SUBMERSED AQUATIC VEGETATION [WILDCELERY (VALLISNERIA AMERICANA) AND SAGO 
PONDWEED (POTAMAGETON PECTINATUS)] RE-ESTABLISHMENT EFFORTS IN LAKE CHAUTAUQUA, 
ILLINOIS RIVER. 

Thad R. Cook and Mark A. Pegg.
Illinois Natural History Survey, Illinois River Biological Station, Long Term 
Resource Monitoring Program, 704 North Schrader Ave., Havana, IL 62644.

Backwaters of the Middle Illinois River were historically described as having 
extensive populations of pondweeds (Potamogeton spp.), wild celery (Vallisneria 
americana), and coontail (Ceratophyllum demersom).  However, submersed aquatic 
vegetation (SAV) soon began to disappear following the diversion of water from 
Lake Michigan in 1900.  Continued human induced alterations furthered the 
decline of SAV in the Illinois River and it’s backwater lakes.  By 1950, only 
the hardiest of submersed and rooted floating leafed species (coontail and 
lotus, Nelumbo lutea) were present in a few backwater lakes.  Similarly, the 
present distribution of SAV within the Lower Illinois River is very limited and 
efforts to re-establish this life form in backwaters have been met with limited 
success.  In 2001, we began investigating factors limiting SAV, specifically 
wild celery and sago pondweed (Potamogeton pectinatus) in Lake Chautauqua, an 
isolated backwater.  Wild celery winter buds were planted in Lake Chautauqua at 
a density of 6.9 buds/m² in two treatments (enclosed 3 x 3-m cage and an 
unprotected 3 x 3-m area) plus an additional enclosed control with no plantings 
in 2001.  We conducted a similar experiment using sago pondweed winter buds in 
2002, where we placed an additional enclosure near the other treatments with a 
wave barrier to protect against wind and waves.  Sites were visited weekly where 
leaf measurements of each plant were taken to evaluate success.  Subsequent 
daughter plants were also documented and measured.  A subset of plants were 
allowed to complete their annual life cycle and harvested to determine success 
of winter bud production in all treatments.  Results for both years’ experiments 
were similar in that all plantings not protected by enclosures encountered a 
high occurrence of leaf cropping and 0% survival.  Initial growth was good in 
both years in all treatments, but unprotected plants were immediately cropped 
following elongation and did not survive the growing season.  Reproduction 
within the enclosures varied, as some sites were unsuccessful whereas others 
grew and reproduced successfully.  Production of winter buds from the initial 
tubers planted within the enclosures averaged 115/m² with a range of 0/m² to 
927/m² for wild celery in 2001 and averaged 122/m² with a range of 0/m² to 
659/m² for sago pondweed in 2002.  Water quality measurements (e.g., 
temperature, DO, turbidity) were relatively similar among treatments and sites.  
However, some were exposed to wind and wave action resulting in varied outcomes.  
Our study suggests that both biotic and abiotic factors can limit growth and 
establishment of submersed aquatics in Lake Chautauqua.  However, our results 
show promise in establishing SAV given the appropriate conditions (i.e., 
protection from herbivory and wind action).

Keywords:  Illinois River, Potamogeton pectinatus, sago pondweed, Vallisneria 
americana, wild celery