Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Table 67. . Examples of published field studies designed to establish a relationship between Nmethyl
carbamate contamination of aquatic habitats and agricultural practices (adapted from
Table 2 in Schulz 2004).
Source
Aerial
application
Concentration
μg/L
0.1-85.1 24
0.05-26.8
Duration Endpoint Species
Few
hours
Carbaryl
aquatic
invertebrate
Drift
Carbofuran
mortality
371
Various
invertebrates
Amphipod
(Gammarus
pulex)
Field studies in ESA-listed salmonid habitats with other AChE inhibitors
Relationship
of exposure
and effect
Likely
Clear
A group of field studies evaluated macroinvertebrate community responses in the orcharddominated
Hood River Basin, Oregon and correlated results with chlorpyrifos and azinphosmethyl
use and detections (Grange 2002, St. Aubin 2004, Van der Linde 2005). Hood River
Basin contains several listed anadromous salmonids, including lower Columbia River steelhead.
The goals of the studies were to determine whether in-stream OPs affected steelhead AChE
activity and changed the aquatic macroinvertebrate community. An additional objective
addressed how changes in macroinvertebrate community might affect salmonid growth. A suite
of reference and orchard-dominated sampling sites within the Hood River Basin were sampled
pre and post the two primary application seasons, spring (chlorpyrifos) and summer (azinphosmethyl).
Significant differences in macroinvertebrate community assemblages were found
between upstream reference sites and downstream agricultural sites (St. Aubin 2004), similar to
the results described in a California stream (Hall, Killen et al. 2006). However, no significant
differences were found at each individual site, before and after summer spraying (St. Aubin
2004). Therefore, the second Hood River study investigated the spring spray events as well as
the summer spray events to determine seasonal effects (Van der Linde 2005). Sharp declines in
species abundance between reference sites and downstream sites during the spring-spray period
correlated to chlorpyrifos applications and subsequent aquatic detections (one site over an 8 d
period showed chlorpyrifos ranging from 0.032 -0.183 µg/L). There were more pollutant
tolerant taxa and less intolerant taxa at the agricultural sites (Van der Linde 2005). Collectorgatherer
species, many of which are salmonid prey items, declined rapidly at agricultural sites