The effect of prior exposure to toxic cyanobacteria on the survival and cyanotoxin accumulation in Daphnia carinata

Shian Liau

    Research output: ThesisMaster's Thesis

    396 Downloads (Pure)

    Abstract

    [Truncated] The presence of toxic cyanobacteria in blooms across various waterbodies such as recreational lakes, wastewater ponds and temporary ponds poses a risk of cyanotoxin accumulation in the zooplankton community, which may then be transferred across the food web. Daphnia, a key grazer in these habitats, is one of the most widely studied ecological indicators to assess the health of ecosystems. Recent studies show tolerance development in Daphnia towards toxic cyanobacteria, which has been attributed to selective grazing, detoxification mechanisms, genetic variation and phenotypic plasticity. However, the connection between cyanotoxin tolerance in Daphnia and its implication on current practice in Daphnia toxicity tests and cyanotoxin accumulation levels is still not fully studied. This research aims to investigate the influence of prior exposure to toxic cyanobacteria on the survivorship and accumulation of microcystin-LR (MC-LR) in Daphnia carinata, a species widely found in Western Australia.

    Experiments were conducted to assess the acute survival and cyanotoxin accumulation in D. carinata from two urban lakes with different algal bloom histories under laboratory conditions. Three different D. carinata populations that differed in their original feeding history were used; namely Lake Yangebup non- and cyanobacteria-exposed Daphnia, and Little Rush Lake Daphnia. On their arrival in the lab, the Lake Yangebup non-exposed and Little Rush Lake Daphnia were fed on the non-toxic Desmodesmus sp., while the cyanobacteria-exposed Daphnia, received 20 % toxic Microcystis aeruginosa out of its total food diet for a month prior to experiment. Both the survival and microcystin-LR accumulation experiments were conducted over 48 h. All three Daphnia populations were used in the survival test, whereas the accumulation experiment was only conducted with Lake Yangebup Daphnia.
    Original languageEnglish
    QualificationMasters
    Publication statusUnpublished - Apr 2015

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