Long-term exposure of Allonais inaequalis to a mixture of antibiotics in freshwater and synthetic wastewater matrices: Reproduction, recovery, and swimming responses.

Antibiotics from sulfonamide, fluoroquinolone, and diaminopyrimidine classes are widely used in human and veterinary medicine, and their combined occurrence in the aquatic environment is increasing around the world. In parallel, the understanding of how mixtures of these compounds affect non-target species from tropical freshwaters is scarce. Thus, this work aimed to study the long-term reproductive, recovery, and swimming effects of mixtures of 12 antibiotics from three different classes (up to 10 µg L-1 ) added to freshwater (FWM) and synthetic wastewater (SWM) matrices on freshwater worm Allonais inaequalis. Results revealed that at the reproduction level, the exposure to antibiotics in the SWM matrix does not cause a significant toxic effect on species after 10 days. On the other hand, exposures to initial dose mixtures (10 µg L-1 each) in FWM caused a significant reduction of offspring by 19.2%. In addition, recovery bioassays (10 days in an antibiotic-free environment) suggested that A. inaequalis has reduced offspring production due to previous exposure to antibiotic mixtures in both matrices. Furthermore, despite slight variation in swimming speed over treatments, no significant differences were pointed out. Regarding antibiotics in the water matrices after 10-day exposures, the highest concentrations were up to 2.7, 7.8, and 4.2 µg L-1 for antibiotics from sulfonamide, fluoroquinolone, and diaminopyrimidine classes, respectively. These findings suggest that a species positioned between primary producers and secondary consumers may experience late reproductive damage even in an antibiotic-free zone, after previous 10-day exposure to antibiotic mixtures. PRACTITIONER POINTS: A mixture of sulfonamide, fluoroquinolone, and diaminopyrimidine antibiotics in freshwater affects the offspring production of A. inaequalis after 10 days. After the 10-day antibiotic exposure, the reproduction of A. inaequalis remains affected in an antibiotic-free environment over the recovery period. The swimming speed of the worms does not change after 10 days of exposure to the antibiotic mixture. The concentration of dissolved solids can limit the natural degradation of sulfonamide, fluoroquinolone, and diaminopyrimidine antibiotics in the aquatic environment.

Automated detection and quantification of Enchytraeus crypticus (Oligochaeta: Enchytraeidae) in tropical artificial soil using image analysis.

The effects of toxic substance in soil matrices are evaluated by assessing adult worm survival and reproduction. Throughout the test, hundreds of juvenile potworms can be found. The current method for Enchytraeus crypticus quantification in soil samples is a laborious and time-consuming procedure that involves manual counting. The present work proposes a method for quick and reliable counting of E. crypticus by using an automated image analysis algorithm applied to soil images. Comparisons between automated and manual methods conducted in double-blind trials involving a large, routine batch of tropical artificial soil samples revealed no statistically significant differences for a wide range of worm densities. The proposed method overcomes time-consuming counts in manual methods and is suited to be deployed routinely for soil toxicity studies involving large batches of samples.

Polyethylene microplastics and substrate availability can affect emergence responses of the freshwater insect Chironomus sancticaroli.

Pollution caused by polyethylene microplastics (MP) has been reported for aquatic environments worldwide. However, despite recurrent research for several aquatic organisms, the effects of MP on the emergence stage of freshwater insects from tropical environments are little known. This study is the first to assess the emergence of the Brazilian native species Chironomus sancticaroli Strixino & Strixino, 1981 when exposed to primary polyethylene microplastics (size 40-48 µm). We performed two exposure scenarios, with a substrate (standard assays) and without substrate (as a stressful experience), and recorded emergence responses. The MP did not affect the species' emergence rate, but these rates were statistically different for the standard and stressful exposure scenarios. In bioassays without substrate, the high concentrations of MP caused anticipation of the insect's emergence (5-6 days). On the other hand, female emergence time was longer than males in standard bioassays. The substrate absence caused a slight increase in the left female wing's length and the potential female fecundity. These findings suggest that the polyethylene microplastics and substrate availability can affect the emergence dynamics of the tropical insect C. sancticaroli.

Global occurrence of SARS-CoV-2 in environmental aquatic matrices and its implications for sanitation and vulnerabilities in Brazil and developing countries.

This paper includes a systematic review of the SARS-CoV-2 occurrence in environmental aquatic matrices and a critical sanitation analysis. We discussed the interconnection of sanitation services (wastewater, water supply, solid waste, and stormwater drainage) functioning as an important network for controlling the spread of SARS-CoV-2 in waters. We collected 98 studies containing data of the SARS-CoV-2 occurrence in aquatic matrices around the world, of which 40% were from developing countries. Alongside a significant number of people infected by the virus, developing countries face socioeconomic deficiencies and insufficient public investment in infrastructure. Therefore, our study focused on highlighting solutions to provide sanitation in developing countries, considering the virus control in waters by disinfection techniques and sanitary measures, including alternatives for the vulnerable communities. The need for multilateral efforts to improve the universal coverage of sanitation services demands urgent attention in a pandemic scenario.

