Coral Reef Resilience in Guam and American Samoa

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Projects : Coral Reef Resilience in Guam and American Samoa

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Overview

Understanding the spatial patterns in environmental conditions and coral reef resilience is central to climate-informed reef management. Numerous environmental drivers contribute to overall reef health and survival.

The objective of this project is to identify areas of reefs with the most favorable environmental conditions for coral growth and survival under multiple climate scenarios in Guam and American Samoa. This information could be combined with an understanding of where coral are already demonstrating resilience to inform where resilience-based management strategies could be suitable now and in the future. This project developed GIS layers to show the spatial patterns in environmental favorability and resilient coral reefs. These layers included:

Favorability of managed environmental conditions
Favorability of non-managed environmental conditions
Overall environmental favorability
Coral monitoring sectors (NOAA National Coral Reef Monitoring Program)

These data support reef managers in determining where to implement different types of management strategies. Additionally, these data are useful for determining where resilient reefs intersect with environmental conditions that further promote resilience and where reefs are resilient despite a sub-optimal environment. Inclusion of multiple climate scenarios assists reef managers in identifying how the spatial distribution of beneficial environmental conditions could change over time.

Figure 1. Fish swim around coral in Tutuila, American Samoa. Photo Credit: NOAA.

Credits

When using these data, please cite the folllowing USGS ScienceBase data repository:

Suggested data citation: Moritsch, M.M. 2021. Favorability of environmental conditions for coral reefs in Guam and American Samoa under multiple climate scenarios. U.S. Geological Survey data release, https://doi.org/10.5066/P9N32V3M.

Contact

If you have questions or comments about the resources and information contained on these pages please contact Monica M. Moritsch (mmoritsch@usgs.gov), Research Ecologist, USGS Western Geographic Science Center.

Data

The data layers generated in this project provide the means to identify where environmental conditions are favorable for coral growth and survival, both now and through the end of the 21^st century. These layers support management aimed at promoting reef resilience and protecting coral reef ecosystems.

All data can be found in the map viewer, and are also available for download in various formats from the categories listed further below.

NOTE: This interactive mapping application is ill-suited for small screen sizes. Below is a screenshot only. Please visit again from a laptop or desktop computer to enable the application or make your browser window bigger.

Environmental Favorability

Managed Conditions

Figure 2. Left: Fish abound in National Park of American Samoa. Photo Credit: NPS. Right: Turbid waters due to sediment runoff after a storm in Guam. Photo Credit: Guam Forestry and Soil Resources Division, Department of Agriculture.

Managers have some ability to support healthy environmental conditions through strategic action at a local and regional scale, such as water quality. These layers synthesized spatial information for several managed conditions to create a relative score for how favorable a given location is for coral growth and survival.

Environmental conditions contributing to these layers included:

Chlorophyll-a concentrations (mg m^-3)
Fish and herbivore biomass (g m^-2)
Turbidity (Kd490) (m^-1)
Macroalgal cover (percent cover)
Ocean-based pollution (index-based; Guam only)

Covariation in these conditions was accounted for using principal component analysis (PCA) to form composite variables of conditions that have strong relationships with one another. The resulting principal components were averaged and scaled from 0 (worst) to 1 (best) to produce the score for Managed Conditions. These data are provided as rasters with a resolution of 1,150 m for Guam and 500 m for American Samoa.

Coral Favorability: Managed Conditions – American Samoa

id: as_usgs_tutma_coralscore_mgt

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Managed Conditions – Guam

id: gu_usgs_all_coralscore_mgt

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

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Non-Managed Conditions

Figure 3. Waves crash over a coral reef. Photo Credit: Curt Storlazzi, USGS.

Many aspects of the environment are outside the control of local or regional resource managers. These conditions may require concerted global action to affect change (e.g., water temperatures) or cannot be controlled at all (e.g., wave power). These layers synthesized spatial information for several non-managed conditions to create a relative score for how favorable a given location is for coral growth and survival.

