Marine citizen science, a sea of data that is still not very accessible

The marine environment faces increasingly intense challenges: climate change, pollution, overfishing, habitat destruction or biodiversity loss. The scientific community increasingly needs to understand how the ocean responds and what management is most effective. In this context, citizen science has become a key tool for gaining more knowledge.

Often, however, the expert community has the perception that there are few initiatives in the marine field compared to the terrestrial one, either because it is more difficult to access the environment or because more training is needed, for example when it comes to taking underwater photographs. In addition, of the activities that do exist, they are believed to be exploited below their potential from the point of view of the expert community in citizen science because most of them do not have open data.

For this reason, an international study with the participation of CREAF puts on the table all marine citizen science initiatives from around the world to carry out an extensive analysis and check whether they meet the basic requirements of open citizen science.

The work, published in the journal Ambio, shows that citizen participation in marine research is much more extensive and diverse than one might think. Specifically, more than 1,260 initiatives are documented, but the fact that an initiative exists does not necessarily mean that the data it generates can be accessed. And this is where the study has made a particularly relevant contribution: analyzing how open the data produced by marine citizen science is.

The analysis was led by the IHE (Delft Institute for Water Education) in collaboration with CREAF researcher Joan Masó, an expert in data interoperability and international standards. To carry out these checks, the FAIR principles (Findable, Accessible, Interoperable, Reusable) were used. FAIR is a set of standard guidelines used internationally to ensure that scientific data can be used for research, integrated into large data infrastructures such as GBIF, or used to support public policies.

The analysis shows compelling data: only 18% of initiatives offer full and open access to their data. To go into more detail, 23% provide partial access, for example through reports or articles. But what is most worrying is that 59% of initiatives do not offer any kind of access to the data.

When the study assesses strict compliance with the four FAIR principles, the results are even more revealing: only two initiatives fully meet all the criteria. Furthermore, if a rigorous criterion of semantic interoperability is applied, i.e. the explicit use of standard vocabulary to describe observations, only 1.8% of the initiatives can be considered truly interoperable. According to the article, the exact meaning of the data depends on its binding to shared dictionaries, which ensures that it can be safely and consistently combined and reused with other data sets.

In this sense, Masó highlights that “using standardized vocabularies is key to avoiding the proliferation of incompatible terminologies and facilitating the integration of data between projects. Otherwise, it is very difficult to group data from different initiatives or use them in advanced tools such as digital twins.”

Another major obstacle preventing data from citizen science projects from being used is the lack of clear licenses. The study reveals that only 73 projects explicitly state which license applies to their data.

"In citizen science, the recognition of the authorship of the data or observations is fundamental because without this information, it is not known what can be done legally with the data, which greatly limits its impact. Adhering to an open data model like Creative Commons is simple to do but there is still a lot of ignorance about the importance of data licenses," warns Masó.

Furthermore, less than 46% of initiatives have a simple mechanism for accessing data, and only 2.4% assign a persistent identifier such as a DOI, a basic requirement for making data locatable for both people and computer systems.

The analysis of the FAIR principles sheds light on one of the great challenges of the sector and offers a solid basis for guiding future initiatives towards more open, interoperable and reusable practices. The authors of the study point out that this work lays the foundation for creating a cumulative inventory of Marine Citizen Science Initiatives (MARCSI), a key tool to better understand what is being done, where and with what results in terms of data. For now, the dataset created, i.e. the inventory of marine citizen science initiatives, is available on Zenodo. The authors point out that progress in this direction will allow strengthening scientific research and amplifying the impact of citizen participation in marine environmental management and ocean sustainability.

We apply these same principles to three Horizon Europe projects on citizen science topics in which CREAF participates. On the one hand, CitiObs, which connects European citizen environmental observatories through collaborative networks where good practices, innovative tools and experiences in the management of the data they collect are shared. On the other hand, More4nature, an initiative that seeks to ensure that participatory science serves to ensure compliance with European environmental regulations, among other things, through more FAIR and validated data. And, finally, Iliad, the European project responsible for establishing an interoperable Ocean Digital Twin with the largest possible amount of data on the oceans, including the valuable voice of citizen science.

Wehn, U., Bilbao Erezkano, A., Somerwill, L. et al. Past and present marine citizen science around the globe: A cumulative inventory of initiatives and data produced . Ambio 54, 994–1009 (2025). https://doi.org/10.1007/s13280-024-02119-z