Coral reefs in a changing world: Climate change and land-based - - PowerPoint PPT Presentation

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Coral reefs in a changing world: Climate change and land-based - - PowerPoint PPT Presentation

Feb 08, 2023 349 likes •675 views

Coral reefs in a changing world: Climate change and land-based pollution issues Hiroya Yamano (National Institute for Environmental Studies) Outline Coral reefs at risk Contribution of remote sensing observations Climate change and

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Coral reefs in a changing world: Climate change and land-based pollution issues

Hiroya Yamano (National Institute for Environmental Studies)

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Outline

  • Coral reefs at risk
  • Contribution of remote

sensing observations

  • Climate change and

land-based pollution

  • Framework for

sustainable land and coastal ecosystem

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ReefBase (http://www.reefbase.org) 18˚C 18˚C in winter

Global distribution of coral reefs

Japan

Coral reefs are an essential component for tropical/subtropical coasts

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Importance of coral reefs

Biodiversity Fisheries Tourism Natural breakwater Island and beach maintenance Estimated value for the ecosystem service $375,000,000,000/year =$6,075/ha/year (Wilkinson, 2002)

Photo: H. Kan Photo: H. Kayanne

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Recent decline of coral reefs

Red: High risk Yellow: Medium risk Blue: Low risk “Reefs at Risk” (http://www.reefbase.org) 1980 2000 year 1990 50% Coral cover in the Caribbean region Sea surface temperature rise Ocean acidification Terrestrial input (sediment/nutrient discharge) Overuse Combined effect of global and regional stresses Gardner et al. (2003)

High risk is suggested for fringing reefs close to land

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Global-scale factors

  • Temperature warming
  • Ocean acidification
  • Sea-level rise

Local-scale factor

  • Land-based

pollution Biological factors

  • Algal overgrowth
  • Acanthaster planci outbreak
  • Overfishing

CO2 emission Socioeconomic Population increase Land use change Precipitation Climate change Coral decline

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Local 60% at risk Local + global 75% at risk Source: Reefs at Risk revisited

Multiple stressors on coral reefs

Observation methods: Remote sensing

  • Satellite data
  • Aerial photographs
  • Surveillance camera
  • Boat-based video

In situ species distribution data

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Outline

  • Coral reefs at risk
  • Contribution of remote

sensing observations

  • Climate change and

land-based pollution

  • Framework for

sustainable land and coastal ecosystem

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Genetic diversity Monitoring Forest Presi dent Agriculture Inland water Marine Remote Sensing Evaluation/ Projection Interface WGs Steering Committee AP-BON GEO-BON

J-BON

JAMSTEC JAXA JaLTER/ILTE R JBIF/GBIF Networking

Japanese Biodiversity Observation Network (J-BON)

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Landsat ETM+: Spatial resolution = 30 m, Accuracy = 64 % IKONOS: Spatial resolution = 4 m, Accuracy = 81 % Coral Seagrass Bare substrate (pavement) Bare substrate (submerged sand) Bare substrate (exposed sand) Land Ocean

Original image Classified image

500 m N Shiraho 5 km N

Satellite remote sensing of coral reefs

Yamano (2013) In: Coral Reef Remote Sensing

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1945: Aerial photo 2010: Satellite data (ALOS AVNIR2)

Satellite/airborne remote sensing of lands

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Satellite remote sensing of sediment discharge

Satellite data (Terra MODIS)

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2,000,000 pixels Data transfer by cellular phone network

Surveillance camera

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2,000,000 pixels Stereo views allows construction of geocoded 3D images

Boat-based video

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Outline

  • Coral reefs at risk
  • Contribution of remote

sensing observations

  • Climate change and

land-based pollution

  • Framework for

sustainable land and coastal ecosystem

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SST warming in the last 100 yrs around Japan

JMA

Sea surface temperatures (SSTs) are rising

IPCC AR4

0.5˚C/100 years

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SST in 1998 and coral bleaching

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Live coral cover Green：50-100 % Yellow：5-50 % Pink：<5 % 2003 (before bleaching) 2008 (after bleaching) Japan 5 km

2007 coral bleaching in Japan

Source: Ministry of the Environment

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Range expansion of corals around Japanese temperate area due to SST warming Maximum speed: 14km/yr

Yamano et al. (2011) Geophysical Research Letters

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SST warming allows poleward range expansion (north) and bleaching (south) of corals in Japan

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Global-scale factors

  • Temperature warming
  • Ocean acidification
  • Sea-level rise

Local-scale factor

  • Land-based

pollution Biological factors

  • Algal overgrowth
  • Acanthaster planci outbreak
  • Overfishing

CO2 emission Socioeconomic Population increase Land use change Precipitation Climate change Coral decline

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Local 60% at risk Local + global 75% at risk Source: Reefs at Risk revisited

Multiple stressors on coral reefs

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Increased sediment discharge due to land development 1962 2010

Paddy field Sugarcane 300 m

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Increased sediment discharge destroys river and coastal ecosystems

Photos provided by Okinawa Prefectural Institute of Health and Environment

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A coral reef not affected by sediment discharge （Sesoko Is., Okinawa） Coral reefs affected by sediment discharge （Okinawa Is.） Bleaching

van Woesik et al. (2011) Hongo and Yamano (2013) PLoS ONE

Recovery

Reducing sediment discharge may help coral recovery after bleaching

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Outline

  • Coral reefs at risk
  • Contribution of remote

sensing observations

  • Climate change and

land-based pollution

  • Framework for

sustainable land and coastal ecosystem

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Kume Island, Okinawa, Japan

Okinawa

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Kume Island, Japan

Land development (paddy field to sugar cane) and poor land management resulted in significant sediment discharge

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Red-soil content

<10kg/m3 10-30kg/m3 30-100kg/m3 >200kg/m3

Gima R. Suhara R. <5% coral cover Absence of Semisulcospira libertina and Luciola owadai Sediment discharge ~10% coral cover Presence of Semisulcospira libertina and Luciola owadai Land use, Crop growth Ecology Civil engineering

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i i i i i B

L d qI A Q ⋅ ⋅ ⋅ ⋅ ⋅ =∑

3 5

) (

*

γ π ε

降雨 地表流による 浸食 + 流送 流域斜面

d qI A qB

3 5

) ( ⋅ =

Measures to prevent sediment discharge qB：Sediment discharge I：Slope q：Surface flow d：Sediment size

Modeling sediment discharge

Application to crop field

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Identifying sediment source areas to set up countermeasures

Setting “green belts”

Interview/discussion Cost estimation Searching incentives Socioeconomics

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Framework for sustainable management of land and coastal ecosystems

Ecology Civil engineering Socioeconomics Modeling/observing sediment discharge

  • >Identification of lands

that have large discharge Cost estimation People’s incentive

  • >Sustainable measures

Biodiversity observation

  • >Setting conservation

goal Presenting options for reducing sediment discharge Adaptive management Identifying allowable limit of sediment discharge

Setting “green belts” Planning land use

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Summary

  • Coral reefs are subject to multiple stressors

across local (e.g., sediment discharge) to global (e.g., SST warming, ocean acidification) scales

  • Increased sediment discharge not only causes

coral decline but also reduces coral resilience to bleaching---Reducing sediment discharge may help coral recovery after bleaching

  • A framework to couple ecology-civil engineering-

socioeconomics is needed for sustainable management of land and coastal ecosystems