Effects of pyrimethanil fungicide on Chironomidae community structure.

The use of agrochemicals in agriculture may impact aquatic ecosystems, particularly influencing the stream insect communities. Among aquatic insects, the family Chironomidae is the most abundant and species-diverse insect group found in freshwater ecosystems. However, in the southern hemisphere, studies with Chironomidae are still sparse, compared to Europe and North America. The present study evaluates the responses of Chironomidae species (Insecta: Diptera) to pyrimethanil fungicide in a mesocosm experiment. Water contamination and chironomid community were monitored over 10 months. After five months of monitoring, the pyrimethanil fungicide was completely degraded and there was a statistically significant increase in the Margalef Richness and Shannon-Wiener Index (H') in the control units when compared with the contaminated mesocosms (p = 0.003). Our results point out that the utilization of agrochemicals can be a harmful factor influencing negatively the Chironomidae populations. This finding has key implications for insect conservation strategies and ecological management environments.

Counting Enchytraeus crypticus Juveniles in Chronic Exposures: An Alternative Method for Ecotoxicity Studies Using Tropical Artificial Soil.

Soil toxicity tests are commonly applied using Enchytraeus crypticus to analyze reproductive outputs. However, the traditional method for counting potworms takes a long time due to the significant number of offspring. This paper compares the conventional total counting of E. crypticus juveniles (M1) and an alternative methodology (M2). The proposed methodology (M2) uses a simple random counting method (1/4) for the partial counting of juveniles and total estimation. Chronic bioassays (21 days of exposure) were performed in tropical artificial soil (TAS) using sugarcane vinasse as a hazardous substance. Comparing the final density of juveniles recorded in M1 and M2, no statistical differences were pointed out in either one. Applying analyses based on effective concentration (EC10 and EC50), no statistical differences were identified there either. The t-test showed that there was no statistical difference between the counting methods (M1 and M2) in each treatment (control and dilutions). Moreover, we ran the Tukey test for M1 and M2 methods separately and observed that 100 % of the vinasse showed a statistical difference compared to the control treatment in both (p ≤ 0.05), affirming that independent of the counting method, the ecotoxicological outputs were similar. Therefore, the proposed alternative is a suitable method for bioassay using. E. crypticus in tropical artificial soil, decreasing to 1/4 the total time required for counting.

Update on the use of Pristina longiseta Ehrenberg, 1828 (Oligochaeta: Naididae) as a toxicity test organism.

Ecotoxicological bioassays have been widely applied to evaluate the toxicity of substances in standardized test organisms. Nevertheless, the main challenge for researchers is the use of native species to express the effects of pollutants on aquatic biota. Thirty years ago, Smith and collaborators evaluate the possible use of Pristina longiseta (as Pristina leidyi) in acute toxicity test, developing some experiments using cadmium and vanadium as toxicants. The present work aimed to update the use of P. longiseta, in acute bioassays, presenting the occurrence and general characteristics of the species; adaptation of cultivation to tropical conditions; sensitivity tests using potassium chloride (KCl) and copper sulfate (CuSO4) as reference substances standardized by OECD, USEPA, and ABNT; and acute exposure to zinc chloride (ZnCl2). The results showed a successful use of this species as tropical test organism, which presented easy laboratory rearing and responded to the classical ecotoxicological index. The present study can increase the utilization of P. longiseta in bioassays for tropical regions and improve the evaluation of environmental impacts using a native species in ecotoxicological studies.

Is the development of Daphnia magna neonates affected by short-term exposure to polyethylene microplastics?

The study presents responses of D. magna newborns exposed during 96 h to polyethylene microplastics (MP) of size 40-48 µm in the concentrations of 20; 40; 80; 160 and 320 mg/L. The experimental design consisted of two exposure scenarios: the first group was fed at the beginning and after 48 h (3x10-5 cells/mL of Raphidocelis subcaptata and fermented solution) and the second group was not fed as an additional stressor. The mobility of the organisms was not significantly affected in the presence of microplastics for both exposure groups. Nevertheless, the qualitative analysis showed that neonates promptly ingested microplastics in the first 24 h of the test, independently of the treatment. Polyethylene microplastics did not influence the molting process, however, significant differences were observed between the number of molts of the exposure without feed and with feed in 24 h (p = 0.0007), 48 h (p = 2.4 x 10-10), 72 h (p = 3.6 x 10-10) and 96 h (p = 0.003). The final body length of D. magna also showed that the food administration model in the tests contributes to the differentiation in responses.

