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Evaluation of Benthic Habitat Change within the National Historic Sites of Hawaiʻi’s Kona Coast

Open-File Report 2026-1061
Coastal and Marine Hazards and Resources Program
Prepared in cooperation with the National Park Service
By: , , , , , , , and 
https://doi.org/10.3133/ofr20261061

Links

Acknowledgments

Funded by the National Park Service, Pacific West Regional Office through Interagency Agreement P20PG00232 and the U.S. Geological Survey’s Coastal and Marine Hazards and Resources Program. Selena Johnson (U.S. Geological Survey) and Peter Dartnell (U.S. Geological Survey) contributed numerous excellent suggestions and a timely review of our work.

Executive Summary

Coral bleaching events have become increasingly common across the Hawaiian Archipelago since 1996 because of more frequent and intense marine heatwaves. The most significant bleaching event to date occurred from 2014 to 2015, which resulted in catastrophic state-wide coral loss. Bleaching events with less severe effects also occurred in 1996 and 2019. To understand the long-term effects of repeated bleaching events, along with other anthropogenic factors such as water quality, storms, sewage runoff, and coastal development, on coral reefs on the Kona Coast of the Island of Hawaiʻi, the U.S. Geological Survey, in collaboration with the National Park Service, collected underwater imagery in the early 2000s (baseline survey) and again in 2022 (resurvey). These images were captured within and adjacent to the National Historic Parks (NHP) and National Historic Sites (NHS) of Kaloko-Honokōhau NHP (KAHO), Puʻuhonua o Hōnaunau NHP (PUHO), and Puʻukohola Heiau NHS (PUHE). Imagery was classified for live coral cover and dominant type (four coral types, rubble, macroalgae, and two bottom substrate types). Change of percent live coral cover was determined for all sites. Change of coral and non-coral dominant types were calculated by aggregating classifications for each park into coral and non-coral. Net coral cover decreased between the baseline and resurvey period across all three parks, though PUHE exhibited the greatest loss of live coral cover. Across all three parks, the occurrence of lower coral cover classes (0–20 percent) increased and higher coral cover classes (greater than 50 percent) decreased. Furthermore, the total occurrence of non-coral dominant type classifications (rubble, macroalgae, sand, and volcanic pavement) increased by approximately 25 percent across all three parks, with PUHE experiencing a nearly 90-percent increase in the occurrence of non-coral types. There was little to no effect of water depth on change of live coral cover, indicating that marine heatwave driven bleaching events and additional anthropogenic influences affected the entire reef across all water depths from the lower fore reef to the reef flat.

Because coral loss was more severe at PUHE and PUHO than KAHO, creating a monitoring framework that utilizes periodic underwater camera surveys and fixed diver transects by the National Park Service would contextualize the periodic spatial surveys to the fixed transects that have greater temporal resolution. Similarly, increased frequency of spatial surveys would allow for the National Park Service to continue monitoring changes to critical nearshore habitats and marine resources relevant to National Park jurisdiction.

Introduction

Large-scale changes are happening to coral reef ecosystems around the world. Bleaching events occur as a result of prolonged increases in sea surface temperature, more commonly known as marine heatwaves (Hughes and others, 2017; Lough and others, 2018). Coral reefs typically exist at their upper thermal limits making them vulnerable to pollution, overharvesting, and marine heatwaves (Donovan and others, 2021). As a result, the resistance to bleaching events and subsequent recovery of coral reefs is dependent on other local anthropogenic stressors such as poor water quality, more frequent storms, and coastal development (Donovan and others, 2021; Baum and others, 2023; Gove and others, 2023). Investigating changes to nearshore coral reef habitat is critical to understanding physical and biological processes that influence live coral patterns across space, time, and biological scales. This is especially relevant in the context of more frequent and intense marine heatwaves that will be highly influential in shaping these systems (Mellin and others, 2024).

Coral bleaching events have become increasingly common across the Hawaiian Islands since 1996 (Rodgers and others, 2015). The most significant bleaching event in 2015 (Eakin and others, 2019; Skirving and others, 2019) resulted in catastrophic coral loss state-wide. Bleaching events with less severe effects also occurred in 1998 and 2019 (McCarthy and others, 2024). These repeated events have led marine resource managers to want more information on benthic habitat status and resources.

The National Park Service (NPS) Pacific Island Inventory and Monitoring (I&M) network tracks coral trends at four parks in the Pacific Ocean on fixed diver transects, including at Kaloko-Honokōhau National Historic Park (KAHO) (NHP) on the Kona Coast, which is on the west coast of the Island of Hawaiʻi. The U.S. Geological Survey (USGS) worked with the NPS in the early 2000s (Cochran and others, 2007a, 2007b; Gibbs and others, 2007) to collect geolocated seafloor imagery seafloor imagery to map the seafloor geomorphology and benthic habitats within or adjacent to the national parks on the Kona Coast. The results of this work (Gibbs and others, 2007) provided NPS resource managers with the necessary information to establish permanent monitoring sites in KAHO in 2007, which have increased the understanding of the diversity and spatial patterns of marine benthic habitats in this region.

Several subtidal monitoring programs show that coral cover is in decline along the Kona Coast. I&M surveys at KAHO found a 77-percent loss in coral cover across the NHP during the 2014–15 bleaching event with little to no recovery of nearly all coral species (with the exception of Porites compressa) through 2019 (McCutcheon and McKenna, 2021). Although information regarding benthic habitat change and the consequences of bleaching events at Puʻukoholā Heiau NHS (PUHE) and Puʻuhonua o Hōnaunau NHP (PUHO) is temporally and spatially limited, it is likely that the other Kona Coast National Parks (PUHO and PUHE) were similarly acutely affected by the 2014–15 bleaching event. The National Coral Reef Monitoring Program (reports every 3 years from 2013 to present) reported similar declines in coral cover between 2013 and 2016 to the I&M findings for the entire Kona coastline (National Oceanic and Atmospheric Administration Pacific Islands Fisheries Science Center, 2018). Prior to the 2014–15 bleaching event, the Hawaiʻi Coral Reef Assessment and Monitoring Program (CRAMP; annual reports from between 1999 and 2012) reported significant declines in coral cover at PUHE for shallow and deep sites (Rodgers and others, 2015).

In 2022, the USGS returned to the Kona coastline with the primary objective to acquire and analyze new underwater imagery to quantify benthic habitat changes across nearly 20 years. In this report, we detail, with high spatial coverage, the changes in the distribution of live coral cover and dominant habitat type observed in 2022 relative to the early 2000s.

Study Sites

There are three National Parks situated along the Kona Coast (fig. 1, table 1), including the terrestrial and submerged lands of KAHO and the terrestrial lands of PUHO and PUHE. Zonation of corals along the Kona Coast is divided into four zones across a steep nearshore slope with incremental depth categories defining those zones: 1) boulder zone: 2.5–8 meters (m), 2) bench zone: 6–14 m, 3) slope zone: 14–30 m, and 4) rubble zone: 30–50 m (Dollar, 1975). Each zone is dominated by a particular species of coral and is in different phases of succession. The boulder zone has bottom cover consisting of basaltic boulders with Pocillopora meandrina dominating coral cover. The bench zone is characterized by sloping basalt with Porites lobata growing in lobed and encrusting colonies. The slope zone is covered by Porites compressa, a highly competitive coral species. Storm waves tend to be most destructive in this zone. Some specialized coral species grow on rubble fragments in the rubble zone, but the lack of solid substrate limit coral growth. This zonation pattern along the Kona Coast is inconsistent with more common coral zonation pattern where there is a reef flat, reef crest, and a forereef.

The Kona Coast is considered a low wave-energy coast but can experience wave events in four primary wave patterns including 1) North Pacific swell, 2) Northeast trade wind waves, 3) Kona storm waves, and 4) Southern swell (Gibbs and others, 2007). The primary wave energies that influence the Kona Coast are from the westerly North Pacific swell, Southern swell, and Kona storm waves. Kona storm waves are erratic and infrequent, and the largest waves are from the southwest in the wintertime. The Kona Coast is protected from the effects of the Northeast trade winds by its location on the west coast of the island. It is also partially protected by the other Hawaiian Islands from all but the most westerly of the North Pacific swell.

The Kona Coast has less vertical accretion of carbonate material and reef growth than the rest of the Hawaiian Islands, likely due to a combination of the geologically young age of the surface where corals grow, combined with episodic destruction of coral colonies by storms and transport of carbonate material downslope. Sediment delivery is low along the Kona Coast because of the relatively younger geologic age of the adjacent volcanoes, poor soil development, and low annual rainfall (Gibbs and others, 2007). However, land-sea effects exist on the Kona Coast. Reefs with increased herbivorous fish and fewer land-based influences experienced lower coral mortality and positive recovery after disturbances such as marine heatwaves (Gove and others, 2023).

