Our research at University of Koblenz-Landau is going virtual at SETAC SciCon! In this three-part blog series, we highlight several poster and platform presentations of our researchers: Today, find out what Elena Adams and Roy Rajdeep have planned for the conference.

This second blog features poster contributions by Elena Adams and Roy Rajdeep. Elena shares how pesticide exposures can impair amphibian fertilization rates and developmental speed of juveniles, while Roy explains how nanoparticles can enhance silver toxicity in freshwater systems.

Stay tuned for the next blog this week! The presented topics are diverse, so everyone should find something interesting or relevant to their research.

Reproductive Health of Common Toads (Bufo bufo) in Viticultural Landscapes

• Presenter: Elena Adams
• Session: Multidisciplinary Efforts to Advance Knowledge on Environmental Risk Assessment of Chemicals for Amphibians and Reptiles
• Poster ID: 4.12P.4

Pesticides have been identified as a major factor of the worldwide declines of amphibian populations. Besides the aquatic exposure in breeding ponds in the agricultural landscape, amphibians can be exposed during their migration from winter habitats to breeding ponds and vice versa. This biphasic exposure can have a negative impact on the reproduction of amphibian populations. Therefore, we investigated the reproduction of common toads in the viticultural landscape of Palatinate in Southwest Germany compared to less or unpolluted habitats.

In a semi-field study, we captured common toad pairs during their migration to five breeding ponds of different contamination level and placed them into net cages until spawning. We investigated the fecundity and the fertilisation rate of the adult toads as well as the survival (number of tadpoles that developed to free swimming tadpoles) and fitness (length of tadpoles) of the offspring.

Females of contaminated ponds laid more eggs than females of less contaminated ponds. However, the fertilization rate as well as the offspring survival and fitness decreased with increasing pesticide contamination. These results suggest that the offspring of toads in contaminated ponds has reduced chances of becoming successfully reproducing adults leading to an impaired population viability. However, the increased quantity of eggs suggests an evolutionary adaption to pesticide exposure to balance the reduced body conditions of the offspring. Therefore, further investigations of pesticide effects and resistances are crucially important for improving the understanding of the consequences of pesticide exposure in respect of amphibian evolution and conservation.

Silver toxicity towards Daphnia magna affected by titanium dioxide nanoparticles and duration of aging

• Presenter: Roy Rajdeep
• Session: Nanotechnology Regulatory and Assessment Frameworks and Nanoremediation Approaches
• Poster ID: 6.05P.4

Immense usage of titanium dioxide nanoparticles (nTiO₂) in consumer products (e.g., cosmetics, food, cleaning agents, filters) undoubtedly leads to their release into freshwater systems. There, nTiO₂ may interact with co-occurring heavy metals affecting their ecotoxicological effects. Additional parameters, such as presence of natural organic matter (NOM) and aging duration, may affect fate and toxicity of both nTiO₂ and heavy metals as well as their interaction. In our present study, we evaluated the effects of nTiO₂ (0.0, 0.6 or 2.6 mg/L) with/without (0 or 8 mg TOC /L) NOM on the toxicity of silver (Ag) (ranging from: 0 – 64 μg/L) towards Daphnia magna (a popular freshwater organism) over various aging durations (0, 1, 3 & 6 days). The results (based on 48 h Ag EC₅₀) suggest that nTiO₂ mostly elevated Ag toxicity ( ̴ 2-6-fold), a pattern independent of the aging duration and confirmed in presence of NOM. The higher Ag toxicity is likely attributed to the adsorption of Ag onto the nTiO₂ surface followed by their ingestion and desorption during gut passage.