Transcript Interactions between species in an anthropogenically

Interactions between species in an anthropogenically altered
ridge-top wetland ecosystem
Contact Information:
Eastern Kentucky University
Department of Biological sciences
521 Lancaster Ave.
Richmond, KY 40475
Chelsea S. Kross and Stephen C. Richter
METHODS
RESULTS
I used 12 wetlands, 6 constructed and 6
naturals, that were located in the Cumberland
District of the Daniel Boone National Forest
(DBNF; Figure 1).
Wood frog eggs were observed at three
constructed wetlands and six natural wetlands
(Table 1) and laid in February and March 2013.
Wood Frog eggs experienced mortality from
abiotic factors (e.g. freezing, drying) and
predation (Table 1).
Wood Frog Sampling:
• Egg mass surveys (January–April 2013;
Figure 2A).
• Mesh minnow traps for presence or
absence of wood frog larva (May 2013;
Figure 2B) .
Figure 1. Wetlands across the Daniel Boone National
Forest. Not all constructed wetlands are shown. The
outbox shows the location and distribution of wetlands
used in this study.
ABSTRACT
No wood frog larvae were caught in traps from
constructed wetlands (Table 1).
Newts were observed eating wood frog eggs
and on average ate 37% of wood frog egg
masses (Table 1).
B.
• Mesh minnow traps were used to capture
newts in May, July, September, November
of 2013 and January–March 2014 (Figure
2B).
• Dipnetting was used to capture newts
(Sampling was considered completed
when no newts were caught after 20
consecutive dips).
• SVL, Mass, and Sex were measured
• Each individual was marked with a unique
code using Visual Implant Elastomer
(VIE) for mark-recapture.
INTRODUCTION
Over 400 wetlands have been constructed
on ridge tops within the Daniel Boone
National Forest (DBNF) in Kentucky.
A.
Newt Sampling:
Hundreds of wetlands have been constructed as permanent water sources in a ridgetop ecosystem in eastern Kentucky where there were naturally only ephemeral
wetlands. Consequently, the ecosystem was colonized by an amphibian community of
species with a larval period that requires a long hydroperiod (e.g., Newts) and many
that are top amphibian predators. In contrast, the natural ephemeral wetlands support
amphibians with a shorter larval period (e.g., Wood Frogs). Some ephemeral wetland
species will breed in constructed wetlands; thus, there could be negative impacts on
these species. Our objectives were to: (1) determine if species of the ephemeral and
constructed amphibian communities interact, and (2) evaluate positive and negative
impacts on these communities. We selected Eastern Newts (Notophthalmus
viridescens) and Wood Frogs (Lithobates sylvaticus) to represent the constructed and
natural amphibian communities, respectively. We sampled six constructed and six
ephemeral wetlands throughout 2013 and 2014. We counted wood frog egg masses
and estimated survival bi-weekly throughout the breeding season (February–May) at
each wetland. Newt populations were sampled once in May, July, September, and
November, 2013 and January, Febrauary, and March, 2014. Individuals were
measured and weighed to determine body condition and individually marked using
visual implant elastomer for recapture. Data suggest that wood frog reproductive
success is negatively impacted when eggs are laid in constructed wetlands. Newts in
constructed wetlands with Wood Frog eggs present had higher body condition.
Understanding the impacts of how amphibian species interact as habitat loss and
modification increase will continue to be critical for amphibian conservation.
Newts in constructed wetlands with wood frogs
had a higher BMI than Newts in wetlands
without Wood Frog eggs (F1, 743 = 118.027, p <
0.001).
Newts in constructed wetlands with wood frog
eggs had a higher mass than newts in wetlands
without wood frog eggs (Figure 3).
Newts in constructed wetlands without wood
frog eggs had a higher average SVL compared
to newts in wetlands with wood frog eggs.
(Figure 4).
We used ANCOVA to determine body condition
indices (BMI) of captured newts from
constructed wetlands.
