Branchiura sowerbyi Beddard, 1892 (Oligochaeta: Naididae) as a test species in ecotoxicology bioassays: a review

Branchiura sowerbyi (Oligochaeta; Naididae; Rhyacodrilinae) is an oligochaete with great potential to be used as a testspecies in toxicology bioassays. Since 1950, its life cycle has been studied and nowadays it is well described in the literature. B. sowerbyi has a cosmopolitan distribution and can be found in places where Tubifex tubifex (normally used in toxicity bioassays) does not occur, especially in tropical regions. Due to its high individual biomass, B. sowerbyi is suitable for use in bioaccumulation bioassays. The present study reviews papers that have used this species in toxicology bioassays and were published between 1950 and the first semester of 2012. In the first part, a brief overview is provided of the biology and the life-cycle parameters of B. sowerbyi. In the second part, the bioassays are presented and discussed, and in the third and last part, conclusions about research to date and perspectives about future studies are presented. Throughout the investigation, it was possible to find a total of 30 papers that tested approximately 65 different substances (insecticides, metals, industrial chemicals and others). The majority of the bioassays run are 96-h acute water-only tests, only five were chronic bioassays and two involved bioaccumulation. The lack of research and the small number of tested substances in comparison with the standardized T. tubifex species (i.e. approximately 9 and 44 tested metals for B. sowerbyi and T. tubifex, respectively) can be explained by the absence of a bioassay protocol for B. sowerbyi, causing researchers to choose other species. It is necessary to undertake more methodological research in order to find a better and common methodology for bioassays.