A Study of the Red-Bellied Turtle (Pseudemys rubriventris) Population in Lake Marburg Located in...
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A Study of the Red-Bellied Turtle ( Pseudemys rubriventris) Population in Lake Marburg Located in Codorus Park,Hanover (PA) INTRODUCTION population of red bellied turtles (Pseudemys rubriventris ), found in Lake Marburg, which is located in Codorus Park, Hanover Pennsylvania. Red-bellied turtles are on the nnsylvania threatened species list due to habitat degradation, mpetition from invasive species, pollution, and disease warth, C. 1999). There are other species of aquatic turtles cated in Lake Marburg, including red-eared sliders, achemys scripta elegans ), yellow-bellied sliders, achemys scrpta scripta), and painted turtles, (Chrysemys a). Both types of sliders are invasive and could potentially mpete with the red-bellied turtles, further impacting their atus within the lake (Stone, J.E. 2010). Understanding the pulations of each species of turtles is crucial for developing nservation strategies. ke Marburg is a large manmade freshwater lake that consists several coves. It is unclear which coves within the lake the rtles utilize for mating, finding food, and building nests. ctors that may impact choice, include, Food availability : Red-bellied turtles are herbivorous as adults and thus require submerged aquatic vegetation. Access to appropriate nesting locations: Red-bellied turtles are known to nest in open areas adjacent to the water, including fields, meadows, lawns and small forest openings (Swarth, C. 1999). In 2007 the Department of Conservation of Natural Resources (DCNR) built a protected beach in Dubs Cove for the turtles to use as a secure nesting site. This location was chosen because it is restricted to the public. However, in previous years there was very little nesting behavior observed at this site. Temperature : Turtles do not need to bask when the air temperature is high (Swarth, C. 1999) and in fact will estivate under conditions of prolonged heat. Temperature within the coves is impacted by the depth of the water and may vary between years. Boating activity : Several coves are used more heavily during the summer months by boaters and fishers and excessive activity may impact the turtle behaviors. The objectives of this study are to: OBJECTIVES erve locations of red-bellied turtles within Lake Marburg ing mating season, nesting season, and throughout the ive summer season in to understand the distribution of the other species of turtles nd in Lake Marburg. imate the population size of red bellied turtles in Lake burg METHODS Lisa Haneschlager, Department of Biology, York College of Pennsylvania Basking traps were set at each cove close to the location of the basking platforms that were introduced by the DCNR. The traps were checked once a day for no longer than two weeks at a time. The traps were reintroduced monthly from May through September. The turtles that were captured in the traps were measured for carapace length, width, and height, and they were weighed. The turtles were marked using a carapace notching system that allows for the identification of a recaptured turtle. Population estimates were made using Schnabel Method.(Schnabel, Z.E. 1938) RESULTS Species Populatio n EST. 95% C.I. + 95%C.I. - RED- BELLIED TURTLE 12 235 2 Table 2: Population estimate of red bellied turtles in Lake Marburg 2010. The Schnabel method was used to calculate this estimate. This estimate is based off of four isolated areas in the lake and may be an underestimation. Number of Turtles Caught per Trap per Day at Each Location in 2010 4 5 6 7 8 9 10 0 1 D ubs C ove C hapel C ove Black Rock M arburg Flats M onths ofthe Year in 2010 N um ber ofTurtles C aptured per Trap per D ay Figure 1: Number of turtles caught per trap in 2010 at each location May through September. A two-way Anova was performed to test the difference between Dubs and Chapel Cove for the year, The test indicated significantly more turtles at Chapel Cove. (P= .0005. ) Difference in Species of Turtles Captured in 2010 Figure 2: Four species of turtles captured per day between May and September of 2010. A two-way Anova was performed to test the difference between painted turtles and red-eared sliders for the year. The test indicated the painted turtle were the most frequently captured species. (P=.0001). Number of Turtles Caught per Trap per Day at Each Location in 2010 5 6 7 8 9 10 0 1 2 3 4 2009 2010 M onths ofthe Year Num ber ofTurtles C aptured per Trap per D ay Figure 3: Relationship between the amount of turtles captured in 2009 and 2010 The results of a two-way Anova demonstrated a statistically higher amount of turtles captured in 2009 than in 2010. (P=.0293) Difference in Temperature (C) Between 2009 And 2010 5 6 7 8 9 10 20 25 30 35 2009 