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Florida International University *

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3013L

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Biology

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Apr 3, 2024

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docx

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EVR 3013L Ecology of South Florida Lab Biological Pollution Introduction Pollution is a broad topic. This week we will be looking at biological pollution. South Florida is the perfect location for arrival of unwanted species by air or sea. The warm frost-free climate eliminates seasonal killing of species from tropical areas. We will look at a selection of plants and animals that threaten the Everglades ecosystem. View the following videos for an introduction to invasive exotic species and answer the following questions: Invasive Exotics in South Florida A Waterways Production and Everglades Invasives 1. What is the difference between a native species, an exotic species and an invasive exotic species? Which one concerns resource managers the most? - A native species is a species that originated from a specific habitat and have been able to adapt and make it home. An exotic species is a non-native plant/animal introduced intentionally or accidentally to an area through human activity. An invasive exotic species is an exotic species that rapidly reproduces and gets out of hand. Resource managers are most concerned about the invasive exotic species because they end up being out of control and hard to manage than originally planned. 2. Summarize the impacts that lionfish are having on the ecology of the reef. - Lionfish are rapidly spreading all the way from the Caribbean to North Carolina. Due to their adaptability in similar water, they’ve been able to colonize and invade all these areas. The overfishing of top predators within these areas has also left them with less competition; it’s left a lot of open niches allowing them to assume those roles. Lionfish are also eating economically/ecologically important species, they are consuming these native species at a much faster rate than they can reproduce. 3. What strategy for removing lionfish from the reef seems to have the best chance for success? - As of right now, the best strategy for removing lionfish from the reef is informing the public and training divers to catch these fish. 4. Summarize the impacts that Burmese pythons are having on the ecology of Everglades National Park? - Burmese pythons are spreading rapidly and decimating many of the Everglades National Park populations because of their broad appetite. The overconsumption of all these species is upsetting the balance of the food web found within this ecosystem. II. The Burmese python Burmese pythons were recognized as being established in Everglades National Park by 2000. This means that there is a population that is surviving and reproducing in the Park. Dorcas et al. (PNAS, Februaray 14, 2012, vol 109, No. 17, P. 2418) showed the following graph for captures of Burmese pythons in Everglades National Park.

1. If the same amount of effort is made each year to capture pythons in Everglades National Park, what conclusion can we reach about the number of pythons living in the park based on the graph? - We can conclude that the number of pythons living in the park is continuing to grow. Larger numbers of python captures with the same amount of effort means that there are more pythons within the Everglades National Park which is causing for such high removal rates. 2. The authors of the paper state that a decline in the number of pythons in 2010 might be due to a severe cold temperature period in the winter of 2010. How might cold weather affect the pythons? - The cold weather might affect the pythons in that it affects their source of food. Since most of the native species within the Everglades National Park are accustomed to the warmer weather, being hit with cold weather may have caused their population levels to decrease from a lack of food and literally freezing to death. The authors of the paper wanted to estimate the impact of the pythons on those animals that were their likely prey. They look at recorded data of animals observed from the roads for the period before 1996- 1997 (before the python establishment) compared to 2003-2011 (after the pythons became established). The results are shown below. The y-axis shows the number of animals observed per 100 km of road, and the x- axis shows the species of animal counted. The green bars are the counts from before 1996-1997, and the red bars are the counts from 2003- 2011. Python Removals from 1995-2010

3. What do the results show in the comparison of the abundances of these animals in the two time periods? - The results show how drastically the sighting levels of all these animals went down after Burmese Pythons were introduced into the environment. 4. The authors attribute the change in abundances to the appearance of Burmese pythons. Is this a reasonable conclusion? Why or why not? - This is a reasonable conclusion because Burmese pythons are known to have a broad appetite and be very voracious. It can be concluded that the reason all of these animal sighting levels went down was due to either the Burmese Pythons decimating their population directly or decimating the population of other prey that animals such as Bobcats and Panthers depend on for survival. III. Threat to Avocados and Everglades alike The red bay ambrosia beetle is an insect native to South and Southeast Asia. It made its first appearance in the U.S. near Savanah, Georgia in 2002. It carries with it an associated fungus. The effect of infection is to interfere with the flow of water from the roots of the trees to the leaves. In its native habitat, the beetle infects injured or weakened trees and performs a service in the forest by killing unhealthy trees and leaving space for new healthy trees. The ambrosia beetle was likely brought into the U.S. on imported lumber. In the U.S. the beetle also infected healthy trees. The disease is called laurel wilt because the beetle and fungus attack trees of the laurel family. The spread of the beetle once it reached the U.S. is shown in the map below.

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