Coral Reefs and Climate ChangeCoral Reefs and Climate ChangeCoral Reefs and Climate ChangeCoral Reefs and Climate Change

Drew HarvellEcology and Evolutionary BiologyCornell University

Disease is a major community Disease is a major community structuring agent in the oceanstructuring agent in the oceanDisease is a major community Disease is a major community structuring agent in the oceanstructuring agent in the ocean

• Coral diseases-- eg Acropora spp over 90% mortality mid 1980s

• Tropical urchins-- eg Diadema over 90% mortality mid 1980s well documented keystone effect of disease

• Temperate urchins

• Lobsters, other crustaceans, oysters, abalone

Sea UrchinSea Urchin (Diadema antillarum) (Diadema antillarum) Die-OffDie-OffSea UrchinSea Urchin (Diadema antillarum) (Diadema antillarum) Die-OffDie-Off

• started in January, 1983

• population density reduced by 97% in one year (Lessios 1988)

• current population density still <3.5% of 1983 (Lessios 1995)

• major community shifts on coral reefs > coral to algae dominated

• unidentified water-borne pathogenPhoto by P. HumannPhoto by P. Humann

Corals-- a colonial invertebrateCorals-- a colonial invertebrateCorals-- a colonial invertebrateCorals-- a colonial invertebrate

Ocean diseases and climate warming: Ocean diseases and climate warming: explosive mixexplosive mix

Ocean diseases and climate warming: Ocean diseases and climate warming: explosive mixexplosive mix

• corals at upper thermal limits, eg bleaching

• pathogens can rapidly evolve new

> temp tolerances• pathogens evolve much more rapidly

> than coral• anthropogenic activities increase

• stir in more new emergent pathogens

Disease and Pathologies of Stony CoralsDisease and Pathologies of Stony CoralsDisease and Pathologies of Stony Corals

Yellow Blotch

Photo by N. Bianchi

White Plague

Photo by S. Miller

Black Band

Photo by E. Peters

Not shown: white banddisease, plague type I,shut down reaction,yellow band,rapid wasting,dark spot, white pox, poritiesulcerative pox

White Band Disease of CoralsWhite Band Disease of CoralsWhite Band Disease of CoralsWhite Band Disease of Corals

•Acropora cervicornis dominated Caribbean Coral Reefs

• from 1950-1970—disappeared thereafter

•Mass mortality from White Band Disease in Belize in 1986

•First time in 3,800 years (Aronson & Precht 1997)

Warming Oceans Can Facilitate Warming Oceans Can Facilitate PathogensPathogens

Warming Oceans Can Facilitate Warming Oceans Can Facilitate PathogensPathogens

•Black band disease of coral increases in summer

• Aspergillosis of coral grows faster at peak summer temperatures

• Perkinsus of oyster moved to Maine when winter temps warmed in the 90s

• Coral bleaching likely facilitates disease

Florida Keys: 63% died during warm El nino

Seafan-aspergillus epizooticSeafan-aspergillus epizooticSeafan-aspergillus epizooticSeafan-aspergillus epizootic

1- Impact in the Keys2- SpatialEcology3- Resistance to Disease

Aspergillosis of Sea Fans Aspergillosis of Sea Fans ~ Dynamics in the Florida Keys ~ ~ Dynamics in the Florida Keys ~

Aspergillosis of Sea Fans Aspergillosis of Sea Fans ~ Dynamics in the Florida Keys ~ ~ Dynamics in the Florida Keys ~

• Are there disease hotspots correlated with water quality?> Prevalence: number of infected individuals

> Virulence: damage from disease

> water quality: temperature, nitrates, chlorophyll a, etc.

• Can sea fans fight back?> chemical resistance

• Could chemicals from soft corals have biomedical applications?> anti-bacterial compounds (Jensen, Harvell, Wirtz, Fenical 1996)

> antifungal compounds (Kim, Kim, Harvell, 2000)

Death of a Diseased CoralDeath of a Diseased CoralDeath of a Diseased CoralDeath of a Diseased Coral

Alisa Alker

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Florida Keys Survey SitesFlorida Keys Survey SitesFlorida Keys Survey Sites

20 km

Carysfort (CARY)

Molasses (MOLA)

Conch(CONC)Alligator (ALLG)

Tennessee (TENN)W. Sambos

(WSAM)Sand Key(SAND)

W. Dry Rocks(WDRK)

Florida

Seafan Disease MonitoringSeafan Disease MonitoringSeafan Disease MonitoringSeafan Disease Monitoring

Permanent TransectsEstablished June 1997Currently 8 sites along the Florida KeysThree 25 m transects per site

Parameters measuredColony height (cm)% infected individuals: Prevalence% colony damage: SeverityDead

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June 1997: Hi prevalence, variable June 1997: Hi prevalence, variable severity-- compromised resistance severity-- compromised resistance

more important than transmission?more important than transmission?

