Skip to main content MCC Crescent Shape Search rss Facebook Twitter Youtube Instagram chevron pointing down

Amphipod Laboratory Experiment - Results

Results for Laboratory Study

The laboratory study was conducted in fall 2007. Data are located in Tables 1-3. As can be seen in Table 1, oxygen levels were significantly lower in experimentals than controls in groups 3 and 4 on October 18. Group 6 showed significantly lower oxygen level in experimental than control on October 23. No jars showed significantly higher oxygen in control than experimental. No significant differences were seen in nitrate concentrations between experimentals and controls (Table 2); however, 19 out of 24 comparisons showed lower nitrate concentrations in experimentals than controls, and only 7 showed lower or equal nitrate concentrations in control compared to experimental. Three of the 7 were on the first day of the experiment before any difference was expected. Table 3 shows mostly high positive correlations between oxygen concentraton and nitrate concentration. Survival rates were good throughout the experiment, and no significant differences were seen in survival between controls and experimentals when animals were counted on October 18 and 23.

Table 1. Effect of food quantity given to amphipods on oxygen concentration. Controls received two hackberry leaf discs four times during the experiment, and experimentals received four leaf discs on the same occasions.

oxygen oct. 9   oct. 11   oct. 18   oct. 23  
group control exper control exper control exper control exper
1#1 4.8 4.8 4.3 4.1 5.8 5.5 5.9 5.2
1#2 5.2 5 3.9 3.9 5.6 5 5.6 5.6
ave 5 4.9 4.1 4 5.7 5.25 5.75 5.4
t test con v exp 0.711723   0.711723   0.296585   0.305373
2#1 7.3 7.2 6.8 6.7 7.2 6.5 8.6 7.8
2#2 7.2 7.2 7.1 6.4 7.1 6.1 8.3 7.5
ave 7.25 7.2 6.95 6.55 7.15 6.3 8.45 7.65
t test con v exp 0.5   0.2   0.130019   0.063671
3#1 6 6 6.5 6.5 5.9 5.3 6.4 5.9
3#2 6 6.1 6.75 6.5 5.8 5.4 6.7 5.8
ave 6 6.05 6.625 6.5 5.85 5.35 6.55 5.85
t test con v exp 0.5   0.5   0.019419   0.107122
4#1 7.6 7.5 5.6 6.9 6.2 5.6 5.1 5.1
4#2 7.5 7.5 5.8 5.9 6.1 5.5 5.5 5.2
ave 7.55 7.5 5.7 6.4 6.15 5.55 5.3 5.15
t test con v exp 0.5   0.38824   0.013606   0.588295
5#1 6 6 5.8 5.5 5 4.7 5.8 5.4
5#2 6.1 6 5.7 5.3 5 4.8 5.1 5.7
ave 6.05 6 5.75 5.4 5 4.75 5.45 5.55
t test con v exp 0.5   0.129048   0.125666   0.82714
6#1 4.8 4.5 6.1 5.5 6 5.6 7.7 7.1
6#2 4.4 4.5 5.5 5.5 5.8 5.5 7.7 7
ave 4.6 4.5 5.8 5.5 5.9 5.55 7.7 7.05
t test con v exp 0.704833   0.5   0.129048   0.048875

 

Table 2. Effect of food quantity given to amphipods on nitrate concentration. Feeding schedule as in Table 17.

nitrate 9-Oct   11-Oct   18-Oct   23-Oct  
group control exper control exper control exper control exper
1#1 2 1.9 1.6 1.9 1.2 2.1 0.9 0.9
1#2 1.8 1.9 1.5 1.5 1.5 1.5 0.9 0.8
ave 1.9 1.9 1.55 1.7 1.35 1.8 0.9 0.85
t test con v exp 1   0.588295   0.349886   0.5
2#1 0.5 0.5 0.4 0.3 0.5 0.4 1.6 1
2#2 0.5 0.6 0.3 0.3 0.4 0.4 2 1.1
ave 0.5 0.55 0.35 0.3 0.45 0.4 1.8 1.05
t test con v exp 0.5   0.5   0.5   0.148663
3#1 3 2.9 3.4 3.2 0.5 0.6 1.1 0.8
3#2 2.9 2.9 3.4 3.2 0.5 0.5 1.2 1
ave 2.95 2.9 3.4 3.2 0.5 0.55 1.15 0.9
t test con v exp 0.5   #DIV/0!   0.5   0.198727
4#1 0.5 0.5 0.3 0.4 0.9 0.9 0.9 0.8
4#2 0.5 0.5 0.4 0.4 1 0.8 1.6 0.7
ave 0.5 0.5 0.35 0.4 0.95 0.85 1.25 0.75
t test con v exp #DIV/0!   0.5   0.292893   0.385136
5#1 5.3 5.1 1.6 1.5 0.6 0.6 0.9 1.1
5#2 5.1 4.9 1.7 1.7 0.7 0.5 0.9 0.6
ave 5.2 5 1.65 1.6 0.65 0.55 0.9 0.85
t test con v exp 0.292893   0.711723   0.292893   0.874334
6#1 2.3 2.4 1.4 1.3 1.1 0.8 1 0.7
6#2 2.3 2.1 1.4 1.2 0.9 0.9 0.8 0.8
ave 2.3 2.25 1.4 1.25 1 0.85 0.9 0.75
t test con v exp 0.795167   0.204833   0.349886   0.349886
ave. of ave.           1.15 0.858333

 

Table 3. Correlation between oxygen and nitrate concentrations in control and experimental jars over four sampling dates. Feeding schedule is given in Table 17.

