Environmental Engineering Reference
In-Depth Information
The NOAEC for the most sensitive zooplankton populations and for the zooplankton
community was 0.1
g L
−1
under both temperate and Mediterranean conditions. The
phytoplankton community was altered and phytoplankton chlorophyll increased at
1
μ
g L
−1
, but only under Mediterranean conditions. Overall, the study supported a
community-level NOAEC value of 0.1
μ
μ
g L
−1
.
Spanish outdoor cosms
. Outdoor plankton-dominated 11-m
3
cosms were treated
with single CPY applications of 0.1 and 1
g L
−1
(López-Mancisidor et al.
2008b
).
Cladocerans, copepods, and some rotifers (
Keratella
sp.) decreased at 1
μ
g L
−1
;
other rotifers (
Brachionus
sp.) increased.
Daphnia galeata
, which had been severely
reduced, recovered rapidly;
Keratella
sp. was still reduced on d-99. There were no
effects at 0.1
μ
g L
−1
. In a subsequent study, López-Mancisidor et al. (
2008a
) sprayed
the cosms four times at weekly intervals to produce concentrations of 0.033, 0.1,
0.33, and 1
μ
g L
−1
. Population densities of cyclopoid copepods and cladocerans
decreased at 1
μ
g L
−1
, while calanoid copepods and some rotifers increased.
Community analysis using PRC indicated signifi cant effects at 0.33
μ
g L
−1
. All taxa
recovered within 12 wk (9 wk after the fi nal CPY application) except at the highest
treatment level (1
μ
g L
−1
). These studies indicated that CPY caused no effects on
zooplankton after single or multiple exposures to CPY at 0.1
μ
μ
g L
−1
.
Thailand outdoor cosms
. In a study in 1-m
3
outdoor cosms in Thailand treated once
0.1, 1, 10, and 100
g CPY L
−1
, cladocerans (
Moina micrura
) were the most sensitive
zooplankton taxa, with signifi cant reductions at 1, 10, and 100
μ
g L
−1
(Daam et al.
2008a
). Other cladocerans (
Ceriodaphnia cornuta
), adult copepods, and copepod
nauplii were reduced for 1 wk at 1
μ
μ
g L
−1
and then recovered. Some rotifers (including
Keratella
) decreased at 100
g L
−1
, while other rotifer species increased. Among mac-
roinvertebrates, Conchostraca (clam shrimp) were eliminated at the three greatest
concentrations. Ostracods and corixids were reduced or eliminated at 10
μ
g CPY L
−1
.
Snails, fl atworms, and mollusks increased in abundance. PRC analysis showed that
both zooplankton and macroinvertebrate communities were affected at the three great-
est concentrations of CPY. Zooplankton communities recovered by d-14 at 1
μ
μ
g L
−1
,
d-35 at 10
g L
−1
; all taxa of macroinvertebrates recovered by
d-70 at all concentrations. Similar studies on the effects of CPY on zooplankton were
conducted in 250-L outdoor cosms in Thailand, treated either once or twice (7-d inter-
val) with 1
μ
g L
−1
, and d-70 at 100
μ
g L
−1
CPY (Daam et al.
2008b
). Cladocerans decreased, while copepods,
rotifers, and ostracods increased; PRC indicated community recovery by d-32 in both
treatments. Overall, the Thai cosm studies indicated a NOAEC of 0.1
μ
μ
g L
−1
.
Conclusions from cosm studies with CPY
. Results of cosm studies of CPY summa-
rized above (except the recent studies) were included in analyses by Brock et al.
(
2000
), van Wijngaarden et al. (
2005b
), Maltby et al. (
2005
), and Brock et al.
(
2006
), in which the cosm results were compared with single-species toxicity data
and regulatory benchmarks for various groups of insecticides. The summarized con-
clusions of these reviews are consistent with the earlier Giesy et al. (
1999
) ecological
risk assessment, and are:
• Sensitivity of species in cosms is similar to the sensitivity of the same or related
taxa in laboratory toxicity tests for single species. For CPY and other acetylcho-
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