A geological perspective on the preservation and ...

A geological perspective on the preservation and restoration of

Florida’s coral reefs

Lauren T. Toth, Ilsa B. Kuffner, & Anastasios StathakopoulosU.S. Geological Survey, St. Petersburg Coastal and Marine Science Center

U.S. Department of the InteriorU.S. Geological Survey

Habitat

Islamorada, FL Keys, after Hurricane Irma

Shoreline protection Tourism

$375 billion/yr to Florida’s economy (NOAA)

1971

Photos courtesy of Gene Shinn

1998

1971 1988

2004

Photos courtesy of Gene ShinnGrecian Rocks, Florida Keys

Hen & Chickens Reef, FL Keys

1998 elevation

Reef erosion is becoming a dominant process

2015 elevation

Reef erosion rate:-5.5 ± 3.2 mm yr-1

Kuffner, Toth, et al. in review

Harold Hudson’s “monuments” (n = 28) used to measure reef

erosion (est. 1998)One of the only direct measurements of

reef erosion rate in Florida

Gene Shinn

USGS Core Archive: http://olga.er.usgs.gov/coreviewer/

The past is the key to the future

185 radiometric ages from 46 cores from

throughout the Florida Keys

Coral reef development in south Florida

Toth et al. 2018. Global Change Biology

Hubbard et al. 2005, 2013; Macintyre and Glynn 1976; Macintyre 1977; Macintyre et al. 1985; Gischler and Hudson 2004

Hubbard et al. 2005, 2013; Macintyre and Glynn 1976; Macintyre 1977; Macintyre et al. 1985; Gischler and Hudson 2004

Anthropogenic warming

Geological shutdown of Florida’s coral reefs

Toth et al. 2018. Global Change Biology

Florida’s reefs have grown little in the last 3000 years

Lirman et al. 2011. PLoS One

Cold-water coral mortality

Timing of reef shutdown

Florida Bay

Florida Bay flooded and was connected to the reefs of the

Florida Keys 8000–5500 years ago

Differences in duration of reef

development explain spatial variability in

reef thickness

Reef accretion Reef erosion

Holocene Thermal Maximum Anthropogenic warmingClimatic cooling

Geological shutdown of Florida’s coral reefs

Toth et al. 2018. Global Change Biology

Cold-water coral mortality

Global tem

perature anomaly (°C)

0.5

-0.5

0

Reefs influenced by Florida Bay stop growing

Acropora palmata

Orbicellaspp.

Brain corals

Porites astreoides

Siderastrea siderea

Other corals

Geological reef frameworkAcropora palmata

Orbicellaspp.

Brain corals

Porites astreoides

Siderastrea siderea

Other corals

Modern ReefsChanges in reef composition

Collaborators: Rob Ruzicka and Mike Colella (FWRI, FL FWCC)http://myfwc.com/research/habitat/coral/cremp/Toth et al. in press. Ecology

>90% Holocene

reef framework

>60% cover on modern

reefs

Acropora palmata

Orbicellaspp.

Brain corals

Porites astreoides

Siderastrea siderea

Other corals

Middle Holocene Reefs

Optimizing coral restoration

• Acropora cervicornis only accounts for 2% of the reef framework in our cores from the Florida Keys

• Does not build lasting reef structure

A geological perspective on coral-reef management• Changing climate and the influence of Florida Bay

have suppressed reef growth in Florida has been suppressed for ~3000 years

• The outcomes of coral-reef management and restoration can be optimized by prioritizing efforts that promote reef growth and mitigate reef erosion

• Preserving the geologic structures that remain is a worthy management goal

• Focus on restoration of reef-building corals such as Acropora palmata and Orbicella spp.

Spatial patterns of reef development

50 km

No significant difference in reef accretion among sectors

(F5,44=0.09, p=0.99)

Reef

acc

retio

n (m

/100

0 y)

Geological senescence of Florida’s coral reefs

3

2

1

0

Reef

acc

retio

n ra

te (m

/ky)

The carbonate budget of a coral reefCarbonate Production(calcification x coral cover x rugosity)

Bioerosion(+ sediment export and dissolution)

P.W. Glynn

1971

E.A. Shinn

Reef accretion

The carbonate budget of a coral reefCarbonate Production(calcification x coral cover x rugosity)

P.W. GlynnE.A. Shinn

2001

Reef erosion

Bioerosion(+ sediment export and dissolution)

The carbonate budget of a coral reefCarbonate Production(calcification x coral cover x rugosity)

E.A. Shinn

2001

Reef erosion

1971

E.A. Shinn P.W. Glynn

Bioerosion(+ sediment export and dissolution)

Kim Yates, Dave Zawada, et al.2017 Biogeosciences

Large-scale trends in reef erosion since the 1930s

Maui, Hawaii

Upper & LowerFlorida Keys

St. Thomas, USVI

Buck IslandSt. Croix, USVI

Pacific Ocean

Atlantic Ocean

CaribbeanSea

-38 Mm3

-6 Mm3-81 Mm3

-22 Mm3

-3 Mm3

Empire State Building Volume

= 1 Mm3

-7.97 - -4.00-3.99 - -3.00-2.99 - -2.00-1.99 - -1.00-0.99 - -0.50-0.49 – 0.000.01 – 0.500.51 – 1.001.01 – 2.002.01 – 3.003.01 – 5.25

Seafloor Elevation Change (m)

-0.4 m

-0.3 m

+0.1 m

Seafloor Erosion

Seafloor AccretionKilomete

rs