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Ecology of Kaloko-Honokōhau National Historic Park

Kaloko-Honokōhau National Historical Park Ecology

Photograph of coastal strand habitat
Dry coastal habitat at Kaloko Honokohau National Historical Park, Big Island, Hawai‘i. (Credit: Dennis LaPointe, USGS.)

Kaloko-Honokōhau National Historical Park is 1,160 acres in size, including 596 acres of marine area. The landscape consists of rocky shoreline, sandy beaches, coral rubble, and mangrove wetland areas, and at one time had a thriving ancient Hawaiian settlement. The site encompasses portions of four different ahupua’a, or traditional sea-to-mountain land divisions. The park was established in 1978 to preserve and protect the traditional native Hawaiian cultural and historical sites. Cultural resources within the park include engineered fishponds, petroglyphs and heiau (religious sites).

 

Fishponds

Historically the area held two fishponds, Kaloko Fishpond and ‘Aimakapa Fishpond, and one fish trap, ‘Ai‘opio Fishtrap. The two fishponds illustrate how native Hawaiians worked with their environment to manage and utilize the ocean’s natural resources. The fishponds were created by a building a rock seawall that separated the bay from the sea with gates that controlled the flow of water between the water bodies. Studies suggest that ancient Hawaiians used the ‘Aimakapa Fishpond for over 600 years. The fishponds serve as an important wetland for migratory birds, hosting a wide variety of species. The National Park Service has been working to restore the natural communities and functions of wetland ecosystems. One species in ‘Aimakapa Fishpond that is disrupting this restoration is the invasive non-native fish species Mozambique tilapia. This species was recently discovered in the fishpond and is present in other national park ponds and wetlands on Hawai’i island. USGS scientists are now working with the NPS to characterize the existing fish populations in ‘Aimakapa Fishpond, identify the impacts of tilapia, and investigate potential management options.

Today visitors can see remnants of the volcanic rock and coral wall that formed the 1.7 acre ‘Ai‘opio Fishtrap. Native Hawaiians used the fishtrap to trap and catch fish during low tide. The fish would enter the trap through an opening or over the submerged walls during high tide and would be stored until needed. The fishponds within Kaloko-Honokōhau National Historical Park create a wetland area that provides a habitat for a variety of native bird species. Other species spend the winter months in the fishpond, having traveled to Hawai‘i from other parts of the world.

This harbor on the south side of Kaloko Honokohau National Historical Park was the site of the beginning of the entertainment te
Looking south along one of the historical fishpond walls at Kaloko-Honokōhau National Historic Park. (Credit: Phil Stoffer, USGS.)

Birds

Hawai‘i’s waterbirds were pushed to the brink of extinction in the early 1900s due to invasive plants, non-native predators, and a reduction of wetlands. All of Hawai‘i’s endemic wetland-dependent waterbird populations have global population estimates of less than 2,000 individuals, making them vulnerable to extinction. Ongoing research aims to continue estimating population sizes and trends and optimizing management strategies to ensure the success of these species.

 

Endemic, Native, and Indigenous

Ae'o (Hawaiian Stilt/Black-necked Stilt) is an endangered bird endemic to Hawai‘i and found nowhere else in the world. They are facing threats of habitat loss, introduced predators, altered hydrology, disease, climate change, non-native invasive plants, and environmental contaminants. While other Hawaiian water birds are largely restricted to wetlands, Hawaiian stilts have been found in modified upland habitats including developed areas, undeveloped fields, and even sports fields. Within Kaloko-Honokōhau National Historical Park, the Ae‘o are year-round residents and are found near the fishponds. They nest on mudflats and near brackish ponds and eat small fish and shellfish.

Image: Black-Necked Stilt (Himantopus mexicanus)
Ae‘o, or Hawaiian Stilt . (Credit: John J. Mosesso, USGS.)

‘Alae ke‘oke‘o (Hawaiian Coot) are endangered, endemic birds that lives in the park year-round. They eat seeds, aquatic vegetation, and aquatic invertebrates. They face threats of habitat loss, introduced predators, altered hydrology, climate change, non-native invasive plants, avian disease and environmental contaminants.

Image: Hawaiian Coot (Fulica alai)
Alae ke'oke'o or Hawaiian Coot swimming in a wetland marsh. (Credit John J. Mosesso, USGS.)

Additionally, migratory birds visit or over winter in Kaloko-Honokōhau including: kōlea, ‘akekeke, ‘ūlili, hunakai, white faced ibis, koloa mohā, koloa māpu, lesser scaup, and American wigeon.

 

Introduced and Non-Native

Several species of non-native birds are also found in the park, including: cattle egret, common myna, red-masked parakeet, gray francolin, northern mockingbird, yellow-billed cardinal, African silverbill, Japanese white-eye, rock dove, spotted dove, and zebra dove.

Hawaiian monk seals are endangered, endemic seals with an estimated population to be around 1,400 individuals. They spend about two thirds of their time at sea and come ashore to breed, rest, give birth, and molt on sand, coral, and volcanic rocky shorelines. They prefer sandy, protected beaches that are surrounded by shallow water, like those at Kaloko-Honokōhau National Historical Park, for giving birth and taking care of their young. Threats to these populations include food limitations, predation, entanglement with marine debris, habitat loss, disease (distemper viruses, West Nile virus, leptospirosis, and toxoplasmosis), and human interaction.  

Image: Hawaiian Monk Seal (Monachus schauinslandi)
Hawaiian monk seal lying on a sandy beach near the western tip of Moloka’i (Credit: Randolph Femmer, USGS.)

