American Samoa National Park Information Page
Here you will find all you need to know about the natural history of the park.
Learn about the geology, trees, mammals, birds, or other plants and wildlife of the area.
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American Samoa National Park Information
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Establishment
Located some 2,600 miles southwest of Hawai`i, this is one of the most remote national parks in the United States. It is also one of the newest; it was authorized by the U.S. Congress in 1988 and officially established in 1993 when a 50 year lease was signed.
Secretary Babbitt Dedicates America's 50th National Park
Office of the Secretary
For Immediate Release: April 16, 1995
The National Park Service is comprised of 374 units, with 54 units designated as national parks. The National Park of American Samoa is the 50th chronological park.
(American Samoa) Today on the picturesque Islands of American Samoa, Secretary of the Interior Bruce Babbitt stood in the village of Vatia located on Tutuila (too too ee la), to dedicate America's 50th National Park. The National Park of American Samoa was authorized in 1988 by Congress to preserve and protect the tropical rainforest ecosystem, flying fox fruit bat habitat, the coral reefs, and the 3,000 year-old Samoan culture and archeological resources.
"Our stewardship commitment extends to preserving for future generations those historic sites and spectacular structures that pay tribute to America's past and the principles upon which our Nation was founded," said Babbitt. "The chiefs of this Polynesian paradise have been great stewards of their land for centuries. The dedication of this National Park is a recognition of their outstanding success in preserving their islands and their natural heritage for future generations."
American Samoa is a magical kingdom where spontaneous adventure waits around every corner and each magnificent coral reef. In 1988, the National Park Service began negotiations for land on three islands - with nine Chiefs in village councils. The negotiations resulted in the 10,520 acre national park being located on the islands, Ofu, Ta'u, and Tutuila, with about 420 acres mostly under water.
"Our National Park System is the envy of the world. When Congress passed legislation authorizing your great National Park, it was actually giving the territory an economic tool whose potential has just begun to be tapped," Babbitt said. "I applaud Governor Sunia for designating 1995 as the Year of the Reef, to promote greater understanding of the plight of coral reefs."
American Samoa is made up of seven islands with a total land area of 76 square miles. The chain of islands is located 2,300 miles southwest of Hawaii and over 4,100 miles southwest of San Francisco. Sydney, Australia is about 2,700 miles further to the southwest, while Auckland, New Zealand is about 1,600 miles southwest. American Samoa is the only United States territory south of the equator.
The seven islands are dispersed over 150 miles of water. Tutuila, the main island, is the center of government and business. Tutuila has a land area of 56 square miles, with an estimated 95 percent of the 56,000 total population living there. The remaining 20 square miles include the islands of Ofu, Olsoega, and Ta'u of the Manu'a group located 60 miles east of Tutuila; Aunu, a small island 1/4 mile off the eastern shore of Tutuila; Rose Atoll, a wildlife refuge 60 miles east of Manu'a; and Swain's Island, 200 miles north of Tutuila.
Last April the National Park Service opened a visitor center in the town of Pago Pago and are working with the Governor of American Samoa to develop tourism opportunities. American Samoans are among the last remaining true Polynesians, along with the Hawaiians, Maori, Tongans and Tahitians. Its famous Pago Pago harbor is one of the Pacific's deepest and most sheltered harbors.
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Size
Acreage - FY 2001 - Gross Area Acres - 9,000
History
American Samoa, the only US Territory south of the equator, consists of five rugged, highly eroded; volcanic islands, and two coral atolls. The land area of the territory is 76 square miles. The population is approximately 60,000, with most people living on the main island of Tutuila. Tuna fishing and canning are major industries. Many Samoans practice subsistence farming.
The nation of Samoa lies 60 miles to the west of Tutuila. The main islands of 'Upolu and Savai'i constitute a much larger land area than American Samoa. Between these two large islands are the small islands of Manono and Apolima. Several uninhibited islets lie just off the eastern shore of 'Upolu.
