Microplastics in marine sponges (Porifera) along a highly urbanized estuarine gradient in Santos, Brazil.

Microplastics (MPs) are ubiquitously found in environmental matrices, particularly affecting aquatic systems. While several marine species have been widely used to assess MP contamination, sponges (Porifera) are less used. The MPs contamination was assessed in the sun sponge (Hymeniacidon heliophila) along a gradient at the Santos Estuarine System (Brazil). A 14-fold difference between concentrations (particles g-1) was verified between the most (1.40 ± 0.81) and least (0.10 ± 0.12) contaminated sites, confirming the local contamination gradient. The MPs found were primarily polypropylene, small (1.2-1000 µm), fibrous, and colored. Considering total concentrations, sizes and shapes these spatial patterns were similar those previously detected in molluscs obtained in the same sites. On the other hand, they differed in polymeric composition and color categories. Such findings give important initial insights into the potential role of marine sponges as putative sentinels of MPs contamination.

Anthropogenic and environmental factors partly co-determine the level, composition and temporal variation of beach debris.

The accumulation of human-derived waste on our coasts is an escalating phenomenon, yet the relative importance and potential interactions among its main drivers are not fully understood. We used citizen-science standardized collections to investigate how anthropogenic and environmental factors influence the level, composition, and temporal variation of beach debris. An average of 58 kg and 803 items/100 m, dominated by single-use items of land (rather than sea) origin, were collected in the 881 beaches sampled. Interactions between anthropogenic and environmental factors (e.g., human use × beach substrate) were the strongest predictors of beach debris, accounting for 34% of the variance explained in its amount and composition. Beach debris showed a highly stochastic temporal variation (adjusted R2 = 0.05), partly determined by interactions between different local and landscape anthropogenic pressures. Our results show that both environmental and anthropogenic factors (at the local and landscape scale) co-determine the level and composition of beach debris. We emphasize the potential of citizen-science to inform environmental policy, showing that land-originated single-use items dominate beach debris, and the importance of considering their multiple anthropogenic and environmental drivers to improve our low predictive power regarding their spatio-temporal distribution.

Microplastics in rocky shore mollusks of different feeding habits: An assessment of sentinel performance.

Microplastics (MPs) accumulation in rocky shore organisms has limited knowledge. This study investigated MPs accumulation in filter-feeding oysters, herbivorous limpets and carnivorous snails to assess their performance as sentinel species in the MPs trophic transfer. The samples were obtained along a contamination gradient in the Santos Estuarine System, Brazil. All three studied species showed MPs concentrations related to the contamination gradient, being the oysters the species that showed the highest levels, followed by limpets and snails (average of less and most contaminated sites of 1.06-8.90, 2.28-5.69 and 0.44-2.10 MP g-1, respectively), suggesting that MPs ingestion rates are linked to feeding habits. MPs were mainly polystyrene and polyacetal. The polymer types did not vary among sites nor species. Despite minor differences in percentages and diversity of size, shape, and color classes, the analyzed species were equally able to demonstrate dominance of small, fiber, transparent, black and blue MPs. Thus, oysters, limpets, and snails are proposed as sentinels of MPs in monitoring assessments.

Microplastic in clams: An extensive spatial assessment in south Brazil.

Microplastic pollution is becoming a continuously growing environmental concern, while bivalve mollusks are particularly vulnerable due to their sessile habits and feeding through water filtration processes. Microplastic incidence in soft tissues of the clam Amarilladesma mactroides was assessed along unconsolidated substrates distributed in extensive coastal regions of southern Brazil. Influence of urbanization levels, distance to rivers and local hydrodynamics on microplastic accumulation by the clam was tested. The average concentration of microplastics was high (3.09 ± 2.11 particles.g-1), considering 16 sampled sites. Particles were mainly composed by polyamide, polyethylene and polyethylene terephthalate, while were mainly smaller, fibrous and colorless. High urbanization and closer proximity to rivers insured higher contamination, which is a trend observed globally. No influence of coastal hydrodynamics was seen. Considering obtained findings, A. mactroides presents good potential to be used as a valuable tool to assess microplastic contamination in unconsolidated substrates of beach areas.

Soil contamination in nearby natural areas mirrors that in urban greenspaces worldwide.

Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socio-economic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbeing.

Anthropogenic pressures enhance the deleterious effects of extreme storms on rocky shore communities.

Climate change is not only changing the mean values of environmental parameters that modulate ecosystems, but also the regime of disturbances. Among them, extreme events have a key role in structuring biological communities. Ecosystems are frequently suffering multiple anthropogenic pressures which can cause effects that are not additive. Thus, the effects of extreme events need to be studied in combination with other pressures to adequately evaluate their consequences. We performed a manipulative approach in two rocky shores in the Mediterranean with contrasting levels of anthropogenic pressure (mainly eutrophication) simulating storms with different disturbance regimes in the intertidal and subtidal zones. In the short-term, an extreme storm had a greater impact on the species assemblage than other disturbance regimes, being especially notable in the area suffering from a high anthropogenic pressure. In this area, the species assemblages that suffered from an extreme storm took a longer time to recover than the ones affected by other disturbance regimes and were generally more affected after the disturbance. The intertidal zone, having more variable environmental conditions than the subtidal zone, was more resistant and able to recover from extreme storms. Our results suggest that the effects of extreme events on biological communities could be strengthened when co-occurring with anthropogenic pressures, especially ecosystems adapted to less variable environmental conditions. Thus, limiting other anthropogenic pressures that ecosystems are suffering is crucial to maintain the natural resistance and recovery capacity of ecosystems towards extreme events such as storms.

