The
Silver Lining to Cancer Deaths
The Silver Lining to Cancer Deaths
Management Plan Project Reflection
For this project, we were learning about the leopard frog and the bullfrog, specifically the status of these species on the Durango Nature Studies Property, in order to write a management plan to promote the native ecosystem of the land. This meant promoting the native leopard frog and eliminating the invasive bullfrog. In order to assess the quality of the existing habitat, we performed a visual encounter survey on leopard frogs and bullfrogs, a wildlife inventory on the surrounding habitat, various water quality tests, and macro-invertebrate sampling. We also assessed the quality of the water habitat through a Shannon-weiner diversity index, and learned how to create spreadsheets and graphs in excel to communicate this information.
This article is basically saying that the idea that a species in wrong in an ecosystem because it is invasive is an outdated theory. The species should be judged by its impacts, not by its point of origin. The article cites examples such as the mountain pine beetle. They say that despite the fact that it is native, it is destroying the ecosystem that it is native to, and so should not get any special rights. The author suggests that we define an invasive species not on whether it is native, but by its impacts on the ecosystem.
I believe that because of the reasons that the American bullfrog is on the list of 100 of the world’s worst invasive alien species (the fungus, and their aggressiveness) they deserve to be removed. Also, this frog has pushed out the native leopard frog before in other habitats, which show that they are a threat to the ecosystem already there. In addition to this, the bullfrog has spread, not naturally but through human methods, to 40 non-native countries around the world. This is of concern because should there have never been humans, these frogs would not be taking over the native habitats of other animals. I agree with the author of this article in that the invasive species problem should be taken case by case, but I think in this case the classification is justified, and our 8 weeks were not wasted.
I think the two things that I have learned about in this project that will be helpful to me in later life are scientific writing and invasive species. The scientific writing I foresee as being helpful due to what colleen mentioned. She was talking about how all her collage science professors got irritated by the level of fluffy English writing that they were getting in their papers. As I hope to become some sort of scientist someday, the skill will be very helpful to me as I move further on my life path. I thought that the invasive species thing was also important for our society to know about, as it is an important thing to understand. I also found it very interesting to learn about the various ways species got introduced, and their affects after they were. That was probably the most engaging part of this project for me.
Species Management Plan for Rana pipiens and Rana catesbeiana on the Durango Nature Studies Nature Center Property
India Waller and Robin Austin
Durango, CO
2011
Field Condition Form: Robin Austin
Durango Nature Studies would like to manage its 140 acres at the Durango Nature Center to promote native ecology, specifically native northern leopard frog populations (Rana pipiens) through the elimination of invasive species, such as the bullfrog (Rana catesbeiana), which the center started seeing three years ago (Figure 1). Bullfrogs negatively impact diversity, specifically in amphibians, because they compete for the same food, have more of a defense against natural viruses, and may cause mortality in other tadpoles through skin excretions as well as changing the natural patterns of the larvae. Durango Nature Studies hosts many school and community programs that focus on natural systems, so would like to address the arrival of the invasive species R. catesbeiana in this management plan.
The tenth grade biology class at Animas High School conducted a visual encounter study of bullfrogs and northern leopard frogs on the Durango Nature Studies property (Figure 2). These surveys allowed for the estimation of where the populations stand now, so we can understand what management practices are needed. In addition to taking stock of the amphibian population, studies were also conducted on the water quality, land use, and animal signs.
Management practices can be done anywhere on the property except where it would interfere with and affect research. Durango Nature Studies is willing to spend $2,000 a year to manage this property.