The Pacific Ocean occupies a third of the Earth's surface. Of the thousands of islands scattered throughout this vast world of water, most are not large enough or hospitable enough for humans to live on. There are some, such as the Samoa Islands, that possess such beauty and exotic quality that they have inspired works by artists and writers.
The Samoa Islands are part of Polynesia, a triangular area of the Pacific bounded by Hawaii, New Zealand, and Easter Island. The Samoa Islands have been populated for 3,000 years, but known to the Western world for little more than two centuries. So important is Samoa to Polynesian culture that some believe this was where all Polynesian people originated.
Creation Legend
The Samoans tell a creation legend sometimes compared to that given in the Bible in the Book of Genesis. The god Tagaloa lived in an expanse of empty space. Tagaloa first created a rock, which he split into clay, coral, cliffs and stones. The breaking of the rock caused the earth, sea and sky to be created. A spring of fresh water came from a piece of the rock. Tagaloa created man and woman and ordered them to people the region supplied with fresh water. Tagaloa propped up the sky, Tu'ite'elagi, with teve, a bitter-root plant. Then Tagaloa created night and day, Po and Ao, who gave birth to the sun and moon. The god also created nine regions of heaven and various other gods. Manu'a, a son of PO and AO, was sent down to rule the people. The Manu'a islands became an important spiritual center of Polynesia.
The Volcano We Live On by P. Craig, NPS
The geology of the Samoan islands is surprisingly interesting. First, we are living on a volcano, which is resting quietly at the moment. Second, our volcano is on the move, it's traveling towards China with us on it. And, finally and most unfortunately, our volcano is doomed and it will eventually sink back into the dark ocean depths.
It is not really an exaggeration to call the Samoan islands 'active volcanos'. These islands were indeed formed by volcanism, and the volcanos are still active, in a geologic timeframe of course, and due to some unusual circumstances as described below.
About 1.5 million years ago, our volcano spewed forth enough lava to rise up out of the ocean and become “Tutuila Island”. Actually, just the tip of the volcano is visible to us, most of the mountain is underwater. While the tallest mountain peak on Tutuila is about one half mile high, the mountain extends another 2 miles below the sea surface.
The most recent volcanic eruptions were a lot more recent than many people realize. In western Samoa, major eruptions occurred in 1905 when lava flows destroyed a village. In the Manu'a islands, subsurface volcanic eruptions and earthquakes occurred in 1866, causing dense clouds of smoke and pumice to erupt from the ocean surface for several months. One hundred years ago is just a blink of the eye to a volcano, which measures time in the millions of years. We humans tend to forget how briefly people have lived upon these shores. Human habitation on Tutuila, even considering the whole 3000-year period that Samoans have dwelt here, represents a mere 0.2% of the time since the sun first shone on this new land.
To explain our volcano's march towards China, we first need to review the nature of the earth's surface or crust. The earth's outer layer, the one we live on, is several miles thick, but that is a thin skin compared to the total size of the earth. This outer layer is made up of many separate sections that seemingly float on top of the earth's molten core and move about in very slow motion. Geologists call these outer sections “plates”. You may recall, for example, that the continents of Africa and South America were once joined together when the earth first formed, but the two continents slowly drifted apart to where they are today. The same process applies to the plates under the Pacific Ocean. The plate we're on is called the Pacific Plate and it is moving westward (towards China) at a leisurely speed of about 3 inches per year. At this rate, in one million years we will be 50 miles closer to China.
It is not accidental that the islands of American Samoa and western Samoa lie roughly in a straight line. Directly underneath us is what geologists call a “hot spot” of thermal activity in the earth's core. It's a volcano just waiting to happen. When the pressure builds up at the hot spot, molten magma bursts up through the Pacific Plate and forms a volcanic island. Then the hot spot calms down for awhile, perhaps a million years or so. During this peaceful interval, the Pacific Plate keeps marching onward, so when the hot spot acts up again, it forms a new volcanic island rather than build upon the previous one. In other words, the hot spot stays in one place but the plate above it keeps moving.
