Land-based Pollution Effects to Hawai`i’s Coastal Resources
(Click here for a downloadable version of this brochure)

A Bit of Coral Biology

An Animal…Corals are composed of tiny living creatures called polyps.

A Mineral…These polyps excrete a mineral called calcium carbonate, which forms the hard outer skeleton.

A Plant…Inside many types of individual coral polyps live zooxanthellae, single-celled algae that receive protection by living within the coral. In return, they give the coral food through a process known as photosynthesis - turning sunlight into energy.

Coral reefs are some of the oldest and most fragile organisms on earth. In order to survive and grow, corals require clean, warm, clear, and shallow waters. Even then, they grow very slowly at a rate of 1/2 to 3 inches per year.

Corals are the basis of our nearshore ecosystems.
Many of Hawai`i’s marine species depend upon their survival.

Coral Reproduction & Recruitment

Most corals reproduce on a lunar cycle. In some species this coincides with the warmest time of year and full moon (meaning high tides). In this small window of time, corals release sperm and eggs in an event known as mass spawning. Each sperm must find an egg before the tide goes out and they are swept away from each other into the open sea.

A fertilized coral embryo will drift like plankton in the ocean until it is ready to recruit. Recruitment is the process that every coral larva must go through to find a place on the reef to settle down. This is the most critical part of young coral development and many, if not most, will not survive this stage.

Effects of Land-based Pollution on Coral Reefs

Land-based pollution (ex. muddy runoff) has been identified as one of the top six threats to coral reefs in the United States. This type of pollution damages reefs and degrades water quality. The degree of damage during a pollution event depends on its concentration (amount of pollutants that enter an area) and residence time (how long pollutants stay in an area).

If the pollution event is SHORT TERM, corals are able to recover, however they may be stressed by…

- Suspended particles in the water prevent light from reaching the zooxanthellae. When this happens, photosynthesis cannot occur and energy is not created. The coral may temporarily excrete or "spit out" these cells and take them back in when less stressed.

- Corals may excrete a mucous coat to keep off sediments that land on them, and in doing so use a lot of energy.

If the pollution event is LONG TERM, the results are much more serious and can lead to effects such as…

- No re-uptake of expelled zooxanthellae, thus losing a major source of energy.

- Storage of polluting chemicals within corals. This is called bioaccumulation.

- Slowed or ceased coral growth.

- No coral reproduction - uses too much precious energy.

- Eventual coral death.

- Impacts on the entire food-web. All fish, mammals, and plants you see (and don’t see) on a reef depend on the coral’s survival. It is their food source, hiding place, meeting place, and home.

If there is pollution/runoff in the area, it can disturb the delicate chemical cues coral larvae depend on to "sense" the reef. Temperature changes, nutrient changes, and deposited sediments make a reef inhospitable to coral larvae. If they do not find a suitable settlement area, they will not survive. Even once the larvae are recruited, corals remain small and fragile and are susceptible to event the slightest environmental change.

Written by Celeste Leroux, Marine Option Program intern, University of Hawaii; Edits by Carey Morishige.

Information References: Personal communication. 2005. Dr. Robert Richmond, University of Hawaii, Kewalo
Marine Laboratory Pacific Biomedical Research Center.

Effects of Marine Debris

Northwestern Hawaiian Islands
by Carey Morishige

The Hawaiian Archipelago, mainly the Northwestern Hawaiian Islands (NWHI), is home to endangered Hawaiian monk seals, sea turtles, many species of seabirds, and 69% of the coral reefs in U.S. waters (Miller and Crosby, 1998). Because of the unique and distinct bathymetry, and relative geography of the NWHI, derelict fishing gear and other forms of maritime marine debris remain a continued threat to wildlife and coral reef ecosystems there (Donohue et al., 2001).

Hawaiian monk seals have the highest entanglement rates among pinnipeds and all main breeding subpopulations of this species are within the NWHI (Henderson, 2001). Endangered hawksbill, olive ridley and leatherback sea turtles also reside in the NWHI. There have been documented entanglements of these species as well as of the threatened green sea turtle (Balazs 1978, 1980, 1985; Henderson, 1984). Ingestion of debris is also a threat to many species of seabirds. They have been found having ingested plastics, styrofoam, fibers, bags, bottle caps and toys (Harrison et al., 1983; Dickerman and Goelet, 1987). Maritime marine debris also causes damage to coral reef ecosystems. Fishing gear can get snagged on a reef, leading to the breakage of coral heads (Donohue et al., 2001).

There have been recent efforts to remove derelict fishing gear and other marine debris from the NWHI. In 1999, a multi-agency effort was made to remove derelict fishing gear from Lisianksi Island and Pearl and Hermes Atoll in the NWHI. Fourteen tons of fishing gear was removed (Donohue et al., 2001). The U.S. Fish and Wildlife Service also has volunteers throughout the year at Tern Island, French Frigate Shoals, NWHI, who remove and categorize beach debris. These efforts still continue today.

Main Hawaiian Islands
by Carey Morishige

We’ve all seen the photos taken of the hundreds of tons of marine debris collected each year in our Northwestern Hawaiian Islands and had our jaws drop open at the sheer amount. The same problem of marine debris exists in our backyard - right here in the main Hawaiian Islands.

Not only does marine debris affect the beauty and aesthetic value of our beaches, but it also poses a threat to many of our marine species. Much of the debris seen in the main Hawaiian Islands is from land-based sources, however we also see our fair share of derelict fishing gear. Fishing gear (e.x. nets, fishing line) can get snagged on reefs and coral heads, and with wave action, cause serious damage and even death. Marine debris can also harm some of our other marine species including everything from endangered Hawaiian monk seals to sea birds. Entanglement and ingestion remain the top two concerns and effects.

In marine debris clean-ups of Kanapou Beach on Kahoolawe in 2003 and 2004, each time more than four tons of debris (mainly plastics - 74% in 2003 and 64% in 2004 - see figures below) were removed. Debris on this beach is made up of mainly derelict fishing gear and ocean-bourne marine debris, followed closely by land-based sources. In yet another clean-up of approximately two miles at South Point on the Big Island in 2003, over 55 tons of marine debris was removed in two days time. Massive balls of tangled net were so large and heavy at times that the help of a front-loader and bob-cat were required. Other areas in our state are similarly impacted and efforts are ongoing to help mitigate this problem. Whether the beach looks like Kanapou Beach, or is scarecly impacted by debris, the problem remains and we can all do something to help.

For more photos of the effects of marine debris, visit http://hawaiihumpbackwhale.noaa.gov/special_offerings/sp_off/photos.html

*The Blue Water Campaign is involved with issues surrounding land-based pollution, such as muddy runoff, as well as marine debris.