes is gaining focus in the context of the environmental sciences. However, laboratory-based experimental research has typically assessed individual ageing processes, limiting environmental applicability. In this study, we propose a multi-tiered approach to study the environmental ageing of polyethylene plastic fragments focusing on the combined assessment of physical and biological processes in sequence. The ageing protocol included ultraviolet irradiation in air and in a range of water solutions, followed by a biofouling test. Changes in surface characteristics were assessed by Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle. UV radiation both in air and water caused a significant increase in the density of oxidized groups (i.e., hydroxyl and carbonyl) on the plastic surface, whereby water solution chemistry influenced the process both by modulating surface oxidation and morphology. Biofouling, too, was a strong determinant of surface alterations, regardless of the prior irradiation treatments. All biofouled samples present (i) specific infrared bands of new surface functional groups (e.g., amides and polysaccharides), (ii) a further increase in hydroxyl and carbonyl groups, (iii) the diffuse presence of algal biofilm on the plastic surface, and (iv) a significant decrease in surface hydrophobicity. This suggests that biological-driven alterations are not affected by the level of physicochemical ageing and may represent, in real settings, the main driver of alteration of both weathered and pristine plastics. This work highlights the potentially pivotal role of biofouling as the main process of plastic ageing, providing useful technical insights for future experimental works. These results also confirm that a multi-tiered laboratory approach permits a realistic simulation of plastic environmental ageing in controlled conditions

Ecology, Status and Conservation of the White Shark, Carcharodon carcharias, in the Mediterranean Sea

The regular occurrence of the white shark, Carcharodon carcharias, in the Mediterranean Sea has been recorded since the Middle Ages (476-1453). Several studies have documented its presence throughout the basin, but only a few authors attempted to undertake a comprehensive study of this species at the scale of the Mediterranean Sea. With the addition of five new contemporary records along the coast of Sardinia (Italy) to the existing available data (sightings and catches), the number of reports of white sharks in the Mediterranean Sea has increased to 627 records, which range from the Middle Ages to 2013. The white shark appears to be more common in the western part of the Mediterranean Sea, in the Adriatic Sea and in the Sicilian Channel. Temporal analysis shows that white sharks are more frequently observed during summer months. All size classes have been recorded in the Mediterranean. However, the highest occurrence of young of the year has been recorded in the Sicilian Channel, in the Adriatic Sea and in the Aegean Sea. In the Mediterranean Sea the white shark exhibits a broad diet: the most common prey found included small cetaceans (Tursiops truncatus, Stenella coeruleoalba), tuna (Thunnus spp.), swordfish (Xiphias gladius) and loggerhead turtle (Caretta caretta). A total of 54 white shark records refer to an interaction with humans, which includes 43 bites and 11 reports of the presence of human remains in the stomach of captured animals. Analysis of temporal variation in mean lengths of white sharks found a decreasing trend from 1913 to 2012. The decreasing body size of great white sharks suggests this species is declining in the Mediterranean Sea. Urgent management decisions are currently needed to address this problem at international level

Ecological factors affecting the whale shark occurrence in Djibouti and presence of contaminants in the trophic web

Djibouti is an important site where the whale shark (Rhincodon typus Smith 1828) regularly aggregates. Sharks gathering off the Djibouti coast are mostly juvenile males and target dense concentrations of zooplankton. However, only few studies has been carried out, leaving a knowledge gap on the main aspects of the whale shark ecology. Therefore, the main outcome of this study is to determine the environmental factors influencing the presence and distribution of this species in Djibouti. A robust understanding of the spatiotemporal distribution is required for developing successful management strategies for the whale shark protection in this area. Moreover, whale sharks may be potentially exposed to relatively high levels of contaminants in Djibouti since they aggregate along one of the world busiest shipping route. Although the massive release of pollutants in African marine ecosystems and the deleterious effects on biota and humans, at present almost nothing is known about the contamination status of the Gulf of Aden, including Djibouti. The scarcity of studies includes all trophic levels, therefore, with a bottom-up approach, starting from zooplankton to get to predatory shark species, this study aims to characterize the trophic chain from an ecotoxicology point of view. With global decline in shark numbers, evaluating the extent of contaminant exposure is an urgent aspect since anthropogenic pollution may exasperate the current situation. Furthermore, since elasmobranchs are component of the artisanal fishery in Djibouti, and seafood consumption is as an important source of contamination for humans, this study aims to estimate for the first time the exposure health risks derived from shark consumption

What Are Lake Beaches Made of? An Assessment of Plastic Beach Litter on the Shores of Como Bay (Italy)

