Unformatted text preview: appear to respond to a t oxicant that is selective for phytop lankton. INDIRECT DIRECT
Effects may be a
decrease in numbers or
an increase in numbers
+ + - - A TEMPORAL DIFFERENCES BETWEEN PRIMARY AND SECONDARY EFFECTS
+ - - Mortality
(effect) + Concentration B CONCENTRATION-RESPONSE USING EFFECTS AT A CERTAIN TIME OR
AREA UNDER THE CURVE Figure 3-221
Use of temporal response (A) and functional data (area under the curve) (B) for interpretation of primary and
secondary effect dose-responses In the final analysis, i t is a question of defining what is meant by a significant change in an
ecosystem. When is the system so different from the norm (if this itself can indeed be defined)
that regulatory or preventative measures need be taken?
3.2.9 Classification of effects in microcosms Responses in microcosms can be categorized in a number of ways. Effect classes for responses
in microcosms have been proposed (Brock et al. 2006). In Europe, these effect classes (Table 32) are used to evaluate semi -field tests submitted for the registration of pesticides.
Table 30. Classes of effects observed in microcosm studies
ocosm) 2 Slight effect Description
No (statistically significant) effects observed as result of the
treatment, and observed differences between treatment and
controls show no clear causal relationship. Causality in this
context is judged throu gh the use of guidelines similar to those
developed for identifying causative agents of disease
(Koch 1942, Hill 1965, IPCS 2002) .
Effects reported in terms of ―slight‖ or ―transient‖ and/or other
Short-term and/or quantitatively restricted response of sensitive Table 30. Classes of effects observed in microcosm studies
Class 3 4 5 3.3 Effect Description
Effects only observed at individual sample times.
Clear response of sensitive endpoints, but full recovery of
affected endpoints within 8 weeks after the 1st (effect class 3A)
effect (A or B) or last (effect class 3B) application (from recovery in treated
Effects reported as ―temporary effects on several sensitive
species‖, ―temporary elimination of sensitive species‖,
―temporary effects on less sensitive species/endpoints‖ and/or
other similar descriptions.
Effects observed at some subsequent sampling instances
Clear effects (such as large reductions in populations of
effect in short - sensitive species) observed, but the study is too short to
demonstrate complete recovery within 8 weeks after the (last)
Clear response of sensitive endpoints and recovery time longer
than 8 weeks after the last a pplication, but full recovery is
effect (A or B) demonstrated to occur in the year of application (effect class
5A) or cannot be demonstrated before termination of the
experiment or before the start of the winter period (effect class
Effects reported as ‗‗long -term effects followed by recovery on
several sensitive and less sensitive species/endpoints‘‘ o...
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