Randall J. Bendis, Ph.D.

Moving from the smaller-scale, single species toxicity tests, my next area of research involved crossing experimental communities with different zooplankton populations that differed only in the naturally-occurring population level resistance to a commonly applied insecticide (see above experiment).  In this experiment, we set up identical communities and only manipulated the genetics of the zooplankton within each experimental community by adding the same number of zooplankton but from different ponds where we had already determined that there was naturally-occurring variation to the insecticide in question.  Other similar community studies usually do not manipulate the population genetics of their zooplankton and stock all communities with the same clone or set of clones to limit the amount of variation within experimental communities.  However, this does not reflect what we see in nature as some populations of zooplankton are naturally more resistant to insecticides due to their close proximity to nearby agricultural fields.  Whereas communities with sensitive zooplankton (that may be naive to these chemicals) are subjected to dramatic trophic cascades through the loss of zooplankton and subsequent phytoplankton blooms, communities with resistant zooplankton are almost entirely buffered from the adverse effects of insecticides.