Environmental conditions contributing to these layers included:

Marine calcite concentration (a proxy for ocean acidification; mmol m^-3)
Irradiance (Photosynthetically Available Radiation)
Thermal stress (Degree Heating Weeks or annual severe bleaching threshold)
Wave power (per meter of wave front)
Proximity to soils eroded by sea level rise (m)

Projections exist for how some of these conditions may change over the next century based on the trajectory of global greenhouse gas emissions. This project explored how the relative favorability of non-managed conditions could change between the Present climate scenario and the rest of the 21^st century. Future climate scenarios include: (1) an Intermediate Emissions scenario (Representative Concentration Pathway 4.5), in which global greenhouse gas emissions peak mid-century and then begin to fall; and (2) a Worst Case Emissions scenario (Representative Concentration Pathway 8.5), in which no action to reduce emissions is taken.

Covariation in these conditions was accounted for using principal component analysis (PCA) to form composite variables of conditions that have strong relationships with one another. For the Present climate scenario, sea level rise-related erosion or timing of annual severe bleaching were not included in the analysis. These two variables were added to analysis for the Intermediate and Worst Case Emissions scenarios. The resulting principal components were averaged and scaled from 0 (worst) to 1 (best) to produce the score for Non-managed Conditions in each of the three climate scenarios. These data are provided as rasters with a resolution of 1,150 m for Guam and 500 m for American Samoa.

Coral Favorability: Non-Managed Conditions: Present – American Samoa

id: as_usgs_tutma_coralscore_nonmgt

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Non-Managed Conditions: Present – Guam

id: gu_usgs_all_coralscore_nonmgt

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Non-Managed Conditions: Intermediate Emissions – American Samoa

id: as_usgs_tutma_coralscore_nonmgt_rcp45

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Non-Managed Conditions: Intermediate Emissions – Guam

id: gu_usgs_all_coralscore_nonmgt_rcp45

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Non-Managed Conditions: Worst Case Emissions – American Samoa

id: as_usgs_tutma_coralscore_nonmgt_rcp85

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Non-Managed Conditions: Worst Case Emissions – Guam

id: gu_usgs_all_coralscore_nonmgt_rcp85

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

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Overall Environmental Conditions

Figure 4. Progression of a coral bleaching event in American Samoa in 2014 to 2015. Photo Credit: NOAA.

The overall condition of the environment is a combination of managed and non-managed factors. While it is difficult for managers to prevent bleaching events, reefs experiencing fewer stressors may recover more quickly than reefs that were highly stressed at the time of bleaching. The scores for Managed and Non-managed conditions were averaged to produce an Overall Environmental Favorability score. These layers represent a relative score for how favorable overall conditions are for coral growth and survival from a scale of 0 (worst) to 1 (best) in each of the three climate scenarios.

These data are provided as rasters with a resolution of 1,150 m for Guam and 500 m for American Samoa.

Coral Favorability: Overall Environmental Conditions: Present – American Samoa

id: as_usgs_tutma_coralscore

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Overall Environmental Conditions: Present – Guam

id: gu_usgs_all_coralscore

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Overall Environmental Conditions: Intermediate Emissions – American Samoa

id: as_usgs_tutma_coralscore_rcp45

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Overall Environmental Conditions: Intermediate Emissions – Guam

id: gu_usgs_all_coralscore_rcp45

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Overall Environmental Conditions: Worst Case Emissions – American Samoa

id: as_usgs_tutma_coralscore_rcp85

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

Coral Favorability: Overall Environmental Conditions: Worst Case Emissions – Guam

id: gu_usgs_all_coralscore_rcp85

Data access: GeoTIFF • WMS-C • WMS • WCS • KML • metadata

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Coral Reef Resilience

Coral Monitoring Sectors

Figure 5. A snorkeler visits a coral reef in American Samoa. Photo Credit: Shaun Wolfe.

Records of coral cover from the recent past can inform management strategies for reef restoration and protection. When combined with data on where current or future environmental conditions are most favorable, we can learn where corals are thriving because of or in spite of a healthy marine environment. NOAA regularly surveys the health of coral reefs in the Pacific Islands as part of the National Coral Reef Monitoring Program (NCRMP). Divers record coral cover at a series of sites across different reef zones and depths. These surveys are then aggregated across spatial sectors, which divide the waters around the island into ecological units useful for management and monitoring.

Resilience can be defined as the ability of a system to resist change during a disturbance or as the ability to recover quickly after a disturbance-induced change. This project analyzed trends in coral cover from the NCRMP from 2009 to 2018 to identify sectors that demonstrated either of these criteria for resilience. Coral sectors that maintained stable coral cover at relatively high levels were considered highly resilient. Sectors that demonstrated relatively rapid increases in coral cover over time were considered moderately resilient, and sectors that lost coral cover were considered to have low resilience. This project examined how the spatial distribution of highly resilient sectors related to areas with high environmental favorability.

