Journal of Environmental Biology

Population level responses of rotifers (Brachionus calyciflorus and Plationus patulus) to the anti-diabetic drug, metformin

G. Garc?a-Garc?a, G.I. Reyes-Carrillo, S.S.S. Sarma* and S. Nandini

Laboratory of Aquatic Zoology, National Autonomous University of Mexico, Campus Iztacala,

Av. de Los Barrios No.1, AP 314, 54090, Los Reyes, Tlalnepantla, State of Mexico, Mexico

*Corresponding Author E-mail: ssssarma@gmail.com

Key words

Drug

Population dynamics

Sub-lethal effects

Zooplankton

Publication Data

Paper received : 21.10.2015

Revised received : 20.07.2016

Re-revised received : 09.01.2017

Accepted : 21.02.2017

Abstract

Aim: Brachionus calyciflorus and Plationus patulus are the two brachionid rotifers that are widely recognized as suitable bioassay species for testing the effects of toxicants and xenobiotics. However, their relative sensitivities vary depending on the duration of exposure, nature of the toxicants and the ecological tools used. Most ecotoxicological works on rotifers have considered one species at a time and mainly tested the effects of pesticides and heavy metals. We quantified the population level changes in the rotifers B. calyciflorus and P. patulus subjected to different concentrations of metformin, a widely used anti-diabetic drug.

Methodology: B. calyciflorus and P. patulus were separately cultured starting with a single parthenogenetic individual. The single-celled green alga, Scenedesmus acutus was used as diet for both the species of rotifers. The experiments were separately conducted using 25 ml of test medium with one of the five concentrations of analytical grade metformin (0 (control), 25, 50, 100 and 200 ?g l-1. The initial density of each rotifer was 1 ind. ml^-1. Daily we quantified the number of rotifers living in each jar and then transferred the surviving individuals to fresh jars containing appropriate metformin-alga combination. The experiments were terminated after 16 days.

Results: Peak population abundance and the rate of population increase (r) of both the rotifers were adversely affected due to metformin. The r in controls of B. calyciflorus and P. patulus were 0.38?0.02 and 0.26?0.01 per day, respectively. For B. calyciflorus and P. patulus the r decreased to 0.19?0.01 and 0.12?0.02 per day, respectively, when exposed to 200 ?g l^-1 of metformin.  

Interpretation: The environmental levels of metformin in effluents are similar to those used in this work. Therefore, metformin should be considered as harmful for rotifers on long term exposure at concentrations of as low as 25 ?g l^-1.

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