Wai‘anae Ecological Characterization

Threats to Marine Ecosystems

The coasts have been called the crossroads of human activities and the sea (Weber 1993). Coastal and marine ecosystems face a wide variety of threats from human activities on land and in the ocean. Global climatic and oceanographic events contribute to sea level rise, severe storm events, coastal erosion, and sea surface temperature, all of which can harm marine ecosystems. Pollution from point and nonpoint sources threatens water quality and the health of coral reef ecosystems, as well as the health of large marine animals. Overexploitation of marine resources can degrade fish stocks and endanger large marine animals from by-catch. Degraded coastal and marine ecosystems provide opportunities for non-native and often invasive marine species to become established and proliferate. Keeping a balance between our use of the sea and the health of the coastal and marine ecosystems is a growing challenge throughout Hawai‘i and the world.

Threats to Coral Reefs

Hawai‘i's coral reefs support a diverse array of marine life and provide substantial economic, aesthetic, and recreational benefits to residents and visitors. They are of great importance to Native Hawaiians who rely on them for subsistence, cultural, and religious needs. Coral reefs around the world are threatened by a variety of human activities that have resulted in overexploitation and degradation of these valuable ecosystems. The U.S. Coral Reef Task Force (USCRTF) identified six priority threats that federal agencies and states must address to protect coral reefs in the United States (National Oceanic and Atmospheric Administration [NOAA] 2002a). The six priority threats are:

• Land-based pollution
• Overfishing
• Lack of public awareness
• Recreational overuse
• Climate change
• Coral disease

In Hawai‘i, the proliferation of non-native, invasive marine species is also considered a major threat. Four species of alien algae have been recorded in the nearshore environment off the Wai‘anae coast. These include three species of red algae (Acanthophora spicifera, Hypnea musciformis, and Kappaphycus alvarezii) and one green calcareous algal (Avrianvillea amadelpha). Alien algae compete for space on the reef and displace native algal species and can cover and kill living corals. In the coastal waters off the Wai‘anae moku, A. spicifera has been observed near Mākaha and Kahe Point (see map).

Alien Algal Species Found in the Hawaiian Islands and Along the Wai‘anae Coast

Species	Date of Introduction	Islands with Species	Species Found in Wai‘anae
Acanthophora spicifera	After 1950	Hawai‘i, Maui, Moloka‘i, Lanai, Kahoolawe, O‘ahu, Kaua‘i	X
Eucheuma denticulatum	1970	O‘ahu
Kappaphycus striatum	1970	O‘ahu
Gracilaria salicornia	1971	O‘ahu, Hawai‘i, Moloka‘i
Hypnea musciformis	1974	Maui, Moloka‘i, Lanai, O‘ahu, Kaua‘i, Necker, Maro Reef	X
Kappaphycus alvarezii	1974	O‘ahu	X
Avrianvillea amadelpha	1981	O‘ahu, Kaua‘i	X

Source: Hunter 2003

Threats to Marine Mammals

Threats to marine mammals occur from both land-based and sea-based activities. Threats to marine mammals include:

• Entanglement and drowning in fishing gear
• Incidental take in sport and commercial fisheries
• Habitat degradation
• Algal blooms
• Sound pollution
• Pollution, including oil spills and organochlorines
• Competition for food sources, including changes in the balance of available prey due to commercial fishing or habitat disturbance
• Vessel traffic and impact
• Disturbance and harassment

Threats to Sea Turtles

Threats to sea turtles occur from land-based and sea-based activities. Land-based activities may affect nesting and foraging areas. Sea-based activities may affect adult and juvenile turtles.

Green Turtles. Threats to green turtle recovery in the Hawaiian Islands identified in the federal Endangered Species Act mandated Sea Turtle Recovery Plan include:

• Loss of foraging habitats to nearshore development in the main Hawaiian Islands from marina construction, artificial beach development, siltation from agricultural runoff, contamination of forage areas from toxic spills, resort development, increased vessel traffic, and boat collisions
• Entanglement in and ingestion of marine debris
• Incidental take in sport and commercial fisheries
• Poaching
• Proliferation of the fibropapilloma virus throughout the turtle population
• Nest predation
• Nest damage from recreational vehicles on sand beaches

Hawksbill Turtles. Threats to hawksbill turtle recovery in the Hawaiian Islands identified in the sea turtle recovery plan include:

