• Surasinghe, T. D. and Baldwin, R. F. (2012). Microhabitat association of Plethodontid salamanders in stream ecosystems along a riparian land-cover gradient. Southeastern Ecology and Evolution Conference, Clemson University, Clemson, SC.

1. Microhabitat association of Plethodontid
salamanders in stream ecosystems along a
riparian land-cover gradient
Thilina Surasinghe & Robert Baldwin
School of Agricultural, Forest & Environmental Sciences,
Clemson University, SC

2. Introduction
What affects habitat associations?
 Climate
 Habitat availability & heterogeneity
 Resource distribution
 Natural disturbances
 Anthropogenic disturbances
What about community interactions?
 Predation
 Intraspecific competition
 Interspecific competition
• Exploitative competition
• Interference competition
• Apparent competition

3. Experimental Species
 Desmognathus quadramaculatus
 Black-bellied salamander (BB)
 Large bodied (SVL:80mm)
 Dominant
 Aquatic
 Disturbance sensitive
 Desmognathus fuscus
 Northern Dusky salamander (ND)
 Small bodied (SVL:50mm)
 Subordinate
 Aquatic/semi-aquatic
 Disturbance adaptive

4. Objectives
 Are Black-bellied
salamanders competitively
dominant over Northern
dusky salamanders in
forested streams?
Do human induced
disturbances in the riparian
zone provide competitive
advantage for certain species
of stream salamanders?

5. Experimental Setup
 Artificial streams simulate four
land-use types with replications:
forested, agricultural, residential,
urban + stock tanks
 Artificial streams filled with
stream substrate materials and
water
 sand, sediment, rocks, gravel, and
woody debris
 Substrate thickness: 4-5 cm in
wetted channel; 15 cm in banks
 Water depth: 8-10 cm
 Air pumps maintain DO in field-
equivalent conditions

6. Experimental Procedure
Capture animals from the wild
Acclimatize
Individuals of same SVL class (40-50 mm for D. fuscus; 80-
90 mm for D. quadramaculatus)
3 phases in each replication
 1. Both species introduced
 2. Remove one species
 3. Reintroduce removed species & remove the one retained
 Each LU type replicated in the same tank, with introduction of
different individuals of each species
 Make observations in each phase

7. Making Observations
 Daily, 20-min observations in every two hours (0900-0100 hrs)
 Aggression
 Use of microhabitats
 All Animal sampling
Percent occurrence of a species at a given
microhabitat type in a certain phase

8. Results & Conclusion – Forested streams
120
Forested Riparian Land-Use
100
BB with ND
ND with BB
80
Percentage Occurrence
BB only
ND only
60
40
20
0
Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface
Microhabitat Types
 D. quadramaculatus microhabitat selection
 Occupied bank crevices 96% and 94% of times in coexistence and
isolation, respectively
 D. fuscus microhabitat selection
 Occupied channel bottom 100% of times in coexistence
 Occupied bank crevices 65% of times under isolation

9. Results & Conclusion – Agricultural streams
100
Agricultural Riparian Land-Use
90
BB with ND
80
ND with BB
70 BB only
Percentage Occurrence
60 ND only
50
40
30
20
10
0
Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface
Microhabitat Types
 D. quadramaculatus microhabitat selection
 Occupied bank crevices 89% and 88% of times in coexistence and
isolation, respectively
 D. fuscus microhabitat selection
 Occupied channel bottom 95% of times in coexistence
 Occupied bank crevices and interface 60% of times under isolation

10. Results & Conclusion – Residential streams
100
Residential Riparain Land-Use Type
90
80
BB with ND
70
ND with BB
Percentage Occurrence
60
BB only
50
ND only
40
30
20
10
0
Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface
Microhabitat Types
 D. quadramaculatus microhabitat selection
 Occupied bank crevices 52% and 88% of times in coexistence and
isolation, respectively
 D. fuscus microhabitat selection
 Occupied channel bottom 88% of times in coexistence
 Occupied bank crevices and interface 56% of times under isolation

11. Results & Conclusion – Urban streams
100
Urban Riparian Land-Use
BB with ND
90
80 ND with BB
70 BB only
Percentage Occurrence
60 ND only
50
40
30
20
10
0
Bank Crevices Channel Bottom Channel-Bank Interface Bank Surface
Microhabitat Types
 D. quadramaculatus microhabitat selection
 Occupied bank crevices 25% and 88% of times in coexistence and
isolation, respectively
 D. fuscus microhabitat selection
 Occupied bank-channel interface 70% of times in coexistence
 Occupied bank crevices 76% of times under isolation

12. General Conclusions
 D. quadramaculatus
 Occupied stream banks and chose rock crevices as their preferred
microhabitat in each land-use simulation
 Showed high site fidelity at each land-use simulation
 Strong domination of microhabitat selectivity over D. fuscus in
forested streams
 Weak domination of microhabitat selectivity over D. fuscus in non-
forested streams
 Some reduction in use of bank crevices in non-forest streams

13. General Conclusions
 D. fuscus
 Exclusively occupied the stream channel in the forested stream in
coexistence
 Marked increase in occupancy of bank crevices and interface in non-
forest streams, which is prominent in the urban stream
 Broad selectivity of interstitial spaces including beneath rocks and
logs, leaf litter, sand and gravel
 Low side fidelity

14. General Conclusions
 No aggression or predation was observed
 D. quadramaculatus competitively displaced D. fuscus in forested
streams
 D. fuscus shifted to the microhabitats previously occupied by D.
quadramaculatus once the later was experimentally removed
 Marked change in the microhabitat selectivity of D. fuscus with
increasing disturbances in the riparian zone
 The study is still continuing and more replications will be done

15. Acknowledgement
 Funded by….
 Creative Inquiry Program
 Numerous undergraduates in Dept. of Biological Sciences
and School of Agricultural, Forest & Environmental
Sciences
 Dr. Mark Scott and SC stream bio-Assessment team, SC
Dept. of Natural Resources
 Dr. Bryan Brown, Dept. of Biological Sciences, Virginia
Tech University
 Dr. Michael Childress, Dept. of Biological
Sciences, Clemson University