The islands formed therefore generally lie in a straight line that is oriented in the direction the plate is moving. The new islands form on the eastern end of the chain, so the islands become progressively older as you move from east to west. For that reason, the islands in western Samoa are about 1 million years older than the islands in American Samoa. (Early geologists got this direction backwards.) The newest volcanic eruption in our island chain is forming about 30 miles east of Ta'u Island, but it will probably be another 100,000 years before this sub-surface volcano, named Vailulu'u, breaks the sea surface.
But something else really exciting also happens in our area. As Tutuila Island glides westward, a part of our plate collides with another plate to the west of us (the Australian Plate), and our plate actually rips in two at this point (see diagram). One piece of our plate continues moving towards China, but the other piece slides down into the 6-mile deep Tongan Trench and under the Australian Plate, never to be seen again.
The collision of these two colossal pieces of the earth's surface causes the seafloor to bend and rip, which in turn probably causes some earthquakes and renewed volcanic activity. Recent surveys suggest how this might be happening. Long cracks in the seafloor have been discovered between the Samoan islands and the Tongan Trench. The cracks are oriented in an east-west direction and seem to be formed as the seafloor bends southward down into the top of the Tongan Trench. These cracks may make it easier for the hot magma beneath the crust to spew upward and emerge as young lava on top of our old islands.
And all this is happening a mere 100 miles south of Tutuila Island. We live in a very unique area.
Finally, all oceanic volcanos must come to an end. As time passes, two things happen. Our volcano erodes continuously as ocean waves attack its shorelines and rivers gouge into its terrain. In addition, the weight of a newly formed volcano is so heavy that it causes the volcano to sink slowly back down into the sea. Rose Atoll and Swains Island are good examples of sunken volcanos. In the distant past, Rose and Swains may have been magnificent mountainous islands with beautiful rainforests and coral reefs. But that's ancient history now, because those islands, over a period of several million years, eventually sank out of sight. All that remains are tiny amounts of coral that grew up from the peaks of the mountains as they slipped below the sea surface.
Not to worry. Tutuila Island should be around for a few more million years.
Our Deep Blue Ocean by P. Craig, NPS
American Samoa is much larger than you might think it is. The whole Territory covers 117,500 square miles, which is about the size of New Zealand or the state of Oregon. The Territory is big because we claim jurisdiction of the ocean that surrounds American Samoa, from the shoreline out to 200 miles offshore. That is standard procedure throughout the world (each country with marine coasts wants to protect its coastline and marine resources from others). To be more precise, American Samoa has jurisdiction over territorial waters out to 3 miles, while the US federal government maintains control of the zone from 3 to 200 miles from shore.
Most of the Territory is open ocean, of course. Only a minuscule 0.1% of the area consists of dry land (all 7 islands total only 76.1 square miles). The other 99.9% marine portion consists of two main habitats, the shallow coastal waters adjacent to the islands (a'au, aloalo) and the deep waters offshore (vasa). Shallow coastal habitats, with their coral reefs and colorful fish, are quite limited in total area because our islands slope steeply down into deeper water and depths of 2000 feet are reached within 0.5-2 miles from shore. So, most of our coral reefs are restricted to a narrow ring around each island. In total, we have about 114 square miles (296 km) of coral reefs in the Territory.
The rest of our marine environment consists of deep blue ocean with a fairly flat seafloor about 2-3 miles below the sea surface. The reason for the blue color of the ocean is an interesting one and it is a key factor to understanding our ocean ecosystem, so we need to get technical for a moment. Water by itself is highly transparent with a bluish tinge. What adds other colors to the ocean are, in large part, small marine plant-like cells called phytoplankton. The more phytoplankton in the water, the greener the water becomes. Phytoplankton require two main ingredients to grow well: sunlight and nutrients (fertilizers). If they have both, they grow in abundance. This, in turn, supports a productive food web: phytoplankton provide food for the microscopic shrimp-like animals (zooplankton), and the zooplankton provide food for the fish to eat.
