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Watershed Study - Purpose

2012

Leaves were collected in December 2011 to be added in Spring Semester 2012. Twelve pounds of leaves were collected of which about 90% were hackberry. The leaves were added in April 2012 to experimental pools four and five. Control pools were one and seven. Because the control pools were dry in July, the nearest pools with water, pools 2 and 6, were substituted as controls; however, these pools did not have nets placed in them in April as did the original controls.

These substitutions must be kept in mind when looking at changes in the pools from May to July. Dissolved oxygen was higher in the experimentals than the controls. Although nitrate increased from May to July in both experimentals and controls, nitrate increased less in the experimentals, which is in agreement with the hypothesis that leaves help reduce nitrates.

There were more total organisms in the experimentals than the controls, also in agreement with the hypothesis that leaves increase the number of organisms in the stream. The types of organisms are of interest, in that mostly Diptera larvae were found in July.

These larvae are pollution tolerant as is expected in low oxygen conditions, but they also metamorphose into terrestrial adults which likely die over land, hence removing nitrogen from the water. Therefore, assimilation can lead to permanent removal of nitrogen as does denitrification.    

2013

In spring 2013 leaves were put in place in two experimental pools #1 and #3 in March. Abiotic data were collected as before. Biotic data were collected by an "equal time" method instead of "equal area" as before. The number of students actively collecting in each pool was multiplied by the number of minutes to give "90 people minutes."       

Table 1.
Living organisms in experimental pools 4 and 5, and control pools 1 and 7 in 2012. In the riffles near pool 4 were found Hemiptera, Diptera larva, Amphipoda, Isopoda, and Gastropoda. In the riffles near pool 1 were found Diptera larva, Amphipoda, Isopoda, and Gastropoda. In the riffles near pool 7 were found Chironomid larva, Amphipoda, and Isopoda. In July Zygoptera, Isopoda, Copepoda, and Isopoda were found near pool 5, and mosquito larvae, Isopoda, Copepoda, and Gastropoda near pool 4. Due to severe drought, control pools 1 and 7 were dry in July and were replaced by pools 2 and 6 without leaves or nets. Near pool 2, Hemiptera, mosquito larvae, and a beetle larva were found; near pool 6, mosquito larva, chironomid larva, Isopoda, Amphipoda, and Copepoda were found.  Experimental pool 4 and control pool 6 (replaced 7 as explained above) were sampled again in September and data given below. Also, in the riffle near pool 4 were found Isopoda, Amphipoda, Decapoda, Gastropoda, and Oligochaeta. In the riffle near pool 6 were found Isopoda.

 

 

ORGANISMS

APRIL

JULY

SEPTEMBER

Pool

1

4

5

7

1(2)

4

5

(6)7

1

4

5

6

Nematoda                        
Oligochaeta       1    1                
Gastropoda       1    1     5          
Isopoda  2  

5

   4     26 2       1
Amphipoda 85  28   67   65           8   26
Decapoda  4  1      1           6   3
Arachnida                        
Coleoptera         1              
Diptera: midge          1   4 3          
Diptera: misc.         3 11 24 2   1    
Hemiptera    1         1 1        
Odonata                        
Copepoda         2 4 16 2   4    
Turbellaria                        
Stream Quality Index 6 6 6 9 4 4 8 6   9   6

Table 2.
Abiotic measures for 1 X 2 m sample areas in April, July, and September 2012. Measurements were taken from the deepest area of pools. Sites 4 and 5 were experimental pools. Sites 1 and 7 were controls. However, due to drying up of pools 1 and 7 in July, pools 2 and 6 were substituted for controls. Dissolved oxygen and nitrate-N were determined by Vernier Lab Pro™ sensor probes.

MEASURE           APRIL       JULY                               SEPTEMBER
Pool    1    4    5    7   1(2)  4  5  (6)7    1     4     5    7(6)
Temperature

(degrees C)

 16 

 15

 

14

 

16

 

20

 

20 20 20  

 

10

 

 

18

 

Depth (cm)  19  21 10 12 17 10.5 7 11   11   7
PH 7.0 7.4 6.6 7.4 7.5 7.6 7.2 7.6   6.7   7.0
Dissolved

Oxygen (ppm)

6.3

 

7.5

 

5.9

 

3.9

 

3.0

 

6.0 5.0 7.0  

 

  7.0

 

 

 

   3.9

 

Nitrate-N

(ppm)

1.9 2.4 3.4 1.9 0.5 1.5 8.3 11.0   2.0   1.7

Table 3. Biotic data for 2013

Pools #1 and #3 were experimental and pools #2 and #6 were controls. In March downstream from pool #1 were found one Amphipoda and one Oligochaeta in the riffle area. In May downstream from pool #1 were eight Isopoda, one Amphipoda, nine Oligochaeta, one Coleoptera, and one Platyhelminthes in the riffle. In March downstream from pool #2 in the riffle were one Amphipoda and one Oligochaeta. In May downstream from pool #2 were three Oligochaeta and five Isopoda. In March downstream from pool #3 in the riffle were Isopoda and Amphipoda, and in May two Amphipoda, five Isopoda, eight Oligochaeta, and one Hemiptera.  In pool #6 in March downstream in the riffle were two Isopoda, and in May downstream were one Amphipoda, one Isopoda, and six Oligochaeta. Organisms in the pools are shown below.

