Master’s Student Tithi Paul walks us through the ETX1 Excursion that students take part in during the first semester. This excursion offers an interdisciplinary exploration of pesticide exposure, biodiversity conservation, and freshwater ecology through direct interaction with stakeholders and ecosystems.
As a Master’s student in Environmental Pollution Management (Ecotoxicology) at RPTU, the ETX1 module led by Prof. Dr. Carsten Brühl provided a valuable opportunity to bridge theoretical knowledge with on-site environmental observations. Over two days, we explored how agricultural practices influence ecological integrity across terrestrial and aquatic systems through expert-led field visits, ecological sampling, and applied discussion.
Day 1: Agricultural Landscapes, Farmer Realities, and Pesticide Exposure
We began with a visit to the Südpfalz Biotope Network, where conservationists from Aktion Südpfalz-Biotope and NVS Natur Stiftung shared their work on restoring biodiversity corridors in intensively cultivated landscapes. Their efforts revealed a reality that is often overlooked in theory: ecological restoration depends not only on ecological expertise but also on social negotiation. They explained how convincing farmers to adopt biodiversity-friendly practices requires time, trust, and a willingness to collaborate. This transition often happens gradually starting with simple agreements on hedgerows or pollinator strips, eventually building toward more integrated conservation goals.
Shortly after, we visited sugar beet fields, striking in their visual emptiness, no weeds, no diversity. These fields are maintained using broad-spectrum herbicides under contractual farming agreements with industrial companies. We learned that most of these lands are not owned by a single entity but rather operated collectively by multiple stakeholders. This fragmented ownership with coordinated monoculture use highlights how agricultural structure can shape both landscape function and ecotoxicological risk.
Nearby, we saw plastic-wrapped fields used for microclimate control, weed suppression, and water retention. Though effective for crop growth, these techniques raise questions about long-term soil degradation and microplastic accumulation.
We then visited a Bioland-certified organic farm. The farmer welcomed us warmly and gave us a detailed overview of his transition away from conventional agriculture. We learned about the costs, labor, and certification regulations involved in organic production. A standout moment was learning how he enriches his soil with crushed bones to naturally supply phosphorus and calcium, resulting in healthier, microbially active soil. Importantly, he also explained the legal protections in place: in case of pesticide drift from adjacent fields, organic farmers can seek financial compensation, but only after contamination is confirmed via certified laboratory tests. These are the kinds of policy mechanisms that often go unnoticed in textbooks but are critical to real-world environmental management.
The day ended with a short hike. Along the trail, we noticed ‘insect hotels’ supporting wild pollinators, small gestures with big ecological impact. From a scenic viewpoint, we looked down upon vineyards nestled beside a kindergarten, prompting a discussion about pesticide drift and public health risks. Vineyards, especially in wine-producing regions like Südpfalz, are among the most chemically intensive crops in Europe. One particularly striking fact shared was that Karlsruhe, a much larger urban center, shows lower pesticide contamination than the rural town of Landau. This unexpected insight illustrated the intensity of agricultural chemical usage in seemingly pristine, green regions, and reminded us how misleading the rural–urban pollution gradient can be.
Day 2: Mesocosm Monitoring and Community Interactions
On the second day, we visited the Ecosystem Research Facility (EERES) in Eußerthal, home to several experimental mesocosms. These artificial yet ecologically realistic ponds allow researchers to study community dynamics, chemical fate, and trophic interactions under semi-controlled outdoor conditions.
We began the day by observing the mesocosms in silence, tasked with mapping visible biotic interactions, noting species presence, behavioral cues, and habitat structure. With notebooks in hand, we documented organisms ranging from amphibians and beetles to submerged macrophytes. During lunch, we regrouped to discuss our sketches and collectively build a conceptual food web, linking species across trophic levels.
Later, we conducted macroinvertebrate sampling, collecting, identifying, and categorizing aquatic insects. Species like mayfly larvae, dragonfly nymphs, and diving beetles served as indicators of water quality, reminding us of their role in biological monitoring indices such as BMWP and SPEAR.
Afterward, we ventured into a stream to assist our classmate Selina in collecting riparian spiders for a study on terrestrial pesticide bioaccumulation. It was a moment of shared laughter and scientific curiosity as we flipped stones, crouched along the banks, and retrieved spiders into vials. We also took biofilm samples from stream stones, rich in microbial and algal life. These films are crucial baseline indicators for nutrient dynamics and can provide valuable reference points for future ecotoxicological comparison studies in protected zones.
Reflections and Takeaways
What made this excursion particularly impactful was its interdisciplinary lens and field immersion. We weren’t just learning about pesticide drift, landscape fragmentation, or species indicators, we were standing in those fields, talking to the people involved, and feeling the complexity of real-world ecotoxicology.
I left with muddy shoes, a full notebook, and a deeper appreciation for the nuances of landscape-level risk, exposure pathways, and the human dimensions of pollution science. As an aspiring ecotoxicologist, this experience reinforced that ecotoxicology is never just about toxicity thresholds, but also about context, cooperation, and consequences.
We all are now doing our AMEO (internships) for the summer semester, and we will be back towards the end of the semester to discuss about everyone experiences.
Author: Tithi Paul