Coral Reef Studies and Products
Ofu Lagoon is chosen for a major climate change study
Chuck Birkeland (UH Manoa) is currently examining factors affecting the resilience of corals to climate change, and their use in designing marine reserves. Interactions among corals, their zooxanthellae and microbial communities are being examined in differing combinations of physical environmental conditions. Ofu lagoon in NPSA was chosen as the study site because a diverse community of corals exists there, and yet is subjected to stressful environmental factors (e.g., a 6 degree daily fluctuation in water temperature; temperatures in some areas briefly reach 35 C, and dissolved oxygen ranges 15-220% saturation). This study is in addition to another 3-yr project funded through NRPP to one of Birkeland's graduate students, Lance Smith, to study the distribution of corals in Ofu lagoon. View Dr. Birkeland's spreadsheet of coral species recorded by various scientists doing coral monitoring work in American Samoa.
Marine scientists have predicted that coral reefs worldwide, including those within the National Park of American Samoa (NPSA), will suffer substantial mortality over the next 20-30 years due to global warming. The particular environmental conditions and diverse coral communities in NPSA provide an exceptional opportunity to find which of these hypotheses is correct and to develop the best management procedures for dealing with the predicted stresses on coral reef systems.
View website on Hawaiian Pacific Islands Cooperative Ecosystems Studies Unit (PI-CESU)
The massive coral heads at Ta'u
Currently, the massive coral heads in Ta'u waters, pictured above, are being studied as being among the very largest and oldest known.
The Park as a Marine Protected Area
The National Park of American Samoa has jurisdiction over 2,550 acres of coral reefs along 17 miles of coastline within park units on Tutuila, Ofu, and Ta'u Islands in American Samoa. The park manages these waters as Marine Protected Areas. Shallow coral reef ecosystems such as these within the park are among the most diverse ecological communities on earth, often supporting several hundred species of fishes and non-coral invertebrates in a small area. Coral reefs here are currently the most robust and pristine within the U.S. and its territories, and one of the primary management objectives in NPSA is to preserve these ecosystems for future generations.1 By law the park allows subsistence fishing by villagers but not commercial fishing.6
However true in concept, unfortunately the park MPAs do not yet provide adequate protection for harvested resources. In American Samoa the NPS lacks an effective enforcement capability or even a Court to present cases. Too, the territory itself has limited ability to conduct marine enforcement activities of any sort. But that's not really the issue - for most fishing, considered 'subsistence,' on the territory's coral reefs is completely legal.5
In 2001 the Territory Department of Marine and Wildlife Resources took a major step by prohibiting the use of scuba gear while fishing. Serious consideration now needs to be given to developing more effective Marine Protected Areas to provide long-term protection to fish stocks.4
Overfishing and the Loss of the Big Fish
Two types of fisheries harvest the park's coral reef fishes and invertebrates--subsistence fishing by villagers (usually shoreline activities with gear, such as rod and reel, spears, gillnet, or gleaning, or small-boat fishermen who jig for bottomfish around the steeply sloping islands, and whose fish are mostly sold at local stores. A trend in these coral reef fisheries is that species such as giant clams and parrotfish are overfished, and there has long been heavy fishing pressure on surgeonfish. There are fewer and/or smaller groupers, snappers and jacks. Few fish larger than 16 inches in length are found on the park's reefs.4,7
The "no large fish" attribute has huge ecological implications. Loss of larger fish means a tremendous loss of spawning potential-consider, one large female red snapper (61 cm) has the spawning potential of 212 smaller females (42 cm). And with life history patterns that mortality of young is extremely high--a fish has to live and spawn for decades in order to insure that at least a few of its juveniles successfully make it back to a reef and grow to maturity. With the number of spawners reduced to a skeleton population through overfishing Samoa's reefs are at a point where production of larvae and subsequent recruitment are greatly impaired. Given the very slow growth of reef fishes, and their normal long life expectancy when not fished, for even a chance to restore a large fish component of the park's reefs will require decades' relief from overfishing.2,5
Subsistence use of the park's MPAs
In spite of the loss of larger fish breeding potential due to overfishing in the parks' waters, all the Pacific Islands parks' waters are subject to local subsistence fishing. This is expressly allowed in the legislation establishing these parks (and in these cases, the parks could not have been established without this compromise). Implicit in the legislation is a widely held view that Native and prehistoric peoples lived in harmony with the land and they left no adverse effect upon their environments.