Tropical oceans are not green because conditions are generally not good for plant growth, so relatively few phytoplankton cells are present in the water. Although phytoplankton have all the sunlight they could ever want in the surface layer, nutrient levels there are too low to support much plant growth. This occurs because the deep tropical ocean is typically stratified into two layers with very different temperatures. The sun heats up the surface layer, which is about 300 feet deep, to a pleasant 84 degrees F, but the deeper layer remains a chilly 42 degrees F. Because warm water is lighter than cold water, the warm ocean water almost always stays on top, the cold water stays on the bottom. The two layers do not mix.
That's the rub. The bottom layer is where the nutrients are, but because of the 2-layer stratification, the nutrients can't get up to the surface layer where they are needed to combine with sunlight for plant growth. So, conditions for phytoplankton are not very good in the tropical ocean. The surface layer has lots of light but few nutrients, while the bottom layer has lots of nutrients but no light. It's pitch black down there. This arrangement doesn't support a very productive foodweb, so there are generally fewer fish in tropical oceans than in non-tropical oceans.
You might wonder, how is it that non-tropical oceans are much more productive? The answer is, again, temperature. Away from the tropics, seasonal changes in water temperature cause the water to mix. Winter temperatures cool the upper layer causing it to sink and mix with the bottom layer, and when this occurs, some nutrients are brought up to the surface. The nutrients in shallow sunlit waters stimulate phytoplankton growth, thus fueling a more productive foodweb.
In the tropics, the 2-layer stratification of the ocean persists year-round because hot sun keeps the surface layer warm. The tropical ocean has been called a 'biological desert' for this reason. That's an exaggeration, of course, because all the tuna out there are finding something to eat. And, many other species live out there as well, from an occasional whale, dolphin, sea turtle or seabird, to numerous species of fish and invertebrates such as jellyfish and shrimp-like crustaceans.
What are some of the marine resources in our offshore waters? Three ocean resources of potential interest to American Samoa are fish, minerals and the water itself. Several kinds of food and sport fish are present in modest numbers: tuna, masimasi, marlin, wahoo, sharks, and flying fish.
Surveys indicate, however, that the abundance of oceanic fishes within our 200-mile limit is probably not high enough to warrant significant commercial development of offshore fisheries. That's the main reason why the big tuna boats that deliver to American Samoa's canneries have to travel far beyond our 200-mile zone to other locations where the tuna are more abundant.
Another resource mentioned from time to time are the mineral deposits, such as manganese nodules, that lie on the seafloor. However, these nodules, even if present in our waters, are too deep for economic extraction by current technologies.
Perhaps a more exploitable resource in the future involves the temperature of the ocean's cold bottom layer. Scientists are working on a technology that extracts energy (to produce electricity) through a heat-exchange mechanism that is made possible by the large temperature difference between the tropical ocean's warm surface and cold bottom layers. A demonstration facility for this technology has been operating in Hawaii since the 1970's. The two requirements for this technology, a large temperature differential in the ocean, and easy access to this temperature difference by land-based facilities, are met in American Samoa. Will our future electricity needs be powered by our own blue ocean?
Tutuila
The volcanic island of Tutuila is the largest of the seven islands that comprise American Samoa. Pago Pago Harbor, a collapsed volcanic caldera is one of the largest natural harbors in the South Pacific. It cuts deeply into the south-central coast almost dividing the island in two. From east to west, a steep mountainous spine runs the 20-mile length of the island, punctuated in places by notable summits including Matafao Peak, Tutuila's tallest mountain at 2,142 feet; North Pioa Mountain, popularly known as Rainmaker Mountain, 1,718; and Mount 'Alava, the steep ridgeline looming to the north of Pago Pago Harbor, marking the south boundary of the park area. About one mile southeast of Tutuila's eastern tip is the volcanic island of Aunu'u the smallest of the inhabited islands; it can be reached by boat and explored by foot in a day. After you visit the National Park, visits to the east and west ends of the island will reveal more island and ocean scenery and insights into Samoan culture.