    9-Oct 11-Oct 18-Oct 23-Oct correlation
    average average average average oxy/nitrate
control oxygen 5 4.1 5.7 5.75 -0.57827
group 1 nitrate 1.9 1.55 1.35 0.9  
exper oxygen 4.9 4 5.25 5.4 -0.43731
group 1 nitrate 1.9 1.7 1.8 0.85  
control oxygen 7.25 6.95 7.15 8.45 0.995591
group 2 nitrate 0.5 0.35 0.45 1.8  
exper oxygen 7.2 6.55 6.3 7.65 0.896288
group 2 nitrate 0.55 0.3 0.4 1.05  
control oxygen 6 6.625 5.85 6.55 0.389051
group 3 nitrate 2.95 3.4 0.5 1.15  
exper oxygen 6.05 6.5 5.35 5.85 0.889467
group 3 nitrate 2.9 3.2 0.55 0.9  
control oxygen 7.55 5.7 6.15 5.3 -0.49086
group 4 nitrate 0.5 0.35 0.95 1.25  
exper oxygen 7.5 6.4 5.55 5.15 -0.73965
group 4 nitrate 0.5 0.4 0.85 0.75  
control oxygen 6.05 5.75 5 5.75 0.711604
group 5 nitrate 5.2 1.65 0.65 0.9  
exper oxygen 6 5.4 4.75 5.55 0.808694
group 5 nitrate 5 1.6 0.55 0.85  
control oxygen 4.6 5.8 5.9 7.7 -0.84663
group 6 nitrate 2.3 1.4 1 0.9  
exper oxygen 4.5 5.5 5.5 7.1 -0.82127
group 6 nitrate 2.3 1.3 0.9 0.8  

Tables 4 and 5 record results for a follow-up experiment to the amphipod lab done on October 7 through October 9, 2008. Not surprisingly Oxyrase® lowered oxygen concentration in the bottom jars with sediment significantly over 48 hours compared to control jars, as seen in all groups. (The effect already occurred in groups 2 and 3 during the 30 minutes or so between adding the enzyme and measuring the oxygen.) Top jars in group 3 also had significantly less oxygen after 48 hours.. However, only one more amphipod died in experimental than control in group 3 (two vs. one). Group 1 lost one in experimental and four in control. Group 2 lost six in experimental and two in control. Nitrate-N concentration was significantly lower in experimental compared to control after 48 hours in group 1 bottom jars. In fact, only one of the groups had higher nitrate-N in experimental compared to control in top or bottom jars, and the difference was not significant. There was no significant difference in initial nitrate-N concentration in any top or bottom jars.  

Table 4. Effect of Oxyrase® on oxygen concentration in experimental jars compared to control jars without Oxyrase® over a period of 48 hours. The jars at the top of the table each contained clean water with five amphipods and two hackberry leaf discs (group 1) or four hackberry leaf discs (groups 2 and 3). The jars at the bottom of the table contained water with sediment and Oxyrase® (experimental) or no Oxyrase® (control).

water Ox Oct. 7   Oct. 9  
group exp control exp control
1#1 6.5 6.4 1.8 6.2
1#2 6.4 6.4 2.8 6.5
ave 6.45 6.4 2.3 6.35
t test exp v con 0.5   0.059052
2#1 7.2 7 4.3 6
2#2 7.1 7 1.7 6.4
ave 7.15 7 3 6.2
t test exp v con 0.204833   0.239124
3#1 8.2 8.6 2.3 6.8
3#2 8.4 8.6 1.9 7.1
ave 8.3 8.6 2.1 7
t test exp v con 0.204833   0.003719
sed. Ox Oct. 7   Oct. 9  
group exp control exp control
1#1 2.1 4.9 1.7 6.3
1#2 2.1 5 1.8 6.4
ave 2.1 4.95 1.75 6.35
t test exp v con 0.011168   0.000236
2#1 3.8 6 3.8 12.7
2#2 3.9 5.95 4 12.7
ave 3.85 5.975 3.9 12.7
t test exp v con 0.003531   0.007234
3#1 4.4 6.8 2.1 6.3
3#2 4.1 6.7 1.4 6.3
ave 4.3 6.8 1.8 6.3
t test exp v con 0.023219   0.048875

Table 5. Effect of Oxyrase® on nitrate-N concentration in experimental jars compared to control jars without Oxyrase® over a period of 48 hours. The jars at the top of the table each contained clean water with five amphipods and two hackberry leaf discs (group 1) or four hackberry leaf discs (groups 2 and 3). The jars at the bottom of the table contained water with sediment and Oxyrase® (experimental) or no Oxyrase® (control).

                                    

water N Oct. 7   Oct. 9  
group exp control exp control
1#1 1.4 1.2 0.4 0.7
1#2 1.5 1.2 0.3 0.7
ave 1.45 1.2 0.35 0.7
t test exp v con 0.125666   0.090334
2#1 1.65 1.7 0.4 0.8
2#2 1.7 1.6 0.4 0.7
ave 1.675 1.65 0.4 0.75
t test exp v con 0.711723   0.090334
3#1 1.4 1.2 0.1 0.2
3#2 1.3 1.2 0.1 0.2
ave 1.4 1.2 0.1 0.2
t test exp v con 0.204833   #DIV/0!
sed. N Oct. 7   Oct. 9  
group exp control exp control
1#1 1.1 1.2 0.5 0.9
1#2 1.1 1.3 0.4 0.8
ave 1.1 1.25 0.45 0.85
t test exp v con 0.204833   0.029857
2#1 1.2 1.1 0.6 0.8
2#2 1.7 1 0.5 0.7
ave 1.45 1.05 0.55 0.75
t test exp v con 0.347806   0.105573
3#1 0.8 1.1 0.1 0.2
3#2 0.7 1.1 0.1 0.1
ave 0.8 1.1 0.1 0.15
t test exp v con 0.090334   0.5

Dr. Stephen Reinbold

Last Modified: 6/1/18