Characteristics and fluxes of plastic debris based on socio-economic data for Patos Lagoon-a choked coastal Lagoon in South Brazil.

Patos Lagoon, located in southern Brazil, is the world's largest choked coastal lagoon. Studies have revealed that plastic pollution affects lagoons; however, to date, they have only focused on a few limited regions of the lagoon. Top-down quantification methods based on socio-economic data from 2010 to 2017 were used to measure the amount of plastic reaching Patos Lagoon, thus broadening the perspective of plastic pollution in this area. According to the findings, Patos Lagoon's hydrographic regions produced an average of 4.54 Mton of plastic during the studied period. 1.86 Mton was consumed on average. High- and low-density polyethylene (HDPE and LDPE, respectively), polypropylene (PP), and polyvinyl chloride (PVC) were the main resins produced. Food-related activities were the largest consumer of plastic (17.98%), indicating a higher amount of single-use plastics being used in the basin. The preforms for plastic bottles, bags, and packaging were the most commonly manufactured plastic utensils. An estimated 8 to 14% of all plastics used to end up as mismanaged waste in the Patos Lagoon hydrographic basin. This resulted in 1.73 and 10.72 Kton, or 0.5 and 3.2 g/per person/per day, of plastic waste flowing into the waters of Patos Lagoon throughout the study period. These findings can help focus on management efforts by providing managers and policymakers with information for better plastic pollution mitigation in this environment.

Salt marshes as the final watershed fate for meso- and microplastic contamination: A case study from Southern Brazil.

Plastics pose a major threat to aquatic ecosystems especially in smaller size fractions. Salt marshes play a crucial role in maintaining the coastal zone and aquatic food web, yet their contamination, including by plastic materials, is still poorly investigated. This work investigated meso- (MEP, 5-25 mm) and microplastic (MIP, 1 µm-5 mm) contamination of a salt marsh, which reached average levels of 279.63 ± 410.12 items kg-1, 366.92 ± 975.18 items kg-1, and 8.89 ± 8.75 items L-1 in surface sediment, sediment cores and water, respectively. Photomicrographs revealed a complex fouling community on plastics surface for both different salt marsh zones and plastic formats. Abundance of plastics in sediment was higher in the dryer, vegetated zones compared to flooded, unvegetated zones. This is consistent with the role of vegetation as a trap for solid litter and final fate of plastic deposition, but also with local hydrodynamics influencing deposition pattern. Plastics were detected up to 66 cm-depth, presenting higher levels at surface sediments. It was also possible to identify the main groups of microorganisms (1638 bacterial cells, 318 microalgae cells, and 20049.93 µm2 of filamentous fungi) composing the Plastisphere communities on all plastic items recorded in the different zones. These results are a pioneer contribution, highlighting that regional salt marshes participate in sequestration and longstanding accumulation of plastic particles in estuarine environments, before exportation to the ocean.

Litter contamination at a salt marsh: An ecological niche for biofouling in South Brazil.

The presence of solid litter and its consequences for coastal ecosystems is now being investigated around the world. Different types of material can be discarded in areas such as salt marshes, and various fouling organisms can associate with such items forming the Plastisphere. This study investigated the distribution of solid litter along zones (dry, middle, flooded) of a salt marsh environment in the Patos Lagoon Estuary (South Brazil) and the association of biofouling organisms with these items. Solid litter quantities were significantly higher in the dry zone when compared to the middle and flooded zones, showing an accumulation area where the water rarely reaches. Most items were made of plastic, as shown for many other coastal areas, and originated from food packaging, fishery and shipping activities and personal use. Although not statistically significant, there was a tendency of increased biofouling towards the flooded zone. Thirteen groups were found in association with solid litter items, mainly algae, amphipods, and gastropods. The preference for salt marsh zones, types of material and items' colour was highly variable among groups of organisms, which can be related to their varied physiological requirements. In summary, significant plastic contamination of salt marshes of the Patos Lagoon was associated with a heterogeneous distribution of fouling communities.

Whole-body autoradiography: an efficient technique to study copper accumulation and body distribution in small organisms.

