Mims
PREDATOR VS. MONSOON: THE ROLE OF BIOTIC AND ABIOTIC DRIVERS
IN SHAPING AQUATIC INVERTEBRATE
COMMUNITIES IN DESERT ENVIRONMENTS
Jessie HaleMeryl Mims, Michael Bogan, Julian Olden
Kahrs
Mims
IUCN
D. Kahrs
- Introduced in 1926 for food, naturally spread
- Considered a nuisance species starting in 1960s
- Bullfrog removal costs about $20,000 annually in Southeast Arizona
AZGFD
monteverde2000
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Ave
rage
Mo
ntl
y P
reci
pit
atio
n (
inch
es)
Elgin, AZ
EARLY MONSOON LATE MONSOON
Questions1. 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?
Hypotheses1. Lower invertebrate abundance and richness in tanks with bullfrogs
0
500
1000
1500
2000
2500
3000
3500
Bullfrog Control2. Higher invertebrate abundance and richness in late monsoon
3. Monsoon seasonality will be of higher relative importance in aquatic invertebrate communities
0
500
1000
1500
2000
2500
3000
3500
Early Late
Pre
cip
itat
ion
Time
United States
Mexico
- Standardized sampling: sampled same area in each tank
- Pooled samples- Used serial rinsing
method
0
2
4
6
8
10
12
14
0 50 100 150 200 250 300 350 400 450 500 550
Nu
mb
er
of
Taxa
Number of Individuals Sampled
Species Accumulation Curve
Subsample Count= 500 individuals
0
1000
2000
3000
4000
5000
6000
Early Late
Ab
un
dan
ce/
sam
plin
g ar
ea
(8
34
.8L)
Monsoon
Invertebrate Abundance
SD= 1409.5
SD= 2634.1
0
5
10
15
20
25
30
35
Early Late
Ric
hn
ess
/sam
plin
g ar
ea
(83
4.8
L)
Monsoon
Invertebrate Richness
SD=6.7SD= 8.1
0
1000
2000
3000
4000
5000
6000
7000
Bullfrog Control
Ab
un
dan
ce/s
amp
ling
are
a (8
34
.8 L
)Invertebrate Abundance
SD=1311.5
SD=2383.5
N=3
N=3
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 5-6 10-50 100s-100,000s
Log
Ab
un
dan
ce/s
amp
ling
are
a (8
34
.8 L
)
Estimated Number of Bullfrogs
Invertebrate Abundance
Early
Late
SD (early)= 0.009SD (late)= 0.30
0
5
10
15
20
25
30
Bullfrog Control
Ric
hn
ess
/sam
plin
g ar
ea
(83
4.8
L)
Invertebrate Richness
SD= 8.8 SD= 4.4
N=3N=3
0
5
10
15
20
25
30
35
0 5-6 10-50 100s-100,000s
Ric
hn
ess
/sam
plin
g ar
ea
(83
4.8
L)
Estimated Number of Bullfrogs
Invertebrate Richness
Early
Late
SD (early)= 4.5SD (late)= 5.0
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
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
Thank you!
• Meryl Mims, Mike Bogan (UCSB) & Julian Olden
• Matt Brawn & Kurt Bahti(AZGFD)
• Scott Kerr (Parker Canyon Lake Store)
• SAFS
• Greg Jensen
Questions?
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