title: Effects of the veterinary pharmaceutical ivermectin in indoor aquatic microcosms.
abstract: The effects of the parasiticide ivermectin were assessed in plankton-dominated indoor microcosms. Ivermectin was applied once at concentrations of 30, 100, 300, 1000, 3000, and 10,000 ng/l. The half-life (dissipation time 50%; DT₅₀) of ivermectin in the water phase ranged from 1.1 to 8.3 days. The lowest NOEC(community) that could be derived on an isolated sampling from the microcosm study by means of multivariate techniques was 100 ng/l. The most sensitive species in the microcosm study were the cladocerans Ceriodaphnia sp. (no observed effect concentration, NOEC = 30 ng/l) and Chydorus sphaericus (NOEC = 100 ng/l). The amphipod Gammarus pulex was less sensitive to ivermectin, showing consistent statistically significant reductions at the 1000-ng/l treatment level. Copepoda taxa decreased directly after application of ivermectin in the highest treatment but had already recovered at day 20 posttreatment. Indirect effects (e.g., increase of rotifers, increased primary production) were observed at the highest treatment level starting only on day 13 of the exposure phase. Cladocera showed the highest sensitivity to ivermectin in both standard laboratory toxicity tests as well as in the microcosm study. This study demonstrates that simple plankton-dominated test systems for assessing the effects of ivermectin can produce results similar to those obtained with large complex outdoor systems.
authors.affiliation: Alterra, Department for Water and Climate, Wageningen University and Research Centre, The Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: Boonstra
authors.forename: Erik P
authors.initials: EP
authors.lastname: Reichman
authors.forename: Paul J
authors.initials: PJ
authors.lastname: van den Brink
mesh_terms: D033304:Amphipoda / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000977:Antiparasitic Agents / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D033361:Cladocera / Q000187:drug effects / Q000378:metabolism; D033342:Copepoda / Q000187:drug effects / Q000378:metabolism; D017753:Ecosystem; D005618:Fresh Water / Q000032:analysis / Q000737:chemistry; D007559:Ivermectin / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D010788:Photosynthesis; D011157:Population Dynamics; D012403:Rotifera / Q000187:drug effects / Q000378:metabolism; D013045:Species Specificity; D014873:Water Pollutants / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D015048:Zooplankton / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000977:Antiparasitic Agents; D014873:Water Pollutants; D007559:Ivermectin