Plan Development: Robin Austin
Northern leopard frogs have different habitat needs depending on their developmental stage and the time of year. During the early development of the leopard frog, the preference of mating leopard frogs is a pond 30-60m in diameter, about 2m deep, as well as ponds that do not support fish populations, and have an open canopy. The ponds must be at least semi-permanent, with a predilection for permanent ponds that dry every few years. After reproducing, the adults of the species move to wet meadows with grasses from several inches to a foot. In the winter, they migrate to sites where they can hibernate under the water. They prefer to be in a river or stream, or near an inlet where oxygen saturation is high because many winter deaths are caused by oxygen depletion. As Smith and Keinath said in their article, R. pipiens prefer meadows, wetlands, or riparian areas. They require multiple ponds with migration corridors open between them to ensure species diversity as well as backup habitat should something happen to the main habitat area. They have a home range of 68-503 m2. Tadpoles are mainly herbivores but they will eat any dead matter. Adult R. pipiens are mainly carnivores and will eat anything that is small enough to fit in their mouth, with their main prey being insects (Smith and Keinath, 2004).
The American bullfrog adapts well to many different climates. This causes it to be quite invasive, and dangerous to natural populations of amphibians. The bullfrog originated in eastern North America, and has since spread to much of the rest of the country (Figure 3), as well as being introduced in many other places in the world. The bullfrog prefers to live in large, deep bodies of water with dense vegetation. The tadpoles require more than one year for metamorphosis, and so the ponds must be permanent. The adults overwinter in the water. They do not seem to be negatively affected by alien fish in the habitat. Male R. catesbeiana are aggressive and one pond can only support between 2 and 4 of them. Cannibalism also contributes to low population densities. Young bullfrogs mainly eat invertebrates, but adults will eat anything that they can catch, from invertebrates to rodents and other frogs. They prefer a temperature range between 8⁰ and 37⁰ C. They are very competitive and can take over a trophic level of the ecosystem. Bullfrog larvae also have a skin excretion that causes deformities and even possibly death in other amphibian species. R. catesbeiana also is much more resistant to and serves as a vector for the most threatening disease that amphibians face, caused by the fungus Chytridiomycosis. This is the main reason that bullfrogs are listed on the list of ‘100 of the World’s Worst Invasive Alien Species’. R. catesbeiana has also been spread by humans as a food source, to many places around the world (Spitzen, 2004)
Durango Nature Studies is 140 acres of wild land under a conservation easement. The Florida River runs through the property. Upstream of the property there is Lemon reservoir and dam, as well as cattle waste runoff and fish stocking, which all can contribute to the downstream habitat. Many varied types of habitat can be found on the property, including riparian, meadows, oak woodlands, pinion juniper forests, and desert arroyos (Durango Nature Studies, 2010).
The tenth grade Biology class at Animas High School performed various tests to assess the quality of the water habitat on the Durango Nature Studies property. The results of these tests can be found in Figures 4 and 5. The tolerance indices of the macro invertebrates found in the pond and river were sufficiently high to indicate fairly healthy conditions. (Figure 6) However, stoneflies, which have a tolerance index of 1 on a scale of one to ten, were not found at all, which shows that there is some pollution affecting the ecosystem. The results of the Shannon-weiner index showed very low biodiversity for both the pond and the river, with the river being slightly higher at 1.02. This scale goes from 0-5 and anything below a one is unstable diversity. Obviously we have a problem in terms of the biodiversity of the water habitats at DNC. The levels of phosphorus were much higher than is to be expected, which is probably due to runoff from upstream. The pH of the pond and river were between 8 and 9 (slightly alkaline) which is the preference of amphibians. The nitrates were at 2ppm, a low value, which is good. Anything above 4 is considered not great, and above 40 is unsafe for drinking. The dissolved oxygen levels were at 8mg/L for the river, and 6.5mg/L for the pond. These are excellent levels for these habitats. Coliform was also found at both locations, but it is uncertain as to the levels. However, high levels of Coliform can cause deformities in the growth of frogs, so it should be monitored (Dunning, 2011). All of these results for the water quality of these areas paint a picture of a reasonably well off habitat, but possibly with higher levels of pollution, as well as the possibility of high Coliform. Other than that, the quality of water at the DNS property is excellent.