Alttext 1: The Kona Coast is on the west coast of the Island of Hawaiʻi. Puʻukoholā Heiau National Historic Site is the northernmost National Park, Puʻuhonua o Hōnaunau National Historic Park is the southernmost National Park, and Kaloko-Honokōhau National Historic Park is in between the first two.
Figure 1.

Index map of the Island of Hawaiʻi showing the location of the three National Parks along the Kona Coast. Shaded relief from U.S. Geological Survey digital data.

Table 1.    

Kona Coast attributes by park.

[Mean depth was determined from the depths of all image locations by park. °, degree; m, meter; PUHE, Puʻukoholā Heiau National Historic Site; KAHO, Kaloko-Honokōhau National Historic Park; PUHO, Puʻuhonua o Hōnaunau National Historic Park]
Park Mean park
longitude (°)		 Mean park latitude (°) Number of sites Mean site depth (m) Standard depth (m)
PUHE −155.8 20.0 29 11.0 5.9
KAHO −156.0 19.7 79 14.2 5.6
PUHO −155.9 19.4 24 15.1 4.8
Table 1.    Kona Coast attributes by park.

Puʻukoholā Heiau National Historic Site

The mapping efforts at PUHE focused on the benthic habitats of the waters offshore of PUHE (fig. 2) and excluded inside the Kawaihae Harbor. PUHE boundaries do not officially extend into the marine environment; however, effects downslope of any activity in PUHE are of concern to NPS management (personal communication). The area of Kawaihae Bay mapped by USGS extends from the north edge of Kawaihae Harbor approximately 3.5 kilometers south to the north edge of the Mauna Kea Golf Course and Beach Resort at Waikoloa, and from the shoreline to depths of approximately 40 m below local mean sea level (LMSL) where the fore reef drops off to the sandy shelf.

PUHE is located within the Kawaihae watershed, which contributes approximately 75 percent of the drainage in the northern portion of the study area. The Waikoloa and Waiulaula watersheds contribute approximately 25 percent of the drainage in the southern portion of the study area (Cochran and others, 2007b). Drainages from these watersheds are responsible for the increased input of sediment and urban runoff relative to other unpopulated areas of the island (Gove and others, 2023).

Alttext 2: The baseline and resurvey locations mostly overlap with each other, except for a few clusters in the southern section that are only resurvey locations. The survey points are scattered throughout Kawaihae Bay.
Figure 2.

Satellite map overlaid with Office for Coastal Management [OCM] Partners (2022) light detection and ranging (lidar) derived depths (in meters) and locations of baseline and resurvey imagery within the Puʻukoholā Heiau National Historic Site area. Base imagery from QGIS and its licensors.

Kaloko-Honokōhau National Historic Park

The only park on the Kona Coast that includes submerged lands and marine resources within its official boundaries is KAHO (fig. 3). KAHO was established in 1978 and is 1,160 acres in size, including 596 acres of marine area. As of 2025, only a portion of the park has been acquired by the NPS, with the remaining acreage either held privately or by the State of Hawaii Department of Land and Natural Resources Division of Aquatic Resources. KAHO is bordered on the south by the Honokōhau small-boat harbor and on the north by residential homes, a resort, and a golf course.

Although the zonation and community structure transitions described above are evident in KAHO, the seafloor morphology in the park is more complex than along much of the Kona Coast. The mid shelf cliffs, the semi-protected environments provided by the pinnacles off Kaloko Fishpond, and the embayed coastline close to the harbor support localized coral ecosystems that are unique to KAHO. The highest coral covers are generally off the harbor mouth and Kaloko Fishpond (Gibbs and others, 2007).

Alttext 3: The baseline and resurvey locations generally overlap with each other. Both kinds of location points follow the shoreline relatively closely.
Figure 3.

Satellite map overlaid with Office for Coastal Management [OCM] Partners (2022) light detection and ranging (lidar) derived depths (in meters) and locations of baseline and resurvey imagery within the Kaloko-Honokōhau National Historic Park area. Base imagery from QGIS and its licensors.

Puʻuhonua o Hōnaunau National Historic Park

The area mapped for PUHO extends from Mīana Point around Puʻuhonua Point to Kiʻilae Bay and past the southern park boundary (fig. 4). PUHO park boundaries do not officially extend into the marine environment; however, effects downslope of any activity in PUHO are of concern to management (personal communication). PUHO lies within the nearly 850-square-kilometer Kiʻilae watershed, which begins at the crest of Mauna Loa (Cochran and others, 2007a). The Kiʻilae Watercourse runs through the southern area of the park and empties into Kiʻilae Bay, but only during periods of extreme rainfall.

PUHO experiences the lowest land-based effects of all three of the parks (Gove and others, 2023), though groundwater flow may be of concern (Cochran and others, 2007a).

Alttext 4: The baseline and resurvey locations generally overlap with each other. Both kinds of location points follow the shoreline closely.
Figure 4.

Satellite map overlaid with light detection and ranging (lidar) derived depths (in meters) and locations of baseline and resurvey imagery within the Puʻuhonua o Hōnaunau National Historic Park area. Base imagery from QGIS and its licensors.

Methods

Reef Surveys

The Kona Coast baseline and resurvey mapping efforts were conducted from the Research Vessel Alyce C, a 32-foot vessel operated by Captain Joe Reich of Molokaʻi, Hawaii.

Baseline Imagery Collection

Baseline underwater imagery for this study were acquired during three field activities conducted by the USGS in 2003 and 2004 (activity IDs A-803-HW, A-204-HW, and A-604-HW), as part of a benthic habitat mapping project done in collaboration with NPS (Cochran and others, 2007a, 2007b; Gibbs and others, 2007).

Georeferenced underwater video was collected along single pass transects distributed throughout the offshore portions of each of the three Kona Coast parks using an underwater standard definition (640 by 480 resolution) video camera illuminated with a light-emitting diode ring designed by SeaViewer Underwater Video Systems. The camera was mounted on a small aluminum hand-deployed frame with a rear-mounted plastic fin. Time, date, location, and ship speed were overlaid on the video using the Sea-Trak global positioning system (GPS) method developed by SeaViewer Cameras, Incorporated. Geographic positioning was obtained using a wide area augmentation system (WAAS) enabled Garmin GPS76 receiver. The stated horizontal accuracy of the Garmin GSP76 is less than 3 m when receiving WAAS corrections.

Video imagery was acquired either by towing the camera along transects while underway (towed video) or by lowering the camera near the seafloor at a given location while drifting slowly (drop camera). Still images were acquired from the videos by sampling one frame every 10 seconds using an automated routine in the Media Mapper software package. The software recorded the GPS coordinates for the resulting images in the image Exif headers. The resulting set of georeferenced images was used for the baseline classifications. The original image set contains 10,229 640- by 480-pixel resolution images of the seafloor from varying heights above the seafloor and from various orientations ranging from oblique to downward looking driven by currents and drag on the camera while the boat was underway.

Positional accuracy and uncertainty varied for baseline imagery collection depending on the method used. The uncertainty of towed video was tens of meters, especially in deeper water where the angle of the cable to the camera was greater than in shallow water. Drop camera imagery had estimated uncertainties of around 5 m from the position of the GPS antenna. The final dataset used for this study was predominantly composed of imagery obtained from towed video (1,512 images from towed video, 112 images from drop camera imagery).

Resurvey Imagery Collection

Resurvey underwater imagery was acquired during a single field activity conducted by the USGS in 2022 (USGS activity ID 2022-615-FA) to investigate changes to the nearshore benthic habitat relative to baseline surveys conducted in 2003 and 2004. A total of 146 sites were resurveyed across all three parks. Sites for resurvey were selected based on where coral cover was observed in the baseline surveys. Imagery was acquired at each site while drifting by lowering the camera to 1 to 2 m above the seafloor at each site. The length of the site transects were similar in length to the baseline survey transect lengths because the goal was to “resurvey” the baseline sites.

The underwater image collection system was comprised of three major components. First, a pole-mounted, downward facing digital camera clamped to the side of the surface vessel which extended approximately 1 m below and above the water surface. A global navigation satellite system (GNSS) antenna was fixed at the top of the pole above the downward facing camera and remained approximately 1 m above the water surface to provide accurate image capture locations. Second, a tethered drop-camera system was lowered below the vessel and held roughly 1–3 m above the seabed (fig. 5). Third, a data acquisition and control system was located in the weather protected space of the surface vessel and operated in real-time to maintain image quality by adjusting camera collection rate, exposure, and gain settings of both cameras. The data acquisition system provided real-time position information via a local area network to a separate laptop located on the flying bridge to assist with navigation in the context of the previous survey and planned resurvey locations.

