In addition to the coral surveys, water temperature is also being monitored at all CREMP sites. 

Why monitor temperature?

Corals are highly sensitive to even small temperature changes and can react through bleaching, reduced growth rates, reduced reproduction, increased vulnerability to diseases, and die-offs. Corals have a mutually beneficial, or symbiotic, relationship with a type of algae known as zooxanthellae. Zooxanthellae live inside the coral and provide them with energy derived from photosynthesis, and the coral provides the algae with shelter. However, corals can tolerate only a relatively narrow temperature range and prefer water between 73-84 degrees, and water temperatures over 86 degrees or under 64 degrees can become stressful and eventually fatal for coral. When the water gets too warm, zooxanthellae release compounds to deal with the heat stress that are harmful to the coral, causing the coral to expel their zooxanthellae and become bleached. Although the coral is still alive, just colorless, they will eventually die from starvation if the zooxanthellae does not return. 

Coral Bleaching
A bleaching boulder brain coral, Colpophyllia natans. The brown areas of coral still have their zooxanthellae, while the white portions have expelled it.
Photo credit: Katy Cummings

Recently, massive, region-wide bleaching events have become more common on the Florida Reef Tract. Six extensive coral bleaching events have affected the entire Florida Reef Tract since 1987, with substantial mass coral mortality occurring during the global bleaching events of 1997/1998 and 2014/2015.  Even beyond these major bleaching episodes, some level of bleaching is occurring nearly every year in the Florida Keys. On the other hand, corals at the northern end of their range - such as those found on the Florida Reef Tract - are also vulnerable to cold winter temperatures. A severe cold snap in 2010 resulted in high mortality of certain coral species on shallow-water patch reefs throughout the Florida Reef Tract (see Colella et al. 2012, “Cold-water event of January 2010 results in catastrophic benthic mortality on patch reefs in the Florida Keys”).

Therefore, long-term temperature monitoring, in conjunction with coral health and population surveys, is key to providing scientists and coral reef managers a better understanding of how temperature stress is affecting corals in the Florida Keys.  CREMP has one of the longest running active bottom temperature datasets for the region and has records going back 20 years for certain reefs in the Florida Keys. By closely monitoring water temperatures, we can determine when coral mortality and stress is most likely due to temperature, and when it may be due to other factors. Anthropogenic climate change is altering water temperatures and resulting in extreme fluctuations which well exceed the normal temperature ranges of corals, and our data has shown that both hot and cold water temperature stress events are increasing in frequency.

What we do

CREMP has been monitoring temperature along the Florida Reef Tract since 1996. We are deploying temperature loggers at every active CREMP site, and currently have 52 loggers recording water temperatures on sites ranging from just south of Biscayne National Park to the waters surrounding Dry Tortugas National Park. See a map of the Florida Reef Tract with our monitoring sites here External Website. This is an ArcGIS map with multiple layers - to turn on the layer showing the temperature monitoring sites, click the “Show Contents of Map” icon on the left above “Unified Florida Coral Reef Tract Map”, then check the box next to “FRT Temperature Monitoring – CREMP Sites”.  We monitor water temperatures on a variety of different reef types and depths, including hardbottom habitats, shallow fore reefs, deep fore reefs, and patch reefs.

We record water temperatures using the HOBO Water Temp Pro v2 loggers (model U22-001; Onset Corporation). These loggers are set to record the temperature every hour, giving us a high resolution, continuous temperature record. Loggers are attached to the metal stakes drilled into the reef used in the CREMP coral surveys using zip ties (see picture).

Temp Logger

A temperature logger attached with zip ties to the CREMP stake at Looe Key Shallow. Photo credit: FWC Corals Program

Data requests

Please direct temperature data requests to Katy Cummings at katy.cummings@myfwc.com with the sites and time frame you are interested in. 

 

CREMP sites with temperature loggers deployed.

Region

Site

Habitat

First Year

Upper Keys

 

Admiral

Patch Reef

2016

Burr Fish

Patch Reef

2009

Carysfort Deep

Offshore Deep Fore Reef

2013

Carysfort Shallow

Offshore Shallow Fore Reef

2013

Conch Deep

Offshore Deep Fore Reef

2008

Conch Shallow

Offshore Shallow Fore Reef

2008

Dove Key

Hardbottom

2008

El Radabob

Hardbottom

2003

Grecian Rocks

Offshore Shallow Fore Reef

2003

Molasses Deep

Offshore Deep Fore Reef

2008

Molasses Shallow

Offshore Shallow Fore Reef

2008

Porter Patch

Patch Reef

2003

Turtle

Patch Reef

2012

 Two Patches

 Patch Reef

 2016

Middle Keys

Alligator Deep

Offshore Deep Fore Reef

2012

Alligator Shallow

Offshore Shallow Fore Reef

2012

Dustan Rocks

Patch Reef

2006

Long Key

Hardbottom

2002

Moser Channel

Hardbottom

2006

Rawa Reef

Patch Reef

2012

Sombrero Deep

Offshore Deep Fore Reef

2009

Sombrero Shallow

Offshore Shallow Fore Reef

2006

Tennessee Deep

Offshore Deep Fore Reef

2010

Tennessee Shallow

Offshore Shallow Fore Reef

2002

Thor

Patch Reef

2010

West Turtle Shoal

Patch Reef

2002

Lower Keys

Cliff Green

Patch Reef

2002

Content Keys

Backcountry Patch Reef

2016

Eastern Sambo Deep

Offshore Deep Fore Reef

2014

Eastern Sambo Shallow

Offshore Shallow Fore Reef

2014

Jaap Reef

Patch Reef

2002

Looe Key Deep

Offshore Deep Fore Reef

2008

Looe Key Shallow

Offshore Shallow Fore Reef

2008

Red Dun Reef

Patch Reef

2009

Rock Key Deep

Offshore Deep Fore Reef

2009

Rock Key Shallow

Offshore Shallow Fore Reef

2009

Sand Key Deep

Offshore Deep Fore Reef

2016

Sand Key Shallow

Offshore Shallow Fore Reef

2016

Smith Shoal

Backcountry Patch Reef

2016

West Washer Women

Patch Reef

2007

Western Head

Patch Reef

2016

Western Sambo Deep

Offshore Deep Fore Reef

2007

Western Sambo Shallow

Offshore Shallow Fore Reef

2002

Wonderland

Patch Reef

2010

Dry Tortugas

Bird Key Reef

Offshore Deep Fore Reef

2006

Black Coral Rock

Offshore Deep Fore Reef

2006

Davis Rock

Patch Reef

2016

Loggerhead Patch

Patch Reef

2017 

Mayer's Peak

Patch Reef

2006

Palmata Patch

Patch Reef

2008

Prolifera Patch

Patch Reef

2017

Temptation Rock

Patch Reef

2006

Texas Rock

Patch Reef

2010

The Maze

Patch Reef

2016

White Shoal

Patch Reef

2016



FWC Facts:
Hard corals are corals with 6 tentacles or multiples of 6 (e.g., 6, 12, 18, 24). Octocorals have 8 tentacles.

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