Visiting Tutuila
Stop first at the visitor center in Pago Pago. A scenic road leads from Pago Pago to the north coast. Allow a few hours for this drive, including stops. You may wish to stay in overnight in the villages next to the park, but prior arrangements should be made. Please observe local customs.
Along the road there are panoramic views, especially from Afono Pass. The Amalau Valley is a good place to watch above the trees for flying foxes. There is a foot trail out towards Pola Island from the village of Vatia.
Mount Alava lies to the north of Pago Pago Harbor. A hiking trail along the maintenance road leads to the 1610 foot summit; the trailhead is located at Fagasa Pass, a short drive west of Pago Pago. The hike is 6 miles round trip; allow 3 hours for your hike up and 2 hours for your return to the pass.
Manu'a Island Group
The Manu'a Island group includes the volcanic islands of Ofu and Olosega (joined by a bridge), and Ta'u. These islands lie 60 miles east (a 30-minute flight on a small plane) from Tutuila; flights are available between Ofu and Ta'u. These islands are sparsely populated, each village has only a few hundred people.
Farther east lies the Rose Atoll, and to the north is Swains Island. These coral atolls are difficult to get to and not possible to visit. Rose Atoll is a US National Wildlife Refuge.
Visiting Ofu
The National Park area on Ofu includes sand beach and coral reef with a mountain backdrop. There is also and excellent view of Lata Mountain (3,170 feet) on Ta'u, the tallest peak in American Samoa.
A section of Ofu's pristine shoreline and fringing reef is protected within the National Park. The beach is fine coral sand, ideal for walking long stretches uninterrupted.
Coral communities are some of the prettiest in the South Pacific. This is an ideal place to snorkel in the protected back-waters of the reef. You must bring gear from Tutuila. Before you visit Ofu, check with the park staff about special rules that may apply.
Visiting Ta'u
Ta'u's national park area is accessible by road to the south of Fiti'uta. The park area includes the southeastern half of Ta'u. Here you can view coastal forest, and rugged coastal cliffs. Ta'u is where Margaret Mead did anthropological research.
Stay overnight in the village of Fitiuta on the northeast coast or in Faleasao or Ta'u in the northwest. You can rent cars locally. Visit Saua, a sacred site considered by many to be the birthplace of the Polynesian people. Hike along the beaches on a plantation road southward from Fitiuta. Beach walking on Ta'u is across coral rubble and rocky coast. If you hike in remote areas, go with a guide. Park staff may be able to arrange a guide service. Watch the sky for flying foxes, particularly at dusk and dawn. The south shore has sea cliffs over 2,000 feet high, quite imposing for humans, but seabirds find safe roosts there.
Natural Resources
American Samoa is home to many different birds and fish and a few very interesting mammals.
Bats are the only native mammals found in American Samoa. They are harmless to people. There are two species of flying foxes (fruit bats) and one insect-eating bat species here. The fruit bats, the Samoan flying fox and the white-collared flying fox, are as large as one pound with a wing span of 3 feet. They eat pollen and fruits and serve an essential role in the ecology of the native rainforest by pollinating plants and dispersing seeds.
On oceanic islands, birds are usually the most abundant and diverse group of animals. This park is home to more than 35 species, both resident and migratory, including seabirds, water birds, forest birds, and shore birds. The cliffs and sea stacks are ideal nesting habitat for tropical seabirds, while the rainforest is home to collared kingfishers, cardinal and wattled honeyeaters, bluecrowned lories, Samoan starlings, purple-capped fruit doves, many-colored fruit doves, Pacific pigeons, and banded rails.
Coral reefs abound in our coastal waters and are the homes of nearly 900 fish species, over 200 coral species, and countless other invertebrates. Many of these are harvested by villagers.
