This is a prestigious lectureship instituted in memory of
Cam Stevenson, the long-time Editor of the Canadian Journal of Fisheries and
Aquatic Sciences (CJFAS),
published by NRC
Press and is conferred upon a young, energetic and creative researcher
at the cutting edge of an aquatic discipline. Each year a Lecturer is selected
by the Journal's Editorial Board. In the Spring of
each year a call for nominations is sent to the Chairs of Zoology and Biology
departments across Canada, as well as to the research directors of the federal
Departments of Fisheries and Oceans and Environment Canada and the National
Research Council. The list of nominees is then sent to the CJFAS Editorial
Board, who provides recommendations and justification for their selections. The
Lecturer delivers a stimulating presentation of their work as the keynote
address in the opening session of the Annual CCFFR meeting. A written version
of the presentation is normally published as the lead article in the January
issue of CJFAS or sometime soon thereafter.
Responses of a freshwater food web to
whole-lake additions of a potent estrogen
Considerable
evidence now exists that fish are being adversely impacted by estrogens and
their mimics in municipal wastewater treatment plant (MWTP) effluents. However, it is not known whether the
responses observed at the organism level, such as the production of egg protein
precursors (vitellogenin) in male fish downstream of MWTPs, are indicative of problems at the population
level. To investigate this unknown
and assess the effects of an estrogen on lower-trophic-level biota, an
estrogen-addition experiment was conducted at the Experimental Lakes Area (ELA)
in northwestern Ontario from 1999-2006.
This study examined the effects of whole-lake additions of the synthetic
estrogen 17a-ethynylestradiol
(EE2) used in birth control pills on fish, amphibian, zooplankton, benthic-invertebrate,
algal, and microbial communities.
In the summers of 2001—2003, EE2 was added continuously to the epilimnetic waters of one lake to achieve constant and
environmentally-relevant concentrations of this estrogen. In the study and reference systems,
population-level data were collected for all trophic levels, and several
tissue- and biochemical-level endpoints were examined in lake trout, white
sucker, pearl dace and fathead minnow.
The experiment was successful at reproducing (no pun intended) the
organism-level impacts observed in wild fish downstream of MWTPs;
we also observed a population collapse of the shortest-lived fish species in
the lake, the fathead minnow, after the second summer of EE2 additions. Results from this study are being used
to understand the magnitude of the impacts that hormone mimics have on aquatic
organisms, and the risks that environmental estrogens pose to freshwater food
webs.