Green sea turtles can be seen swimming offshore feeding on seaweed or resting on the rocks or sand. They are threatened and protected by both state and federal regulations. The endemic Hawaiian green sea turtle population was severely depleted by overexploitation prior to protection under the U.S. Endangered Species Act in 1978. Since then, the stock has increased significantly despite its exposure to the chronic disease fibropapillomatosis (FP), a tumor-forming disease associated with herpes viruses. The disease has been prevalent in green sea turtle populations for more than 25 years with the hot spot increasing after a 1980’s outbreak, peaking in the mid-1990’s, and declining steadily since. Additionally, a study was conducted over a 22-year period (1982-2003) to determine the cause and spatial trends of sea turtle stranding events in the Hawaiian Islands found that the most common cause of green sea turtle strandings was FP disease, followed by hook-and-line fish gear trauma, gillnet fishing gear trauma, boat strike, and shark attack. Despite these data it was concluded that green sea turtle populations are continuing to recover since the protection of the species. Measures to reduce these stranding incidents have increased, specifically those related to fishing gear.

Green sea turtle
Green sea turtle swimming. (Credit: NOAA/NMFS/PIFSC. Public domain.)

Plants

View of Hualalai volcano beyond the coastal vegetation along the beach at Kaloko.
Plants flourish on the back-beach sand that covers solidified lava flows. The foreground features naupaka, a native shrub species. The trees in the background of this photo are non-native including thorny mesquite which was introduced to provide cattle with food and shade, but is now a problematic invasive throughout Hawai‘i. (USDA, 2010).

Maiapilo (The Hawaiian Caper Plant) is an endemic species found on coral, basalt, and rocky soil along the coast. Maiapilo is a small shrub 2-3 feet tall with large, fragrant white flowers. The species is considered vulnerable and may become endangered in the near future.

Hala pepe is an endemic and endangered plant that ranges from a small shrub or small tree to 30 feet tall with aerial roots. Other native species found within the park include pua kala (Hawaiian poppy), pōhuehue, pā‘ū o hi‘iaka, naio (false sandalwood), loulu, and ko‘oko‘olau. Noni is native to southeast Asia and Australia and was introduced by Polynesians. It is a small shrub or tree 10-20 feet tall with large yellow to white oval fruit.

 

Invasive plants

Image: Red Mangrove Trees
Red mangrove trees and their roots above and below the water surface. (Credit: Caroline Rodgers, USGS.)

Many plants within the park are invasive to the native ecosystem and are outcompeting the native vegetation and damaging historical sites. Invasive plants include barleria, bitter melon, buffelgrass, ekoa (haole koa), fountain grass, lantana, pickleweed, and pigweed. Non-native red mangrove has aggressively moved into shoreline habitats in Hawai’i. In the mid-1970s red mangrove overran Kaloko and ‘Aimakapa ponds but was removed by National Park Service after acquiring the land. National Park Service management staff continue to monitor and control this invasive plant.

 

Invasive mosquitoes that can host viruses such as dengue, chikungunya, and Zika are present in this National Historical Park. The USGS is researching the seasonal dynamics of mosquitoes in Kaloko-Honokōhau and Pu‘uhonua O Hōnaunau National Historical Parks to investigate the role of precipitation, infrastructure, and anchialine pools on the presence and abundance of mosquitoes.

 

 

 

 

 

 

 

 

 

 

 

Ecosystems

Kaloko-Honokōhau National Historical Park consists of carbonate sand beaches, coral rubble, rocky shorelines, and mangrove wetland areas. These unique features form a variety of ecosystems within the historical park.

Two small anchialine pools near the heiau at ‘Ai‘opio fishtrap
Two small anchialine pools adjoin the heiau at 'Ai'opio fishtrap. NPS.

Anchialine pools are found near the shoreline and hold a small number of species of crustaceans, mollusks, and ‘opae‘ula, a small endemic species of red shrimp. Although they appear to have no connection with the ocean, their hydrologic connection to groundwater and the ocean can be seen as the pool water levels rise and fall with ocean tides. They are made up of brackish water, which is a mixture of fresh groundwater from rainfall in the mountains that is linked to the ocean underground. More than half of the world’s known anchialine pools are found in the Hawaiian Islands. Kaloko-Honokōhau National Historical Park alone harbors over 200 of them, a reason early settlement was possible in west Hawai’i as it provided access to fresh water. Non-native fish species that were introduced to the anchialine pools are a significant threat to the native species they prey on, including ‘opae‘ula.  

 

 

Tidepools

Basalt (an extrusive, igneous rock that cools from lava) extends into the ocean to create pools of many different depths and sizes that form a suitable habitat for marine organisms, especially intertidal zone invertebrates. Animals that live in tidepools are well-adapted to be covered by water at high tide and exposed to air at low tide. Common species in these habitats include sea cucumbers, sea stars, hermit crabs, and various types of seaweed.

Kaloko-Honokau National Historic Park
Rocky shore looking north along the coast. (Credit: Phil Stoffer, USGS)

Coral Reefs

About half of Kaloko-Honokōhau National Historical Park is under the ocean and these waters are a State of Hawai’i Fisheries Management Area where only nets  hand made of native materials can be used. The area is known for its biodiversity and wide variety of fish, invertebrates, and marine algae. The coast lining the park is paralleled by shallow reefs that are vulnerable to sea level rise, storm damage, increased water temperatures, land runoff, and sedimentation.