Plan Implementation: India Waller
The northern leopard frog is a native species of Colorado that is considered a species of special concern by the Colorado Division of Wildlife. To promote growth of the R. pipiens population on the Durango Nature Studies property their habitat should be improved. The best way to promote the native leopard frog population is to eliminate bullfrogs. The methods for this are outlined in a later section. Improving water quality, lowering phosphate levels in the pond and the river is another way to promote leopard frog populations. Too much phosphate has potential to cause an algal bloom, which would result in reduced dissolved oxygen levels (Smith & Keinath, 2004). Bluegills (Lepomis macrochirus) were introduced to the pond in 2001. L. macrochirus are predators of the northern leopard frog; therefore their population in the established ponds should be monitored and controlled. Another pond should be built on the property as a breeding pond that is void of predatory fish (Figure 7). This will give the R. pipiens another breeding ground where the bluegills will not be a threat (Smith & Keinath, 2004).
To lower phosphate levels an investigation must first be done to find the main sources of phosphate along the Florida River upstream of Durango Natures Studies. Once main sources are located, mediation with the owners of the property can be attempted to reduce phosphate use and/or reduce phosphate run-off into the Florida River. Initial research to locate main sources will be done in September, 2012 by two Animas High school students.
To build the breeding pond a contractor should be hired. The pond should be 0.032ha because it is thought to be an adequate size for the breeding of the northern leopard frog and fits into the budget allowed. The construction of the pond including manual labor will cost $360. For a rubber lining to prevent the water from permeating into the soil there is an additional $130.83 added (Figure 8). Water will have to be delivered and will cost around $180 (Burton, 2005). The combined cost of this project is $700.93, well in the $2,000 budget of the Durango Nature Studies. Since northern leopard frogs tend to return to the pond they were born in to breed, we should also transport larvae from the inhabited pond on the property to the new breeding pond. Animas High School students and/or volunteers will do the transportation of the larvae in the spring, 2013. The pond should be built in September, 2012 so an ecosystem can be started before the larvae are transported in the spring or summer. These seasons are when there would be an abundance of larvae. Half the larvae mass from the establish pond should be transported to the new pond; this way the R. pipiens population will be evenly distributed between the two. The bluegills will be managed and monitored by the fishing activities already established on the property.
In the interest of promoting R. pipiens population it is crucial to monitor and manage the invasive R. catesbeiana population. To do this the following is suggested: monitor bullfrog population, and remove the bullfrogs that are there now. Doing these tasks will control the invasive bullfrog population and therefore, since bullfrogs can be harmful to the native species of northern leopard frog it will promote R. pipiens population. September was chosen because this is when the Animas High School students are available.
The monitoring of the R. catesbeiana population at the Durango Nature Studies pond should be done by mark recapture study or by observation, by Animas High School biology students, each year in September. This study should be done on the pond and river on the Durango Nature Studies property. The removal of all the bullfrogs should be done using direct removal, by Animas High School, also in September. The direct removal will be done by means of pitfall trap arrays. For this five shovels are needed. This will cost $29.90, with a cost of $5.98 per shovel. Pitfall trap arrays will be placed around the existing pond in fall, 2012 prior to construction of the new pond. This will be done 0.5 to 3.0km around the pond and river on the Durango Nature Studies property (Smith and Keinath, 2004). Pitfall trap arrays will be used again in 2014 around the newly established pond in order to estimate the new leopard frog population and check for existing bullfrogs. All removed bullfrog will be given to Animas High School and/or to Mountain Middle School to be used as class pets or dissection.