These layers represent geospatial polygons of the NRCMP coral sectors.

Coral Resilience By NOAA NCRMP Sector – American Samoa

id: as_noaa_tutma_coral_resilience

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

Coral Resilience By NOAA NCRMP Sector – Guam

id: gu_noaa_all_coral_resilience

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

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Other Overlays

Marine Protected Areas – American Samoa

id: as_comp_all_mpa

Marine Protected Areas (MPAs) of American Samoa, including National Parks, National Marine Sanctuaries, National Wildlife Refuges, ecological reserves, and Territorial Seashore Parks. Compiled from multiple sources, including the National Park Service (NPS), National Marine Sanctuaries (NMS), Fish and Wildlife Service (FWS), and the World Database of Protected Areas (WDPA). For use in planning purposes only, not for use in litigation.

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

Marine Protected Areas – Guam

id: gu_comp_all_mpa

Marine Protected Areas (MPAs) of Guam, including National Parks, National Marine Sanctuaries, National Wildlife Refuges, ecological reserves, and Territorial Seashore Parks. Compiled from multiple sources, including the National Park Service (NPS), National Marine Sanctuaries (NMS), Fish and Wildlife Service (FWS), World Database of Protected Areas (WDPA), Guam Bureau of Statistics and Plans (BSP), and the Guam Coastal Management Program (GCMP). For use in planning purposes only, not for use in litigation.

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

Watersheds, Major – Manuʻa, American Samoa

id: as_dw_manall_wshed_major

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

Watersheds, Minor – Tutuila, American Samoa

id: as_dw_tut_wshed_minor

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

Watersheds, Major – Southern Guam

id: gu_weri_sog_wshed_major

Data access: Shapefile • GeoJSON • WMS-C • WMS • WFS • KML • metadata

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Partners

This project was led by the United States Geological Survey (USGS), Western Geographic Science Center, Moffett Field, CA and supported by Ecologic Consulting, LLC. It was funded by the USGS Pacific Islands Climate Adaptation Science Center (PI-CASC) and supported in part by the Pacific Islands Regional Ocean Data Sharing Initiative, coordinated by PacIOOS with funding from the National Oceanic and Atmospheric Administration (NOAA) Award #NA16NOS0120024.

Data Sources

Variable	Place	Description	Units	Scenario	Source	Dates	Original Resolution
Managed Variables
Chlorophyll	GU	Chlorophyll-a annual mean	mg m^-3	All	NASA Ocean Biology DAAC (2020)	1997-2018	4.8 km
Chlorophyll	AS	Chlorophyll-a annual mean	mg m^-3	All	NOAA PIFSC et al. (2021a)	1998-2018	5.4 km
Herbivore biomass	GU, AS	Herbivore biomass from NCRMP surveys	g m^-2	All	Swanson et al. (2018)	2015-2017	Point
Fish biomass	GU, AS	Total reef fish biomass from NCRMP surveys (excluding sharks and rays)	g m^-2	All	Swanson et al. (2018)	2015-2017	Point
Turbidity (Kd490)	GU	Total organic and inorganic matter held in solution and suspension in the water column	m^-1	All	NASA Ocean Biology DAAC (2020)	2003-2020	4 km
Turbidity (Kd490)	AS	Total organic and inorganic matter held in solution and suspension in the water column	m^-1	All	NOAA PIFSC et al. (2021c)	1998-2018	0.5 km
Ocean-based pollution	GU	Pollution coming from commercial shipping and ports, based on shipping volume and modeled plumes within 100 km from ports	Index-based	All	Halpern et al. (2015)	2003-2011	0.934 km
Macroalgal cover	GU, AS	Average percent cover of marcoalgae by sector in NCRMP surveys	Percent (%)	All	Swanson et al. (2018)	2009-2018	Polygon
Non-Managed Variables
Calcite	GU, AS	Mean monthly calcite concentration	mmol m^-3	All	Assis et al. (2018)	2000-2014	7 km
Irradiance	GU	Photosynthetically available radiation (PAR)	E m^-2 ^d-1	All	NASA Ocean Biology DAAC (2020)	2002-2019	4.6 km
Irradiance	AS	Photosynthetically available radiation (PAR)	E m^-2 ^d-1	All	NOAA PIFSC et al. (2021b)	2013-2018	0.5 km
Cumulative thermal stress	GU, AS	Average monthly maximum Degree Heating Weeks (°C above the maximum monthly mean per week, cumulative over the prior 12 weeks)	Degree Heating Weeks (°C)	Present	NOAA Coral Reef Watch (2020)	2013-2020	5 km
Wave energy	GU	Mean daily wave energy along shoreline based on wind direction, wind speed, and fetch length, created with University of Guam Marine Lab Wave Energy ArcGIS Extension	J m^-3	All	Jenness and Houk (2014)	2014	0.33 km
Wave energy	AS	Long-term mean cumulative annual wave power based on NOAA WaveWatch III global wave model data and coastline analysis of wave exposure	MW hr^-1 ^m-1	All	NOAA PIFSC et al. (2021d)	2002-2012	0.5 km
Future thermal stress	GU, AS	Year of annual severe bleaching using RCP 4.5 and RCP 8.5 sea surface temperature projections	Year	RCP 4.5, RCP 8.5	van Hooidonk et al. (2016); UNEP (2017)	2015	4.8 km
Sea level rise	GU, AS	2100 projections for sea level rise heights of 2 ft (~RCP 4.5 = 0.57 m) and 3 ft (~RCP 8.5 = 0.76 m)	m	RCP 4.5, RCP 8.5	NOAA Digital Coast (2017)	2100	3 m
Soil type	GU, AS	Erosion-prone soil geomorphic types	Polygon	RCP 4.5, RCP 8.5	Soil Survey Staff (2020)	2020	10 m
Coral Sectors
NOAA NCRMP Sectors	GU, AS	Units used for aggregating coral survey data from the National Coral Reef Monitoring Program	Polygon	All	NOAA (2018); Oliver et al. (2020)