The surface camera was a 12.3-megapixel machine vision camera with a global shutter and a 2.8-centimeter (cm) sensor. The camera was made by Teledyne FLIR (model #BFS-PGE-122S6C-C). The lens used was a manual focus computer (model #V12280MPY) 12-millimeter (mm) focal length, which is approximately equivalent to a 30-mm focal length full frame (35-mm) camera lens. The lens was fixed at f-stop 5.6. The purpose of the surface camera was to collect larger area imagery coincident with the drop camera to facilitate estimating the extent of and continuity of features imaged at close range with the drop camera. The surface camera was designed with a slightly longer focal length lens and higher pixel count than the drop camera so the ground sample distance (amount of seabed imaged per pixel) would be more closely comparable to the drop camera.

The drop camera was a 5.0 MP machine vision camera with a global shutter and a 1.7-cm sensor. The camera was made by Teledyne FLIR (model #BFS-PGE-50S5C-C). The lens used was a manual focus Fujinon (model #HF6XA-5M) 6-mm focal length, which is approximately equivalent to a 23-mm focal length full frame (35-mm) camera lens. The lens was fixed at f-stop 5.6. The drop camera package was tethered to the surface with a sea-cable that provided unlimited power and enabled real-time camera control and image data transfer. In addition to the camera, the subsurface package included dual Ikelite DS160 light-emitting diode strobes modified to accept external power and were included to improve color rendering and image exposure with the limited natural light available at depth. A Tritech PA500 precision altimeter was mounted on the drop camera to measure and display the height above the seafloor to assist with our attempt to maintain a relatively consistent height above the reef.

The drop- and surface-camera housings were designed with identical 50-mm diameter dome windows made from 5-mm-thick optical quality BK7 glass. In both cases, the cameras were rigidly mounted longitudinally in alignment with the long axis of the housings and adjusted fore and aft so that the entrance pupil of the lens aligned with the dome window radius of curvature. This provided the maximum depth of focus and minimized distortion away from image center.

The surface acquisition system included a Trimble R7 GNSS, an electronics interface box that provided power and network communication to the drop camera, a hand reel which incorporated a slip ring for the drop camera tether, and a computer system on which two instances of custom acquisition software were run concurrently to control and acquire images from the two cameras and record the associated GNSS position and precise Coordinated Universal Time (UTC) time at the instant of image capture from either system. Image acquisition frequency was typically set on both cameras to record at a rate of one image every 2 seconds.

The GNSS data for the imagery were post-processed using nearby GNSS base stations from the National Park Service real-time GNSS network. The North American Datum of 1983 (NAD83) ellipsoid heights for the GNSS positions were transformed to orthometric heights referenced to LMSL using the National Geodetic Survey GEOID12B. Precise positions were derived for each image using the GNSS-synchronized image acquisition times and were written into the image Exif headers. Orthometric heights for the imagery from the boat-mounted camera were calculated using the 2.005-m fixed vertical offset between the GNSS antenna and the camera lens. Vertical positions were not recorded for the towed camera imagery; instead, the vertical measurements to the seabed from the camera-mounted altimeter were recorded in the image Exif tags.

Alttext 5: The drop-camera system is a large camera suspended in the water by a wire.
Figure 5.

U.S. Geological Survey photographs of the tethered drop-camera system. A, Camera system lowered below the vessel. B, Camera system held roughly 1–3 meters above the seabed.

Image Analysis

Sub-Selection of Underwater Imagery for Classification

Images from the baseline and resurvey datasets were subsampled to facilitate comparable classification of the images. For the baseline data, still frames from the underwater video were created by sampling one frame every 10 seconds using an automated routine in the Media Mapper software package. These baseline images were further subsampled by targeting selected sites where coral cover was previously observed (n=1,621; Cochran and others, 2007a, 2007b; Gibbs and others, 2007) but does not fully exclude other predominant benthic habitat types such as sand and volcanic pavement. For the resurvey data, to ensure a more consistent comparison with the baseline imagery, images from the surface camera were excluded from classifications and only the images from the resurvey drop camera system were used. The images were subsampled to select one image every 10 seconds as an initial step to reduce the large number of images from the same location. The resurvey images were further sub-sampled by only keeping images with GPS positions within a 5-m radius of a baseline image location. Finally, if multiple resurvey images fell within a 2-m grid space, only a single image was kept for classification (n=3,332).

Image Classification Platform

Percent live coral cover (referred to hence forth as “coral cover”) and dominant bottom type classifications of selected baseline and resurvey imagery were performed manually by a single specialist with a background in ecological studies. The open-source software, Label Studio version 1.4 (Tkachenko and others, 2020), was used to enable efficient classification of the baseline and resurvey images using a custom, two-variable classification scheme for live coral cover and dominant bottom type (described in more detail in the “Image Classification of Live Coral Cover” section). The software provided the functionality to sequentially display each image to the specialist and allowed for the use of keyboard hot keys to rapidly assign classification labels to each image. At the end of each classification session, a tabulated comma delimited text file was generated containing the image filenames, geographic coordinates, and classification labels, which were then imported to Python for data analysis.

Image Classification of Live Coral Cover

Coral cover is a commonly measured attribute of coral community composition and was the primary metric used to assess change in coral abundance at the Kona Coast parks. Coral cover was determined visually by assessing the live coral cover as a fraction of total coral (live and dead) cover in each image relative to reference diagrams of percent cover after Terry and Chilingar (1955). Cover estimates were made in multiples of 10 from 0 to 100 percent. A total of 4,282 baseline and resurvey images were visually classified for percent cover. A total of 783, 2,798, and 701 images were classified for PUHE, KAHO, and PUHO, respectively. The classified baseline and resurvey images and associated classifications are available in a USGS data repository (Logan and others, 2025).

The baseline and resurvey imagery differed in resolution, field of view, and camera orientations at each site. This unavoidably resulted in differing image footprints and scales between the surveys, meaning we were unable to ensure the same amount of reef area was covered and analyzed between sampling periods. To mitigate this, we averaged the coral cover by site before determining change in coral cover. We also relied on park-wide density distributions of coral to assess larger scale change.

Image Classification of Dominant Bottom Type

A total of eight coral and non-coral categories were used to classify the dominant bottom type of the imagery. Each image was only assigned one dominant bottom type class (fig. 6). Coral dominant bottom type categories were selected based on the most common coral species occurring along the Kona Coast and included Montipora capitata, Pocillopora meandrina, Porites compressa, and Porites lobata. We distinctly classified P. compressa (finger coral) and P. lobata (lobe coral), but because of morphological genus it is possible that corals classified as either may have similarities across the different Porites species.

Alttext 6: Underwater photographs of the different types of classified coral and non-coral dominant bottom types.
Figure 6.

Images of classified coral and non-coral dominant bottom types from resurvey imagery. A, Pocillapora meandrina. B, Porites compressa. C, Porites lobata. D, Macroalgae. E, Rubble. F, Sand. G, Volcanic pavement.

The non-coral dominant bottom type categories were macroalgae, coral rubble, sand, and volcanic pavement. The non-coral categories were selected based on 1) what common benthic habitat classes were previously classified at the three parks (for instance, sand and volcanic pavement; Cochran and others, 2007a, 2007b; Gibbs and others, 2007), and 2) the hypothesis that reef composition shifts from coral to non-coral cover after coral bleaching events. We hypothesized that macroalgae occurrence would increase between the two survey periods due to a coral-macroalgal phase shift that often occurs following bleaching events (Fukunaga and others, 2022). Furthermore, we hypothesized that coral rubble would increase in occurrence as bleaching events produce dead and bleached coral that can then break down and produce rubble.

A total of 2,047 images were assigned one of the 8 above dominant bottom type classifications and 2,235 images were assigned an “Unknown” dominant type classification (table 2).

Quantifying Change

Percent Live Coral Cover

Change in live coral cover for each park and site was determined by:

Δ C = C ¯ R −   C ¯ B C ¯ B   ×   100
(1)

where

Δ C is the percent change of live coral cover,

C ¯ R is the mean resurvey coral cover, and

C ¯ B is the mean baseline coral cover.

Sites that did not have at least two images classified for the baseline and resurvey were excluded from the coral change analysis (PUHE: 2 sites; KAHO: 6 sites; PUHO: 4 sites).

Dominant Bottom Type

Because of the uneven distribution of the number of images within each dominant bottom type category (table 2), all eight dominant types were aggregated by park into either coral or non-coral prior to calculating percent change of these two groups by:

Δ P C   = P C R   −   P C B P C B   ×   100
(2)
Δ P N   = P N R   −   P N B P N B   ×   100
(3)
P C = ∑ C o ∑ C o + N C
(4)
P N = ∑ N C ∑ C o + N C
(5)

where

Δ P C

is the percent change of aggregated coral,

Δ P N

is the percent change of non-coral dominant types,

P C

is the proportions of coral ( C o ) classifications to the total classifications calculated for both the baseline ( P C B and P N B ) and resurvey ( P C R and P N R ), and

P N

are the proportions of non-coral ( N C ) classifications to the total classifications calculated for both the baseline ( P C B and P N B ) and resurvey ( P C R and P N R ).