• Destruction or disturbance of nesting areas. Fishermen, campers, and other uncontrolled beachgoers constitute a significant threat to hawksbill and their nests in the main Hawaiian Islands. Driving on the beach causes sand compaction and rutting, and can accelerate erosion. Driving on beaches used by nesting turtles can crush incubating eggs, crush hatchlings in the nest, and trap hatchlings after they emerge from the nest cavity and begin their trek to the sea. In the latter case, hatchlings are exposed to exhaustion and predators when they fall into and cannot climb out of tire ruts that are typically oriented parallel to the sea.
• Damage to coral reefs. Hawksbills depend upon sea grass and/or coral reef habitats for food and refuge. Degradation of coral reef environments due to coastal development, sedimentation, non-point source pollution, and overfishing or overuse is a widespread and serious threat to the recovery of depleted hawksbill stocks.
• Loss of eggs to non-human predators including domestic animals, such as cats, dogs, and pigs, as well as wild species such as rats, mongoose, and birds.
• Incidental catching. Incidental catches of hawksbill turtles occur primarily in nearshore gillnets.

Other Threatened and Endangered Turtles. Threats to leatherback, loggerhead, and olive ridley turtle recovery in the Hawaiian Islands identified in the sea turtle recovery plans include:

• Hawaiian longline fishery poses the most important threat to leatherbacks and loggerhead turtles, particularly as fishing effort increases. Research is needed to identify ways of reducing hooking mortality and modifying techniques to avoid capture.
• Olive ridleys have occasionally been killed by commercial fishing vessels. The entanglement of juveniles and adults in marine debris around the Hawaiian Islands is reported from Kailua-Kona (Hawai‘i), Pukoo (Moloka‘i), Hana (Maui), and O‘ahu.

References Cited

Hawaii Coral Reef Initiative Research Program (HCRI). 2000. Alien and Invasive Algae in Hawaii. http://www.botany.hawaii.edu/GradStud/smith/websites/Alien-Bishop.htm

Hunter, C. 2003. Final Report, Hawaii Coral Reef Initiative, Report No. 99-00.

National Oceanic and Atmospheric Administration (NOAA). 2002a. National Coral Reef Action Strategy: Report to Congress. 118 pp. http://www.coris.noaa.gov/activities/actionstrategy/actionstrategy.html

Weber, P. 1993. Worldwatch Paper #116: Abandoned Seas: Reversing the Decline of the Oceans. Worldwatch Institute. Washington, D.C. 66 pp.

Related References

State of Hawaii Department of Land and Natural Resources (DLNR). 2003c. Aquatic Invasive Species Management Plan. Division of Aquatic Resources (DAR) and the Nature Conservancy of Hawaii. http://www.hawaii.gov/dlnr/dar/pubs/ais_mgmt_plan_final.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998a. Recovery Plan for U.S. Pacific Populations of the Green Turtle (Chelonia mydas). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Green_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998b. Recovery Plan for U.S. Pacific Populations of the Hawksbill Turtle (Eretmochelys imbricata). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Hawksbill_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998c. Recovery Plan for U.S. Pacific Populations of the Leatherback Turtle (Dermochelys coriacea). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Leatherback_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998d. Recovery Plan for U.S. Pacific Populations of the Loggerhead Turtle (Caretta caretta). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Pacific_Loggerhead_Recovery_Plan.pdf

National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (USFWS). 1998e. Recovery Plan for U.S. Pacific Populations of the Olive Ridley Turtle (Lepidochelys olivacea). NOAA National Marine Fisheries Service. http://www.nmfs.noaa.gov/prot_res/readingrm/Recoverplans/Olive_Ridley_Recovery_Plan.pdf

U.S. Environmental Protection Agency (EPA), Natural Resource Conservation Service, Hawaii Department of Health, Hawaii Coastal Zone Management Program, National Oceanic and Atmospheric Administration, U.S. Fish and Wildlife Service, and U.S. Geological Survey. 2004. Hawaii's Local Action Strategy to Address Land-Based Pollution Threats to Coral Reefs. Prepared by Tetra Tech EM Inc. under EPA Contract No. 68-W-02-021. 61 pp. http://www.hawaii.gov/health/environmental/water/cleanwater/prc/pdf/LAS.CR-LBP_fnl_3-22-04.pdf

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