Island Streams by P. Craig, NPS
Tutuila Island has about 160 small streams that flow year-round along at least a portion of their main channel. These streams are steep, shallow and short (most are less than a mile). Stream flows are generally low but they can flood quickly in response to heavy downpours. But even with the high rainfall in our mountains (200-300 inches per year), the water drains quickly to sea or percolates into the porous volcanic soil to recharge our groundwater supply of drinking water.
Our streams support surprisingly few species, there are only 10-12 freshwater fish species and not many more freshwater invertebrates here. The principal species are freshwater eels (tuna), gobies (apofu, mano'o), mountain bass (sesele, inato), shrimp (ulavai) and snails (sisivai). Additional species may enter the lower ends of streams, but they are not restricted to a freshwater environment. Two non-native fish species were also introduced here, probably in the 1970s: mollies (fo-vai) to control mosquitoes and tilapia to grow in aquaculture. The impact of these alien species on the native populations is not known. Additionally, we can only wonder about the impact of the alien marine toad (lage) that sometimes has thousands of its young tadpoles swimming in local creeks.
The low number of species in our streams is in stark contrast to the many marine species living in our coastal marine waters (890 fish species and countless invertebrates). Part of the explanation for this difference is simply that our streams are small and offer limited habitat for stream-dwelling organisms. But another more interesting aspect of this low diversity is: how did any freshwater species get to American Samoa in the first place?
We are a small island surrounded by hundreds of miles of deep ocean. Freshwater species generally cannot survive in saltwater, so how could these freshwater fish, shrimps and snails cross the ocean barrier to get here? The trick is that they all have a marine stage in their life cycle. After they spawn, their newly hatched larvae wash out of the stream into the ocean where they drift about as marine plankton for a few weeks or months. Some make their way back to a coastline where they seek a stream to live out the rest of their lives. It might be expected that the few freshwater species that got to our remote islands have evolved over thousands of years into unique (endemic) species found nowhere else in the world, but the opposite is true. The marine stage of these species allows a wide dispersal and continual genetic mixing of populations, so the species inhabiting our streams are widely distributed across the South Pacific region.
Because streams drain the valleys we live in, they serve as good indicators of how well we are taking care of the land. Sad to say the message is not good. Our streams once provided food and drinking water, but now they are treated as a place for people to throw rubbish and piggery wastes. And, after a heavy rainfall, some streams turn chocolate brown with the dirt that erodes from the landscape. Much of this soil erosion is due to poor land-use practices such as the farmer's bare-earth clearings for plantations on steep mountain slopes and the run-off from inadequately designed construction sites. In the former case, the farmer not only loses the soil needed to grow his crops, but the eroded dirt fouls our streams and ends up in coastal waters where it degrades our coral reefs. It does not have to be this way. There are better ways to dispose of rubbish and to prevent erosion that can make streams a healthier place for fish as well as for the children who play in the streams.
Biodiversity in our Rainforests and Coral Reefs by P. Craig, NPS
There's a certain mystique about the word 'biodiversity' that seems to be associated with images of steamy jungles or wondrous new medicines, but the word usually refers to the number of species or 'species richness' of an area. One reason why tropical areas are so fascinating is that they contain the highest numbers of plant and animal species found anywhere on earth.
American Samoa sits squarely in the tropics, so we should have a high biological diversity here, but we do and we don't. There is a sharp contrast between the number of plant and animal species that live on land here (few) versus those that live in our coastal waters (many). Most small islands in the South Pacific share this characteristic.
To start at the beginning, when our islands emerged as fiery volcanos above the sea surface, they were devoid of plants or animals. As time passed and the terrain became more hospitable, life for organisms became possible, but the plants and animals still had to cross major ocean barriers to get here from someplace else.
A quick look at a map will show one reason why few land species got here. We are really quite isolated in the Pacific Ocean, far from potential sources of plants and animals. To reach our shores, organisms would either have to blow in on the wind, drift for hundreds or thousands of miles on some piece of floating debris, or be carried in by another organism like plant seeds in a bird's stomach. The species that were successful probably got here by 'island hopping' across the Pacific, spreading from island to island over the course of many thousands or millions of years.
