title: Identifying primary stressors impacting macroinvertebrates in the Salinas River (California, USA): relative effects of pesticides and suspended particles.
abstract: Laboratory dose-response experiments with organophosphate and pyrethroid pesticides, and dose-response experiments with increasing particle loads were used to determine which of these stressors were likely responsible for the toxicity and macroinvertebrate impacts previously observed in the Salinas River. Experiments were conducted with the amphipod Hyalella azteca, the baetid mayfly Procloeon sp., and the midge Chironomus dilutus (Shobanov, formerly Chironomus tentans). The results indicate the primary stressor impacting H. azteca was pesticides, including chlorpyrifos and permethrin. The mayfly Procloeon sp. was sensitive to chlorpyrifos and permethrin within the range of concentrations of these pesticides measured in the river. Chironomus dilutus were sensitive to chlorpyrifos within the ranges of concentrations measured in the river. None of the species tested were affected by turbidity as high as 1000 NTUs. The current study shows that pesticides are more important acute stressors of macroinvertebrates than suspended sediments in the Salinas River.
authors.affiliation: Department of Environmental Toxicology, University of California, Davis, CA 95616, USA. anderson@ucdavis.edu
authors.forename: B S
authors.initials: BS
authors.lastname: Anderson
authors.forename: B M
authors.initials: BM
authors.lastname: Phillips
authors.forename: J W
authors.initials: JW
authors.lastname: Hunt
authors.forename: V
authors.initials: V
authors.lastname: Connor
authors.forename: N
authors.initials: N
authors.lastname: Richard
authors.forename: R S
authors.initials: RS
authors.lastname: Tjeerdema
mesh_terms: D033304:Amphipoda; D000818:Animals; D002140:California; D002683:Chironomidae; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D007313:Insecta; D007448:Invertebrates / Q000187:drug effects*; D007928:Lethal Dose 50; D009946:Organothiophosphorus Compounds / Q000633:toxicity; D052638:Particulate Matter; D010575:Pesticides / Q000633:toxicity*; D011722:Pyrethrins / Q000633:toxicity; D045483:Rivers; D018675:Toxicity Tests; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D009946:Organothiophosphorus Compounds; D052638:Particulate Matter; D010575:Pesticides; D011722:Pyrethrins; D014874:Water Pollutants, Chemical