Unknown classifications were not included in the total number of classifications.

Percent change of individual dominant bottom types was also calculated, but M. capitata, macroalgae and volcanic pavement were excluded from the results because of low sample size (less than n=5) in either one or both survey periods (table 2).

Elevation Data

Elevation data were extracted for each baseline and resurvey image location from the U.S. Army Corp of Engineers National Coastal Mapping Program topobathy light detection and radar (lidar) data collected in 2013 for the Island of Hawaiʻi (Office for Coastal Management [OCM] Partners, 2022). The digital elevation model (DEM) data were derived from lidar data that were adjusted to LMSL with a spatial resolution of 1 m. Elevation data are relative to LMSL, and negative elevations were converted to positive depth values to examine patterns of coral cover and live coral cover change.

Water depth has been determined to be an important driver of recovery and predictor of ecosystem trajectory (Graham and others, 2015). To understand if baseline and resurvey coral cover differed in their water depth dependent patterns, we compared 10-m binned water depth density distributions of coral between the two survey (early 2000s baseline survey and 2022 resurvey) periods. We also evaluated the influence of water depth as a driver of coral change by applying least squares regression analysis to water depth and live coral cover change at each park.

Results

General Patterns of Coral Cover and Other Dominant Types

A decrease in coral cover was observed across all three Kona Coast parks. PUHE experienced the greatest decrease of 61.6 percent, followed by PUHO with a decrease of 52.2 percent, and KAHO with a decrease of 11.7 percent (fig. 7A; table 3). Site variability of coral cover was high in the baseline and resurvey (figs. 7B, 7C; appendix 1; figs. 1.1, 1.2, 1.3; tables 1.1, 1.2, 1.3), indicating high spatial variability of coral cover. Despite this high spatial variability, distinct patterns of coral cover loss were evident, especially at PUHE and PUHO.

Alttext 7: All three National Parks experienced coral loss, but the loss at Puʻukoholā Heiau National Historic Site and Puʻuhonua o Hōnaunau National Historic Park was greatest.
Figure 7.

Graphs depicting coral cover depending on the park. A, Bar plot of mean coral cover change for each Kona Coast park (Puʻukoholā Heiau National Historic Site [PUHE], Kaloko-Honokōhau National Historic Park [KAHO], and Puʻuhonua o Hōnaunau National Historic Park [PUHO]). B, Mean baseline coral cover, colored by park. C, Mean resurvey coral cover, colored by park. Vertical gray lines represent the standard deviation of the coral cover for each site. Colored horizontal dashed lines represent the mean baseline and resurvey coral cover, separated by park. Solid black horizontal line indicates 50 percent coral cover (B and C).

Table 2.    

A summary of the number of assigned classifications for each dominant bottom type category, unknown category, and the total number of known classifications for each survey type at each of the three Kona Coast parks.

[PC, proportion of all aggregated coral types; PN, proportion of non-coral types; PUHE, Puʻukoholā Heiau National Historic Site; BL, baseline; RS, resurvey; KAHO, Kaloko-Honokōhau National Historic Park; PUHO, Puʻuhonua o Hōnaunau National Historic Park]
Park Survey Montipora capitata Pocillopora meandrina Porites compressa Porites lobata Macroalgae Rubble Sand Volcanic pavement Unknown Total known P C 1 (percent) P N 1 (percent)
PUHE BL 0 0 64 40 0 0 11 0 17 115 90.4 9.5
PUHE RS 0 5 344 167 2 45 79 0 9 642 80.4 19.6
KAHO BL 1 12 2 43 1 25 50 1 777 135 43.0 57.0
KAHO RS 0 0 42 227 0 110 111 22 1,354 511 52.5 47.4
PUHO BL 0 15 63 103 3 2 11 0 16 197 91.2 8.1
PUHO RS 0 4 207 169 0 37 9 0 62 426 89.2 10.8
Table 2.    A summary of the number of assigned classifications for each dominant bottom type category, unknown category, and the total number of known classifications for each survey type at each of the three Kona Coast parks.
1

Proportion of all aggregated coral types ( P C ) and non-coral ( P N ) types relative to the total known samples assigned a dominant bottom type.

Table 3.    

Percent change of live coral cover, percent change of coral dominant types, percent change of non-coral dominant types, and percent change of dominant bottom types with greater than five samples by park.

[%, percent; Δ, change in; PUHE, Puʻukoholā Heiau National Historic Site; —, no data; KAHO, Kaloko-Honokōhau National Historic Park; PUHO, Puʻuhonua o Hōnaunau National Historic Park]
Park Change of live coral cover (%) Change of coral dominant types (%) Change of non-coral dominant types (%) Δ Pocillopora meandrina Δ Porites compressa Δ Porites lobata Δ Rubble Δ Sand
PUHE −61.6 −11.1 105.2 — −3.7 −25.2 7.0 28.6
KAHO −11.7 22.3 −16.8 −100.0 453.7 39.2 16.0 −41.5
PUHO −52.2 −2.9 32.9 −87.7 51.9 −24.1 755.5 −62.2
Table 3.    Percent change of live coral cover, percent change of coral dominant types, percent change of non-coral dominant types, and percent change of dominant bottom types with greater than five samples by park.

Table 4.    

Baseline (BL) and resurvey (RS) percent live coral cover statistics including mean and standard deviation of percent live coral cover, and median of percent live coral cover.

[%, percent; PUHE, Puʻukoholā Heiau National Historic Site; KAHO, Kaloko-Honokōhau National Historic Park; PUHO, Puʻuhonua o Hōnaunau National Historic Park]
Park Survey Mean (%) Standard deviation (%) Median (%)
PUHE BL 60.4 25.2 60
PUHE RS 23.2 24.5 10
KAHO BL 28.7 24.9 20
KAHO RS 25.3 24.7 20
PUHO BL 52.3 31.5 60
PUHO RS 25.0 23.0 20
Table 4.    Baseline (BL) and resurvey (RS) percent live coral cover statistics including mean and standard deviation of percent live coral cover, and median of percent live coral cover.

Puʻukoholā Heiau National Historic Site

The mean coral cover of PUHE was 60.4 plus or minus (±) 25.2 percent and 23.2±24.5 percent in the baseline and resurvey periods, respectively (table 4; fig. 7). There were no obvious spatial patterns of live coral cover or coral cover change between the baseline and resurvey (fig. 8). There was widespread decrease in live coral cover (park mean= −61.6 percent; table 3; figs. 7, 8), although there were three sites where positive changes in live coral cover were observed (fig. 8C).

The occurrence of coral cover between 0 and 40 percent increased, whereas the occurrence of coral cover greater than 40 percent decreased at PUHE between the baseline and resurvey periods (figs. 9A, 9B). Most of the site-specific coral cover change was negative, with a strong bias towards 100-percent loss in the distribution curve of percent change (fig. 9C).

Coral types were classified as the dominant type in 90.4 percent of the baseline imagery (table 2; fig. 9). P. compressa was the most common coral type, comprising 55.7 percent of the known dominant type classifications. P. lobata was also relatively common, making up 34.8-percent of the known baseline classifications. The most common non-coral type was sand. In the resurvey, coral types were classified as the dominant type in 80.4 percent and non-coral types were classified in 19.6 percent of the images. Again, P. compressa and P. lobata were the most common coral types in the resurvey at 53.6 percent and 26.0 percent, respectively. Sand continued to be the most common non-coral type, whereas rubble increased between the baseline (0 percent) and resurvey (7.0 percent).

PUHE experienced the greatest increase in non-coral of the three parks (105.2 percent; table 3; fig. 9F), and the greatest decrease of coral (−1.1 percent). This pattern was driven by an increase in the proportion of sand and rubble classification and a decrease in the proportion of P. lobata.

Alttext 8: Overall, the percentage of live coral cover substantially decreased at Puʻukoholā Heiau National Historic Site.
Figure 8.

Maps of spatial patterns of live coral cover and change by site at Puʻukoholā Heiau National Historic Site. A, Mean baseline survey of percentage of live coral cover ( C ¯ B ). B, Mean resurvey of percentage of live coral cover ( C ¯ R ). C, Percent change of live coral cover ( Δ C ) between the baseline and resurvey. Park boundaries are represented in white. Base imagery from Esri and its licensors.

Alttext 9: The charts all denote a decline in coral cover. Porites compressa is the dominate bottom type in both the baseline and resurvey.
Figure 9.