The difficulty in getting here is best illustrated by the sparse representation of native mammal species. Over the past 1.5 million years that Tutuila Island has existed, only 3 mammal species (all bats) got here and established viable populations. Our native species list also includes about 471 flowering plants and ferns, 24 resident land and water birds, 20 resident seabirds, 7 skinks, 4 geckos, 2 sea turtles, 1 snake, and occasional other visitors (this list does not include all the introduced non-native species like rats, dogs, pigs, toads, myna birds, and many weeds).
There's a second reason for our low diversity on land, the small size of our islands. In general, the smaller the island, the fewer the species on it. For example, tiny Rose Atoll (0.4 sq mi) supports only 5 native plant species, 21 birds (virtually all seabirds), 2 geckos, and 2 sea turtles.
So, although American Samoa technically has 'tropical rainforests' due to our high level of rainfall (200-300 inches per year in some mountainous areas), we lack the high species richness found in the jungle rainforests of Indonesia, Africa or South America that are filled with hooting monkeys, poison dart frogs, pythons and flesh-eating piranhas.
On the other hand, because of our isolation, some terrestrial species in Samoa have evolved over many thousands of years to such an extent that they have become distinctly different species found nowhere else but here. For example, 1% of our plant species occur only in American Samoa; 32% of our plant species and the Samoan starling (fuia) occur only in the Samoan archipelago (which includes western Samoa); and the Samoan fruit bat occurs only in the Samoan and Fijian islands. So, our rainforest may lack diversity, but it contains some species found nowhere else on earth.
Turning to our marine environment, we find the opposite situation. There is an incredibly diverse ecosystem just beneath the waves. Coral reefs are among the most species-rich ecosystems in the world. We have, for example, 890 nearshore fish species which is an amazingly high number compared to many other coastal areas. To get a sense of this species-rich environment, if you were to dive on our reefs once a week, you could in theory see a new fish species on every dive for 17 years.
Although coral reefs are limited to shallow waters, mostly around the fringes of islands, most coral reef species have eggs and larvae that can survive for weeks or months in the open ocean and get dispersed by ocean currents to new locations. As a result of this genetic exchange of marine organisms between islands, there are probably few marine species that are unique to the Samoan islands.
Finally, superimposed over the South Pacific region is a larger-scale pattern of species distributions. Most of our marine and land species can be traced back to the same or related species inhabiting mainland and insular southeast Asia. From that center of remarkably high diversity, rainforest and coral reef species radiated out, spreading eastward across the South Pacific islands. But like ripples in a pond, the farther away one gets from that 'center', the fewer the species (see figure). This pattern applies to corals, fishes, sea turtles, seagrasses, mangroves, land birds and plants. Very few species reached here from the opposite direction (South America) probably due to the much greater distance and fewer islands in that direction to facilitate 'island hopping'.
Rainforest
From the mountaintops down to the ocean's edge, the islands are covered with mixed species, paleotropical (Old World) rainforest. Samoa's rainforest is closely related to that of Asia and Africa, as opposed to neotropical (New World) rainforests of Central and South America. In mixed species forests, no single tree or plant species dominates. This is the only rainforest of its kind protected within a US national park.
Of the park's total area of 10,500 acres about 8,000 acres are rainforest. Depending on the elevation, the forest can be characterized as coastal, lowland, ridge, montane, or cloud forest. In addition to many species of trees, plants found here include vines, ferns, lichens, eoiohytes (air plants), and mosses.
Because fa'asamoa is important to this park, subsistence farming is allowed on some park lands. Near villages that border on the rainforest are small plantations where taro, coconut, banana, breadfruit, papaya, mango and other crops are grown for a family's consumption. Don't confuse these crops with native rainforest.
Coral Reef
Each of the islands of American Samoa supports a coral reef ecosystem in coastal waters. Two islands, Rose Atoll and Swain's Island, are coral atolls with well developed reef systems. The remaining five islands are extinct volcanoes surrounded by narrow fringing reefs. Offshore from the volcanic islands of Tutila, 'Aunu'u, Ofu, Olosega, and Ta'u are drowned barrier reef.