The environmental effect on the seabed of an offshore marine fish farm in the tropical Pacific.

Marine aquaculture is expanding offshore, where the environmental interactions are not yet fully understood. We performed a benthic environmental assessment of an offshore fish farm on unconsolidated sediment. The physicochemical variables showed marked changes just under the fish farm, although the structure of the community and its bioturbation potential were not influenced. Under no or minimum influence from the fish farm, the physicochemical variables, including acid-volatile sulphides and redox, were notably different to those found in unaffected coastal areas. For this reason, classifications of the environmental status based on physicochemical variables should be adapted to offshore areas. Despite the low degree of impact detected, the organic matter carrying capacity should be carefully determined to avoid environmental drawbacks in terms of fine-grained offshore sediments. Offshore aquaculture could have a lower environmental impact than other types of aquaculture located closer to the coast, but further research is needed to obtain conclusive results.

Biodegradable plastics can alter carbon and nitrogen cycles to a greater extent than conventional plastics in marine sediment.

The seabed constitutes a global sink for plastic debris, where they can remain for centuries. Biodegradable plastics offer the advantage of having less persistence in the environment than conventional ones. The seabed is responsible for key ecosystem functions related to the cycling of elements by decomposing the labile fraction of organic matter and fueling primary production, while storing the most recalcitrant part of this organic matter and limiting CO2 emissions. Although plastics are expected to affect these processes, knowledge on this matter is scarce. In controlled microcosms, we show that biodegradable plastics can stimulate the decomposition of marine-buried carbon and reduce the release of inorganic nitrogen. We found that conventional and biodegradable plastics promoted anaerobic sediment metabolic pathways. Biodegradable plastics produced a two-fold CO2 release to the water column, which suggests the decomposition of not only plastics, but also of buried organic carbon. The stimulation of sediment metabolism could be due to excessive carbon consumption by bacteria that derives from a rise in the carbon:nitrogen ratio. Accordingly, the NH4+ flux to the water column lowered. As NOx fluxes also lowered, biodegradable plastics might promote nitrification-denitrification coupling. If biodegradable plastics become a major component of marine pollution, then sediment biogeochemical cycles might be strongly influenced, which could affect the carbon sequestration of coastal ecosystems and compromise their mitigation capacity against climate change.

Bioturbation may not always enhance the metabolic capacity of organic polluted sediments.

Marine sediments are a major sink of organic matter, playing a crucial role in the global cycling of major elements. Macrofauna, through the reworking of particles and movement of solutes (bioturbation), enhances oxic conditions and the sediment metabolic capacity. Increases in the inputs of organic matter can lead to profound changes in the seabed and impact benthic ecological functions. Through a microcosm experiment, the effect of bioturbation of the polychaete Lumbrineris latreilli on biogeochemical fluxes under scenarios of increasing loads of organic matter was quantified. We found that bioturbation can buffer the negative consequences of anoxic conditions produced by organic enrichment, preventing the build-up of toxic by-products derived from anaerobic metabolic pathways by maintaining oxic conditions. However, the maintenance of oxic conditions by bioturbation is at the expense of limiting the sediment metabolic capacity. The maintenance of oxic conditions may limit anaerobic metabolic pathways, and consequently, the metabolic capacity of sediment. Thus, under organic matter pollution conditions, bioturbation may lessen the metabolic capacity of the sediment.

Monitoring polymer degradation under different conditions in the marine environment.

The perdurability of plastics in the environment is one of the major concerns of plastic pollution and, as a consequence, oceans are accumulating large amounts of plastic. The degradation of conventional and biobased materials was evaluated through a laboratory experiment for a year simulating four different conditions in the marine environment. The water column environmental compartment was simulated under euphotic and aphotic (with and without light availability) conditions. The seafloor environmental compartment was simulated with sediment under non-polluted and polluted conditions. By combining weight loss (%), spectroscopic and thermal analyses, the degradation patterns regarding the polymer structure were assessed. The studied biobased materials were polylactic acid (PLA) based materials and showed higher degradability than conventional ones. The weight loss of conventional materials was not influenced by the water column or sediment, while in PLA-based materials, the degradation rates were ca. 5 times greater in the sediment than in the water column. The absorbance (Abs) value at 3400 cm-1 for polyethylene terephthalate (PET), and carbonyl (CO) index for PET and PLA could be useful to detect early signs of degradation. The crystallization index could be a useful parameter to discriminate degradation stages. The obtained results highlight the different degradability rates of materials depending on the specific environmental marine conditions.

Plastic debris accumulation in the seabed derived from coastal fish farming.

In this study, we assessed plastic accumulation in marine sediments due to finfish aquaculture using floating net-pens. We studied plastic concentrations around three fish farms located at the Mediterranean coastline of Spain. The macroplastic categories and abundances were determined by video monitoring, detecting the majority of elements (78%), including ropes, nets and fibres, a basket trap and a cable tie, close to the facilities, which were not exclusively linked to fish farming but also to fishing activities. Concentrations of microplastics (<5 mm) ranged from 0 to 213 particles/kg dry weight sediment with higher values in sites directly under the influence of the fish farms. Most particles (27.8%) were within the size fraction from 1.1 to 2.0 mm and fibre was the most common shape with 62.2%. The Infrared spectroscopy analysis showed that PE and PP were the predominant types of polymers analysed. In addition, changes in the enthalpy of melting (ΔHm (J/g)) and the degree of crystallinity indicate degradation of the microplastics analysed. This study shows that, in the studied fish farms, levels of microplastic pollution can be one order of magnitude lower compared to other areas suffering other anthropogenic pressures from the same or similar regions. Nevertheless, more research effort is needed to get concluding results.