coral bleaching in the hawaiian islands€¦ · (10-75%) 36% (16-65%) exposure triggers bleaching...

Coral Bleaching

in the Hawaiian Islands

Kohana’iki

What is Bleaching?

Photo credit: Mike Hazard

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What causes

bleaching?

What causes

bleaching?

Historical Background

Bleaching Will Occur More Frequently

2030s: Mass Bleachingin 30-50% of years

2050s: Mass Bleaching In 80-100% of years

Do corals have the ability to adapt to temperature change?

EconomicTourismFishing

Shoreline Protection

Coral Reef Ecosystem

Social/Cultural value

Coral loss-What’s at stake?

2014 – 2015 Hawaiian Bleaching Event :What we know.

2014-2015: In HawaiʻiUnprecedented Back-to-Back Mass Bleaching

2014-2015: In HawaiʻiUnprecedented Back-to-Back Mass Bleaching

Temperature

2014-2015: In HawaiʻiUnprecedented Back-to-Back Mass Bleaching

Temperature

Bleaching

2014-2015: In HawaiʻiUnprecedented Back-to-Back Mass Bleaching

Temperature

Bleaching

Sep

2014

Sep

2015

2014-2015: In HawaiʻiUnprecedented Back-to-Back Mass Bleaching

Hawaii Coral Bleaching Collaborative Dataset: Main Hawaii Islands, 2014-2015

6 Institutions: • DLNR/DAR, UHM (HIMB),

UHH,TNC, HIHWNMS,NOAA-ESD

- 11 Groups- 895 Obs.- 2014-01-12 :

2016-02-15

Nearly half of all corals in the state bleached:

46% +/- 4%PercentAffected

Statewide

Nearly half of all corals in the state bleached:

46% +/- 4%PercentAffected

Statewide

56%(23-91%)

44%(6-66%)

32%(10-75%)

36%(16-65%)

2013 to 2016 Mortality EstimatesMany, Many Corals Died:Change in Coral Cover Before and After 2015 Event

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2013 to 2016 Mortality EstimatesMany, Many Corals Died:Change in Coral Cover Before and After 2015 Event

Pe

rce

nt

Live

Co

ral C

ove

r

47%61%

42%

48%

50-75%7-85%

51-57%

2013 to 2016 Mortality EstimatesMany, Many Corals Died:Change in Coral Cover Before and After 2015 Event

Pe

rce

nt

Live

Co

ral C

ove

r

47%61%

42%

48%

8-30%

~0.5%

50-75%7-85%

51-57%

2013 to 2016 Mortality Estimates:Coral Cover Lost

We asked what spatial variables correlated with

more or less bleaching: 56%

(23-91%)

44%(6-66%)

32%(10-75%)

36%(16-65%)

Exposure triggers bleaching impacts.Temperatures Above ThresholdLight

Resistance limits exposure’s damage.Sewage reducesPrevious thermal stress (2014) reducesTemperature Variability enhances

Recovery returns reefs to normal.Keep algae low (many herbivores, low nutrients)Promote coral growth/reproduction

Exposure triggers bleaching impacts.Temperatures Above Threshold Light

Resistance limits exposure’s damage.Sewage reducesPrevious thermal stress (2014) reducesTemperature Variability enhances

Recovery returns reefs to normal.Keep algae low (many herbivores, low nutrients)Promote coral growth/reproduction

Exposure triggers bleaching impacts.Temperatures Above Threshold High LightShallow waters

Resistance limits exposure’s damage.Sewage reducesPrevious thermal stress (2014) reducesTemperature Variability enhances

Recovery returns reefs to normal.Keep algae low (many herbivores, low nutrients)Promote coral growth/reproduction

Exposure triggers bleaching impacts.Temperatures Above Threshold High LightShallow waters

Resistance limits exposure’s damage.Sewage reducesPrevious thermal stress (2014) reducesTemperature Variability enhances

Recovery returns reefs to normal.Keep algae low (many herbivores, low nutrients)Promote coral growth/reproduction

Exposure triggers bleaching impacts.Temperatures Above Threshold High LightShallow waters

Resistance limits exposure’s damage.Sewage reducesPrevious thermal stress (2014) reducesTemperature Variability enhances

Recovery returns reefs to normal.Keep algae low (many herbivores, low nutrients)Promote coral growth/reproduction

Analysis and Ranking ofEcological Effectivenessof the 22 most promising management actions to promote coral ecosystem recovery after bleaching impacts, based on:

1. Global Expert Survey2. Hawaiʻi Workshop3. Literature Review