Organic enrichment can increase the impact of microplastics on meiofaunal assemblages in tropical beach systems.

The cumulative impact of microplastic and organic enrichment is still largely unknown. Here, we investigated the microplastic contamination, the organic enrichment and their effects on meiofaunal distribution and diversity in two islands of the Maldivian archipelago: one more pristine, and another strongly anthropized. Field studies were coupled with manipulative experiments in which microplastic polymers were added to sediments from the non-anthropized island (i.e., without organic enrichment) to assess the relative effect of microplastic pollution on meiofauna assemblages. Our results reveal that the impact of microplastic contamination on meiofaunal abundance and taxa richness was more significant in the anthropized island, which was also characterized by a significant organic enrichment. Meiofauna exposed experimentally to microplastic contamination showed: i) the increased abundance of opportunistic nematodes and copepods and ii) a shift in the trophic structure, increasing relevance in epistrate-feeder nematodes. Based on all these results, we argue that the coexistence of chronic organic enrichment and microplastics can significantly increase the ecological impacts on meiofaunal assemblages. Since microplastic pollution in the oceans is predicted to increase in the next decades, its negative effects on benthic biodiversity and functioning of tropical ecosystems are expected to worsen especially when coupled with human-induced eutrophication. Urgent actions and management plans are needed to avoid the cumulative impact of microplastic and organic enrichment.

Early-stage anomalies in the sea urchin (Paracentrotus lividus) as bioindicators of multiple stressors in the marine environment: Overview and future perspectives.

The morphological anomalies of the early development stages of the sea urchin Paracentrotus lividus, caused by exposure to environmental stressors, are used as biomarker in ecotoxicological and ecological investigations. Here, we reviewed the available literature and classified the embryo and larval anomalies identified so far, to highlight potential commonalities or differences related to the biological action of the different stressors and their ecological impact. Morphological anomalies are influenced by a) the developmental stage of exposure to stressors; b) the intensity of the stress; c) the intra- and inter-cellular mechanisms affected by the exposure to environmental agents. The classification and analysis of embryo and larvae anomalies, either observed by the authors of this review and reported in literature, indicate that sea urchin abnormalities, caused by exposure to different stressors, can be very similar among them and classified into 18 main types, which can occur individually or mixed. All anomalies can be used to calculate an Index of Contaminant Impact to assess the impact of multiple stressors and to identify relationships between morphological anomalies and compromised biological mechanisms. This approach could be useful for a first screening of the presence of potential stressors impairing the growth and development of the early life stages of marine organisms, thus providing a relevant advancement for in future monitoring activities devoted to assess the health status in coastal marine ecosystems.

An age and space structured SIR model describing the Covid-19 pandemic.

We present an epidemic model capable of describing key features of the Covid-19 pandemic. While capturing several qualitative properties of the virus spreading, it allows to compute the basic reproduction number, the number of deaths due to the virus and various other statistics. Numerical integrations are used to illustrate the adherence of the evolutions described by the model to specific well known real features of the present pandemic. In particular, this model is consistent with the well known relevance of quarantine, shows the dramatic role of care houses and accounts for the increase in the death toll when spatial movements are not constrained. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13362-020-00090-4) contains supplementary material.

The Riemann problem for a Two-Phase model for road traffic with fixed or moving constraints.

We define two Riemann solvers for the Two-Phase traffic model proposed in [1], given by a system of two conservation laws with Lipschitz continuous flow, under fixed and moving constraints. From the traffic point of view this situation corresponds to the study of vehicular flow with fixed constraints as, for instance, a traffic light, a toll gate or a construction site. On the other hand, the presence of a slow moving large vehicle, like a bus, corresponds to the case of a moving constraint. In the latter case, we have to consider a mixed system where the conservation laws are coupled with an ordinary differential equation describing the trajectory of the large vehicle.

Impact of inorganic UV filters contained in sunscreen products on tropical stony corals (Acropora spp.).

Most coral reefs worldwide are threatened by natural and anthropogenic impacts. Among them, the release in seawater of sunscreen products commonly used by tourists to protect their skin against the harmful effects of UV radiations, can affect tropical corals causing extensive and rapid bleaching. The use of inorganic (mineral) filters, such as zinc and titanium dioxide (ZnO and TiO2) is increasing due to their broad UV protection spectrum and their limited penetration into the skin. In the present study, we evaluated through laboratory experiments, the impact on the corals Acropora spp. of uncoated ZnO nanoparticles and two modified forms of TiO2 (Eusolex®T2000 and Optisol™), largely utilized in commercial sunscreens together with organic filters. Our results demonstrate that uncoated ZnO induces a severe and fast coral bleaching due to the alteration of the symbiosis between coral and zooxanthellae. ZnO also directly affects symbiotic dinoflagellates and stimulates microbial enrichment in the seawater surrounding the corals. Conversely, Eusolex® T2000 and Optisol™ caused minimal alterations in the symbiotic interactions and did not cause bleaching, resulting more eco-compatible than ZnO. Due to the vulnerability of coral reefs to anthropogenic impacts and global change, our findings underline the need to accurately evaluate the effect of commercial filters on stony corals to minimize or avoid this additional source of impact to the life and resilience ability of coral reefs.

Sunscreen products impair the early developmental stages of the sea urchin Paracentrotus lividus.

Marine ecosystems are increasingly threatened by the release of personal care products. Among them, sunscreens are causing concern either for the effects on skin protection from UV radiation and for the potential impacts on marine life. Here, we assessed the UVA protective efficacy of three sunscreens on human dermal fibroblasts, including two common products in Europe and USA, and an eco-friendly product. The sunscreens' effects were also tested on Paracentrotus lividus, a marine species possibly threatened by these contaminants. We found that all tested sunscreens had similar efficacy in protecting human fibroblasts from UVA radiation. Conversely, the sunscreens' effects on embryo-larval development of P. lividus were dependent on the product tested. In particular, the USA sunscreen, containing benzophenone-3, homosalate and preservatives, caused the strongest impact on the sea urchin development, whereas the eco-friendly sunscreen determined the weakest effects. These results suggest that although the tested products protected human skin cells from UVA-induced damage, they might severely affect the success of recruitment and survival of the sea urchin. Our findings underline the importance of developing eco-friendly sunscreens for minimising or avoiding the impact on marine life while protecting human skin from UV damage.

Marine Microbial-Derived Molecules and Their Potential Use in Cosmeceutical and Cosmetic Products.

The oceans encompass a wide range of habitats and environmental conditions, which host a huge microbial biodiversity. The unique characteristics of several marine systems have driven a variety of biological adaptations, leading to the production of a large spectrum of bioactive molecules. Fungi, fungi-like protists (such as thraustochytrids) and bacteria are among the marine organisms with the highest potential of producing bioactive compounds, which can be exploited for several commercial purposes, including cosmetic and cosmeceutical ones. Mycosporines and mycosporine-like amino acids, carotenoids, exopolysaccharides, fatty acids, chitosan and other compounds from these microorganisms might represent a sustainable, low-cost and fast-production alternative to other natural molecules used in photo-protective, anti-aging and skin-whitening products for face, body and hair care. Here, we review the existing knowledge of these compounds produced by marine microorganisms, highlighting the marine habitats where such compounds are preferentially produced and their potential application in cosmetic and cosmeceutical fields.