Molokaʻi

satellite image of the island of Moloka'i

Landsat satellite image from NASA

The Friendly Isle of Molokaʻi encompasses 673 sq km (260 sq mi), making it the fifth largest of the main eight Hawaiian Islands. The north and west coasts of the island have little coral growth due to impact from northwest swell. However, protected from the southern swell waves by the islands of Lānaʻi and Kaho‘olowe, the south shore of Molokaʻi boasts the longest continuous fringing reef of the U.S. and its holdings. Studies by scientists at the University of Hawaiʻi Coral Reef Assessment and Monitoring Program have shown that Molokaʻi has sites with the best coral coverage in the main eight Hawaiian Islands. Yet impacts from sediment run-off into the nearshore ecosystem have also caused areas of degredation of the south Molokaʻi reef.

The USGS has used the south Molokaʻi reef as its test ground for developing benthic habitat mapping methods including remote sensing and underwater videography. Investigations into sedimentation along the south coast involve deployment of instrument packages to measure oceanographic conditions such as turbidity, currents, waves, temperature, and salinity. Click on the links below to learn about some of these efforts.

Recent work on Molokaʻi includes looking into the coral record to find clues to past sedimentation events. You can read a brief article about some of this project here.

View click-and-zoom panorama of Kaunakakai Wharf, Molokaʻi (1.4 Mb)

View click-and-zoom panorama of Kawela ahupuaʻa, Molokaʻi (1.9 Mb)

View movie of coral reef near Kamalō (11.3 Mb)

View movie of coral reef offshore from Kapuāiwa (King Kamehameha V) coconut grove (12.3 Mb)

View movie of coral reef near Pālāʻau (11.8 Mb)

Examples of coral reef mapping techniques, on Molokaʻi:
   Aerial Photomosaics
   Hyperspectral Mapping
   Lidar Mapping
   Underwater Videography

USGS Open File Report 2005-1070
Molokaʻi Benthic Habitat Mapping

USGS Open File Report 02-158
Molokaʻi Fieldtrip Guidebook: selected aspects of the geology, geography, and coral reefs of Molokaʻi

Quantifying suspended sediment with multi-spectral aerial imaging

Underwater video groundtruthing of SHOALS data for benthic habitat mapping

U.S. Geological Survey Open File Report 2005-1244
Summary and preliminary interpretations of USGS cruise A-2-02-HW: Underwater video surveys collected off of Oʻahu, Molokaʻi, and Maui, Hawaiʻi, June-July 2002

U.S. Geological Survey Scientific Investigations Report 2007-5101
The coral reef of south Molokaʻi, Hawaiʻi; Portrait of a sediment-threatened reef

U.S. Geological Survey Open File Report 2010-1155
Terrigenous sediment provenance from geochemical tracers, south Molokaʻi reef flat Hawaiʻi

U.S. Geological Survey Fact Sheet 2011-3049
From ridge to reef--Linking erosion and changing watersheds to impacts on the coral reef ecosystes of Hawaiʻi and the Pacific Ocean

Other selected works

Bothner, M.H., Reynolds, R.L., Casso, M.A., Storlazzi, C.D. and Field, M.E., 2006, Quantity, composition and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii: Marine Pollution Bulletin, v. 52(9), p. 1034-1047, doi:10.1016/j.marpolbul.2006.01.008.

Engels, M.S., Fletcher, C.H., Field, M.E., Storlazzi, C.D., Grossman, E.E., Rooney, J.J.B., Conger, C.L., and Glenn, C., 2004, Holocene reef accretion: Southwest Molokai, Hawaii, U.S.A.: Journal of Sedimentary Research, v. 74(2), p. 255-269, doi:10.1306/073003740255.

Engels, M.S., Fletcher, C.H., Field, M.E., Conger, C.L., and Bochicchio, C., 2008, Demise of reef-flat carbonate accumulation with late Holocene sea-level fall; evidence from Molokai Hawaii: Coral Reefs, v. 27, no. 4, p. 991-996, doi:10.1007/s00338-008-0410-7.

Ogston, A.S., and Field, M.E., 2010, Predictions of turbidity due to enhanced sediment resuspension resulting from sea-level rise on a fringing coral reef; evidence from Molokai, Hawaii: Journal of Coastal Research, v. 26, i. 6, p. 1027-1037, doi:10.2112/JCOASTRES-D-09-00064.1.

Ogston, A.S., Storlazzi, C.D., Field, M.E. and Presto, M.K., 2004, Currents and suspended sediment transport on a shallow reef flat; South-central Molokai, Hawaii: Coral Reefs, v. 23, no. 4, p. 559-569, doi:10.1007/s00338-004-0415-9.

Piniak, G.A., and Storlazzi, C.D., 2008, Diurnal variability in turbidity and coral fluorescence on a fringing reef flat; Southern Molokai, Hawaii: Estuarine, Coastal and Shelf Science, v. 77, i.1, p. 56-64, doi:10.1016/j.ecss.2007.08.023.

Presto, M.K., Ogston, A.O., Storlazzi, C.D., Field, M.E., 2006, Temporal and spatial variability in the flow and dispersal of suspended-sediment on a fringing reef flat, Molokai, Hawaii: Estuarine, Coastal and Shelf Science, v. 67, i. 1-2, p. 67-81, doi:10.1016/j.ecss.2005.10.015.

Prouty, N.G., Field, M.E., Stock, J.D., Jupiter, S.D., and McCulloch, M.T., 2010, Coral Ba/Ca records of sediment input to the fringing reef of the south shore of Molokaʻi, Hawaiʻi, over the last several decades: Marine Pollution Bulletin, v. 60(10), p. 1822-1835, doi:10.1016/j.marpolbul.2010.05.024.

Prouty, N.G., Field, M.E., Jupiter, S.D., and McCulloch, M.T., 2009, Coral proxy record for decadal-scale reduction in base flow from Molokaʻi, Hawaiʻi: Geochemistry, Geophysics, Geosystems, v. 10, Q12018, doi:10.1029/2009GC002714

Storlazzi, C.D., Elias, E., Field, M.E., and Presto, M.K., 2011, Numerical modeling of the impact of sea-level rise on fringing coral reef hydrodynamics and sediment transport: Coral Reefs, v. 30, Supplement 1, p. 83-96, doi:10.1007/s00338-011-0723-9.

Storlazzi, C.D., Field, M.E., Rogers, K., Jokiel, P.L., Brown, E., and Dykes, J.D., 2005, A model for wave control on coral breakage and species distribution in the Hawaiian Islands: Coral Reefs, v. 24, no. 1, p. 43-55, doi:10.1007/s00338-004-0430-x.

Storlazzi, C.D., Ogston, A.S., Bothner, M.H., Field, M.E., and Presto M.K., 2004, Wave- and tidally-driven flow and sediment flux across a fringing coral reef: Southern Molokai, Hawaii: Continental Shelf Research, v. 24(12), p. 1397-1419, doi:10.1016/j.csr.2004.02.010.

Storlazzi, C.D., Logan, J.B., and Field, M.E., 2003, Quantitative morphology of a fringing reef tract from high-resolution laser bathymetry: Southern Molokai, Hawaii: Geological Society of America Bulletin, v. 115, no. 11, p. 1344-1355, doi:10.1130/B25200.1.

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