 

ORGANISMS

MARCH

MAY

NOVEMBER

Pool

1

2

3

6

1

2

3

6

1

2

3

6

Nematoda                        
Oligochaeta 0 0   1   4 3 4 1        
Gastropoda                        
Isopoda 0  0

5

  2 2 0 2 3        
Amphipoda 2  0    5   3 2 0 2 4        
Decapoda             0          
Arachnida                        
Coleoptera                        
Diptera: midge         0   0          
Diptera: misc.                        
Hemiptera 2 0       2            
Odonata                        
Collembola                        
Turbellaria               1        
 

Stream Quality Index

5 0 5 4 5 3 5 7        

Table 4. Abiotic data for 2013.

Abiotic data are shown below. Pools #1 and #3 are experimentals and pools #2 and #6 are controls. Data were lost for pool #6 in March. Oxygen levels were reading too high to be likely accurate, probably due to cold water temperatures.

 

MEASURE           MARCH       MAY                               NOVEMBER
Pool    1    2    3 6   1  2  3  6    1     2     3    6
Temperature

(degrees C)

 11 

  5

 

 5

 

 

 

14

 

15 15 10  

 

  

 

 

 

 

Depth (cm) 10 13 18   12 12 20  9        
PH 7.4 6.6 7.5   5.9 8.9 8.1 7.0        
Dissolved

Oxygen (ppm)

10.5

 

11.0

 

8.8

 

 

 

8.0

 

9.7 9.0 10.0  

 

 

 

 

 

  

 

Nitrate-N

(ppm)

2.2 2.4 12.0   6.0 5.0 7.8 8.0        

Discussion

The data will be examined to determine the effects of added leaf litter on invertebrate number and diversity and chemical parameters.  In detrital ecosystems nitrates and phosphates are taken up by bacteria instead of green plants.  Additional carbon from the leaves might enhance reduction of nitrate to amino acids by bacteria and remove this pollutant from the stream.  Additionally, the added carbon might enhance species diversity by increasing the bacterial base of the food chain.  Higher plant diversity in the riparian zone increases diversity of dissolved organic substances and hence microbial diversity (Palmer et al., 2000).  Macroinvertebrates mix sediments and increase oxygenation and decomposition of organic matter.  Species have preferences for certain types of leaves.  “This is an area in which creative experiments are needed” (Palmer et al., 2000). In 2010 both numbers of organisms and SQI were lower for experimental pools in July.

According to Naiman and Décamps (1997), nitrogen can be removed in two ways by riparian forests.  Bacteria take up nutrients (nitrate assimilation) in a manner similar to plants, followed by growth, death, decomposition, and eventual nutrient release.  Also, some bacteria in anaerobic microhabitats convert nitrate to nitrogen gas or nitrogen oxide (denitrification), which are released from the ecosystem.  The presence of organic matter, such as decomposing leaves, enhances assimilation and denitrification. 

In an article by Bernhardt et. al. (2005), it was found that nitrate export by streams in the Hubbard Brook Experimental Forest has declined over the 40 years in which data have been recorded.  The study concluded that this decline was due to in-stream processing of nitrate by assimilation by biota and by denitrification in anoxic zones caused by vernal dams.  It was thought that maturing of the forest had resulted in more vernal dams.  The Longview study may afford confirmation of this hypothesis by simulating vernal dams with leaves held in place in the stream by netting.  The results of the study might predict the effect of allowing the forest in the watershed to mature. In 2010 the nitrate removal hypothesis was supported.

Recommendations

The study has been carried out for nine years so far, from 2004 to 2012.  At the recommendation of several of the first year's participants, the leaves were left under the nets in the experimental sites for a longer period of time in the second year (2005).  A longer decomposition period from April to July allowed potentially more nitrate to be removed and aquatic insects to increase in abundance. The study was repeated in 2005-2006 in a similar manner, except that the students in the second year recommended including more upstream, rockier sites.  The study was repeated in 2006-2007 and included studying a similar, but less disturbed (reference), watershed in the Longview Lake basin area.

According to Naiman and Décamps (1997), management and restoration of a water shed might best be achieved with a multi-species riparian corridor with three zones.  These are (1) a permanent forest ten meters wide, (2) shrubs and trees four meters wide, and (3) herbaceous vegetation seven meters wide.  The forest and shrub zones help remove nitrogen, phosphorus, and sediments.  The herbaceous zone spreads water flow as a sheet and helps remove coarse sediments.  The north side of the watershed is more restricted as far as meeting this plan.  Shrubs might be added south of the baseball field and in the parking lot drainage area east of the recreational trail.  The south side of the watershed is relatively well protected, but the amount of forest and shrub area could be increased.  

