title: A critical body residue approach for predicting persistent bioaccumulative toxicant effects on reproduction and population dynamics of meiobenthic copepods.
abstract: Critical body residues (CBRs) are the measured tissue toxicant concentrations yielding a median dose-response on a dry-weight or lipid-normalized basis. They facilitate management decisions for species protection using tissue analysis. Population CBR is the mean dose yielding 50% population suppression and was predicted here in Amphiascus tenuiremis for fipronil sulfide (FS) using lifetables and the Leslie matrix. Microplate bioassays (ASTM E-2317-14) produced biomass sufficient for dry mass and lipid-normalized CBR estimates of reproduction (fertility) and population growth suppression. Significant FS toxic effects were delayed naupliar development (at ≥0.10 µg L(-1)), delayed copepodite development (at 0.85 µg L(-1)), decreased reproductive success (at ≥ 0.39 µg L(-1)), and decreased offspring production (at 0.85 µg L(-1)). A reproductive median effective concentration (EC50) of 0.16 µg L(-1) (95% CI: 0.12-0.21 µg L(-1)) corresponded to an adult all-sex CBR and lipid-normalized CBR of 0.38 pg FS · µg(-1) dry weight (95% CI: 0.27-0.52 pg FS · µg(-1)) or 2.8 pg FS · µg(-1) lipid (95% CI: 2.2-3.6 pg FS · µg(-1)), respectively. Copepod log bioconcentration factor (BCF) = 4.11 ± 0.2. Leslie matrix projections regressed against internal dose predicted fewer than five gravid females in a population by the third generation at 0.39 and 0.85 µg FS · L(-1) (i.e., 9.6-10.2 µg FS · µg(-1) lipid), and 50% population suppression at a CBR of 1.6 pg FS · µg(-1) lipid. This more integrative population CBR as a management tool would fall 1.75 times below the CBR for the single most sensitive endpoint-fertility rate.
authors.affiliation: Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA. tchandler@sc.edu
authors.forename: G Thomas
authors.initials: GT
authors.lastname: Chandler
authors.forename: P Lee
authors.initials: PL
authors.lastname: Ferguson
authors.forename: W W
authors.initials: WW
authors.lastname: Klauber
authors.forename: K M
authors.initials: KM
authors.lastname: Washburn
mesh_terms: D000818:Animals; D001681:Biological Assay; D033342:Copepoda / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D005260:Female; D005298:Fertility / Q000187:drug effects; D008055:Lipids / Q000032:analysis; D008297:Male; D008954:Models, Biological; D011157:Population Dynamics; D011720:Pyrazoles / Q000633:toxicity; D012098:Reproduction / Q000187:drug effects; D012623:Seawater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D008055:Lipids; D011720:Pyrazoles; D014874:Water Pollutants, Chemical; C082360:fipronil