Abstract
Previous work during a major sediment resuspension event (March 1988) in southern Lake Michigan demonstrated that nutrients and carbon derived from resuspended sediment stimulated intense winter heterotrophic production while simultaneously decreasing light availability and autotrophic biomass. However, the role of riverine inputs on plankton metabolism remained unclear. Here we present results from a simulated enrichment experiment (March 2000) designed to examine the influence of resuspended sediments and riverine inputs on Lake Michigan plankton dynamics. Lake water amended with realistic levels of river water, coastal resuspended sediment and river water + sediment all showed enhanced heterotrophic bacterial production and plankton respiration rates, relative to the lake water control. Bacterial production increased by approximately 4x in river water treatments and by a factor of 2.5x for the sediment only treatment compared to lake water controls. Rates of net primary production were stimulated by river water (8.5x) and resuspended sediment (3x), but most by a combination of river water + sediments (11x). Community respiration showed a similar response with rates approximately 8x higher in river water amendment treatments and 3.5x higher in the sediment treatment. Extrapolating experimentally determined production rates to the southern Lake Michigan basin indicated that heterotrophic and autotrophic production in this nearshore region may be enhanced by as much as 3x and 5.2x due to these source inputs. Indeed, field measurements throughout southern Lake Michigan from 1998-2000 support these experimental results. Experimental and field observations suggest that both seasonal riverine inputs and episodic resuspended sediments influence the regional scale ecosystem metabolism and biogeochemistry in Lake Michigan.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 213-227 |
| Number of pages | 15 |
| Journal | Journal of Great Lakes Research |
| Volume | 34 |
| Issue number | 2 |
| DOIs | |
| State | Published - 2008 |
Bibliographical note
Funding Information:We thank the NOAA Great Lakes Environmental Research Lab for use of the field station for the experiments and to Dr. Gary Fahnenstiel for helping plan and coordinate the study. We also thank the crew of the R/V Laurentian for assistance during all field sampling for the EEGLE program. This research was supported by a jointly funded program through NOAA and NSF as part of the EEGLE program (NOAA-46290000) administered through the Cooperative Institute for Limnology and Ecosys- tems Research at the University of Michigan. Dr. Biddanda received additional support for this research from NSF grant (MIP 0603944).
Keywords
- Lake Michigan
- Plankton metabolism
- River runoff
- Sediment resuspension