| Abstract: | ABSTRACT: It is suggested that new impoundments undergo an initial period of trophic upsurge lasting one to three years because of organic detritus and inorganic nutrients from the inundated basin. The new Monksville Reservoir in Passaic County, New Jersey, provided an opportunity to study the accelerated transformation of the Wanaque River into a 200-ha lake and to compare productivity with the older Wanaque Reservoir located immediately downstream. A one-year investigation of both reservoirs was conducted during 1988. The primary productivity (0.547 g C m?2 d?1) of the new Monksville Reservoir was not significantly different from that of the established Wanaque Reservoir (0.668 g C m?2 d?1). Mean surface chlorophyll a concentrations were similar (3.0–4.0 μg 1?1), although the Monksville Reservoir exhibited more pronounced chlorophyll peaks in spring and late autumn. Phytoplankton and zooplankton populations were consistently larger and fluctuated sharply in the Monksville Reservoir. Both reservoirs became thermally stratified, but only the Monksville Reservoir developed a metalimnetic dissolved oxygen minimum. The results demonstrated that the predicted trophic upsurge in the new reservoir did not occur in the first year therefore, the ecosystem dynamics did not fit the model for larger reservoirs. |