2010 M onths ofthe Year Tem perature (C o ) DUBS COVE CHAPEL COVE BLACK ROCK MARBURG FLATS VEGETATION LOW LOW HIGH HIGH WATER DEPTH DEEP DEEP SHALLOW SHALLOW BOATING ACTIVITY LOW LOW HIGH LOW MONTH LOCATION CAPTURED MAY, AUGUST CHAPEL COVE OBSERVED MATING MAY CHAPEL COVE, MARBURG FLATS Table 1: Months and locations where red-bellied turtles were captured and observed mating. Figure 4: Difference in temperature during the days of research between 2009 and 2010. A two way Anova indicated higher temperatures in 2010 . P=.0001) CONCLUSIONS •Turtles were more frequently captured in Chapel Cove. This is the only location where the red-bellied turtles were captured in 2010. Fu research could focus on this as a probable locati for nesting activity. • Red-bellied turtle mating behaviors were observed in Chapel Cove and Marburg Flats primarily in Ma These locations differ in water depth and vegeta however both locations have low boating activity. • More turtles were captured in 2009 when the temperature was lower. Temperature contributes to the turtles behaviors and should be considered wh analyzing the population estimates and for future studies. Acknowledgments: Dr J. Nolan, Dr K. Kleiner, Rick Harabin The Biology Department of York College, Department of Conserv Of Natural Resources and Codorus Park for allowing the resear Literature Cited: • Swarth, Christopher, W. 1999. Natural History and Reproductive Biology of the Red Bellied Turtle Conservation and Ecology of Turtles of the Mid- Atlantic Region. 30: 73-83. • Stone, E. 2010. Distribution and abundance of non- native red-eared slider turtles (Trachemys scripta elegans) and native red-bellied turtles (Pseudemys rubriventris). • Schnabel, Z.E. 1938. The estimation of the Total Fish Population of a Lake. American Mathematic Monthly. 45: 348-352. 4 5 6 7 8 9 10 0 1 2 Red-Bellied Painted Red-Eared Yellow-Belly M onths ofthe Year in 2010 Num berofTurtles Captured PerDay
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Transcript of A Study of the Red-Bellied Turtle (Pseudemys rubriventris) Population in Lake Marburg Located in...
A Study of the Red-Bellied Turtle (Pseudemys rubriventris) Population in
Lake Marburg Located in Codorus Park,Hanover (PA)
INTRODUCTION• A population of red bellied turtles (Pseudemys rubriventris), is found in Lake Marburg, which is located in Codorus Park, in Hanover Pennsylvania. Red-bellied turtles are on the Pennsylvania threatened species list due to habitat degradation, competition from invasive species, pollution, and disease (Swarth, C. 1999). There are other species of aquatic turtles located in Lake Marburg, including red-eared sliders, (Trachemys scripta elegans), yellow-bellied sliders, (Trachemys scrpta scripta), and painted turtles, (Chrysemys picta). Both types of sliders are invasive and could potentially compete with the red-bellied turtles, further impacting their status within the lake (Stone, J.E. 2010). Understanding the populations of each species of turtles is crucial for developing conservation strategies. • Lake Marburg is a large manmade freshwater lake that consists of several coves. It is unclear which coves within the lake the turtles utilize for mating, finding food, and building nests. Factors that may impact choice, include,
Food availability: Red-bellied turtles are herbivorous as adults and thus require submerged aquatic vegetation.
Access to appropriate nesting locations: Red-bellied turtles are known to nest in open areas adjacent to the water, including fields, meadows, lawns and small forest openings (Swarth, C. 1999). In 2007 the Department of Conservation of Natural Resources (DCNR) built a protected beach in Dubs Cove for the turtles to use as a secure nesting site. This location was chosen because it is restricted to the public. However, in previous years there was very little nesting behavior observed at this site.
Temperature: Turtles do not need to bask when the air temperature is high (Swarth, C. 1999) and in
fact will estivate under conditions of prolonged heat. Temperature within the coves is impacted by the depth of the water and may vary between years.
Boating activity: Several coves are used more heavily during the summer months by boaters and fishers and excessive activity may impact the turtle
behaviors.
The objectives of this study are to:
OBJECTIVES
• Observe locations of red-bellied turtles within Lake Marburg during mating season, nesting season, and throughout the active summer season• Begin to understand the distribution of the other species of turtles found in Lake Marburg.• Estimate the population size of red bellied turtles in Lake Marburg
METHODS
Lisa Haneschlager, Department of Biology, York College of Pennsylvania
Basking traps were set at each cove close to the location of the basking platforms thatwere introduced by the DCNR.