Graphs showing park trends of percent baseline, resurvey, and change of live coral cover and dominant types for Puʻukoholā Heiau National Historic Site. A, Density distribution of percentage of baseline and resurvey coral cover. B, Bar graph showing the difference in baseline and resurvey density distributions (resurvey minus baseline). C, Density distribution of live coral cover ( Δ C ). D, Pie chart of the eight dominant bottom types in the baseline imagery (n equals 115). E, Pie chart of the eight dominant bottom types in the resurvey imagery (n equals 642). F, Bar graph showing the change of coral ( Δ P C ) and non-coral ( Δ P N ) dominant types.

Kaloko-Honokōhau National Historic Park

The mean percent live coral cover at KAHO was 28.7±24.9 percent and 25.3±24.7 percent for the baseline and resurvey periods, respectively (table 4; figs. 7, 10A, 10B). The variability of coral cover was higher at KAHO than PUHE and PUHO. In both the baseline and resurvey, the highest percent coral cover was found adjacent to Kaloko Fishpond and near the northern end of the park (fig. 10).

Live coral cover in KAHO decreased by 11.7 percent between the baseline and resurvey (table 3). Despite this loss, there were sites where an increase in coral cover was observed (fig. 10C), including many of the sites adjacent to Kaloko Fishpond and around the harbor. This positive change in coral cover was also reflected in the change of coral and non-coral types, where non-coral types decreased by 16.8 percent and coral types increased 22.3 percent (table 3).

Though there were similar distributions of coral cover between the baseline and resurvey periods at KAHO (fig. 11A), the lowest coral cover bin (0 to 10 percent) showed the greatest increase in occurrences, whereas coral cover bins with percentages greater than 10 percent varied in gains or losses (fig. 11B). Most of the site-specific coral cover change was negative, with a strong bias towards 100-percent loss in the distribution curve of percent change (fig. 11C). The distribution of coral change at KAHO was more weighted towards positive change than PUHE and PUHO with the tail of the distribution extending to gains of 400-percent (fig. 11C). These large gains in cover were relatively rare (n=2) and may be driven by high uncertainties in the locational data of the baseline imagery or the heterogeneity of coral cover of a particular site.

KAHO was more characteristic of lower coral cover in the baseline and resurvey periods as evidenced by a higher proportion of non-coral type classifications (table 2; figs. 11D–F). The most common dominant bottom type in the baseline survey was sand (37 percent), but rubble was significantly more common at KAHO than the other two parks across both surveys. In the resurvey, the occurrence of coral and non-coral types was nearly equal with corals comprising 52.5 percent and non-coral types comprising 47.4 percent of the images. P. lobata was the most common coral type in both survey periods. KAHO was the only site where positive change of coral types and negative change of non-coral types was observed (table 3; fig. 11F).

Alttext 10: The percentage of live coral cover change at Kaloko-Honokōhau National Historic Park is mostly very negative, but there are a few spots near the shoreline that lean positive.
Figure 10.

Three maps of spatial patterns of live coral cover and change by site at Kaloko-Honokōhau National Historic Park. A, Mean baseline survey of percentage of live coral cover ( C ¯ B ). B, Mean resurvey of percentage of live coral cover ( C ¯ R ). C, Percentage of live coral cover change ( Δ C ) between the baseline and resurvey. Park boundaries are represented in white. Base imagery from Esri and its licensors.

Alttext 11: The charts all denote a decline in coral cover. Sand was the primary bottom type at the baseline survey, and Priortes lobata was the dominate type in the resurvey.
Figure 11.

Graphs showing park trends of percent baseline, resurvey, and change of live coral cover and dominant types for Kaloko-Honokōhau National Historic Park. A, Density distribution of percentage of baseline and resurvey coral cover. B, Difference in baseline and resurvey density distributions (resurvey minus baseline). C, Density distribution of live coral cover ( Δ C ). D, Pie chart of the eight dominant bottom types in the baseline imagery (n equals 135). E, Pie chart of the eight dominant bottom types in the resurvey imagery (n equals 512). F, Change of coral ( Δ P C ) and non-coral ( Δ P N ) dominant types.

Puʻuhonua o Hōnaunau National Historic Park

The mean percent live coral cover at PUHO was 52.3±31.5 percent and 25.0±23.0 percent in the baseline and resurvey periods, respectively (table 4; figs. 7, 12). Live coral cover decreased by 52.2 percent between the baseline and resurvey (table 3; figs. 7, 12). Generally, live coral cover decreased across the entire park (fig. 12C).

Like PUHE, the occurrence of coral cover between 0 and 40 percent increased, whereas the occurrence of coral cover more than 50 percent decreased at PUHO (figs. 13A, 13B). Most of the site-specific coral cover change was negative, with a strong bias towards 100 percent loss in the distribution curve of percent change (fig. 13C). Despite overwhelming negative coral change across the park, there were some sites that experienced positive change in live coral cover.

Coral types were classified as the dominant type in 91.2 percent of the baseline images at PUHO (table 2; fig. 13). For the baseline survey, P. lobata was the most common bottom type (52.3 percent), followed by P. compressa (32.0 percent). Non-coral types were classified as the dominant type in 6.6 percent of the baseline images. In the resurvey, coral types were classified in 89.2 percent of the images and non-coral in 10.8 percent. P. compressa was the most common dominant bottom type in the resurvey (47.9 percent); however, P. lobata was still relatively common (40.7 percent). Rubble increased from 1.0 percent of all classified dominant bottom types to 8.7 percent (a nearly 800-percent change) between the baseline and resurvey.

Alttext 12: The percentage of live coral cover change at Puʻuhonua o Hōnaunau National Historic Park overall decreases.
Figure 12.

Three maps of spatial patterns of live coral cover and change by site at Puʻuhonua o Hōnaunau National Historic Park. A, Mean baseline survey of percentage of live coral cover ( C ¯ B ). B, Mean resurvey of percentage of live coral cover ( C ¯ R ). C, Percentage of live coral cover change ( Δ C ) between baseline and resurvey. Park boundaries are represented in white. Base imagery from Esri and its licensors.

Alttext 13: The charts all denote a decline in coral cover. Priortes lobata was the primary bottom type at the baseline survey, and Priortes compressa was the dominant type in the resurvey.
Figure 13.

Graphs showing park trends of percent baseline, resurvey, and change of live coral cover and dominant types for Puʻuhonua o Hōnaunau National Historic Park. A, Density distribution of percentage of baseline and resurvey coral cover. B, Difference in baseline and resurvey density distributions (resurvey minus baseline). C, Density distribution of live coral cover change ( Δ C ). D, Pie chart of the eight dominant bottom types in the baseline imagery (n equals 197). E, Pie chart of the eight dominant bottom types in the resurvey imagery (n equals 426). F, Change of coral ( Δ P C ) and non-coral ( Δ P N ) dominant types.

Depth Associated Patterns of Coral

Overall, the patterns of coral cover, live coral change, and dominant type were not found to be strongly associated with depth. PUHE sites were the shallowest site on average (mean depth=11±5.9 m), followed by KAHO (mean=14.2±5.6 m) and then PUHO (mean=15.1±4.8 m).

Depth Distributions of Live Coral Cover

The depth distribution of coral cover bins demonstrated high variability between the baseline and resurvey periods across all three parks (fig. 14). However, high percent cover bins became more concentrated at mid-depths (20 to 15 m) in the resurvey, especially at PUHE and PUHO.

Alttext 14: Plot showing distribution of 10 percent coral cover classes at depth bins at each of the three parks for the baseline and resurvey image sets. Water depth had moderate or little influence on live coral cover change across all three parks.
Figure 14.

Plot of density distribution of 10 percent coral cover classes at depth bins at Puʻukoholā Heiau National Historic Site (PUHE), Kaloko-Honokōhau National Historic Park (KAHO), and Puʻuhonua o Hōnaunau National Historic Park (PUHO) from baseline (A, C, E) and resurvey (B, D, F) imagery classifications. Histograms do not have a common normalization.

Depth Related Associations of Live Coral Cover Change

Water depth had moderate or little influence on changes in live coral cover across all three parks (fig. 14). The relation between live coral cover change and water depth was significant at all three parks (probability value less than 0.005), but the relations were corroborated by low correlation values (R2<0.2), especially at KAHO and PUHO. At KAHO, increases in coral cover up to 400 percent were observed at certain sites. PUHE exhibited the strongest relation between coral change and depth (correlation value=0.48), where live coral cover loss was pronounced at shallower depths. However, the opposite was observed at KAHO, where coral loss was pronounced at deeper depths and large gains occurred at shallow depths.

Alttext 15: Plots of coral cover change as a function of depth with least squares regression statistics. The relation between live coral cover change and water depth was significant at all three parks, but the relations were corroborated by low correlation values.
Figure 15.

Plots of coral cover change as a function of depth with least squares regression statistics (equation, correlation [R2], and p-value), sorted by park. A, Puʻukoholā Heiau National Historic Site (PUHE). B, Kaloko-Honokōhau National Historic Park (KAHO). C, Puʻuhonua o Hōnaunau National Historic Park (PUHO).

