Effects of microplastic ingestion on feeding activity in a widespread fish on the southwestern Atlantic coast: Ramnogaster arcuata (Clupeidae).

The presence of microplastics (MPs) in the fish gastrointestinal tract has been documented in several studies. However, it is unclear whether this ingestion is active or passive and whether it affects feeding activity in natural environments. In this study, three sites with different anthropogenic pressure were selected from the Bahia Blanca estuary, Argentina, and the small zooplanktivorous pelagic fish Ramnogaster arcuata was used to evaluate MP ingestion and its effect on specie's trophic activity. We analyzed the zooplanktonic composition, levels, and types of MPs in both the environment and the stomach contents of R. arcuata. Moreover, we assessed the trophic behavior of R. arcuata to determine electivity, stomach fullness, and vacuity indexes. The results showed that despite the availability of prey in the environment, 100 % of the specimens ingested MPs, and their levels and characteristics were different according to the site. Stomach contents at sites related to harbor activities presented the lowest MPs concentrations, most of them were paint fragments, with the smallest sizes and a low diversity of colors. The highest MP ingestions were found near the principal sewage discharge, being mostly microfibers, followed by microbeads, and with a greater variety of colors. Electivity indices showed that R. arcuata has a passive or active ingestion according to the size and shape of MPs. In addition, the lowest stomach fullness index and the highest vacuity index values were associated with the highest level of MP ingestion near the sewage discharge. Altogether, these results demonstrate a negative effect of MPs in the feeding activity of R. arcuata and help to elucidate some mechanisms by which these particles are ingested by a bioindicator fish used in South America.

Lakes with or without urbanization along their coasts had similar level of microplastic contamination, but significant differences were seen between sampling methods.

The influence of sampling method on microplastic (MP) quantification and the impact of population density on the levels of MP contamination in surface waters from Patagonian lakes were investigated. Six lakes located in Northern Patagonia (Argentina) were studied using two different sampling protocols widely reported in the literature: water collected in glass bottles vs. water collected using a 50 µm mesh size net. To assess the influence of population density on MP contamination, lakes with urbanization at shores (Nahuel Huapi, Gutierrez and Moreno) and lakes without urbanization on their shores (Espejo, Espejo Chico and Mascardi) were considered. We identified contamination with secondary MP at all the freshwater lakes studied, with predominance (>90 %) of textile-based microfibers (MF). Remarkably the levels of contamination were similar in all the lakes, independently of whether they were impacted by urbanization along their coasts or not, which supports the notion that there is atmospheric transport of MP. The greatest variability found was among sampling methods, with differences above of three orders magnitude. Samples collected directly in 1-l bottles had an average of 5257 MP/m3 in comparison to 1.57 MP/m3 in the samples that were collected with a 50 µm net. Interestingly, Nahuel Huapi lake samples collected with bottles where the WWTP discharges effluents were significantly more contaminated (SD 9400 ± 4351 MP/MF per m3) than samples collected 5 km west of the plant (2100 ± 1197 MP/MF per m3). Results highlight the significance of textile microfibers as microplastic contaminants of freshwater, and the need to address mesh size when looking for textile microfibers and to develop standardized sampling protocols to make studies on freshwater MF contamination comparable.

Microplastic levels on sandy beaches: Are the effects of tourism and coastal recreation really important?

This study assessed the effect of tourism and other recreational activities on microplastic (MP) levels and their characteristics in the sand and surf zone of the seawater. Six sites were chosen belonging to three sandy beaches with similar geomorphologic and morphodynamic characteristics but with different tourism activities. On average, a concentration of 1133.3 ± 811.3 items/kg dry weight (d.w.) and 12.7 ± 14.9 items/m3 were found in the sand and seawater samples, respectively. Fibers and films predominated and were less than 1 mm in length. In the sand, the films mainly matched the PE polymer spectra and the fibers matched PET polymer, cotton, and indigo blue dye; in the seawater samples, PP films and PET fibers prevailed. At the Pehuén-Co - Monte Hermoso Coastal Marine MPA where the flow of tourists is low, the MP levels were the lowest and the largest particles were found, mainly blue or black fibers, with less polymer diversity, cotton and PET being the most prevalent suggesting a recent input of textile fibers to this site. Moreover, the highest concentration of MPs was found on the southern site of a beach considered to be more pristine due to negligible human activity, including the smallest size pattern, mostly composed of white films or fibers with a greater diversity of polymers, predominantly PE > PET > PP. A great occurrence of PVC white films was also found in the surf zone at this site. Proximity to the mouth of a river, littoral drift, and other point sources were identified as the main sources, indicating that, apart from the local tourism and recreational activities, other sources might play a major role in the input of MPs to sandy beaches, such as extensive/intensive agricultural land use and irrigation areas.

First evidence of microplastics in nine lakes across Patagonia (South America).

Microplastics (MPs) on lakes have been reported mainly from Europe, Asia, and North America. Then, this study aimed to address the quantification and identification of MPs in nine lakes from the Argentine Patagonian Region. Blue colored fibers were dominant, with a size range between 0.2 and <0.4 mm. The mean MPs concentration was 0.9 ± 0.6 MPs m-3, suggesting a low pollution state when compared to other worldwide lakes. Raman microscopy analysis showed a predominance of Indigo Blue Polyethylene terephthalate (PET) particles. The upper-gradient runoff from urban settlements, textiles, and fisheries were identified as the main MPs sources and levels positively correlated with the higher area, shallower depth, and with an end-position in the watershed. These findings fill a gap in the geographical distribution knowledge, setting a baseline that emphasizes the need for better treatment of urban and fisheries wastes in continental lakes.