The traps were checked once a day for no longer than two weeks at a time. Thetraps were reintroduced monthly from Maythrough September.
The turtles that were captured in the trapswere measured for carapace length, width,and height, and they were weighed.
The turtles were marked using a carapacenotching system that allows for the identification of a recaptured turtle.
Population estimates were made using Schnabel Method.(Schnabel, Z.E. 1938)
RESULTS
Species Population
EST.
95% C.I. +
95%C.I. -
RED- BELLIED TURTLE
12 235 2
Table 2: Population estimate of red bellied turtles in Lake Marburg 2010. The Schnabel method was used to calculate this estimate. This estimate is based off of four isolated areas in the lake and may be an underestimation.
Number of Turtles Caught per Trap per Day at Each Location in 2010
4 5 6 7 8 9 100
1
Dubs CoveChapel CoveBlack RockMarburg Flats
Months of the Year in 2010
Nu
mb
er o
f T
urt
les
Cap
ture
d p
er T
rap
per
Day
Figure 1: Number of turtles caught per trap in 2010 at each location May through September. A two-way Anova was performed to test the differencebetween Dubs and Chapel Cove for the year, The test indicated significantly more turtles at Chapel Cove. (P= .0005. )
Difference in Species of Turtles Captured in 2010
Figure 2: Four species of turtles captured per day between May and September of 2010. A two-way Anova was performed to test the differencebetween painted turtles and red-eared sliders for the year. The test indicated the painted turtle were the most frequently captured species. (P=.0001).
Number of Turtles Caught per Trap per Day at Each Location in 2010
5 6 7 8 9 100
1
2
3
42009
2010
Months of the Year
Nu
mb
er o
f T
urt
les
Cap
ture
d p
er T
rap
per
Day
Figure 3: Relationship between the amount of turtles captured in 2009 and 2010 The results of a two-way Anova demonstrated a statistically higher amount of turtles captured in 2009 than in 2010. (P=.0293)
Difference in Temperature (C) Between 2009And 2010
5 6 7 8 9 1020
25
30
35
20092010
Months of the Year
Tem
per
atu
re (
Co)
DUBS COVE
CHAPEL COVE
BLACKROCK
MARBURG
FLATS
VEGETATION
LOW LOW HIGH HIGH
WATER DEPTH
DEEP DEEP SHALLOW SHALLOW
BOATINGACTIVITY
LOW LOW HIGH LOW
MONTH LOCATION
CAPTURED MAY, AUGUST
CHAPEL COVE
OBSERVEDMATING
MAY CHAPEL COVE,MARBURG
FLATS
Table 1: Months and locations where red-bellied turtles were captured and observed mating.
Figure 4: Difference in temperature during the days of research between 2009 and 2010. A two way Anovaindicated higher temperatures in 2010 . P=.0001)
CONCLUSIONS•Turtles were more frequently captured in Chapel Cove. This is the only location where the red-bellied turtles were captured in 2010. Future research could focus on this as a probable location for nesting activity.• Red-bellied turtle mating behaviors were observed in Chapel Cove and Marburg Flats primarily in May. These locations differ in water depth and vegetation, however both locations have low boating activity.• More turtles were captured in 2009 when the temperature was lower. Temperature contributes to the turtles behaviors and should be considered when analyzing the population estimates and for future studies.
Acknowledgments: Dr J. Nolan, Dr K. Kleiner, Rick HarabinThe Biology Department of York College, Department of ConservationOf Natural Resources and Codorus Park for allowing the research.
Literature Cited:• Swarth, Christopher, W. 1999. Natural History and
Reproductive Biology of the Red Bellied Turtle Conservation and Ecology of Turtles of the Mid- Atlantic Region. 30: 73-83.
• Stone, E. 2010. Distribution and abundance of non-native red-eared slider turtles (Trachemys scripta elegans) and native red-bellied turtles (Pseudemys rubriventris).
• Schnabel, Z.E. 1938. The estimation of the Total Fish Population of a Lake. American Mathematic Monthly. 45: 348-352.
4 5 6 7 8 9 100
1
2
Red-BelliedPaintedRed-EaredYellow-Belly
Months of the Year in 2010
Num
ber
of T
urtle
s C
aptu
red
Per
Day
