State of Sanctuary Resources
This section provides summaries of the condition and trends within four resource areas: water, habitat, living resources, and archaeological resources. For each, sanctuary staff and selected outside experts considered a series of questions about each resource area. Answers are supported by specific examples of data, investigations, monitoring, and observations, and the basis for judgment is provided in the text and summarized in the table for each resource area. Where published or additional information exists, the reader is provided with appropriate references and web links.
Water
American Samoa has nearly 240 kilometers of coastline. Fringing coral reefs characterize the coastal embayments and open coastal waters. Pollution from poorly constructed human and pig waste disposal systems, increased turbidity and nutrients from soil erosion, pose the greatest threats to near-shore water quality in American Samoa. Solid waste from improper trash disposal adds another significant threat to coastal waters.
With over a century of development, Pago Pago Harbor is the most populated and industrialized embayment in American Samoa. In addition to the non-point source pollution mentioned above, Pago Pago Harbor is potentially affected by pollution from marina and port traffic and a small shipyard. In the outer harbor, regulated effluent from the tuna canneries and sewage treatment plant is discharged. Due to the segregation and transportation of cannery waste beyond the inner harbor, better treatment of sewage, and more effective monitoring and prosecution of commercial vessels that pollute the harbor, the water quality in the inner harbor has greatly improved in the last decade.
Outside the harbor, offshore waters of American Samoa are low in nutrients and other contaminants in part because they are rapidly diluted to open ocean conditions. High strength wastes (solids, nitrogen, phosphorus) from the tuna canneries are dumped in a designated offshore area approximately eight kilometers south of Tutuila. From data collected by the canneries, the waste is considered to have only a localized effect on the marine environment. As a result, Fagatele Bay is considered to be unaffected by any pollution that leaves the harbor or from the cannery waist.
The municipal landfill for Tutuila is less than one and a half kilometers from Fagatele Bay. Although separated from Fagatele Bay by the high ridge that surrounds the bay, this landfill has the potential to leach contaminants into groundwater that flows into Fagatele Bay. Monitoring of groundwater and springs in the vicinity is needed to be sure this facility is not affecting water quality.
A direct threat to Fagatele Bay is the increase in water temperature that can cause corals to bleach. This phenomenon has occurred more often in recent years throughout the territory.
Summary Assessment of Water Conditions
The following is an assessment by sanctuary staff and American Samoa marine researchers of water quality in Fagatele Bay National Marine Sanctuary and how it may be affecting the environment:
Are specific or multiple stressors, including changing oceanographic and atmospheric conditions, affecting water quality?
High water clarity and the bay's rich biodiversity and apparent resilience would suggest that water quality in Fagatele Bay is good. However, the frequency with which high sea temperatures are causing corals to bleach and die is increasing. For this reason water quality based on stressors is considered to be only fair. Temperature impacts on bleaching are expected by many to intensify in the future.
What is the eutrophic condition of sanctuary waters and how is it changing?
Nutrient levels in the bay are currently low, as is appropriate for a tropical coral reef. However, there is concern that land clearing and associated human habitation in Fagatele Bay's watershed may be increasing nutrient levels near streams and beaches used by residents. At present, this activity is not considered to be changing nutrient conditions offshore, but measures are needed to ensure this does not reduce the bay's water quality in the future.
Do sanctuary waters pose risks to human health?
Sanctuary waters do not appear to pose risks to human health. However, an assessment of the potential effects of the nearby landfill on ground and marine waters is needed.
What are the levels of human activities that may influence water quality and how are they changing?
Extensive land clearing for agriculture on the east side of the bay has impacted the forest and may have compromised its ability to prevent soil and sediments from entering sanctuary waters.
Water Quality Status and Trends
Status: Good Good/Fair Fair Fair/Poor Poor Undet.
Trends:
▲ Conditions appear to be improving.
- Conditions do not appear to be changing.
▼ Conditions appear to be declining.
? Undeterminted trend.
N/A Question not applicable.
| # |
Status |
Rating |
Basis For Judgement |
| 1. |
Stressors |
|
Increasing number of warm water events causing coral bleaching |
| 2. |
Eutrophic Condition |
|
Low nutrient levels, good water clarity, lack of fleshy algae |
| 3. |
Human Health |
?
|
No known risks |
| 4. |
Human Activities |
|
Land clearing for agriculture, proximity of island landfill |
Habitat
A series of reef surveys starting in the early 1980s for Tutuila and Fagatele Bay suggests that in the early to mid-1980s, hard coral cover was increasing. An outbreak of crown-of-thorns starfish in 1978 had killed 90 percent of the corals in the bay, and the increases seen in the 1980s demonstrate the recovery from that event. Then, in 1990 and 1991 coral populations were reduced by severe tropical cyclones. A mass-bleaching event in 1994 killed many of the remaining corals. Since that time, survey results show coral populations have recovered. According to the most recent surveys (2005), coral covers an average of 40 percent of reef surfaces. Crustose coralline algae dominates the remainder of reef surfaces, which, together with high levels of grazing by fishes, encourages new coral recruitment and growth. These cycles of coral destruction and subsequent recovery and re-growth attests to the resilience of the reef ecosystem in Fagatele Bay.
