Microcrustaceans in rice fields: A scientometric analysis from 1977 to 2019

We evaluated the worldwide trends in studies of the active and dormant forms of microcrustaceans in rice fields, and the potential of this environment as a stock of diversity through a scientometric analysis. Web of Science and Scopus databases were used to compile the 77 studies published before 2019. Publications were distributed over 35 years, with a positive correlation between the number of studies and the year of publication (rho = 0.34). The identified studies were from 18 countries, and 58.4% were conducted in Japan, Italy, the United States, and Spain. Most studies addressed more than two groups of microcrustaceans (37.6%), followed by those focused on Cladocera (27.2%) and Ostracoda (18.1%). We quantified 301 species from six groups of microcrustaceans, the majority of which were Cladocera (41.5%) and Ostracoda (39.8%). The greatest richness of microcrustaceans identified in studies were found in Italy, Thailand, Malaysia, Spain, France, Japan, and Brazil. Of the studies, 87% were centered on the active forms of microcrustaceans rather than dormant forms. We found that 15.5% of the countries that grow rice have identified the richness of microcrustaceans, and even though they are artificial environments, rice fields have high potential to store a high diversity of microcrustaceans.