Work package 3: How do pharmacuetical effects at the individual and group levels impact aquatic communities?
Given that exposure to pharmaceutical pollutants is predicted to compromise individual and group-level behaviour in wildlife, the ecological pressure that animals exert may change, leading to fundamental shifts in food-webs. For example, fish school to gain antipredator benefits such as increased vigilance and/or increased foraging efficiency. Thus, schooling fish tend to exert greater top-down (by eating more or less) and bottom-up (by not being eaten) food-web pressure than non-schooling fish. Work package 3 will use a semi-natural replicated mesocosm system to identify both the direct and indirect effects of pharmaceuticals on fish behaviour and schooling, as well as the subsequent impacts on lower food-web communities.
The experiment will be conduced over 8 weeks in a semi-natural replicated pond system (20 ponds, each pond 6m x 12m x 2m; five per treatment), in which groups of fish will be subjected to one of three pharmaceutical exposure treatments. Treatments will be administered via slow-release implants that allow direct quantification of pharmaceutical-induced behavioural effects on community structure without whole-pond contamination. All ponds are equipped with passive integrated transponder (PIT) antennas. Before introduction to ponds, all fish will be surgically implanted with a PIT tag. The PIT tag will provide tracking data of individual’s movement and location throughout the experiment. From the beginning of the experiment, water, plankton net, and leaf pack samples will be collected weekly from each pond to measure changes in aquatic community structure. This will involve comparing zooplankton, phytoplankton and invertebrate communities between mesocosm treatments. Together, this information will be used to examine changes in fish behaviour and community structure in response to pharmaceutical exposure
Top: 20 replicated experimental ponds at the Umea Experimental Ecosystem Facility. Bottom left: Smaller mesocosm setup. Bottom right: A look inside of the initial stages of the smaller mescosms