Hard coral cover trends for Tutuila from three studies show periods of recovery interrupted by events causing mortality. (Sources: Birkeland et al. 1997, Green 2002, Houk et al. 2005.)
Surveys at different depths show that different habitats have experienced different patterns of coral cover through time. From 1985 through 2001, reef slope surveys found coral cover to be low, increasing to high levels in 2002. Surveys of coral on the reef flat found the opposite pattern, with the highest cover from 1985 to 1995 and low levels in 1997 and 2002.
Hard coral cover trends for Fagatele Bay (Birkeland et al. 2004). Surveys on the reef slope in 2004 and 2005, while not directly comparable to these data, indicated there has been no decline, and probably an increase, in coral cover. (Sources: Green et al. 2005, Whaylen and Fenner 2005)
The reef flat and reef slope are very different habitats due to exposure to wave action, low tide events and extremes in water temperature. Coral cover did not increase from 1985 to 1995 as a result of the three cyclones and the major bleaching event that damaged coral populations during this period. The loss of live hard corals on the reef flat after 1995 was due to a series of extreme low-tide events in 1998. Coral cover had increased in all habitats by 2001 and surveys in 2004 and 2005 indicate this trend continues.
Left: New coral colonies grow on the grey-pink, coralline algae encrusted surface of a large dead table coral. (Photo: Richard Murphy) Right: New life from old: coralline algae and juvenile coral colonies re-build the reef after the death of a coral.
Summary Assessment of Habitat Conditions
The following information provides an assessment by sanctuary staff and American Samoa marine researchers of the status and trends pertaining to marine habitat:
What are the abundance and distribution of major habitat types and how are they changing?
Corals are the primary builder of habitats in Fagatele Bay and their abundance and distribution control, to a large extent, the numbers of other invertebrates and fishes. Coral populations in Fagatele Bay are presently diverse (200 species) and abundant, and they have increased following a series of destructive events in the 1980s and 1990s. However, the trend in coral cover is uncertain because the apparent natural resilience of the system may be affected by an increase in potentially destructive fishing activities in the bay and the potential for increasing periods of coral bleaching due to high water temperature.
What is the condition of biologically-structured habitats and how is it changing?
As a result of coral recovery from several destructive events, and in spite of some coral diseases, the condition of the biologically structured habitats is generally good and does not appear to be changing.
What are the contaminant concentrations in sanctuary habitats and how are they changing?
Contaminants do not appear to be present in the reef structure or in the sediments.
What are the levels of human activities that may influence habitat quality and how are they changing?
Although some human-induced damage has occurred, the level of human activity is relatively low and does not appear to be changing.
Habitat Status and Trends
Status: Good Good/Fair Fair Fair/Poor Poor Undet.
Trends:
▲ Conditions appear to be improving.
- Conditions do not appear to be changing.
▼ Conditions appear to be declining.
? Undeterminted trend.
N/A Question not applicable.
| # |
Status |
Rating |
Basis For Judgement |
| 5. |
Abundance/ Distribution |
?
|
Resilient coral populations; destructive fishing activities, diseases present |
| 6. |
Structure |
|
Destructive events have not reduced biodiversity |
| 7. |
Contaminants |
|
None identified |
| 8. |
Human Activities |
|
low visitation, but fishing impacts occur |
Living Resources
Corals and Coralline Algae
The abundance of corals and coralline algae in Fagatele Bay, as discussed above, indicates considerable ecosystem resilience. Natural events such as cyclones, crown-of-thorns population explosions and low-tide events have resulted in extreme but relatively short-lived interruptions in coral growth. Coral cover fluctuations, especially in shallow water, have approached 40 percent over very short (decadal) intervals, owing to high levels of recruitment and growth, which are likely stimulated by good water quality and high coralline algae cover.
Scientists and managers are concerned, however, that recently identified threats could undermine continued resilience of Fagatele Bay's coral reefs. These include increasing levels and frequency of coral bleaching (perhaps resulting from increasing water temperature), increasing occurrence of diseases that affect corals and coralline algae, and the impacts of certain destructive fishing techniques. Together, these additional threats could diminish important characteristics of the reef. Coralline Lethal Orange Disease could significantly reduce coralline algae abundance, which could result in coral recruitment reduction. Also of concern is that diseases among corals could spread quickly in the dense populations that currently exist in Fagatele Bay. Blast fishing destabilizes reef surfaces and puts corals at additional risk during high energy events such as storms. Given these threats, it is expected that the recovery capacity of reef populations will be less than previous observations suggested following future natural disturbances.
Fish
There is currently debate as to why populations of large carnivorous fishes are low on the coral reefs in American Samoa. The narrow fringing reefs that drop quickly into deep water may limit the extent of critical shallow water habitats as well as the extent of off-reef forage areas for these fishes. However, most of the reef fish species expected to be found in American Samoa are seen and periodically caught by fishermen. Their small size and numbers suggest fishing is keeping these fishes from recovering to levels that would be expected on reefs in the region.