GU = Guam, AS = American Samoa.

References

Assis J., L. Tyberghein, S. Bosch, H. Verbruggen, E.A. Serrão, O. De Clerck, and D. Tittensor (2018) Bio‐ORACLE v2.0: Extending marine data layers for bioclimatic modelling. Global Ecology and Biogeography 27: 277–284. https://doi.org/10.1111/geb.12693.
Halpern B.S., M. Frazier, J. Potapenko, K.S. Casey, K. Koenig, C. Longo, J.S. Lowndes, R.C. Rockwood, E.R. Selig, K.A. Selkoe, and S. Walbridge (2015) Spatial and temporal changes in cumulative human impacts on the world’s ocean. Nature Communications 6: 7615. https://doi.org/10.1038/ncomms8615.
Jenness, J.S. and P. Houk (2014) UOGML Wave Energy ArcGIS Extension. University of Guam Marine Lab.
NASA Ocean Biology DAAC (2020) MODIS Ocean Color Web Products. Ocean Biology DAAC, Greenbelt, Maryland, USA. Accessed January 07, 2021. Kd490, chlorophyll, and irradiance products; time period: 1997 to 2020. https://oceandata.sci.gsfc.nasa.gov/opendap/.
NOAA Coral Reef Watch (2020) Updated daily. NOAA Coral Reef Watch Version 3.1 Daily Global 5km Satellite Coral Bleaching Degree Heating Week Product, 1985-2020. College Park, Maryland, USA: NOAA Coral Reef Watch. Data set accessed 2021-02-01 at ftp://ftp.star.nesdis.noaa.gov/pub/sod/mecb/crw/data/5km/v3.1/nc/v1.0/daily/dhw/.
NOAA Digital Coast (2017) Digital Coast Sea Level Rise Viewer. https://coast.noaa.gov/slr/.
NOAA (2018) U.S. Coral Reef Monitoring Data Summary 2018. NOAA Coral Reef Conservation Program. NOAA Technical Memorandum CRCP 31: 224 pp. https://doi.org/10.25923/g0v0-nm61.
NOAA Pacific Islands Fisheries Science Center (PIFSC), NOAA Coral Reef Conservation Program (CRCP), and European Space Agency (ESA) Climate Change Initiative (CCI) (2021a) Chlorophyll-a Long-term Mean, 1998-2018 – American Samoa. Distributed by the Pacific Islands Ocean Observing System (PacIOOS). http://pacioos.org/metadata/as_noaa_all_chlor_avg.html.
NOAA Pacific Islands Fisheries Science Center (PIFSC), NOAA Coral Reef Conservation Program (CRCP), and NASA Ocean Biology Processing Group (OBPG) (2021b) Photosynthetically Active Radiation (PAR) Long-term Mean, 2003-2018 – American Samoa. Distributed by the Pacific Islands Ocean Observing System (PacIOOS). http://pacioos.org/metadata/as_noaa_all_par_avg.html.
NOAA Pacific Islands Fisheries Science Center (PIFSC), NOAA Coral Reef Conservation Program (CRCP), and European Space Agency (ESA) Climate Change Initiative (CCI) (2021c) Turbidity (Kd490) Long-term Mean, 1998-2018 – American Samoa. Distributed by the Pacific Islands Ocean Observing System (PacIOOS). http://pacioos.org/metadata/as_noaa_all_turb_avg.html.
NOAA Pacific Islands Fisheries Science Center (PIFSC), NOAA Coral Reef Conservation Program (CRCP), and NOAA National Centers for Environmental Prediction (NCEP) (2021d) Wave Power Long-term Mean, 2002-2012 – American Samoa. Distributed by the Pacific Islands Ocean Observing System (PacIOOS). http://pacioos.org/metadata/as_noaa_all_wave_avg.html.