Plastic waste dispersion is a well-recognized environmental threat, despite continuous efforts towards improving waste disposal management over the last few decades. Plastic litter is known to strongly impact upon water bodies and shorelines, affecting the health of ecosystems and impacting upon the aesthetic value of sites. Moreover, plastic waste that is abandoned on beaches contributes towards different degradation processes that potentially lead to the formation of secondary microplastics (MPs), with likely cascade effects upon the whole ecosystem. In this view, this study aims to characterize the plastic beach litter found on the shores of the western basin of Como Lake (Italy) to better understand the origin of MPs in littoral sediments, including the recognition of object typologies and the chemical characterization of polymers using Fourier-transformed infrared analysis (FTIR). The results highlighted that the most abundant polymers on beaches are polypropylene (PP) and polyethylene (PE), representing 73% of the collected polymers. This confirms that floating, low-density polymers are more likely to accumulate on beaches. Moreover, almost 66% of litter is represented by commonly used manufactured items (disposable objects, packaging, and everyday items). This evidence, combined with the analysis of the main environmental features of the sampling sites (the main winds, distance to urban areas, and the presence of tributaries) indicate that abundance of beached litter is mainly linked to beach accessibility and the local winds. These results highlight that multiple factors affect the environmental fate of plastic litter and give insights into the assessment of secondary microplastics in beach sediments

Cuvier's beaked whale (Ziphius cavirostris) detection through surface-sourced eDNA: A promising approach for monitoring deep-diving cetaceans

Among cetaceans, the Cuvier’s beaked whale is considered an extreme diver, thus not one of the easiest cetacean species to be studied due to its elusive behaviour and a preference for deep offshore waters. Although dedicated cetacean surveys have increased our knowledge on the distribution of Cuvier’s beaked whales in the Mediterranean Sea, knowledge gaps still remain where the study effort is non-existent. In this context, the use of new molecular methodologies capable of intercepting small traces of DNA left in the environment (eDNA) by marine organisms represents a valid approach to infer species’ occurrence. Moreover, the collection of water from the superficial layer is suitable for targeting marine mammals, as the constraints imposed by their nature implies periodic and frequent surfacing in order to breathe, releasing exhalants rich in their epithelial cells. Therefore, we designed and tested a taxon-specific primer set to infer Cuvier’s beaked whale presence, with the aims of 1) examining the effectiveness of the eDNA technique to detect the presence of a deep-diving cetacean in open waters, using the Cuvier’s beaked whale as case study; 2) providing data on the occurrence of this species within the Canyon of Caprera over a six-months study period and 3) assessing the species presence in adjacent waters in the central northern Mediterranean Sea based on the analysis of samples collected in a Citizen Science campaign. Results from this study demonstrated that superficial waters may retain biological traces of this cetacean despite the fact that it mostly inhabits deep waters. Specifically, this study provides evidence of the regular presence of Cuvier’s beaked whale in the Canyon of Caprera, with a preference for bathymetry in the range of 700–1000 m. Molecular traces’ distribution suggests a potential inshore movement of this species during Fall, which might be related to migration of its cephalopod prey or a shift in prey preferences, although this aspect requires further investigation. Overall, this study showed that the stronger positive signals were recorded in sampling stations located on surfaces above submarine canyon systems, demonstrating the importance of these areas as elective habitats for the Cuvier’s beaked whale, thus the pivotal priority to their conservation

Assessing sources and fractions of metals associated with environmental plastics: a case study in Lake Como (Italy)

Understanding plastic–metal interactions is paramount to unveil the ecological risks of plastic pollution. Besides including a (variable) amount of metal-containing additives, plastic objects can adsorb metals on their surface in the environment. This work aims at measuring and assessing the possible origin of metals in environmental plastics deposited along the shores of Lake Como (Italy). Samples were characterized through Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and water contact angle. Then, the total metal load was analysed by acid digestion. Surface extraction with nitric acid was also performed to detect labile metals and a three-step extraction scheme enabled the determination of physisorbed, carbonate-bonded and organic matter-bonded metals, respectively. Eighteen metals (Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Ag, Cd, Sn, Ba, Pb and U) were analysed in total. Newly produced plastic items were also analysed as a reference. Our findings revealed that environmental samples retained a higher concentration of metals compared to virgin ones, especially in the loosely bonded acid-extractable fractions, indicating their potential bioavailability. The source of metals on plastics was extremely variable: some metals were predominantly sorbed from the environment (e.g., Mn and Pb), and others were mainly leached from the plastic matrix (Ba, Cu and Ti) or had a mixed origin (Zn, Fe, Sn, Sr and Al). This work shed light on the changes in bioavailability of metals induced by plastic environmental ageing, set baseline values for a freshwater site, and provided insights into the potential bioavailability exerted by metals associated with plastic litter.publishedVersio