Trends in freshwater microcrustaceans studies in Brazil between 1990 and 2014

This study presents a review of scientiometric data about freshwater microcrustaceans (Copepoda, Ostracoda, Branchiopoda: Cladocera, Anostraca, Notostraca and Conchostraca) in Brazil from 1990-2014. This review is based on 179 papers published across four databases, using the following keywords in the search: microcrustaceans, Copepoda, Cyclopoida, Calanoida, Harpacticoida, Ergasilidae, Daphniidae, Moinidae, Cladocera, Ostracoda, Conchostraca, zooplankton, reservoir, river, ponds, reservoirs, wetlands, caves, lakes, limnology, ecology, aquatic, taxonomy, systematics, morphology and biogeography. No studies were identified that addressed freshwater microcrustaceans in four (Amapá, Roraima, Alagoas and Espírito Santo) of the 27 Brazilian Federative States. Forty-five percent of the included studies were concentrated within three of the most populous states (São Paulo, Minas Gerais and Paraná), which also have a long tradition of limnological study. The included studies mostly addressed reservoirs for hydropower generation (22%), multiple environments (22%), rivers (14%) and small artificial reservoirs (11%). Pools, ponds, small lakes, wetlands and phytothelma were not widely studied. Cladocera (48%) and Copepoda (48%) were the most studied groups. No studies were identified that addressed Notostraca, Anostraca or Conchostraca. The sharp increase in the number of published freshwater studies after 2000 is likely a result of increased internet facilities and the implementation of the Scielo platform. Ecology was most frequently the study focus (~50%), followed by taxonomy. Three journals (two Brazilian and one international) accounted for the publication of 44% of the Brazilian studies on microcrustaceans. We expect the frequency of studies employing newer technologies to increase in the coming years. Based on our findings, we propose that future studies should focus on the least well-studied states and should integrate biogeography and systematic approaches. Further data on the fauna within environmental sub-types in Brazil is required.