Recent archeological studies refute that view. Studies at Ofu of midden sites continuously spanning some 3,000 years show that human occupants did modify the landscape and biota. Among the discoveries were earliest strata containing bird bones of five species of petrels or shearwaters and a megapode, none of which now occur at Ofu. On Ofu not a single species of petrel or shearwater (a highly exploited human food) survived the three millennia of human occupation. Though all fish genera still remain-the larger individuals, crucial to effective reproduction, are now missing.9
The park's current reef monitoring indicates that several large sanctuaries to exclude all fishing--continuously for decades--must be established within the park's MPAs for fish populations to recover. This will require concurrence of the Village owners of the park's lands and waters.3,8
There is an old parable in the southwest Indian Country about fools who, to their own doom, would "eat their 'seed corn.'" Folks overharvesting their big fish (with reproductive potential many hundred fold greater than a little fish) surely are folks who would "eat their seed corn.'"
Coral Reefs and Global Warming
Because of effects of global warming, coral reefs are one of the world's most endangered ecosystems. Global warming will result in higher sea surface temperatures which can be lethal to corals. During the warming event in the south Pacific during 1994, extensive mortalities occurred among branching acroporid and pocilloporid corals throughout American Samoa and especially on a shallow reef on Ofu Island within NPSA. In 1999 and 2000, American Samoa narrowly missed being affected by a warm water mass that caused severe coral damage in the nearby islands of Fiji and (western) Samoa. In 2002 and 2003, widespread coral bleaching occurred in American Samoa. Available evidence indicates that reef-building corals will be subjected to steadily increasing temperatures in future decades. Many of these reef coral species are already living near their thermal limits, thus warming events result in unprecedented mass coral bleaching and mortality, such as occurred in 1998.1,10
The park has identified "target areas" within existing and proposed park units containing coral populations most likely to survive, or recover from, coral bleaching events caused by global warming. There they are experimenting and monitoring coral conservation strategies to increase the likelihood that the corals there will survive, or recover from, bleaching events and provide seed populations for reefs on which corals have been killed.1
The park's marine products cited above are:
1. Craig, 2001. Managing NPSA Coral Reefs in the Face of Global Warming. NPS NRPP-Research Funding Proposal. Western Region, National Park Service.
2. Craig, Peter. 2004. Opinion piece: Where are the fish? The Island Connection, Issue 9, pg 4. View as a pdf file.
3. Craig, Peter. 2005. Opinion piece: The Impaired Coral Reefs of NPSA. The Island Connection, Issue 10, pg 4. View as a pdf file.
4. Craig, Peter. 2006. American Samoa: Environmental Trends. Meeting handout, 2006, Pago Pago.
5. Craig, P. and A. Green. 2006. Overfished Coral Reefs in American Samoa. Reef Encounter (33):21-22.
6. Craig, Peter, Suesan Saucerman and Sheila Wiegman. 2000. Central South Pacific Ocean (American Samoa), Chapt. 103. In Sheppard (ed.) Seas at the Millennium: an environmental evaluation. Elsevier Science, NY. 2(103):765-772.
7. Craig, Peter, Guy DiDonato, Douglas Fenner, and Christopher Hawkins. 2004. Status of Coral Reefs in American Samoa 2004. In NOAA State of Coral Reef Ecosystems in the U.W., 2004 (Draft)
8. Craig, P., A. Green and F. Tuilagi. 2007. Subsistence harvest of coral reef resources in the outer islands of American Samoa: modern, historic and prehistoric catches. 16 pp, in prep. Nat’l Park of Amer. Samoa.
9. Kirch, P.V., and T.L. Hunt (Ed.) 1993. The To’aga Site: Three Millennia of Polynesian Occupation in the Manu’a Islands, American Samoa. Contrib. of the Univ. of Cal. Archaeological Research Facility, Berkeley. Funded by the National Park Service through the ASG Hist. Pres. Office. 248 pp.
10. Smith, Lance and Charles Birkeland. 2003. Managing NPSA’s Coral Reefs in the Face of Global Warming: Research Project Report for Year 1. Hawaii Coop Fishery Unit, UH, Manoa. 32 pp.
For a complete list of the National Park of American Samoa coral reef publications see the UH CESU park page.
The Park's Fish Lists Taxonomy
Last updated: February 28, 2015