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Yearly Summary

2006

• Vegetation sampling was conducted in Pools 4, 8, and 13 (see methods).
  
  
• Overall, submersed aquatic vegetation (SAV), rooted, floating-leaf vegetation (RFV), and emergents (EM) remained the same or increased in all study areas (Figure 2).
  
  
• The percent frequency of occurrence (hereafter referred to as percent frequency) of SAV, RFV, and EM in Pool 4 increased to the highest level recorded since the study began in 1998 (Table 2).

• The percent frequency of SAV in lower Pool 4 increase 6% from the previous year (57.4% in 2004) and exceeds previously recorded levels of SAV (Table 2).  Secondary channels had the largest increase (16.8%; Table 3).
  
  
• The percent frequency of SAV in upper Pool 4 remained low (14.6%), although it did increase slightly from the previous 5 years of sampling. The largest increases occurred in the Lake Pepin and main channel border strata (Table 3).  Percent frequency of EM increased by 10% in main channel border areas (Table 7).

• Coontail (Ceratophyllum demersum L.) increased in percent frequency by more than 10% in lower Pool 4, Pool 8 and Pool 13 (Table 4).
  
  
• The frequencies of coontail, Eurasian watermilfoil (Myriophyllum spicatum L.), and wild celery (Vallisneria americana Michx.) in Pool 4 have all increased to their highest level recorded since 1998 (Table 4).
  
  
• Submersed aquatic vegetation, percent frequency and abundance index, has continued to increase in Pool 8 since 2001 (Table 2, Figure 2). Both variables were the highest recorded since the stratified random sampling began in 1998, but were not much different from 2005. However, SAV in secondary channels increased in percent frequency by 13.9% (Table 3).  Wild celery has increased steadily since 2001 (Table 4).
  
  
• Rooted, floating-leaf and emergent vegetation also remained about the same as 2005 in Pool 8 (Figure 2).  A decrease in RFV of 17.5% was recorded in isolated backwaters (Table 6).

• Submersed aquatic vegetation in Pool 13 exhibited the highest percent frequencies in the impounded, main channel border, and secondary channel areas since 1998 (Table 3).  Poolwide percent frequency estimates of SAV also reached an all time high (Figure 2).

• The highest percent frequency and percentage of SAV, RFV, and EM were recorded in Pool 13 since the study began in 1998 (Figure 2). Overall, EM percent frequency increased slightly in Pool 13 (Table 2) with the largest increase occurring in isolated backwaters (28%; Table 7).

• More summary statistics including percent frequency, abundance index, and distribution maps along with species information can be interactively generated for all study areas using the Vegetation SRS Graphical Browser. The graphical browser also lets you download the summary data for each search. Raw data can be obtained from the Aquatic Vegetation Data Browser.

2005

• Vegetation sampling was only conducted in Pools 4, 8, and 13 (see methods). Pool 26 and La Grange Pool were removed from yearly monitoring because of the lack of submersed aquatic vegetation.
  
  
• Sample size was adjusted based on the variance from the previous year (Table 1) but was capped at 450 sites per pool.
  
  
• Overall, submersed aquatic vegetation (SAV) and rooted, floating-leaf vegetation (RFV) increased in all study areas.
  
  
• The percent frequency of occurrence (hereafter referred to as percent frequency) of SAV in Pool 4 increased to levels not seen since 2001 (Table 2). Percent cover of RFV was near the highest ever recorded (Table 2; Figure 2), although emergent vegetation declined (Table 2; Figure 2).
  
  
• The percent frequency of SAV in lower Pool 4 experienced a 10% increase (to 57.4%) from the previous year (46.4% in 2004), and exceeds previously recorded levels of SAV (Table 2).
  
  
• The percent frequency of SAV in upper Pool 4 remained low (10%), although it did increase slightly from the previous 4 years of sampling. This pattern is most pronounced in the backwater contiguous and upper Lake Pepin strata (Table 3).
  
  
• The frequencies of coontail (Ceratophyllum demersum L.), Eurasian watermilfoil (Myriophyllum spicatum L.), and wild celery (Vallisneria americana Michx.) in Pool 4 have all increased to their highest level recorded since 1998 (Table 4), whereas the frequency of sago pondweed (Stuckenia pectinatus [L.] Boerner) has reached its lowest level since 1998 (Table 5).
  