Summary and Conclusions

This study aimed to investigate changes in live coral cover and bottom composition across three national parks on the Kona Coast through a comprehensive analysis of underwater imagery in the early 2000s and again in 2022. Our results indicate there was reduction of live coral cover across all three parks and increases in non-coral dominant bottom types at Puʻukoholā Heiau National Historic Site (PUHE) and Puʻuhonua o Hōnaunau National Historic Park (PUHO). PUHE experienced the greatest decrease of live coral cover, whereas Kaloko-Honokōhau National Historic Park (KAHO) experienced the smallest decrease in live coral cover.

Despite most of the sites in all three parks showing declines in live coral cover, there were sites where positive change in coral was observed. In KAHO, these sites were predominantly adjacent to Kaloko Fishpond and the southern half of the park. The protected nature of the pinnacles off Kaloko Fishpond and the embayment around the harbor may provide reprieve from storm damage and wave energy allowing coral to recover in these areas of KAHO. Furthermore, the highest historical coral cover measured was at these locations and indicates more recovery was possible than at other exposed sites in the KAHO study area. This explanation also supports the negative relation between depth and coral cover change at KAHO (fig. 15) where the shelf begins to transition into a steep shelf break at 12- to 20-m depths. At these depths, coral cover naturally declines and uncolonized substrate increases, indicating that wave stress and damage might be driving coral cover and coral change. Unlike KAHO, there was a positive relation between depth and coral cover change at PUHE (fig. 15). This trend may be driven by patterns in depth distribution of aggregate reef, where the proportion of dominant substrate structure composed of aggregate reef peaks at 25 m, indicating deeper environments are more favorable for coral colonization at PUHE. Positive coral change was only observed at one site in PUHO and there was no significant relation between depth and coral cover change (fig. 15). This positive coral change may be due to locational errors between the baseline and resurvey periods.

Declines in coral cover have been observed in subtidal surveys across the Kona Coast by National Park Service Inventory and Monitoring (NPS I&M), National Coral Reef Monitoring Program, and Coral Reef Assessment and Monitoring, though none are across the same period as the results presented from this study. Records of declining coral cover from multiple organizations, sampling strategies, and periods in this region demonstrate that continued and consistent monitoring across all three parks could be used to inform future decision making and policy development.

Because KAHO is currently the only park to have a fixed, long-term marine monitoring program, expanding the current KAHO I&M surveys to include permanent subtidal monitoring sites at PUHO and PUHE could provide relevant information on coral change for all three parks on the Kona Coast. Despite park boundaries not officially extending into the marine environment, these important ecosystems occur downslope of the parks and are of concern to NPS management. Additionally, validating survey results by crossing future periodic boat-based drop-camera surveys with I&M fixed diver transects across all three park regions would allow the managers to have a more robust understanding of coral cover and change. Continuing U.S. Geological Survey camera surveys in the future would provide consistency in imagery acquisition methodology by utilizing the approach taken in the resurvey period moving forward. Compared to the baseline surveys, the drifted survey approach in the resurvey provides higher-resolution imagery and increased positional control. Combining the drifted survey approach with precise GNSS global positioning system data would likely reduce uncertainty in the locational data across years.

Because of the collective multi-agency approach to management in this region, expanding survey efforts (such as systematic larger area camera system surveys, in conjunction with diver surveys concentrated on smaller sites of particular interest) could benefit multiple state and local agencies. Furthermore, ongoing and expanded surveys could help inform potential future protections of marine systems within NPS boundaries. These continued assessment surveys would enable the NPS to continue monitoring changes to critical nearshore habitats and marine resources under and adjacent to National Park jurisdiction.

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Appendix 1

Appendix 1 provides the site-specific means, standard deviations, and distributions of baseline and resurvey percent live coral cover for Puʻukoholā Heiau National Historic Site (PUHE), Kaloko-Honokōhau National Historic Park (KAHO), and Puʻuhonua o Hōnaunau National Historic Park (PUHO).

Live Coral Cover Distributions by Site

Table 1.1.    

Baseline (BL) and resurvey (RS) mean longitude, mean latitude, mean percent live coral cover ( C ¯ ), standard deviation of percent live coral cover ( σ C ), and the number of images classified by site at PUHE (Puʻukoholā Heiau National Historic Site).

[°, degree; %, percent]
Site Survey type Mean site longitude (°) Mean site latitude (°) C ¯ (%) σ C (%) Number of classified images
PUHE01 BL −155.830 20.016 80 14.1 4
PUHE01 RS −155.830 20.016 26.4 23.1 25
PUHE02 BL −155.834 20.015 43.3 5.8 3
PUHE02 RS −155.834 20.015 13.5 11.5 23
PUHE03 BL −155.834 20.016 48 44.4 5
PUHE03 RS −155.834 20.016 25.4 38.5 28
PUHE05 BL −155.836 20.020 55 13.2 16
PUHE05 RS −155.837 20.020 34.1 18.7 39
PUHE06 BL −155.830 20.019 80 10 3
PUHE06 RS −155.830 20.019 11.3 11.3 15
PUHE07 BL −155.829 20.023 93.3 5 9
PUHE07 RS −155.829 20.023 17.3 13.7 37
PUHE08 BL −155.834 20.027 87.5 9.6 4
PUHE08 RS −155.834 20.027 21.4 17.3 22
PUHE09 BL −155.837 20.028 23.3 5.8 3
PUHE09 RS −155.837 20.028 29.3 12.2 15
PUHE10 BL −155.839 20.040 85 7.1 2
PUHE10 RS −155.839 20.040 68.3 23.3 12
PUHE11 BL −155.836 20.039 65 35.4 2
PUHE11 RS −155.836 20.039 23.8 16.9 8
PUHE12 BL −155.838 20.034 60 14.1 2
PUHE12 RS −155.838 20.034 66.7 18.6 6
PUHE13 BL −155.835 20.033 42 11 5
PUHE13 RS −155.835 20.033 12.6 14 27
PUHE14 BL −155.837 20.031 65 7.1 2
PUHE14 RS −155.837 20.031 60.5 23.1 21
PUHE15 BL −155.834 20.029 20 14.1 2
PUHE15 RS −155.834 20.029 10 7.7 11
PUHE16 BL −155.833 20.029 36.7 5.8 3
PUHE16 RS −155.833 20.029 0 0 17
PUHE17 BL −155.835 20.027 70 17.3 3
PUHE17 RS −155.835 20.027 5.2 7.5 21
PUHE19 BL −155.829 20.025 27.1 17 7
PUHE19 RS −155.829 20.025 7.6 7 34
PUHE20 BL −155.833 20.023 70 24.5 4
PUHE20 RS −155.833 20.023 20.6 14.7 18
PUHE21 BL −155.831 20.021 65 15.1 8
PUHE21 RS −155.831 20.021 9.6 11.1 23
PUHE22 BL −155.829 20.020 25 7.1 2
PUHE22 RS −155.829 20.020 3.3 4.9 15
PUHE24 BL −155.832 20.014 40 14.1 2
PUHE24 RS −155.832 20.014 57.1 13.8 7
PUHE25 BL −155.832 20.016 70 24.5 4
PUHE25 RS −155.832 20.016 3.1 7.9 26
PUHE26 BL −155.833 20.019 67.1 34 7
PUHE26 RS −155.833 20.019 11.3 15.7 31
PUHE27 BL −155.836 20.021 55 7.1 2
PUHE27 RS −155.836 20.020 26.3 20.9 16
PUHE29 BL −155.837 20.029 60 14.1 5
PUHE29 RS −155.837 20.029 30.9 21.3 35
PUHE30 BL −155.837 20.036 60 28.3 2
PUHE30 RS −155.837 20.036 50 30.4 14
PUHE31 BL −155.838 20.032 65 29.3 8
PUHE31 RS −155.838 20.032 51.3 21 23
PUHE32 BL −155.836 20.031 56 13.4 5
PUHE32 RS −155.836 20.031 20.6 28.1 35
PUHE36 BL −155.836 20.023 81.7 9.8 6
PUHE36 RS −155.836 20.023 23.6 16.5 39
Table 1.1.    Baseline (BL) and resurvey (RS) mean longitude, mean latitude, mean percent live coral cover ( C ¯ ), standard deviation of percent live coral cover ( σ C ), and the number of images classified by site at PUHE (Puʻukoholā Heiau National Historic Site).
Graphs showing density distribution curves for percent live coral cover for baseline and resurvey sites at Puʻukoholā Heiau National Historic Site (PUHE). Dashed vertical lines indicate the mean percent live coral cover for each survey period.
Figure 1.1.

Graphs showing density distribution curves for percent live coral cover for baseline and resurvey sites at Puʻukoholā Heiau National Historic Site (PUHE). Dashed vertical lines indicate the mean percent live coral cover for each survey period.

Table 1.2.    