June 1997: Hi prevalence, variable June 1997: Hi prevalence, variable severity-- compromised resistance severity-- compromised resistance

more important than transmission?more important than transmission?

Kim and Harvell in press

New disease and force of New disease and force of infectionMortality Hotspots-- infectionMortality Hotspots--

indicator of disease process scale?indicator of disease process scale?

New disease and force of New disease and force of infectionMortality Hotspots-- infectionMortality Hotspots--

indicator of disease process scale?indicator of disease process scale?

Seafan Corals: Impact of a Fungal Seafan Corals: Impact of a Fungal DiseaseDisease

Seafan Corals: Impact of a Fungal Seafan Corals: Impact of a Fungal DiseaseDisease

Aspergilli cause diseases in immune compromised hosts.Is resistance of seafans compromised?

K.Kim photo

Seafan Resistance to AspergillusSeafan Resistance to AspergillusSeafan Resistance to AspergillusSeafan Resistance to Aspergillus

• Antifungal chemicals

• Hyperplastic tumors

• Melanization response

NSF, NOAA

Aspergillus sydowii:optimal temp is hotAspergillus sydowii:optimal temp is hotAspergillus sydowii:optimal temp is hotAspergillus sydowii:optimal temp is hot

Growth Rate(mm/d, ±SE)

Temperature (˚C)

20 25 30 35 40

8

6

4

2

Alker et al

Antifungal Activity in Gorgonian Antifungal Activity in Gorgonian Corals Corals (Kim et al, 2000)(Kim et al, 2000)

Antifungal Activity in Gorgonian Antifungal Activity in Gorgonian Corals Corals (Kim et al, 2000)(Kim et al, 2000)

Pseudopterogorgia acerosaPseudoplexaura wagenaariPseudoplexaura flagellosa

Pseudoplexaura porosaPseudopterogorgia americana

Gorgonia ventalinaPlexaura kuna

Eunicea succineaPseudopterogorgia bipinnata

Plexaura flexuosaPlexaura homomalla

Pterogorgia citrinaBriareum asbestinum

Erythropodium caribaeorumPseudopterogorgia rigida

Plexaurella griseaPlexaurella nutans

Muricea atlanticaMuriceopsis flavida

Pterogorgia guadalupensis

Minimum Inhibitory Concentrations (mg/ml)5101520

increasing activity

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K. Kim

Time course of inductionTime course of inductionTime course of inductionTime course of induction

Clonal Variation in Inoculation SuccessClonal Clonal Variation in Inoculation SuccessVariation in Inoculation Success

Inoculation protocol for clonaldesign

Inoculation protocol for Inoculation protocol for clonalclonaldesigndesign

A. Alker

A. Alker

July 99

Your TestYour TestYour TestYour Test

•Will the fungus cause seafan exinction?

•Need to know: coral mortality rate, longevity, recruitment rate…

•…it could because mortality hi, long-lived, and no repro

•Is climate warming a threat to corals?

•BIG THREAT

•Where might new coral diseases come from?

•Aquaculture, land, ballast shipping, existing pathogens

•Can seafans fight back?

•Rapid induction (4-8 days)

•Antifungal chemicals, melanin (purpling), gorgonin tumors

•Will seafans evolve to be more resistant?

•Maybe, clonal variation for selection to act on.

Diseases in Marine CommunitiesDiseases in Marine Communities~ Changing Perspectives ~~ Changing Perspectives ~

Diseases in Marine CommunitiesDiseases in Marine Communities~ Changing Perspectives ~~ Changing Perspectives ~

CoralsCorals

Competition

Predation

Abiotic Factors

Disease

CoralsCorals

Competition

Predation

Abiotic Factors