  
• Submersed aquatic vegetation percent frequency and abundance index has continued to increase in Pool 8 since 2001 (Table 2, Figure 2). Both variables were the highest recorded since the stratified random sampling began in 1998. Most of the increase occurred in the impounded stratum (Table 3).
  
  
• Rooted, floating-leaf and emergent vegetation also increased in Pool 8, but to a lesser degree (Figure 2). Canadian waterweed (Elodea canadensis Michx), narrow-leaf pondweeds (Potamogeton spp. L.), water stargrass (Heteranthera dubia [Jaqc.] MacM.), and coontail percent frequencies all increased by more than 10% from 2004 to 2005.
  
  
• Submersed aquatic vegetation in Pool 13 exhibited the highest percent frequencies in the contiguous and isolated backwater and impounded areas since 1998 (Table 3). Poolwide percent frequency estimates of SAV reached an all time high also (Figure 2).
  
  
• Rooted, floating-leaf species covered the highest percentage of shallow water areas (water less than 3 m) in the contiguous and isolated backwaters since 2001 (Table 6). One possible cause is that Pool 13 and most of the area south experienced a natural drawdown this year due to the lack of rain allowing rooted, floating-leaf species to become established.
  
  
• More summary statistics including percent frequency, abundance index, and distribution maps along with species information can be interactively generated for all study areas using the Vegetation SRS Graphical Browser. The graphical browser also lets you download the summary data for each search. Raw data can be obtained from the Aquatic Vegetation Data Browser.
  
  

2004

• In 2004, aquatic vegetation sampling was conducted in LTRMP key Pools 4, 8, 13, and 26 of the Mississippi River and La Grange Pool of the Illinois River. Sample size was adjusted based on the variance from the previous year (Table 1).
  

Submersed Aquatic Vegetation

• Since 1998, poolwide percent frequency of occurrence of SAV in Pools 8, 13, and 26 has remained relatively stable (Figure 2).
  
  
• Pool 13 recorded the highest percent frequency of SAV since stratified random sampling began in 1998 (Table 2).
  
  
• In upper Pool 4, the percent frequency of SAV declined steadily from 1998 (22%) to 2001 (7%) and has remained low. This pattern is most pronounced in the backwater contiguous and upper Lake Pepin strata (Table 3).
  
  
• Wild celery in Pools 8 and 13 has steadily increased in percent frequency from 1998 (10% and 15%; respectively) to 2004 (25% and 19%; respectively). Contrastingly in lower Pool 4, wild celery has declined to a new low (20.1%) since 1998 (Table 4).
  
  
• In the backwater isolated strata of the lower Alton Pool of the Illinois River, SAV increased in percent frequency from 2002 (6%) to 2003 (25%) then declined to 2% in 2004. All other strata had little or no SAV (Table 3). This same pattern was noted for sago pondweed (Table 5) in the lower Alton Pool of the Illinois River as well as rooted, floating-leaf (Table 6) and emergent species (Table 7).
  
  
• Percent frequency of SAV in the impounded strata of Pool 8 has increased from 2001 (37%) to 2004 (56%). This may be due in part to the building of islands in lower Pool 8 providing protection from wind and wave action.
  

Rooted, Floating-leaf Vegetation

• In Pools 4, 8, and 26 and La Grange Pool, RFV has remained relatively stable from 1998 to 2004 (Figure 2).
  
  
• In Pool 13, an increase in RFV has been occurring from 1998 (18%) to 2004 (27%;Figure 2).
  

Emergent Vegetation

• In Pools 4, 8, and 13, and La Grange Pool, emergent vegetation has remained relatively stable from 1998 to 2004 (Figure 2).
  
  
• In lower Pool 26, emergent vegetation has shown a slight increase trend from 2001 to 2004 (Figure 2).
  
  
• A water level drawdown was conducted in Pool 8 in 2001 and 2002. In 2001, Pool 8 remained above flood stage until late June, and water was not drawn down until early July. Percent frequency of emergent vegetation showed little change from 2000 (12%) to 2001 (10%) then increased in 2002 (16%) and remained steady in 2003 (18%) and 2004 (17%). The increase in emergent vegetation in 2002 may have resulted from the drawdowns conducted in 2001 and 2002.
  

