The Experiment
Correlation between Dissolved Oxygen and Insect Larvae
Problem:
 "Can resident insect populations be used to determine water quality?"
 
Hypothesis:
 "We believe the amount of dissolved oxygen
will have a correlation to the quantities of  different species of insect larvae"
Materials:
HACH Dissolved Oxygen Kit
Surber Aquatic Insect Collecting Apparatus
Collection Bottles
Magellan GPS Receiver
Thermometer
 
Procedures:
1.  Match physical characteristics of sites
2.   Control variables of sites
3.   Place thermometer in creek water above site
4.   Measure Dissolved Oxygen below site  using the Hach test kit protocol (fig1)
5.   Approach larvae collection site from downstream, not to disturb site
6.   Place net frame firmly on substrate with opening faced upstream
7.   Trail netting downstream from opening
8.   Rub and remove all stones within frame (fig 2)
9.   Stir substrate with hands carefully so no material leaves frame
10. Remove net in forward scooping motion
11. Place collection bottle in net and rinse material into it
12. Take sample to lab for microscopic counting of larvae (fig 3)
 
(figure 1)                        (figure 2)
  
(figure 3)
Data:
Site 1
Dissolved       Oxygen    #Chironomid   #Trichoptera  Temperature  Latit & Longit Derivative Ratio
    2.5 mg/l 
 		          6           5 18 degrees C 40'20.10N 74'39.36W       .83
Site 2
Dissolved Oxygen   #Chironomid   #Trichoptera   Temperature  Latit & Longit Derivative Ratio
    3.0 mg/l         2          1 20.5 degrees C 40'20.64N 74'39.04W        .5
 
Planaria
     2
Conclusions:
    Our study results were inconclusive. Due to our small sample sizes and the restricted area of study it is difficult to make statistically accurate correlations of dissolved oxygen content to different species success.  This also holds true for our low dissolved oxygen results, as protocols were not followed exactly. Our testing bottle had been destroyed in transport so alternative methods were used. However, we feel this does not undermine the success of our project.  What we actually accomplised was a field survey which gave  information as to what we may expect.  The need for a larger sample size and the investigation of the planaria we found as possible indicators of dissolved oxygen has yet to be explored.  The concept that the resident population will be good indicators of stream health appears to be a valid premise.   Lifeless streams can have an adverse effect on entire aquatic systems, so the reasons are critical to our understanding.  Streams are very dynamic and diverse in the qualities they possess.  Problems such as nitrate loading, heavy metals, or fecal coliform may have a much greater impact on insect larvae than does dissolved oxygen.  It became very obvious to us that many parameters need to be measured before a streams health can be deduced.  Evidence of this can be seen from our temperature data and it's similar weak correlation to insect populations.  Also to our dismay we found that the stream with a higher dissolved oxygen content had fewer insects. We fully expected this to be the other way around, with high oxygen content providing an abundance of larvae. The ramifications of this experiment's findings include, a plethora of future investigations, verification that hypothesis are sometimes wrong, and that clear procedures must be established. Through our failures we have been able to experience many of the pitfalls students will encounter as they begin to initiate an experiment or study of their own.

   Return To Home                      Process                         Standards                  
LINK TO HAWAII'S ENVIRONMENT
NENE are the endangered state bird of Hawaii 
           Click on the NENE to go to the Nature Conservancy of Hawaii 

Hawaii's Green Sea Turtle 
The Hawai`i Chapter of the Sierra Club CLICK Turtle 
Mail for more info click here