Intermittent aeration strategy for azo dye biodegradation: A suitable alternative to conventional biological treatments?

Most solutions for biological treatment of azo dyes are based on conventional anaerobic-aerobic processes, but transition to full scale demands technology simplification and cost reductions. We suggest a new approach, in which aeration is intermittently supplied for simultaneous removal of color and toxic metabolites in a single compartment. Effects of aeration strategy and glucose concentration on decolorization and organic matter removal were assessed using factorial design (32) and response surface analysis. Bioreactors were inoculated with microorganisms previously acclimated to Direct Black 22 (DB22), which was the azo compound used in this study. Assays performed with synthetic textile wastewater showed that long-term decolorization was not impaired at a moderate level of aeration (4 hourly-cycles per day). Aerated batches presented lower color removal velocities, but these negative impacts were offset by increasing initial glucose concentration. Higher degrees of mineralization of the azo compound and higher organic matter removals were achieved in intermittently aerated experiments, which led to lower toxicity to Daphnia magna. Biomolecular analysis revealed that the microbial community structure was strongly associated with operational efficiency parameters. These findings suggest intermittent aeration can be implemented to accomplish enhanced azo dye biodegradation.

Chironomus sancticaroli (Diptera, Chironomidae) as a Sensitive Test Species: Can We Rely on Its Use After Repeated Generations, Under Laboratory Conditions?

In ecotoxicological assays, previously selected and standardized organism tests are exposed to an environmental sample. Some species of the Chironomus genus have been extensively used in ecotoxicological assays. Among these, Chironomus tentans is usually utilized in the USA and Chironomus sancticaroli in Brazil. We conducted ecotoxicological bioassays to compare a population of C. sancticaroli, kept for 6 years under laboratory conditions, with a sylvatic population of the same species, collected in the field. The aim was to test the hypothesis that populations of C. sancticaroli, maintained in the laboratory for long periods, could have a different response to stressors/substances. We analyzed the responses of C. sancticaroli for potassium chloride, zinc chloride, potassium dichromate, linear alkylbenzene sulphonate (LAS) and caffeine. The results showed no significant differences between the two populations in the analyses and seems to indicate the possible use of C. sancticaroli from populations kept in the laboratory for long periods.

Chironomus sancticaroli generation test: A new methodology with a Brazilian endemic insect.

This paper presents a new ecotoxicological test to investigate the response of a Brazilian endemic insect Chironomus sancticaroli through its life cycle and its future generations. This test can evaluate differences between the endpoints analyzed in diverse generations, describing the long-term impact of a substance or matrix effects along the time of exposure. Despite earlier papers already present the generation test with Chironomus riparius, there are still no studies with long-term test applied to C. sancticaroli. In this sense, this study evaluated different conditions for the development of a methodology that prolonged the duration of the test and allowed the best sampling of the organism on environmental toxicity tests. The distinct conditions tested were: volumes of test solution, frequency of feed, number of larvae, type of vessel and test solution replacement. The best condition for the C. sancticaroli generation test includes the exposition of 20 larvae to 340 or 500 mL of test solution, 60 g formulated sediment, feeding with Tetramin® each 10 days and, from a spawn, a new test will be prepared with the same characteristics of the previous one. This new methodology can reveal toxic effects along the exposure time and brings advances on toxicology area. •Prolonged testing makes it possible to analyze the long-term effects•The methodology "C. sancticaroli generation test" allows to evaluate the responses of organisms in different life cycles•The methodology allows to analyze the effects of substances in liquid medium and environmental quality through exposure to sediment.

Environmental diagnosis of metals in streams near sugarcane cultivation areas: current and historical analysis in the central region of the State of São Paulo.

In Brazil, innumerable regions of native landcover have been removed and replaced by agricultural cultivation, especially of sugarcane. In this culture, the application of fertilizers containing metals has caused impacts on the water resources causing contamination of stream sediments and occasioning bioaccumulation of metals in aquatic invertebrates. In the year of 2006, an environmental diagnosis of metals in sediments of streams located near sugarcane cultivation areas and in streams located in preserved areas, was published. That study pointed to high concentrations of metals in stream sediments in agricultural areas. These streams have been monitored over the last 10 years conducting analyses of metals and monitoring possible changes in land use. In the present paper, a historical comparison of metals contamination in the sediments of the same streams is conducted, aiming to present a status of 10 years later, analyzing 5 metals (Zn, Cd, Mn, Cr and Fe) found in the sediments of 8 streams, five located in areas of sugarcane cultivation and three located in preserved areas. This study also shows that there is higher concentration of metals in the sediments of streams near sugarcane cultivation than in preserved areas. The temporal historical evaluation showed high concentrations of Cd in 2016 when compared to the year 2006 for streams near sugarcane cultivation.