Amphibian population estimates and ecosystem assessment on the Durango Nature Studies property
Marisa Evans-Looney
Introduction
Durango Nature Studies is a place of opportunity for students and families to learn about the environment and the science of nature. It covers 140 acres off of US Highway 550 South, 30 minutes from Durango, Colorado. DNS is made up of riparian, meadows, oak woodlands, pinon-juniper forests, and desert arroyos habitats. The Florida River runs along the west side of the property.
In Colorado the current status of the bullfrog (Rana catesbeianus) is invasive. The status of Rana catesbeianus is a concern because they are out-competing the native species for resources. The presence of both the bluegill sunfish (Lepomis gibbosus) and Rana catesbeaianus is harmful to the northern leopard frog (Rana pipiens) because the invasive species work together. Because of the Rana catesbeaianus's aggressive nature it drives the Rana pipiens into the center of the pond. Because of the Rana pipiens' poor ability to swim in deep waters, it drowns and the Lepomis gibbosus eat it. The Lepomis gibbosuses also eat the Rana pipiens tadpoles. The current status of the Rana pipiens is now endangered.
Natural History
Rana pipiens mate from late April to early June. When females lay their eggs, they attatch them to floating plants or sticks in clumps of about 5,000. It takes about 5 to 7 days for the eggs to hatch. The tadpole turns into a froglet after about 60 days, some stay tadpoles during winter and then turn to froglets the next summer. Rana pipiens eat an array of organisms, from insects to crayfish to other frogs and baby mice and birds.
Rana catesbeianus begins its life as an egg. The female Rana catesbeianus lays about 20,000 eggs in a clump that floats on the water. When the eggs hatch, tadpoles, or polliwogs emerge. After a year the tadpole begins to grow legs and arms. During this stage the tadpole's tail begins to shorten and it starts to develop lungs. The tadpole then becomes a froglet, it keeps some of its tail and is now able to hop on land a breath oxygen. It takes 2 to 3 more years for the froglet to fully mature. The Rana catesbeianus lives about 7 to 9 years. The mature Rana catesbeianus is carnivorous and aggressive in nature. It will eat anything it can fit in its mouth, this includes insects to fish to small mammals.
Methods & Materials
To estimate amphibian populations of Rana pipiens and Rana catesbeianus on the DNS property four pitfall traps were set up and checked daily four times. For four days visual encounter surveys were conducted also. A one hour mark session and a one hour recapture session was conducted.
To test the water quality the nitrogen, phosphate, dissolved oxygen, and pH levels were tested. The population of plant species was estimated using four random Veg Plot Surveys. In the river, macroinvertebrates were collected using a kick method. In the pond a dip net was used to collect macroinvertebrates.
Results
In 2011 the diversity index for the pond was 0.99, in 2012 it was 1.21. The diversity index for the Florida River in 2011 was 1.03, in 2012 it was 0.88. No stoneflies, which have a low pollution tolerance, were found in either year. In 2011 the most found macroinvertebrate in the pond was the mayfly, which has a low pollution tolerance. In 2012 the mayfly was the second most found macorinvertebrate in the pond. The pH levels in both the river and pond were Alkaline. In both the river and pond the nitrate and phosphate levels were high. In the river the dissolved oxygen level was normal, and in the pond the level of dissolved oxygen was low.
Conclusion & Discussion
Since there were no stoneflies collected in the pond or river in either year, it is probable that both habitats had too much pollution to be adequate for the stonefly. In 2012 the diversity index increased, this suggests that the pollution in the pond decreased. In 2012 the Florida River's diversity index decreased, this suggests that the water quality decreased. The quality of the water is essential to both amphibian and macroinvertebrates and other organisms. Amphibian populations depend on depend on other amphibian populations around them, and also the stability of their habitat. The pond is at risk for an algal bloom because the coliform test was positive. To prevent an algal bloom the amount of cow manure that reaches the pond through the river.
When collecting data, the areas where data is collected should be more specific. When Veg Plot Surveys are conducted, plant species should be known.
Citations
"Durango Nature Studies - Environmental Education in Durango, Southwest Colorado, and the Four Corners." Durango Nature Studies - Environmental Education in Durango, Southwest Colorado, and the Four Corners. N.p., n.d. Web. 3 Oct. 2012. <http://www.durangonaturestudies.org/index.htm>.
"Introduced Species." Introduced Species. N.p., n.d. Web. 04 Oct. 2012. <http://amphibiaweb.org/declines/IntroSp.html>.
"Amphibians of Manitoba: Leopard Frog." Amphibians of Manitoba: Leopard Frog. N.p., n.d. Web. 05 Oct. 2012. <http://www.naturenorth.com/1np/Species/amphibian/1Ffrle.html>.