Copepods have been widely used to evaluate toxicity of metals present in marine environments. However, a technical difficulty is to understand the possible routes of metal uptake and to identify in which tissues or organs metals are being accumulated. Traditional techniques are hard to be employed once each organ has to be analyzed separately. Autoradiography is an alternative technique to circumvent this limitation, since metal distribution in tissues can be visualized and quantified, even in small organisms like copepods. In the present study, accumulation and distribution of (64)Cu in the copepod Calanus hyperboreus was studied using autoradiography. Copepods were exposed for 2 h to copper (2.3 mg L(-1); 1.08 MBq (64)Cu mg(-1) Cu) and then allowed to depurate for 2 h in clean seawater. Total (64)Cu was determined by gamma-spectrometry after a metal exposure and a depuration period. (64)Cu distribution was determined based on images generated by autoradiography. Metal accumulation was observed on all external surfaces of the copepods, being accumulated mostly on the ventral region, followed by dorsal, urossoma and internal regions. After depuration, radioactivity levels had a decrease in the sum of external body surface. Our results show that copper uptake by C. hyperboreus is fast and that a non-negligible proportion of the accumulated metal can reach internal tissues, which may lead to detrimental physiological effects. Moreover, whole-body autoradiography was demonstrated to be an efficient technique to study copper accumulation and body distribution in a very small organism such as the copepod C. hyperboreus.

Does light-stick content pose any threat to marine organisms?

Light-stick is a light attractor used in longline fishing which is often dumped or lost into the ocean after used, becoming a potential pollutant to marine organisms. In the present study, toxicity was evaluated by exposing Artemia to light-stick contents. The effects were observed on the survival of nauplii and hatchability of cysts. The LC(50) was 0.063mLL(-1) after 24h of exposure, whilst hatchability was 100% reduced after 48h of exposure to 0.8mLL(-1). The results showed that its content can be toxic to marine organisms, especially under low dilution conditions or direct contact.

Mechanism of acute silver toxicity in the euryhaline copepod Acartia tonsa.

Acute silver effects on whole-body ion regulation and Na(+),K(+)-ATPase activity were evaluated in the euryhaline copepod Acartia tonsa. Experiments were run at 20 degrees C, three different salinities (5, 15 and 30 ppt), in either the absence or the presence of food (diatom Thalassiosira weissflogii; 2 x 10(4)cells/mL). Standard static-renewal procedures were used. Copepods were acutely (48 h) exposed to silver (AgNO(3)) concentrations equivalent to the 48-h EC10 (dissolved Ag=3, 49, and 94 microg/L), 48-h EC30 (dissolved Ag=5, 71, and 125 microg/L) or 48-h EC50 (dissolved Ag=7, 83, and 173 microg/L) values in the absence of food or to the 48-h EC50 (dissolved Ag=35, 90, and 178 microg/L) values in the presence of food. These values were previously determined under the same experimental conditions at salinities 5, 15 and 30 ppt, respectively. Endpoints analyzed were whole-body ion concentrations (Na(+), Cl(-), and Mg(2+)) and Na(+),K(+)-ATPase activity. In starved copepods, lower whole-body Na(+) and Mg(2+) concentrations were observed in salinities 5 and 30 ppt, respectively. Also a higher whole-body Na(+),K(+)-ATPase activity was observed in all salinities tested. Data from fed copepods indicate that all these salinity effects were completely associated with starvation. Silver exposure induced a decrease in the whole-body Mg(2+) concentration in starved copepods in salinities 5 and 30 ppt and a Na(+),K(+)-ATPase inhibition in both starved and fed copepods in all salinities tested. Thus, food addition in the experimental media completely protected against silver effects on Mg(2+) concentration, but not against those on Na(+),K(+)-ATPase activity. In starved copepods, enzyme inhibition was dependent on silver concentration and a relationship between this parameter and mortality was observed in all salinities tested. Therefore, Na(+),K(+)-ATPase molecules seem to be a key site for acute silver toxicity in marine invertebrates, as reported for freshwater fish and crustaceans.