Oliver T.A., H. Barkley, C. Couch, T. Kindinger, and I. Williams (2020) Downscaling ecological trends from the spatially randomized datasets of the National Coral Reef Monitoring Program. NOAA Technical Memorandum NMFS-PIFSC-106: 59. https://doi.org/10.25923/2fef-8r42.
Swanson D.W., H. Bailey, B. Schumacher, M. Ferguson, and B. Vargas-Ángel (2018) Ecosystem Sciences Division standard operating procedures: Data collection for rapid ecological assessment benthic surveys. NOAA Technical Memorandum NMFS-PIFSC-71: 63. https://doi.org/10.25923/39jh-8993.
United Nations Environment Programme (UNEP) (2017) Coral Bleaching Futures: Downscaled projections of bleaching conditions for the world’s coral reefs, implications of climate policy and management responses. 71 pp. https://wedocs.unep.org/20.500.11822/22048.
van Hooidonk R., J. Maynard, J. Tamelander, J. Gove, G. Ahmadia, L. Raymundo, G. Williams, S.F. Heron, and S. Planes (2016) Local-scale projections of coral reef futures and implications of the Paris Agreement. Scientific Reports 6: 39666. https://doi.org/10.1038/srep39666.

Projects : Coral Reef Resilience in Guam and American Samoa

Overview

Credits

Contact

See Also

Data

Environmental Favorability

Managed Conditions

Coral Favorability: Managed Conditions – American Samoa

Coral Favorability: Managed Conditions – Guam

Non-Managed Conditions

Coral Favorability: Non-Managed Conditions: Present – American Samoa

Coral Favorability: Non-Managed Conditions: Present – Guam

Coral Favorability: Non-Managed Conditions: Intermediate Emissions – American Samoa

Coral Favorability: Non-Managed Conditions: Intermediate Emissions – Guam

Coral Favorability: Non-Managed Conditions: Worst Case Emissions – American Samoa

Coral Favorability: Non-Managed Conditions: Worst Case Emissions – Guam

Overall Environmental Conditions

Coral Favorability: Overall Environmental Conditions: Present – American Samoa

Coral Favorability: Overall Environmental Conditions: Present – Guam

Coral Favorability: Overall Environmental Conditions: Intermediate Emissions – American Samoa

Coral Favorability: Overall Environmental Conditions: Intermediate Emissions – Guam

Coral Favorability: Overall Environmental Conditions: Worst Case Emissions – American Samoa

Coral Favorability: Overall Environmental Conditions: Worst Case Emissions – Guam

Coral Reef Resilience

Coral Monitoring Sectors

Coral Resilience By NOAA NCRMP Sector – American Samoa

Coral Resilience By NOAA NCRMP Sector – Guam

Other Overlays

Other Overlays

Marine Protected Areas – American Samoa

Marine Protected Areas – Guam

Watersheds, Major – Manuʻa, American Samoa

Watersheds, Minor – Tutuila, American Samoa

Watersheds, Major – Southern Guam

Partners

Data Sources

References