Plan Evaluation: Robin Austin
Durango Nature Studies promotes community understanding of our native southwest environment. It has various programs to educate the community about their surroundings, including Children Discovering Nature, adult and family programs, research projects, and a range of other seasonal programs. The proposed plan will disturb these programs because of the unnatural upsetting of the habitat. However, because the most disruptive part of the plan (the construction of the pond) is being done in September, it will be less troublesome for the programs, as they run primarily in the winter, spring, and summer (Durango Nature Studies, 2010). The interference with the habitat is more severe, as the building of a pond will require bulldozers and other construction equipment. Due to the time it is being put into action, however, it is unlikely to be irreparably damaging to the habitat. The species of concern, Rana pipiens, is not likely to be disrupted because this activity will not greatly upset the water habitats of the area (Smith and Keinath, 2004).
In order to keep tabs on the populations of R. pipiens, the Animas High School Biology class will perform a visual encounter survey in September. They will keep a record of the numbers found, and make sure that the leopard frogs are steady or increasing in population. To monitor R. catesbeiana populations, Animas will capture any sighted and they will give them to schools for instructional purposes. If there are none who are interested, then we will dispose of them in a cooler full of CO2. This will give the nature center more information about the current situation of the amphibians of their property.
To ensure that the management plan is working as planned, Animas will continue to keep records of population sizes. If there has not been a bullfrog sighted or caught for 5 years, then we can consider the area free of bullfrogs, but Animas High School will continue to monitor the population sizes. If there are more sightings of R. catesbeiana, Animas High School will resume the removal of the frogs. This plan is intended to sustainably increase the numbers of R. pipiens. Animas High School will keep records of the results of the visual encounter survey, and make sure that numbers of R. pipiens increase in the projected way.
Pond Levels
|
Analysis
| |
pH
|
8 or 9
|
more alkaline
|
Nitrogen
|
1ppm
|
unpolluted
|
Dissolved Oxygen
|
6.5mg/L
|
high
|
Phosphorus
|
2ppm
|
high
|
Coliform
|
positive
|
existing
|
Figure 4
River Levels
|
Analysis
| |
pH
|
8 or 9
|
more alkaline
|
Nitrogen
|
2ppm
|
unpolluted
|
Dissolved Oxygen
|
8.5mg/L
|
high
|
Phosphorus
|
1ppm
|
high
|
Coliform
|
positive
|
existing
|
Figure 5
DNS Pond
|
Florida River
| |
Damselfly
|
53
|
0
|
Mayfly
|
41
|
125
|
Midge
|
5
|
15
|
Caddisfly
|
2
|
120
|
Dragonfly
|
1
|
0
|
Blackfly
|
0
|
5
|
Coleoptera
|
0
|
5
|
Stonefly
|
0
|
0
|
Total Number
|
102
|
270
|
Diversity Index
|
0.98
|
1.02
|
Figure 6
Figure 7
Vendor
|
Description
|
Cost per Unit
|
Quantity
|
Total Cost
|
Contractor
|
Construction of a Pond
|
2.50 per yd.3
|
0.032ha
|
$360
|
Water Delivery
|
Water
|
$90 per 0.016ha
|
0.032ha
|
$180
|
Contractor
|
Rubber liner
|
$0.50 per ft.2
|
261.67 ft2
|
$130.83
|
Home Depot
|
Shovel
|
$5.98
|
5
|
$30
|
Animas High
|
Net
|
0
|
3
|
$0
|
Total
|
$700.73
|
Figure 8
Reference List
Burton, T., 2005, How Much Does It Cost to Build a Proper Koi Pond, Mid-Atlantic Koi Club, http://www.makc.com/pondconst_tb.pdf (October 17, 2011)
Durango Nature Studies, 2010. Durango Nature Center. Durango Nature Studies. http://www.durangonaturestudies.org/center.htm
Smith, Brian E. and Keinath, Doug. 2004. Species Assessment for the Northern Leopard Frog (Rana pipiens) in Wyoming. United States Department of the Interior. Cheyenne, Wyoming.
Spitzen – van der Sluijs, A. M. & R. Zollinger, 2010. Literature review on the American bullfrog Rana catesbeiana (Shaw, 1802). Stichting RAVON, Nijmegen, the Netherlands.
