Water Chestnut (Trapa natans L.) Infestation in the ... - SUNY Oneonta

Nutrient Concentrations
DISCUSSION
Unfortunately, the nutrient concentrations in the wetland can only be discussed in
the context of the massive flooding of the Susquhanna River in June 2006. The first three
samples before the flooding reported very high concentrations of nutrients and then a
sudden decline, which corrosponds exactly with the time of the flooding (TABLE 3). It
appears that this flushed the system and the levels remained low throughout the
remainder of the project (FIG 15 and 16). Unfortunately, this could suggest that the
effects of the flood were so substantial that they obscured impacts of the water chestnut
population or its management on nutrient concentrations.
There was a non reliable datum reported from the water testing. The ammonia
concentration reported for 14 Aug 07 is higher than total nitrogen, which is impossible
beause all nitrogen components are to be converted to nitrate, which is what is then
analyzed. This could be due to incomplete conversion of ammonia during the digestion.
Therefore, total nitrogen must have been higher that what was reported (TABLE 4).
The concentrations of phosphorus in the first three samples in 2006 are nearly 50
times the concentrations normally found in other areas of the Susquehanna; nitrogen
concentrations were about 10 times greater (TABLE 3). However, when disregarding the
very high concentrations recorded for the nutrients on 22 May, 30 May and 15 June of
2006, the results of the water nutrients of the wetland are quite low when compared to
other portions of the river. This comparison supports the speculation that the flood in
June 2006 flushed the wetland and kept conentrations low. Nutrient data collected in
more southern areas of the Susquehanna watershed in streams of Towanda, Marietta, and
Conestoga (all in Pennsylvania) taken over the past 20 years have shown to have
relatively high and consistent nitrogen levels, while phosphorous levels have been
continuously improving (decreasing) (Edwards 1996). In comparison, nitrogen levels in
the Blasetti wetland are extremely low, less than half of the nitrogen at the other sites in
the watershed. Phosphorus levels are also low, approximately 0.01-0.03 mg/L less
(TABLE 12).
Although there are no water nutrient data from the wetland prior to the start of the
project or before the chestnut invasion, it can only be assumed that the nutrient
concentrations were high (a typical wetland charateristic) and consistent with the data
reported for May and June 2006. It can be speculated that the increased nutrient levels
only enhanced the suitability of the wetland for the infestation of the invasive water
chestnut and curly pond weed.
In addition, establishing causality of nutrient and sediment trends is not a simple
task, given the complex interactions of human acitvites. In the Susquheanna River Basin
over the past 30 years trends indicate that phosphorous and sediment concentrations have
been holding steady or improving, but nitrogen levels are of concern. The cummulative
effect of phosphate detergent bans, agricultural best management practices (BMPs) and
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