escribe the relationship between lethal (>90%) mortality (black shading) and water temperature at the four sites.

EVR 3013L Ecology of South Florida Lab

Summer 2018

Worksheet 4 – Climate and the Everglades Restoration



Name ________________________________________     Panther ID ________________________




The activities this week involve looking at data concerning extreme weather events in the southern Everglades that had significant impacts on both wildlife and plant communities. Information sources from the Web must be listed with your answers.


This worksheet is due Tuesday June 12 at 11:59 pm uploaded through the link provided in Canvas


Part I – Changing climate and environmental tolerances of species


In the recorded lecture I showed you a chart from Jackson & Overpeck (Paleobiology, 26/4 supp, P294-220, 2000). The current climate is represented by the gray horizontally shaded oval. The new climate is represented by the gray vertically shaded oval. Explain how the change in climate could affect the ability of species A-F to survive under the new conditions.




Part II – Ocean water temperature variation and coral reefs


Although South Florida is known for its warmth, wintertime cold fronts pass through the area. The winds change direction to the NW bringing cold air and winds that cool surface ocean waters as well. This graph compares water temperatures at the depths of coral reef in S. Florida (light blue) compared to the U.S. Virgin Islands (dark blue) from Jan 2004 to mid-2013.

  1. Compare the water temperatures at the depths that coral reefs live for the U.S. Virgin Islands and South Florida. How do water temperatures vary over the year at each location?
  2. I have drawn a red line at 30°C water temperature. What is the significance of that temperature for corals? What is the impact on the coral reef with each summer’s temperatures?
  3. I have circled the S. Florida water temperature in Jan 2010. What do you think might be the significance of this temperature on the coral?


  1. How might the variation in ocean temperature in South Florida impact the survivability of coral as compare to the U.S. Virgin Islands?









Part III – January 2010 study of cold spell on Florida Bay corals


In January 2010, unusually strong Arctic cold fronts passed through South Florida. There was an extended period of colder than normal temperatures. The following table shows water temperature readings for the reef locations surveyed during this period.


Site Depth

Measured (m)

Ave January

Temp (°C)

Minimum Temp

at location (°C)

Duration (hours)

<16°C     <12°C

Upper Keys        
Burr Patch (BP) 5 19.6 11.2 150           32
Middle Keys        
West Turtle Shoal


8 19.9 11.7 89              2
Dustan Rocks (DR) 5 19.4 12 133            1


The following graph shows the percent of the coral colonies suffering different severities of mortality as a result of the cold spell. For Thor Patch (TP) temperature profile, use the information for Dustan Rocks. Data from Collela et al, Coral Reefs (2012), 31:621-632.


  1. Describe the relationship between lethal (>90%) mortality (black shading) and water temperature at the four sites.


  1. Why did the authors focus on 16°C as a critical minimum temperature?


  1. What characteristics of temperature seemed to be the most important in determining the mortality of the coral
  2. What have you learned about the sensitivity of coral species to changes in ocean temperature? How might this sensitiviy affect the coral under scenarios of future climate change?

Part IV – January 2010 study of cold spell on Florida Bay corals

Low water temperatures also adversely affect fish. Monitoring studies on the southern Everglades fisheries picked up the change in fish populations as a result of the January 2010 cold spell. Data are shown below for four categories of fish: estuarine prey, freshwater fishes, snook and non-natives. Each year is divided into wet and dry seasons, and the time period covered is 2005 wet season through 2012 dry season. The vertical blue line indicates the January, 2010 cold spell. Air temperatures in the southern Everglades did not go above 11.5°C for 12 consecutive days. The source of this information is Recover: 2014 System Status Report – Effects of the 2010 Cold Event on Everglades Biota.

  1. Research on the Internet the ecological role of each of the native fish in panels B, C and D. For example: Where do they live? Are they herbivorous (primary consumer) or predator (secondary consumer)? Are they temperate species at their southern limit or tropical species at their northern limit? Would you expect these species to be sensitive to cold?
  2. Let’s look further at the non-native species grouped in panel E. What are the sources of non-native fish species found in the Everglades? Are these likely to be temperate or tropical species?
  3. Based on the graph, how were the fish affected or not affected by the cold spell? Can you use the answers to the first two questions to explain the results that you see in the graph?
  4. The cold event of January 2010 was widespread. What do you think the effect might have been on crocodile and manatee populations in south Florida?


Part V – Resilience of coral reefs to warming oceans

El Niño is a climatological phenomenon that is associated with changes in major atmospheric wind patterns in the Pacific Ocean. The 1997-1998 El Niño event resulted in exceptionally warm ocean temperatures in the eastern Pacific Ocean and the Gulf of Mexico. In the study below researchers examined the response of coral reefs to this warming episode. Two sites were examined: one site at Key West (KW) and the other site in the Dry Tortugas (DT)

Dry Tortugas


The graph below shows water temperatures at these two locations over the study period. Data are from Santavy et al, Diversity (2011), 4: 628-640.

  1. Compare the water temperatures for 1997 (solid line) and 1998 (dotted line). How long were temperatures above 30°C in 1997 compared to 1998?
  2. Based on what you have learned so far, what would expect the impact of these elevated

temperatures to be on the coral reef?

The figure below shows the percent of coral colonies affected by disease from 1998 through 2002. Data is also from Santavy et al.


Light gray: Dry Tortugas

Dark gray: Key West


  1. What was the difference in disease incidence between Key West and Dry Tortugas coral colonies?


  1. What response of coral to elevated temperatures might make them more susceptible to disease?

Part VI – Summary


Write a 250-300 word summary of this exercise. What did you learn about the response of organisms in Florida Bay and the coral to extreme weather events?
























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