Pelagic food web interactions and hypolimnetic oxygen depletion: Results from experimental enclosures and lakes |
| |
| Authors: | Asit Mazumder D J McQueen W D Taylor D R S Lean |
| |
| Institution: | (1) National Water Research Institute, P.O. Box 5050, L7R 4A6 Burlington, Ontario, Canada;(2) Department of Biology, York University, M3J 1P3 North York, Ontario, Canada;(3) Department of Biology, University of Waterloo, N2L 3G1 Waterloo, Ontario, Canada |
| |
| Abstract: | Large lakes enclosures were used to examine the influence of nutrient (P, N) enrichment and planktivorous fish (1 + yellow perch) predation on hypolimnetic oxygen depletion. Results were compared to similar data for lakes with high (Lake St. George) and low (Haynes Lake) abundances of planktivorous fish. In both the unfertilized and fertilized enclosures, fish predation on large cladocerans increased the biomasses of pico- and nanoplankton (0.2–20 µm), phytoplankton (chlorophyll a) and total phosphorus (TP), reduced sedimentation, water clarity, and hypolimnetic oxygen concentrations (AHO). Fertilized enclosures without fish had highest TP and sedimentation rates, but the AHO were low. The high planktivore lake had higher pico- and nanoplankton, higher chlorophyll a, reduced water clarity, and lower AHO than the low planktivore lake. Areal hypolimnetic oxygen depletion (AHOD) rates were strongly related with Secchi depth and plankton size-distribution (r
2 = 0.77, and 0.79, respectively), but not as strongly with TP, chlorophyll a, and sedimentation rates (r
2 = 0.25, 0.53, and 0.02, respectively). Such observations are useful in forming a generalized hypothesis that lakes with low planktivory and high water clarity have lower oxygen depletion because 1) plankton that are settling are larger and spend less time in the hypolimnetic water column before reaching the sediment, and therefore undergo less decomposition, and 2) the euphotic depth extends into the hypolimnion and production of oxygen can take place. |
| |
| Keywords: | Pelagic food webs hypolimnetic oxygen depletion lake restoration water clarity predation and fertilization enclosure experiment |
| 本文献已被 SpringerLink 等数据库收录！ |
|
