Reducing plastic pollution in rivers, lakes, and oceans is beneficial to aquatic animals and human livelihood. To achieve this, reliable observations of the abundance, spatiotemporal variation, and composition of plastics in aquatic ecosystems are crucial. Current efforts mainly focus on collecting data on the open ocean, on beaches and coastlines, and in river systems. Urban areas are the main source of plastic leakage into the natural environment, yet data on plastic pollution in urban water systems are scarce. In this paper, we present a simple method for plastic hotspot mapping in urban water systems. Through visual observations, macroplastic abundance and polymer categories are determined. Due to its simplicity, this method is suitable for citizen science data collection. A first application in the Dutch cities of Leiden and Wageningen showed similar mean plastic densities (111–133 items/km canal) and composition (75–80% soft plastics), but different spatial distributions. These observations emphasize the importance of long-term data collection to further understand and quantify spatiotemporal variations of plastics in urban water systems. In turn, this will support improved estimates of the contribution of urban areas to the plastic pollution of rivers and oceans.

In the field of investigating and addressing plastic pollution, the public is increasingly involved in research as citizen scientists. Long-term monitoring for this topic is needed, and recruiting and retaining volunteers is challenging. Therefore, it is important to learn more about the demographic background, motivations and expectations of involved citizen scientists, and if these change during participation. Our research studied these aspects of the citizen scientists in the Dutch Clean Rivers project, who monitor plastic pollution on riverbanks. Participants (n = 122) completed pre- and post-survey after one year of the project. While there was no gender bias, the participants were mostly middle-aged and highly educated, and almost half had previous experience with scientific research. Their motivation to participate was mostly activistic, as they wanted to tackle the source of plastic pollution and contribute to solutions. More personal motivations, such as wanting to learn more and because it is fun to do scientific research, decreased significantly after one year of participation. Their expectations were in line with the main motivations. Understanding the background, motivations and expectations of volunteers helps this project, and the field of citizen science in plastic pollution research.

Males of Opadometa are difficult to associate with conspecific females, and sex-matching errors may persist in the taxonomic literature. Recommended best practices for definitive sex matching in this genus suggest finding a male in the web of a female, or better yet, mating pairs. A male Opadometa was observed hanging on a frame line of the web of a female Opadometa sarawakensis, a species for which the male was previously undescribed. This occurred during a tropical ecology field course held at the Danau Girang Field Centre in Sabah, Malaysia. A taxonomic description was completed as a course activity.

Under growing anthropogenic pressures, wildlife rehabilitation organizations care for sick, injured and displaced wildlife. Records on admitted wildlife are increasingly used for scientific research to understand threats to wildlife, including diseases. As volunteers are actively involved in wildlife rehabilitation, their contributions can be viewed as a form of citizen science. However, we know little about rehabilitators’ backgrounds, motivations, and experiences with data collection and research.To fill this gap, we interviewed representatives from thirteen Dutch wildlife rehabilitation centers and surveyed 205 Dutch rehabilitation volunteers. Our findings show that rehabilitators are primarily driven by an interest in and a desire to help animals. Women and middle-aged volunteers were overrepresented in the sample, compared to the Dutch population, while educational and employment background as well as their attitude towards science, were representative. Regarding the data collection, they are positive about the quality although finding location can be improved. Rehabilitators are open to sharing the data, especially to study success rate and diseases. Interviewees believed that education is an important part of their work. However, taking on tasks like research and education are experienced as challenging due to a lack of time and funding. The involvement of wildlife rehabilitators in scientific research could extend the benefits of citizen science to a broader and more diverse audience than typically reached by citizen science or nature volunteering. By understanding wildlife rehabilitators' roles, challenges, and preferences, this study highlights the potential to involve them in scientific knowledge generation, thereby broadening the scope of citizen science.