Marisa Evans-Looney
Introduction
Durango Nature Studies is a place of opportunity for students and families to learn about the environment and the science of nature. It covers 140 acres off of US Highway 550 South, 30 minutes from Durango, Colorado. DNS is made up of riparian, meadows, oak woodlands, pinon-juniper forests, and desert arroyos habitats. The Florida River runs along the west side of the property.
In Colorado the current status of the bullfrog (Rana catesbeianus) is invasive. The status of Rana catesbeianus is a concern because they are out-competing the native species for resources. The presence of both the bluegill sunfish (Lepomis gibbosus) and Rana catesbeaianus is harmful to the northern leopard frog (Rana pipiens) because the invasive species work together. Because of the Rana catesbeaianus's aggressive nature it drives the Rana pipiens into the center of the pond. Because of the Rana pipiens' poor ability to swim in deep waters, it drowns and the Lepomis gibbosus eat it. The Lepomis gibbosuses also eat the Rana pipiens tadpoles. The current status of the Rana pipiens is now endangered.
Natural History
Rana pipiens mate from late April to early June. When females lay their eggs, they attatch them to floating plants or sticks in clumps of about 5,000. It takes about 5 to 7 days for the eggs to hatch. The tadpole turns into a froglet after about 60 days, some stay tadpoles during winter and then turn to froglets the next summer. Rana pipiens eat an array of organisms, from insects to crayfish to other frogs and baby mice and birds.
Rana catesbeianus begins its life as an egg. The female Rana catesbeianus lays about 20,000 eggs in a clump that floats on the water. When the eggs hatch, tadpoles, or polliwogs emerge. After a year the tadpole begins to grow legs and arms. During this stage the tadpole's tail begins to shorten and it starts to develop lungs. The tadpole then becomes a froglet, it keeps some of its tail and is now able to hop on land a breath oxygen. It takes 2 to 3 more years for the froglet to fully mature. The Rana catesbeianus lives about 7 to 9 years. The mature Rana catesbeianus is carnivorous and aggressive in nature. It will eat anything it can fit in its mouth, this includes insects to fish to small mammals.
Methods & Materials
To estimate amphibian populations of Rana pipiens and Rana catesbeianus on the DNS property four pitfall traps were set up and checked daily four times. For four days visual encounter surveys were conducted also. A one hour mark session and a one hour recapture session was conducted.
To test the water quality the nitrogen, phosphate, dissolved oxygen, and pH levels were tested. The population of plant species was estimated using four random Veg Plot Surveys. In the river, macroinvertebrates were collected using a kick method. In the pond a dip net was used to collect macroinvertebrates.
Results
In 2011 the diversity index for the pond was 0.99, in 2012 it was 1.21. The diversity index for the Florida River in 2011 was 1.03, in 2012 it was 0.88. No stoneflies, which have a low pollution tolerance, were found in either year. In 2011 the most found macroinvertebrate in the pond was the mayfly, which has a low pollution tolerance. In 2012 the mayfly was the second most found macorinvertebrate in the pond. The pH levels in both the river and pond were Alkaline. In both the river and pond the nitrate and phosphate levels were high. In the river the dissolved oxygen level was normal, and in the pond the level of dissolved oxygen was low.
Conclusion & Discussion
Since there were no stoneflies collected in the pond or river in either year, it is probable that both habitats had too much pollution to be adequate for the stonefly. In 2012 the diversity index increased, this suggests that the pollution in the pond decreased. In 2012 the Florida River's diversity index decreased, this suggests that the water quality decreased. The quality of the water is essential to both amphibian and macroinvertebrates and other organisms. Amphibian populations depend on depend on other amphibian populations around them, and also the stability of their habitat. The pond is at risk for an algal bloom because the coliform test was positive. To prevent an algal bloom the amount of cow manure that reaches the pond through the river.
When collecting data, the areas where data is collected should be more specific. When Veg Plot Surveys are conducted, plant species should be known.
Citations
"Durango Nature Studies - Environmental Education in Durango, Southwest Colorado, and the Four Corners." Durango Nature Studies - Environmental Education in Durango, Southwest Colorado, and the Four Corners. N.p., n.d. Web. 3 Oct. 2012. <http://www.durangonaturestudies.org/index.htm>.
"Introduced Species." Introduced Species. N.p., n.d. Web. 04 Oct. 2012. <http://amphibiaweb.org/declines/IntroSp.html>.
"Amphibians of Manitoba: Leopard Frog." Amphibians of Manitoba: Leopard Frog. N.p., n.d. Web. 05 Oct. 2012. <http://www.naturenorth.com/1np/Species/amphibian/1Ffrle.html>.