The growth of citizen science has revolutionized the knowledge of biological diversity worldwide, improving the knowledge on the species diversity for particular areas and improving the accuracy of known distributional ranges of the species. This study evaluates the current impact of the iNaturalist platform on understanding marine bivalve diversity along the East Pacific coast, from Alaska (71.39°N) to Cape Horn (54.86°S).

All marine bivalve observations along the East Pacific coast (to mid-June 2024) were obtained from the iNaturalist platform. The geographic coverage of these observations, and the accuracy of this set of information, was evaluated, and this information was contrasted with the total diversity currently known about in this area.

At the time of this analysis, a total of 77,207 marine bivalve observations, comprising 572 species and 62 families, was available in iNaturalist. This represents 45.0% of the total number of species and 77.5% of the total number of families known to the area. Most of these observations (80.5%) come from North America, followed by Central America (14.8%), and only 4.7% come from South America. The greater number of these observations (76.7%) appears to be identified at the species level, while the remaining observations refer to a higher taxonomic level (e.g. Genus, Family, or even Class). Observation quality was categorized as follows: 57.7% as "Research Grade", 41.2% as "Needs ID", and 1.1% as "Casual".

Despite the great number of observations of marine bivalves currently available in iNaturalist, the coverage of this platform is still limited. This phenomenon is registered both at a geographic scale, particularly in the case of South America, and a diversity scale, with more than a half of the known species not yet documented therein.