This article examines certain guiding tenets of science journalism in the era of big data by focusing on its engagement with citizen science. Having placed citizen science in historical context, it highlights early interventions intended to help establish the basis for an alternative epistemological ethos recognising the scientist as citizen and the citizen as scientist. Next, the article assesses further implications for science journalism by examining the challenges posed by big data in the realm of citizen science. Pertinent issues include potential risks associated with data quality, access dynamics, the difficulty investigating algorithms, and concerns about certain constraints impacting on transparency and accountability.

Citizen science continues to grow, potentially increasing competition among projects to recruit and retain volunteers interested in participating. Using web analytics, we examined the ability of a marketing campaign to broaden project awareness, while driving engagement and retention in an online, crowdsourced project. The campaign challenged audiences to support the classification of >9,000 pairs of images. The campaign was successful due to increased engagement, but it did not increase the time participants spent classifying images. Engagement over multiple days was significantly shorter during the campaign. We provide lessons learned to improve targeted recruitment and retention of participants in online projects.

This paper provides an analysis of the implementation and the outcomes of Scienza Attiva, an Italian national project for secondary school students, that makes use of deliberative democracy tools to address socio-scientific issues of great impact. The analysis has required a mixed method including surveys of students' pre- and post-project opinions, focus groups and interviews with students and teachers. The results from this evaluation study provide evidence that the project improves students' understanding of socio-scientific issues, strengthens their awareness of the importance of discussion and positively influences interactions in the classroom.

In today's society a variety of challenges need attention because they are considered to affect our well-being. Many of these challenges can be addressed with new innovations, yet they may also introduce new challenges. Communication of these new innovations is vital. This importance is also addressed by the concept of Responsible Research and Innovation. In the present commentary we draw on a dataset of 196 research projects and discuss the two research streams of Science Communication and Responsible Research and Innovation and how they are complements to each other. We conclude with suggestions for practitioners and scientists.

This issue forms Part II of JCOM's collection of articles and essays exploring the field of citizen science. Here I introduce the articles in Part II, outlining how they contribute to our understanding of the ways that volunteers participate in citizen science projects, what motivates this participation and what learning arises as a result of participation.

We investigate the development of scientific content knowledge of volunteers participating in online citizen science projects in the Zooniverse (http://www.zooniverse.org). We use econometric methods to test how measures of project participation relate to success in a science quiz, controlling for factors known to correlate with scientific knowledge. Citizen scientists believe they are learning about both the content and processes of science through their participation. We don't directly test the latter, but we find evidence to support the former — that more actively engaged participants perform better in a project-specific science knowledge quiz, even after controlling for their general science knowledge. We interpret this as evidence of learning of science content inspired by participation in online citizen science.

There is growing recognition that effective science communication should not merely focus on addressing scientific literacy but must also open dialogue between scientists and the public, build trust, and increase public interest in environmental research. Citizen science BioBlitzes offer a useful approach for science communicators to address many of these key aims. We explore the BioBlitz concept, learnings and outcomes based on a case study of a BioBlitz held in Sydney, Australia. We found that participants valued learning about biodiversity on the day and importantly, all participants (scientists and citizen scientists) rated interacting and learning from the experience as one of the main benefits.

Online citizen science projects have demonstrated their usefulness for research, however little is known about the potential benefits for volunteers. We conducted 39 interviews (28 volunteers, 11 researchers) to gain a greater understanding of volunteers' motivations, learning and creativity (MLC). In our MLC model we explain that participating and progressing in a project community provides volunteers with many indirect opportunities for learning and creativity. The more aspects that volunteers are involved in, the more likely they are to sustain their participation in the project. These results have implications for the design and management of online citizen science projects. It is important to provide users with tools to communicate in order to supporting social learning, community building and sharing.

Volunteer water quality monitors represent the intersection between citizen science and environmental stewardship. Understanding what motivates participation will enable project managers to improve recruitment and retention. This survey of 271 volunteers from eight water quality monitoring organizations in the U.S. found the strongest motivators to participate are helping the environment or community and contributing to scientific knowledge. No variation by gender was found, but younger volunteers have different motivations and preferences than older volunteers. Volunteers value the communication of tangible results more than recognition or reward.

The participation of non-professionally trained people in so-called citizen science (CS) projects is a much discussed topic at the moment. Frequently, however, the contribution of citizens is limited to only a few narrow tasks. Focusing on an initiative dedicated to the study of the human microbiome, this paper describes such a case where citizen participation is limited to the provision of funding, samples, and personal data. Researchers opted for a crowdsourced approaches because other forms of funding and recruitment did not seem feasible. We argue that despite the narrow understanding of participation in the context of some CS projects, they can address some of the democratic concerns related to scientific knowledge creation. For example, CS and crowdsourcing can help to foster dialogue between researchers and publics, and increase the influence of citizens on research agenda setting.