Presentation for Winter 2013 Capstone Symposium on my work comparing invasive bullfrogs and summer monsoons as drivers in aquatic invertebrate communities.

1. Mims

2. PREDATOR VS. MONSOON:
THE ROLE OF BIOTIC AND ABIOTIC DRIVERS
IN SHAPING AQUATIC INVERTEBRATE
COMMUNITIES IN DESERT ENVIRONMENTS
Jessie Hale
Meryl Mims, Michael Bogan, Julian Olden
Kahrs

5. Mims
IUCN

6. - Introduced in 1926 for
food, naturally spread
- Considered a nuisance
species starting in 1960s
- Bullfrog removal costs
about $20,000 annually in
Southeast Arizona
D. Kahrs

7. AZGFD
monteverde2000

8. 5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Average Montly Precipitation (inches)
Elgin, AZ
EARLY MONSOON LATE MONSOON

9. Questions
1. What is the effect of bullfrogs on aquatic
invertebrate communities?
2. What is the effect of monsoonal seasonality on
aquatic invertebrate communities?
3. What is the relative importance of these two
factors in shaping aquatic invertebrate
communities?
4. How do bullfrog presence and monsoon
seasonality affect aquatic invertebrate
community composition?

10. Hypotheses
1. Lower invertebrate
abundance and richness in
tanks with bullfrogs
3500
3000
2500
2000
1500
1000
500
2. Higher invertebrate
0
Bullfrog Control abundance and richness in
3500
3000
late monsoon
2500
2000
3. Monsoon seasonality will
1500
1000
500
be of higher relative
0
Early Late
importance in aquatic
invertebrate communities

11. Precipitation
Time
United States
Mexico

12. - Standardized
sampling: sampled
same area in each
tank
- Pooled samples
- Used serial rinsing
method

14. 14
12
10
8
6
4
2
0
Species Accumulation Curve
Subsample
Count= 500
individuals
0 50 100 150 200 250 300 350 400 450 500 550
Number of Taxa
Number of Individuals Sampled

15. 6000
5000
4000
3000
2000
1000
0
Invertebrate Abundance
Early Late
Abundance/ sampling area (834.8L)
Monsoon
SD=
1409.5
SD=
2634.1

16. 35
30
25
20
15
10
5
0
Invertebrate Richness
SD= 8.1 SD=6.7
Early Late
Richness/sampling area (834.8 L)
Monsoon

17. 7000
6000
5000
4000
3000
2000
1000
0
Bullfrog Control
Abundance/sampling area (834.8 L)
Invertebrate Abundance
SD=1311.5
SD=2383.5
N=3
N=3

18. 4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Invertebrate Abundance
0 5-6 10-50 100s-100,000s
Log Abundance/sampling area (834.8 L)
Estimated Number of Bullfrogs
Early
Late
SD (early)= 0.009
SD (late)= 0.30

19. 30
25
20
15
10
5
0
Bullfrog Control
Richness/sampling area (834.8 L)
Invertebrate Richness
SD= 8.8 SD= 4.4
N=3
N=3

20. 35
30
25
20
15
10
5
0
Invertebrate Richness
0 5-6 10-50 100s-100,000s
Richness/sampling area (834.8 L)
Estimated Number of Bullfrogs
Early
Late
SD (early)= 4.5
SD (late)= 5.0

24. Conclusions
1. Negative relationship between number of
bullfrogs and richness/abundance
2. Monsoon seasonality not as much of a driver
as we hypothesized, possibly due to low
sample sizes
3. Evidence for differentiation in aquatic
invertebrate community composition
between control and bullfrog tanks

25. Management Implications
• Complete removal of
bullfrogs may not be
necessary (target
gravid females and egg
masses)
• Out of 26 known stock
tanks in the area, it
was difficult to find
tanks with bullfrogs

26. Thank you!
Meryl Mims, Mike
Bogan (UCSB) &
Julian Olden
Matt Brawn &
Kurt Bahti
(AZGFD)
Scott Kerr (Parker
Canyon Lake
Store)
SAFS
Greg Jensen

27. Questions?