Baseline (BL) and resurvey (RS) mean longitude, mean latitude, mean percent live coral cover ( C ¯ ), standard deviation of percent live coral cover ( σ C ), and the number of images classified by site at Kaloko-Honokōhau National Historic Park (KAHO).

[°, degree; %, percent]
Site Survey type Mean site longitude (°) Mean site latitude (°) C ¯ (%) σ C (%) Number of classified images
HN05 BL −156.030 19.670 36 27.2 10
HN05 RS −156.030 19.670 52.3 34.4 22
HN07 BL −156.029 19.669 10 14.1 2
HN07 RS −156.029 19.669 80 11.5 7
KAHO01 BL −156.039 19.688 27.9 25.9 70
KAHO01 RS −156.039 19.688 29.6 26 91
KAHO02 BL −156.033 19.674 22.2 21.3 73
KAHO02 RS −156.033 19.675 15.6 21.1 135
KAHO04 BL −156.036 19.685 24.3 5.3 7
KAHO04 RS −156.036 19.686 22.2 10.1 27
KAHO05 BL −156.037 19.686 17 17 10
KAHO05 RS −156.035 19.677 15 13 22
KAHO06 BL −156.037 19.689 20 8.9 6
KAHO06 RS −156.037 19.688 42.4 16.7 38
KAHO07 BL −156.037 19.686 38 31.1 5
KAHO07 RS −156.035 19.682 30.4 24.1 26
KAHO08 BL −156.037 19.688 100 0 3
KAHO08 RS −156.037 19.688 78.3 11.7 6
KAHO09 BL −156.037 19.687 77.5 22.2 4
KAHO09 RS −156.037 19.687 45.2 25 31
KAHO10 BL −156.036 19.687 47.5 32.8 8
KAHO10 RS −156.036 19.687 49 23.3 10
KAHO11 BL −156.036 19.686 25 20 8
KAHO11 RS −156.036 19.686 34.3 18.9 28
KAHO12 BL −156.035 19.686 28 17.8 15
KAHO12 RS −156.035 19.686 57.1 16.5 24
KAHO13 BL −156.035 19.686 25 7.1 2
KAHO13 RS −156.035 19.686 82.9 4.9 7
KAHO15 BL −156.035 19.685 30 6.7 10
KAHO15 RS −156.035 19.685 35.7 14 7
KAHO16 BL −156.036 19.684 26.7 13.7 12
KAHO16 RS −156.036 19.684 21.6 15.2 25
KAHO17 BL −156.036 19.677 22.8 11.8 18
KAHO17 RS −156.036 19.677 26 19.1 40
KAHO18 BL −156.035 19.676 8.5 10.3 27
KAHO18 RS −156.035 19.676 5.8 5.9 40
KAHO19 BL −156.035 19.675 13.6 16.2 28
KAHO19 RS −156.035 19.675 12.3 10 40
KAHO20 BL −156.034 19.674 8.5 6.9 13
KAHO20 RS −156.034 19.674 6 5.2 10
KAHO21 BL −156.032 19.672 35.1 20.8 45
KAHO21 RS −156.032 19.672 42.1 23.3 39
KAHO22 BL −156.031 19.672 35.8 23.9 12
KAHO22 RS −156.031 19.672 49.5 18.1 19
KAHO23 BL −156.031 19.671 22.5 8.9 8
KAHO23 RS −156.031 19.671 12.3 14.2 13
KAHO24 BL −156.030 19.670 44.3 30.3 23
KAHO24 RS −156.030 19.670 43.5 23.4 17
KAHO25 BL −156.029 19.669 54.4 39.7 9
KAHO25 RS −156.029 19.668 26.9 25.3 26
KAHO26 BL −156.030 19.668 20.8 11.2 13
KAHO26 RS −156.030 19.668 12.5 18.9 4
KAHO27 BL −156.048 19.694 31.7 18.5 12
KAHO27 RS −156.048 19.694 3.1 8.1 29
KAHO28 BL −156.043 19.691 12.5 5 4
KAHO28 RS −156.043 19.691 8 11.4 10
KAHO29 BL −156.039 19.690 15 7.6 8
KAHO29 RS −156.039 19.690 10.5 13.6 21
KAHO30 BL −156.038 19.689 20 18.5 8
KAHO30 RS −156.038 19.689 12.1 15.3 24
KAHO31 BL −156.038 19.689 22.5 12.2 12
KAHO31 RS −156.037 19.689 27.5 25.1 20
KAHO33 BL −156.037 19.688 12.1 10.5 14
KAHO33 RS −156.037 19.688 16.5 16.4 40
KAHO34 BL −156.036 19.689 36 15.2 5
KAHO34 RS −156.036 19.688 46.1 8.9 23
KAHO35 BL −156.036 19.688 15 10.7 8
KAHO35 RS −156.036 19.688 35.7 15.1 7
KAHO36 BL −156.035 19.687 48.6 10.7 7
KAHO36 RS −156.035 19.687 49.4 11.2 16
KAHO37 BL −156.035 19.687 23.3 5.8 3
KAHO37 RS −156.035 19.687 47 10.6 10
KAHO38 BL −156.036 19.686 31.4 10.7 7
KAHO38 RS −156.036 19.686 68.4 25 19
KAHO39 BL −156.035 19.685 20 11.8 11
KAHO39 RS −156.035 19.685 36.8 17 40
KAHO40 BL −156.035 19.684 30 20 3
KAHO40 RS −156.035 19.684 23.7 14.6 19
KAHO41 BL −156.036 19.683 6.7 5.8 3
KAHO41 RS −156.036 19.683 14.3 6.5 14
KAHO42 BL −156.037 19.684 26.4 31.4 11
KAHO42 RS −156.037 19.684 0 0 17
KAHO43 BL −156.037 19.684 10 10.4 12
KAHO43 RS −156.037 19.684 0.3 1.7 35
KAHO44 BL −156.036 19.682 20 17.3 3
KAHO44 RS −156.037 19.682 9.1 7 11
KAHO45 BL −156.037 19.681 5 5.5 6
KAHO45 RS −156.037 19.681 0 0 12
KAHO46 BL −156.034 19.681 52 13 5
KAHO46 RS −156.034 19.681 22 7.7 20
KAHO47 BL −156.037 19.680 10 8.5 15
KAHO47 RS −156.037 19.680 0.3 1.6 39
KAHO48 BL −156.036 19.679 13.3 5.8 3
KAHO48 RS −156.036 19.679 5.8 5.1 12
KAHO49 BL −156.035 19.679 10 6.3 11
KAHO49 RS −156.035 19.679 10.5 2.3 19
KAHO51 BL −156.035 19.677 14.3 5.3 7
KAHO51 RS −156.035 19.677 9.3 2.6 15
KAHO53 BL −156.033 19.674 10 8.2 4
KAHO53 RS −156.032 19.674 25.6 13.3 9
KAHO55 BL −156.030 19.671 17.5 9.6 4
KAHO55 RS −156.030 19.671 21.2 17.3 17
KAHO56 BL −156.029 19.670 52.1 26.4 14
KAHO56 RS −156.029 19.670 41.3 18.9 8
KAHO57 BL −156.029 19.670 42.5 9.6 4
KAHO57 RS −156.029 19.670 28 11 5
KAHO58 BL −156.030 19.669 76.2 22.6 13
KAHO58 RS −156.030 19.669 70.5 15.7 20
KAHO59 BL −156.030 19.669 30 21.7 18
KAHO59 RS −156.030 19.669 9.2 8.3 37
KAHO60 BL −156.029 19.669 67.7 14.2 13
KAHO60 RS −156.029 19.669 41.3 15.1 15
KAHO61 BL −156.040 19.691 12.5 5 4
KAHO61 RS −156.040 19.691 12.9 9.5 7
KAHO62 BL −156.039 19.691 37.5 17.5 8
KAHO62 RS −156.039 19.690 25.3 9.9 15
KAHO63 BL −156.038 19.689 56.1 29.1 18
KAHO63 RS −156.038 19.689 10.6 13.9 31
KAHO64 BL −156.038 19.689 42 25.3 10
KAHO64 RS −156.037 19.689 28.4 19.7 31
KAHO65 BL −156.037 19.689 65 5.8 4
KAHO65 RS −156.037 19.689 46.5 15.5 26
KAHO66 BL −156.037 19.688 45 18.7 6
KAHO66 RS −156.037 19.688 2.3 4.3 22
KAHO67 BL −156.037 19.688 26.3 16 8
KAHO67 RS −156.037 19.688 43.8 22.6 8
KAHO68 BL −156.037 19.687 80 10 3
KAHO68 RS −156.037 19.687 1 3.2 10
KAHO71 BL −156.036 19.680 30.6 18.9 17
KAHO71 RS −156.036 19.680 5.7 11.2 21
KAHO72 BL −156.038 19.680 10 19.1 7
KAHO72 RS −156.038 19.680 2.5 4.5 16
KAHO73 BL −156.035 19.679 19 9.9 10
KAHO73 RS −156.034 19.679 13.2 5.7 22
KAHO74 BL −156.034 19.677 5 5.3 10
KAHO74 RS −156.034 19.677 23.8 13.6 16
KAHO75 BL −156.036 19.676 0 0 3
KAHO75 RS −156.036 19.676 0 0 4
KAHO76 BL −156.034 19.675 14 5.5 5
KAHO76 RS −156.034 19.675 25.7 11.3 7
KAHO79 BL −156.029 19.669 25.3 21.2 17
KAHO79 RS −156.029 19.669 12.4 13.9 33
KAHO80 BL −156.028 19.669 28.8 29 8
KAHO80 RS −156.028 19.669 50 24.5 13
KAHO81 BL −156.046 19.692 82.5 9.6 4
KAHO81 RS −156.046 19.692 14.7 5.2 15
KAHO82 BL −156.042 19.691 45 63.6 2
KAHO82 RS −156.042 19.691 20 26.2 10
KAHO83 BL −156.037 19.683 21.3 22.3 8
KAHO83 RS −156.037 19.683 15.3 16.1 19
KAHO84 BL −156.035 19.682 27.5 20.5 8
KAHO84 RS −156.035 19.682 17.1 17.6 21
KAHO85 BL −156.034 19.679 25 21.2 2
KAHO85 RS −156.034 19.679 45.7 7.9 7
KAHO87 BL −156.030 19.671 85 12.2 6
KAHO87 RS −156.030 19.671 83.7 11.6 19
WHAP11 BL −156.030 19.671 86.7 5.8 3
WHAP11 RS −156.030 19.671 57.8 21.8 18
Table 1.2.    Baseline (BL) and resurvey (RS) mean longitude, mean latitude, mean percent live coral cover ( C ¯ ), standard deviation of percent live coral cover ( σ C ), and the number of images classified by site at Kaloko-Honokōhau National Historic Park (KAHO).
Density distribution curves for percent live coral cover for baseline and resurvey sites at Kaloko-Honokōhau National Historic Park (KAHO). Dashed vertical lines indicate the mean percent live coral cover for each survey period.
Figure 1.2.