# Clutches Predation
(%)
977 C
977 N
Big Perry C
Big Perry N
Elk Lick C
Elk Lick N
Gas Line C
Gas Line N
High Energy C
High Energy N
Jones Ridge C
Jones Ridge N
The constructed wetlands negatively affect
the natural community of amphibians
(Denton and Richter 2012) because they
might:
• Act as a population sink for natural
community amphibians due to
increased predation.
How the communities interact and impact
each other are unknown.
0
37
68
54
0
125
89
143
0
76
69
46
Elk Lick
977
High Energy
Gas Line
Big Perry
Jones Ridge
Average Absent
Average Present
3.6
3.4
3.2
3
0
2.) To evaluate positive and negative
impacts on these communities.
Late Stage Larva
Capture
0
100
10
0
0
68
50
20
0
40
25
50
0
0
0
0
0
0
0
907
0
28
0
82
Absent
Overall
Present
1
2
3
4
Figure 3. Average mass of newts from each wetland without wood
frog eggs (Absent) and with wood frog eggs (Present). An overall
average for present and absent are presented with ±1SE.
SVL (cm)
Mass (g)
1.) To determine if species of the
ephemeral and constructed
communities interact.
Died due to abiotic
factors (%)
4
3.8
OBJECTIVES
0
0
70
0
0
0
15
0
0
0
30
0
Wood frogs were negatively impacted by
the presence of constructed wetlands and
newts.
• Wood frogs did not successfully
reproduce.
• Predation can be one of the most
important factors influencing larval
survival (e.g., Boone et al. 2004).
• Freezing had greater impacts on
breeding success in 2012 than the
previous 5 years (Richter et al.
unpubl. data).
Most constructed wetlands are population
sinks for wood frogs and potentially
ecological traps.
Newts benefit from the presence of wood
frog eggs.
Table 1. The number of wood frog egg masses present and the proportion of egg mortality, due to abiotic
factors and predation, at each natural and constructed wetland. (C=Constructed, N=Natural)
Wetland
CONCLUSIONS
• Repeated failure to successfully
reproduce can lead to local population
declines and extinctions (Semlitsch
2000).
Constructed wetlands are different from the
natural wetlands because they are:
• Permanent water sources (Brown
and Richter 2012).
• Distinctly different amphibian
community compared to ephemeral
wetlands (Drayer 2011).
Figure 2. (A) Picture of wood frog egg masses. (B) Trap
set-up for newt and wood frog capture.
4.8
4.6
4.4
4.2
4
3.8
3.6
3.4
3.2
3
• Due to the extra-food source, newts
have an increase BMI in wetlands with
wood frogs compared to wetlands
without newts.
• Prey abundance is related to
predator body condition (Pope and
Matthews 2002).
The presence of permanent water is having
a negative impact on most members of
amphibians in the natural community. Most
of the constructed wetlands should be
restored to a more historically accurate
hydroperiod.
Elk Lick
977
High Energy
Gas Line
Big Perry
Jones Ridge
Average Absent
Average Present
ACKNOWLEDGEMENTS
Thank you to Jennifer Strong, Kristin Hinkson, John Bourne, Jesse Godbold,
and other undergraduate and gradaute students for help in the field. This
research was partially funded by EKU’s Department of Biological Sciences
and the Kentucky Academy of Sciences. Research was approved by Eastern
Kentucky University Institutional Animal Care and Use Committee protocol
No. 05–2013.
LITERATURE CITED
0
1
Absent
2
3
Overall Present
4
Figure 4. Average SVL of newts from each wetland without wood frog
eggs (Absent) and with wood frog eggs (Present). An overall average
for present and absent are presented with ±1SE.
Boone, M.D., E.E. Little, R.D. Semlitsch. 2004. Copeia. 2004:683–690.
Brown, D.R., and S.C. Richter. 2012. Sustain. 25:22–33.
Denton, R.D., and S.C. Richter. 2013. Journal of Wildlife Management. 77:886–889.
Drayer, A. 2011. Master’s Thesis. Eastern Kentucky University.
Pope, K.L., and K.R. Matthews. 2002. Herpetologica. 58: 354–363.
Semlitsch, R.D. 2000. Journal of Wildlife Management. 64:615–631.