Citizen science contributes to the understanding of the occurrence and distribution of cetaceans in southeastern Brazil - A case study

Citizen Science projects involve ordinary people in scientific research, providing new insights and perspectives. Interested members of the public may contribute valuable information as they learn about wildlife in their local communities. This study investigates the spatiotemporal occurrence and distribution of cetaceans off the coast of Rio de Janeiro, Brazil, based on data obtained by citizen scientists (opportunistic observations - 2013/2016) and by cetacean researchers (dedicated observations - 2011/2016). The citizen scientists recorded 178 sightings of eight cetacean species along the whole Rio de Janeiro coast. Boat surveys (N = 118) were conducted by the authors in two Marine Protected Areas (MPA) and adjacent waters, resulting in a total of 77 records of four cetaceans species. Within the same area surveyed, citizen scientists contributed 98 reports of these four species. There was a high degree of information overlap, although the citizen scientists also expanded the database on the occurrence and distribution of cetaceans. The citizen scientists also confirmed the occurrence in the study area of four additional cetacean species, not recorded during the surveys. Opportunistic observations obtained from citizen scientists are thus a fundamentally important complementary tool for this type of investigation. The distribution records of the two datasets were also broadly compatible, in particular for the inshore sightings and the seasonal distribution of three of the four principal species. Overall, then, the data provided by from citizen scientists off the coast of Rio de Janeiro were validated by the boat surveys, which focused specifically on the area of the MPAs and adjacencies. The information provided by the combined dataset provides important insights for the creation of a buffer zone, which provide an additional layer of protection for the region's marine biota.