ALBERT

Description: Most agricultural soils are expected to be contaminated with agricultural chemicals. As the exposure to pesticides can have adverse effects on non-target organisms, avoiding contaminated areas would be advantageous on an individual level, but could lead to a chemical landscape fragmentation with disadvantages on the metapopulation level. We investigated the avoidance behavior of juvenile common toads (Bufo bufo) in response to seven pesticide formulations commonly used in German vineyards. We used test arenas filled with silica sand and oversprayed half of each with different pesticide formulations. We placed a toad in the middle of an arena, filmed its behavior over 24 hours, calculated the proportion of time a toad spent on the contaminated side and compared it to a random side choice. We found evidence for the avoidance of the folpet formulation Folpan® 500 SC, the metrafenone formulation Vivando® and the glyphosate formulation Taifun® forte at maximum recommended field rates for vine and a trend for avoidance of Wettable Sulphur Stulln (sulphur). No avoidance was observed when testing Folpan® 80 WDG (folpet), Funguran® progress (copper hydroxide), SpinTorTM (spinosad), or 10% of the maximum field rate of any formulation tested. In the choice-tests in which we observed an avoidance, toads also showed higher activity on the contaminated side of the arena. As video analysis with tracking software is not always feasible, we further tested the effect of reducing the sampling interval for manual data analyses. We showed that one data point every 15 or 60 minutes results in a risk of overlooking a weak avoidance behavior, but still allows to verify the absence/presence of an avoidance for six out of seven formulations. Our findings are important for an upcoming pesticide risk assessment for amphibians and could be a template for future standardized tests.

Description: Highlights: • The fate of PS microbeads in an exposure experiment was assessed over 50 h. • Targeted and realized MP concentrations can differ largely in controlled laboratory experiments. • Clearance rates of mussels were significantly decreased in the presence of MP. • Reduction of clearance rates was more pronounced in mussels that had recently spawned. Abstract: The fate of microplastic particles (MP) in exposure experiments is mostly unclear. We measured the recovery of polystyrene (PS) microbeads, which were applied in various concentrations from 0.07 to 47.47 beads/ml, from the different compartments of an experimental system with mussels (Mytilus spp.). At the end of the experiment, we detected a significant loss of MP indicating that the mussels were exposed to less particles than intended. If such a discrepancy remains un-recognized by the experimenter, observed effects are related to an inaccurate particle concentration. Additionally, we observed reduced clearance rates of the mussels in the presence of MP and the effect size increased with increasing particle concentration. This effect was more pronounced in mussels that had recently spawned than in mussels that still had mature gonads. This is a hint that effects of MP may depend on the reproductive status of an organism.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. The effect of PS beads on the filtration was assessed by measuring the clearance rates. Clearance rate of the food algae Rhodomonas baltica was measured during the first hour of exposure and standardized by shell length. Since the reproductive status of the mussels can have an influence on the feeding activity, this factor was taken into account. Therefore, the mussels were inspected for the presence or absence of gonads at the end of the experiment. This resulted in four different treatment groups: control group with or without gonads and the microplastic-exposed group with or without gonads. Presence of PS beads and the reproductive status had a significant influence on the clearance rates.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. The number of PS beads in the softbody of the mussels was determined after the exposure phase of 2 hours and after a 48 hours depuration phase in filtered sea water. Depuration in clear water lowered the amount of microplastic in the mussels' softbodies significantly.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. Feces was collected after the exposure phase of 2 hours and after 24 and 48 hours of depuration in filtered sea water and the amount of PS beads was determined.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. The fate of PS beads within the experimental set up was assessed in four compartments (exposure water, depuration water, feces, softbody) after 2 hours of exposure, 24 hours and 48 hours of depuration in filtered sea water. Additionally, the loss of microplastic as the difference of the sum of all recovered PS beads and the measured concentration at the start of the experiment was determined to obtain a complete mass balance. The total number of PS beads and the number of PS beads per unit as well as the percentage recovery is given.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. During the first hour of exposure the decrease of particles (algae or PS beads) was recorded every 15 min. The particle concentration is given in particles per milliliter and as a percentage of the starting concentration.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. A significant loss of PS beads in pilot studies was traced back to the aeration of the exposure units. Therefore, the aeration was paused during the exposure phase of 2 hours. In a pilot study, the oxygen saturation was measured over 2 hours with mixing every 20 min in four treatment groups: with or without mussel in an aerated or non-aerated (static) set-up. Oxygen saturation lowered to 96.0 % (equivalent to 9.6 mg O2/ml) at the end of the 2 hours of exposure in the non-aerated set-up with mussels due to their respiration.

Description: Adult blue mussels (Mytilus spp.) were exposed to microplastic particles in a controlled laboratory experiment. The study was conducted to investigate I) the effect of polystyrene particles (spherical PS beads, 40µm) on the filtration of mussels and II) the fate of PS beads within the experimental set up. The data was obtained in May and June 2019 with mussels collected from the Kiel Fjord, Germany. The mussels were exposed in a closed system to an intended initial microplastic concentration of 0.4 and 40 PS beads/ml. To correct for deviations from these two concentrations, the measured PS bead concentrations were used. Mussels were exposed to microplastic for 2 hours, followed by a 48 hours depuration phase in filtered sea water. Clearance rate of the food algae Rhodomonas baltica was measured during the first hour of exposure. The fate of PS beads was determined after exposure and after depuration in four compartments: exposure water, feces, softbody, depuration water. Additionally, the loss of microplastic was determined to obtain a complete mass balance.