2003

• In 2003, 650 sites were sampled in Pool 8 and 580 in Pool 13. Because of budget reductions, no aquatic vegetation sampling was conducted in Pools 4 and 26 and La Grange Pool. However, aquatic vegetation was sampled from the three pools by other agencies using LTRMP protocols, and the data were graciously provided to the LTRMP.  Pool 26 was sampled by the Illinois Natural History Survey under a grant provided by the National Great Rivers Research and Education Center. La Grange Pool was sampled by the Illinois Natural History Survey under a grant provided by the Illinois Department of Natural Resources. Aquatic vegetation data from Pool 4 was provided by the U.S. Fish and Wildlife Service and the Division of Fisheries, Minnesota Department of Natural Resources.
  
  
• Submersed aquatic vegetation (SAV) was most frequently collected in lower Pool 4 (58% of the sites) and in Pools 8 (55%) and 13 (41%; Table 2).  Lower Alton Pool (21%) and upper Pool 4 (9%) had a moderate amount,whereas no SAV was found in Pool 26 and La Grange Pool.  Abundant SAV was recorded in the lake stratum of La Grange Pool (93%; Table 3).  The lake stratum was not included in the poolwide estimate for La Grange Pool because the lakes were located behind large agricultural levees and were never flooded by the Illinois River.
  
  
• The SAV frequency has remained fairly constant from 1998 to 2003 in lower Pool 4, in Pools 8, 13, and 26, and La Grange Pool (Figure 2).  Upper Pool 4 SAV has shown a steady decline since 1998, whereas the SAV in lower Alton Pool increased by 16% from 2002 to 2003.
  
  
• Coontail was frequently observed in lower Pool 4 (32%) and in Pools 8 (31%) and 13 (27%) in 2003 (Table 4).  Coontail was rarely observed in upper Pool 4 (3%) and in lower Alton Pool (3%) and not recorded in Pool 26 and La Grange Pool. Eurasian watermilfoil and wild celery were abundant in Pool 4, common in Pools 8 and 13, and rare or absent in upper Pool 4, Pool 26, and La Grange Pool (Table 4).  Sago pondweed was most frequently observed in Pool 13 (19%) followed by lower Alton Pool (16%), Pool 8 (14%), lower Pool 4 (11%), and upper Pool 4 (7%).  No sago pondweed was recorded in La Grange Pool (Table 5).
  
  
• American lotus (Nelumbo lutea Willd.) was most frequently recorded in Pool 13 (23%), whereas broadleaf arrowhead (Sagittaria latifolia Willd.) was most frequently recorded in Pool 8 (10%; Table 5).  Both were recorded in less than 10% of the sites in all other pools.
  
  
• Rooted, floating-leaf vegetation was common in lower Pool 4 (28%), in Pools 8 (21%) and 13 (27%), infrequent in lower Alton Pool (13%), and rare in upper Pool 4 (3%), Pool 26 (2%), and La Grange Pool (1%; Table 2).
  
  
• The RFV has remained constant in upper Pool 4, in Pools 8 and 26, and in La Grange Pool and lower Alton Pool (Figure 2).  Lower Pool 4 RFV increased 11% from 2001 to 2003.  Pool 13 showed a small but steady increase in RFV from 1998 to 2003.
  
  
• Emergents were most common in lower Alton Pool representing an increase of 17% from 2002 to 2003 (Table 2).  Emergents were infrequently observed within the sampling area in lower Pool 4 (14%), in Pools 8 (18%), 13 (7%), and 26 (7%), and rarely observed in La Grange Pool (3%).  No emergents were recorded in upper Pool 4 in 2003.
  
  
• With the exception of lower Alton Pool, frequency of emergent vegetation has remained fairly constant in all pools from 1998 to 2003 (Figure 2).
  
  
• Within all pools, all three life forms were more common in areas of low flow (contiguous and isolated backwaters) than higher flow (impounded, secondary channels, and main channel border; Tables 3, 6, and 7; respectively).

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