Bernhardt et al. (2005) hypothesized that maturation of forest in headwater streams increased the amount of debris that was dropped from trees, hence causing vernal dams that slowed flow and created anoxic zones where denitrification occurred.  In the context of headwater streams, denitrification can be considered positive with regard to water quality since nitrates can cause eutrophication downstream where more open bodies of water are subject to algal blooms.  The present watershed study appears to support this hypothesis.  Leaves added to the experimental sites simulated vernal dams that would occur with a more mature forest, and the results indicated that nitrate levels were indeed decreased.  Field results were corroborated by laboratory results in October 2007. The recommendation is that the forest corridor be allowed to mature and maintained at least at its present size. The students in Spring 2013 voted to use "equal time" instead of "equal area" for sampling pools. More students were involved this way but it was difficult for all of them to work in a small area.

Acknowledgements

First of all, I wish to thank all of those students who participated in this project but are too numerous, nearly two hundred, to name individually.  I also wish to thank Karla Horkman for helping with identification of invertebrates and for reading this manuscript.  This project was partially funded by a Longview Community College Action Plant Grant to Stephen L. Reinbold.

 

References  

Ambler, Pelovitz, Ladd, and Steucek. 2001. A demonstration of nitrogen dynamics in oxic & hypoxic soils & sediments. The American Biology Teacher 63(3): 199-206.

Bernhardt, E.S., G.E. Likens, R.O. Hall Jr., D.C. Buso, S.G. Fisher, T.M. Burton, J.L. Meyer, W.H. McDowell, M.S. Mayer, W.B. Bowden, S.E.G. Findlay, K.H. Macneale, R.S. Stelzer, and W.H. Lowe.  2005. Can't see the forest for the stream?  In-stream processing and terrestrial nitrogen exports.  Bioscience 55 (3): 219-230.  AcademicSearch Elite.  EBSCO.  Longview Community Coll. LIB., Lee's Summit, MO.  3 June 2005 <http://search.epnet.com>.

Naiman, R.J. and H. Décamps.  1997.  The ecology of interfaces: riparian zones.  Annual Review of Ecology and Systematics 28: 621-658.  AcademicSearchPremier. EBSCO. Mid Continent LIB., Lee's Summit, MO. 31 July 2004 <http://search.epnet.com>.  

Palmer, M.A., A.P. Covich, S. Lake, P. Biro, J.J. Brooks, J. Cole, C. Dahm, J. Gibert, W. Goedkoop, K. Martens, J. Verhoeven, and W. J. van de Bund.  2000.  Linkages between aquatic sediment biota and life above sediments as potential drivers of biodiversity and ecological processes.  Bioscience 50 (12): 1062-1075. AcademicSearch Elite. EBSCO.  Longview Community Coll. LIB., Lee's Summit, MO. 31 Oct. 2003 <http://search.epnet.com>.

Perry, J.W., D. Morton, and J.B. Perry.  2002.  Laboratory for Starr's Biology: Concepts and Applications.  p. 722-726.  Brooks/Cole.  Pacific Grove.

Sebilo, M., Mayer, B., Nicolardot, B., Pinay, G., and Mariotti, A. 2013. Long-term fate of nitrate fertilizer in agricultural soils. Proceedings of the National Academy of Sciences Open Access. 5 pages.

 

Other Sources

Bernhardt, E., G. Likens, D. Buso, and C. Driscoll.  2003.  In-stream uptake dampens effect of major forest disturbance on watershed nitrogen export.  Proceedings of the National Academy of Science 100(18): 10304-10308.  AcademicSearch Elite.  EBSCO.  Longview Community Coll. LIB., Lee’s Summit, MO.  29 Aug. 2005.  <http://search.epnet.com>. 

Brookshire, E., H. Valett, T. Steven, J. Webster.  2005.  Coupled cycling of dissolved organic nitrogen and carbon in a forest stream.  Ecology 86(9): 2487-2496.  AcademicSearch Elite.  EBSCO.  Longview Community Coll. LIB., Lee’s Summit, MO.  (abstract only)  16 Sept. 2005.  <http://search.epnet.com>.

Peterson, B., W. Wollheim, P. Mulholland, J. Webster, J. Meyer, J. Tank, E. Marti, W. Bowden, H. Valett, A. Hershey, W. McDowell, W. Dodds, S. Hamilton, S. Gregory, and D. Morrall.  2001. Control of nitrogen export from watersheds by headwater streams.  Science 292(5514): 86-88.  AcademicSearch Elite.  EBSCO.  Longview Community Coll. LIB., Lee’s Summit, MO.  29 Aug. 2005.  <http://search.epnet.com>.

Wallace, J., S. Eggert, J. Meyer, and J. Webster.  1997.  Multiple trophic levels of a forest stream linked to terrestrial litter inputs.  Science 277(5322): 102-104.  AcademicSearch Elite.  EBSCO.  Longview Community

Dr. Stephen Reinbold

Last Modified: 6/1/18