Coral reefs support a wide variety of marine life representative of the tropical Indo-Pacific waters. To date, nearly 900 species of fish and nearly 200 species of coral have been documented. The fringing reef on the south side of the island of Ofu within the park is one of the best preserved reefs in this part of the South Pacific. It is an excellent place for snorkeling. Remember that coral is made up of living organisms and can be easily damaged. It is unlawful to collect coral, or any other marine life.
Coral by P. Craig, NPS
The islands of American Samoa are blessed with an abundance of coral, so this article presents an introduction to these unusual organisms.
Corals are animals like ourselves, although that may not be readily apparent because many look like whitish rocks, especially those washed up on the beach. In a sense, corals are indeed partly rock, because only the outer thin layer of the coral is inhabited by the coral animal itself. In that way, corals are like large trees – the inner part is hard and provides structural support, the outer part is the living, growing organism. And, like trees, most coral animals are permanently attached to one spot on the reef.
The coral rubble that Samoans traditionally spread outside their houses, and the coral rocks along our beaches, are old, dead pieces that broke off the reef during a storm, got tumbled around and tossed up on the beach.
Living corals grow primarily on the outer reef flat and in deeper water. Although they take varied shapes, the coral animals inhabiting the surface of all these types are similar. They look somewhat like miniature sea anemones (matamalu, ulumane) or upside-down jellyfish (alualu) with short tentacles that give the coral a slightly fuzzy appearance when the tentacles are extended. Each single coral animal is called a polyp, but the coral branch or block we see on the reef is actually not a single animal but a colony of hundreds or thousands of tiny polyps living side by side, giving the appearance of being a single coral animal.
The coral's short tentacles can be pulled back into the hard part of the coral when the animal is disturbed or when the coral is exposed at low tide, so even a live coral can look like a rock at
It seems almost inconceivable that these tiny coral polyps can build the hard coral ‘rocks’ that we see on the reef. They do this by secreting layers of a hard substance (calcium carbonate) beneath their living cells. It’s as if each tiny polyp built a rock-solid house for itself but then, as it grows taller, it decides to close-off the bottom rooms in its house. Then it grows some more and closes-off another layer of bottom rooms, and so on. In this way, the coral polyp always lives in the outer, top layer, which has been built upon layers and layers of rooms below.
Each polyp also cements its high-rise house to those of its adjacent neighbors which strengthens the whole structure, resembling a solidly built apartment complex. Adding on these new rooms is a slow process. Growth varies from about 0.5-3 inches per year depending on the species. The very largest corals on our reefs may be hundreds of years old. Over very long time periods, these corals grow into massively strong reef structures that can bear the brunt of powerful waves that crash upon them day after day.
Corals are one of the few organisms on earth that continually build on top of their old ‘houses’, forming such large solid structures. This is not like a bird that might build its nest on top of another nest, because both of these nests decay and disappear in a short time. In fact, most organisms on earth leave little trace after they die as their bones or shells disintegrate (dust to dust). Not corals. They build structures much larger and longer-lasting than the Pharaoh's pyramids. What other organism can do this (except modern man with his steel and cement)?
Consider Swains Island or Rose Atoll, for example. Both are the remnants of old volcanos that, after millions of years, finally sank back down beneath the ocean’s surface and disappeared altogether as volcanic islands usually do (see This volcano we live on). But as they slowly sank, the coral continued to grow on top of the submerged mountain tops, layer by layer, keeping pace with the sinking rate of the mountain. The thickness of the coral there now is probably hundreds or thousands of feet thick on top of the old mountain peak and it's all that’s left poking above the ocean surface. Were it not for this thick coral foundation on top of these old mountains, Swains Island and Rose Atoll would not exist today.
Information from the National Park Service
American Samoa National Parks Page
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by John William Uhler
