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@PHDTHESIS{Kulkarni:229066,
author = {Kulkarni, Devdutt},
othercontributors = {Schäffer, Andreas},
title = {{A} combined approach of experiments and modelling for the
implementation of freshwater copepods in ecological risk
assessment},
address = {Aachen},
reportid = {RWTH-CONV-144042},
pages = {129 S. : graph. Darst.},
year = {2014},
note = {Zsfassung in dt. und engl. Sprache; Aachen, Techn.
Hochsch., Diss., 2014},
abstract = {Standardized test guidelines used in ecological risk
assessment (ERA) consider a relatively small set of test
species. For instance in most standard risk assessments,
Daphnia magna is the only required species representing
freshwater invertebrates which assumes that tests with such
standard species in combination with relatively large
assessment factors are protective for other species in the
field. Standard test species are usually selected based on
intrinsic sensitivity as well as practicability i.e. the
ease of rearing. However, species in the field may employ
variable life-history strategies which may have consequences
concerning the ecological vulnerability of these species to
toxicants. The variability in the intrinsic sensitivity of
different species can be assessed by testing additional
species and constructing species sensitivity distributions
while ecological vulnerability can be addressed using
community-level studies e.g. mesocosms and ecological
modelling. Copepods are important animals in the aquatic
food chain. They are predators of other plankton and act as
prey for fish, consequently enabling the transfer of energy
and substances though the food chain. Copepods, owing to
their complex life-history strategies, are potentially
vulnerable organisms and therefore, useful as ecological
indicators of risk. For marine risk assessment, copepods are
now being considered and an OECD test guideline for
bottom-dwelling harpacticoid copepods is under way. However,
in freshwater ecotoxicology, copepods are largely ignored
except in mesocosm studies. To facilitate the consideration
of freshwater copepods in higher-tier ERA there is a need
for the development of robust test methods and models to
facilitate extrapolation between environmental conditions,
exposure patterns and species. This thesis delivers the
basics of a combined approach of laboratory experiments and
modelling for better consideration of freshwater copepods in
ERA. With a particular focus on plant protection products,
an exhaustive literature review was carried out to identify
a representative species of freshwater copepods, which could
be a good compromise between a potentially vulnerable
relevant species as well as a good laboratory species. The
literature review revealed Mesocyclops leuckarti as a good
representative species for freshwater copepods for
ecotoxicological studies. The suitability of this selected
species was demonstrated by establishing a stable laboratory
culture. To demonstrate the intrinsic sensitivity of this
species, a model chemical, triphenyltin (TPT), was used to
conduct acute toxicity tests with this species in the
laboratory. Experiments confirmed M. leuckarti to be
sensitive to TPT with the naupliar stages showing a higher
sensitivity compared to older stages. Furthermore, various
experiments to study the life-cycle processes of this
species namely- feeding, development, reproduction,
survival, etc. were conducted using different food sources
and feeding regimes. To facilitate the extrapolation of
individual-level effects to more relevant population-level
responses, an individual-based model (IBM) was developed for
this selected species. The model was parameterised based on
parameters of eco-physiological processes obtained from
laboratory experiments. The toxicokinetics and
toxicodynamics of TPT were described and modelled using the
General Unified Threshold model for Survival (GUTS) based on
the aforementioned laboratory toxicity tests. The combined
model was used to analyse the population-level effects TPT
under different feeding regimes. The main outcome of model
simulations was the identification of the synergistic effect
of cannibalism as well as TPT stress on the nauplii as the
cause of increased susceptibility of M. leuckarti
populations under toxic exposure. Furthermore, a case study
wherein the ecological sensitivity of M. leuckarti was
compared to D. magna and Chaoborus crystallinus by means of
population modelling was carried out. It was observed that
population-level sensitivities of the three species used in
the case study were higher than those on the individual
level. Also, the species that was least sensitive at the
individual level (C. crystallinus) was found to be most
sensitive on the population level. Furthermore, M. leuckarti
was less sensitive than D. magna at the individual level and
more sensitive than D. magna at the population level. This
thesis confirmed the relevance and practicability of
copepods for ERA as well as the significance of population
modelling in predicting population-level responses from
individual-level data. This approach of combining laboratory
experiments and population modelling of a representative
vulnerable species to allow mechanistic extrapolation to the
population level and to other exposure patterns can also be
applied to other taxa in order to build up a set of test
species and models useful for refined and more realistic
ERA.},
keywords = {Umwelttoxikologie (SWD) / Pflanzenschutzmittel (SWD) /
Modellierung (SWD) / Ruderfußkrebse (SWD)},
cin = {160000 / 162005},
ddc = {570},
cid = {$I:(DE-82)160000_20140620$ / $I:(DE-82)162005_20140620$},
shelfmark = {WQ 2200 * WI 2500 * WI 4820 * AR 12450},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-opus-49964},
url = {https://publications.rwth-aachen.de/record/229066},
}
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