NTU Undergraduates' research April 2014 - Biosciences | Seite 53

Max Haywood (N0314321) Abstract
Ecotoxicity bioassays are important tools for both the monitoring of water quality and investigation of the effects of pollutants, at both
individual and population levels. There are many amphipod ecotoxicity bioassays developed for behavioural attributes. The aim of this
study was to compare the sensitivity, efficiency, cost and relevance of four bioassays, using the gammarid Gammarus Pulex and silver (Ag).
We found that there was a decrease in feeding activity, with a LOEC of less than 0.01 µg Ag L-1, a decrease in percentage of time active,
with a LOEC of between 0.1 and 1 µg Ag L-1, and an increase in mortality at 48 hours exposure, with a LOEC of between 1 and 3 µg Ag L-1.
Using mortality as an endpoint has several disadvantages, including the fact that it does not take into account disruption of biotic processes
by low concentrations of a pollutant. The main mechanism of toxicity of G. pulex by Ag is through loss of Na+, resulting in osmoregulatory
disruption of the haemolymph. The study concludes that the feeding rate is the most sensitive bioassay and has the best potential to be used
in situ.