Density distribution curves for percent live coral cover for baseline and resurvey sites at Kaloko-Honokōhau National Historic Park (KAHO). Dashed vertical lines indicate the mean percent live coral cover for each survey period.

Table 1.3.    

Baseline (BL) and resurvey (RS) mean longitude, mean latitude, mean percent live coral cover ( C ¯ ), standard deviation of percent live coral cover ( σ C ), and the number of images classified by site at Puʻuhonua o Hōnaunau National Historic Park (PUHO).

[°, degree; %, percent]
Site Survey type Mean site longitude (°) Mean site latitude (°) C ¯ (%) σ C (%) Number of classified images
PUHO01 BL −155.916 19.425 2 4.5 5
PUHO01 RS −155.916 19.425 0 0 10
PUHO02 BL −155.915 19.425 63.1 34.6 16
PUHO02 RS −155.915 19.425 10.8 9.5 25
PUHO03 BL −155.915 19.425 40.5 23.4 19
PUHO03 RS −155.915 19.425 23 8 20
PUHO04 BL −155.914 19.425 72 15.7 15
PUHO04 RS −155.914 19.425 16.7 19.5 15
PUHO05 BL −155.914 19.425 65.5 35 11
PUHO05 RS −155.914 19.425 17.8 14.4 18
PUHO10 BL −155.914 19.424 86.7 5.8 3
PUHO10 RS −155.914 19.424 69.2 9.5 13
PUHO11 BL −155.914 19.423 81.7 7.5 6
PUHO11 RS −155.914 19.423 21.4 20.4 7
PUHO12 BL −155.916 19.422 41.7 27.9 6
PUHO12 RS −155.916 19.422 23.3 10.7 12
PUHO13 BL −155.916 19.421 53.3 20.8 3
PUHO13 RS −155.916 19.421 15.3 12.5 15
PUHO14 BL −155.915 19.420 41.1 19 9
PUHO14 RS −155.915 19.420 20.5 8.3 20
PUHO15 BL −155.913 19.417 20 14.1 2
PUHO15 RS −155.913 19.417 14.2 16.8 12
PUHO16 BL −155.913 19.417 43.3 26.6 15
PUHO16 RS −155.913 19.417 24.4 20.4 27
PUHO17 BL −155.910 19.415 30 7.1 5
PUHO17 RS −155.910 19.415 23.8 13.6 32
PUHO19 BL −155.908 19.411 80 0 2
PUHO19 RS −155.908 19.411 36.7 11.2 9
PUHO20 BL −155.908 19.407 70 25.1 14
PUHO20 RS −155.908 19.407 44 18.8 40
PUHO21 BL −155.907 19.408 20 0 3
PUHO21 RS −155.907 19.408 75.3 9.6 19
PUHO22 BL −155.907 19.410 82.5 9.6 4
PUHO22 RS −155.907 19.410 60.9 20.7 11
PUHO24 BL −155.916 19.418 37 25.8 10
PUHO24 RS −155.916 19.418 8.8 9.1 40
PUHO25 BL −155.914 19.423 64.8 32.1 31
PUHO25 RS −155.914 19.423 32.5 15 40
PUHO27 BL −155.913 19.424 88 4.5 5
PUHO27 RS −155.913 19.424 55.7 12.7 7
PUHO28 BL −155.918 19.426 17.5 9.7 12
PUHO28 RS −155.918 19.426 5.9 6.1 34
PUHO29 BL −155.916 19.425 50 14.1 4
PUHO29 RS −155.916 19.425 8.7 3.5 15
PUHO30 BL −155.916 19.420 40 14.1 2
PUHO30 RS −155.916 19.420 10 0 7
PUHO31 BL −155.915 19.418 4.3 5.3 7
PUHO31 RS −155.915 19.418 0 0 21
Table 1.3.    Baseline (BL) and resurvey (RS) mean longitude, mean latitude, mean percent live coral cover ( C ¯ ), standard deviation of percent live coral cover ( σ C ), and the number of images classified by site at Puʻuhonua o Hōnaunau National Historic Park (PUHO).
Density distribution curves for percent live coral cover for baseline and resurvey sites at Puʻuhonua o Hōnaunau National Historic Park (PUHO). Dashed vertical lines indicate the mean percent live coral cover for each survey period.
Figure 1.3.

Density distribution curves for percent live coral cover for baseline and resurvey sites at Puʻuhonua o Hōnaunau National Historic Park (PUHO). Dashed vertical lines indicate the mean percent live coral cover for each survey period.

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain
centimeter (cm) 0.3937 inch (in.)
millimeter (mm) 0.03937 inch (in.)
meter (m) 3.281 foot (ft)
square kilometer (km2) 247.1 acre
square kilometer (km2) 0.3861 square mile (mi2)

Datum

Vertical coordinate information is referenced to the local mean sea level (LMSL).

Horizontal coordinate information is referenced to the Pacific Plate realization of the North American Datum of 1983 (NAD83(PA11)).

Vertical positions used for depth are referenced to the Local Mean Sea Level (LMSL) tidal datum.

Abbreviations

CRAMP

Coral Reef Assessment and Monitoring Program (Hawai‘i)

DEM

digital elevation model

GNSS

global navigation satellite system

GPS

global positioning system

I&M

inventory and monitoring

KAHO

Kaloko-Honokōhau National Historic Park

LED

light-emitting diode

lidar

light detection and radar

LMSL

local mean sea level

NCRMP

National Coral Reef Monitoring Program

NHP

national historic park

NHS

national historic site

NPS

National Park Service

PUHE

Puʻukoholā Heiau National Historic Site

PUHO

Puʻuhonua o Hōnaunau National Historic Park

USGS

U.S. Geological Survey

Disclaimers

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested Citation

McPherson, M.L., Logan, J.B., Alkins, K.A., Groff, S., Hatcher, G.A., Gibbs, A.E., Cochran, S.A., and Storlazzi, C.D., 2026, Evaluation of benthic habitat change within the national historic sites of Hawaiʻi’s Kona Coast: U.S. Geological Survey Open-File Report 2026–1061, 28 p., https://doi.org/10.3133/ofr20261061.

ISSN: 2331-1258 (online)

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Evaluation of benthic habitat change within the national historic sites of Hawaiʻi’s Kona Coast
Series title Open-File Report
Series number 2026-1061
DOI 10.3133/ofr20261061
Publication Date April 14, 2026
Year Published 2026
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pacific Coastal and Marine Science Center
Description Report: vii, 28 p.; Data Release
Country United States
State Hawaii
Other Geospatial Kona Coast
Online Only (Y/N) Y
Additional publication details