Reef fish are harvested in both subsistence and artisanal fisheries on the five main islands of the territory. Artisanal fishing includes both nighttime free-divers who spear reef fish and small boat fishers who target deepwater bottomfish. There is currently no export of coral reef fish to off-island markets or the aquarium trade.
A fisherman on Tutuila with a large Maori wrasse. These fish have become extremely rare on American Samoa's reefs (photo: Samoa News)
Subsistence fishing has declined steadily over the past two decades as American Samoa has shifted from a subsistence to a cash-based economy, suggesting the size and number of targeted species should be increasing. Even so, while small surgeonfish and parrotfish are abundant, the number and size of other larger coral reef fishes such as grouper and snapper are small. It is unclear if the present fishing effort or other factors continue to suppress recovery of these fish populations. Furthermore, the ecological impacts of changing size structure in the fish community would include not only changes in the abundance of non-targeted species, but cascading effects that involve reductions in herbivory and perhaps increases in leafy algae abundance that alter benthic community structure. It will be important to include these parameters within the monitoring program to both understand them better and respond appropriately to changes. Also, carefully controlled experiments are necessary to determine the effects of present fishing pressures.
There are two types of monitoring programs in the territory that document characteristics of fish populations. First, underwater visual surveys (fisheries-independent surveys) describe the types of fish observed by divers on the reef. Second, surveys of fish harvests or creel surveys (fisheries-dependent surveys) document the actual species and quantities of fish extracted from the reefs. The Department of Marine and Wildlife Resources has monitored artisanal catches since 1982, but harvests by night-divers and subsistence fisheries have been monitored only intermittently.
Territory-wide visual fish surveys document that large fish are rare on the reefs around the five main islands, a strong indication that populations have been overfished. These include sharks, Maori wrasse, and large species of grouper and parrotfish. The surveys indicate that reefs have had few large fish for at least eight years. Additionally, the surveys show that densities of large fish are higher on American Samoa's remote reefs (Swain Islands and Rose Atoll).
Size structure of populations of important fisheries species in Fagatele Bay. (Source: Green, Miller and Mundy 2005)
Size of targeted fishes at 17 sites on Tutuila in 2002. (Source: Green 2002)
It is critically important to understand the direct relationship between fishing pressure and the character of fish populations in American Samoa. This understanding will likely not be gained until functioning no-take areas are established and monitored. Fagatele Bay National Marine Sanctuary regulations still allow fishing, but put restrictions on how fish are caught. Through its upcoming management plan review process, the sanctuary could become a no-take area and provide a valuable laboratory for understanding the role of fishing in structuring fish populations in American Samoa.
Sea Turtles
A green turtle in American Samoa. The adult green can reach one meter (3 feet) long and weigh over 90 kilograms (200 pounds) and is caught for food and its beautiful carapace, or shell, which is used to manufacture jewelry and other products. (Photo: Gerry Davis).
Samoans traditionally harvested sea turtles for food. Turtle shells were made into jewelry, ceremonial decorations and utilitarian items. Federal and territorial laws now protect turtles and their eggs from harvest in American Samoa's waters and on its beaches. Hawksbill and green turtles are the most common species in the area, and hawksbills nest on beaches of Tutuila. There is one report of a turtle nesting on one of the small beaches of Fagatele Bay.
Sea turtle populations have declined, both locally and throughout the South Pacific, due to harvest, loss of nesting beach habitats and incidental catches in fishing gear. In American Samoa, a few turtles and their eggs are still illegally harvested, but public education programs have helped to make people aware that turtle populations are seriously threatened, some with extinction, if such harvests continue. In 2003, American Samoa established a sanctuary for sea turtles and marine mammals in its territorial waters (0-3 miles offshore).
Marine Mammals
A humpback whale calf photographed in American Samoa in 2004. (Photo: David Mattila)
Southern humpback whales migrate from their Antarctic feeding grounds to American Samoa to calve and mate between July and October. Some individuals documented in American Samoa waters have also been recorded in other parts of the South Pacific, but their migratory patterns within the region are unclear. Other marine mammals, such as sperm whales, rough-toothed and spinner dolphins, and false killer whales occur in American Samoa's waters. NOAA initiated annual marine mammal surveys around Tutuila in 2003. Photographs are taken of flukes and DNA analysis of tissue samples allows comparisons with populations in other regions. Whale populations in American Samoa show low incidence of fishing gear entanglements.
Summary Assessment of Living Resources Conditions
The following information provides an assessment by sanctuary staff and American Samoa marine researchers of the status and trends pertaining to the sanctuary's living resources:
What is the status of biodiversity and how is it changing?
Biodiversity in the Fagatele Bay sanctuary does not appear to be changing. Fish diversity in Fagatele Bay is higher than most other sites on Tutuila. However, individual numbers of some fish species are lower than expected.
What is the status of environmentally sustainable fishing and how is it changing?
In spite of restrictions on fishing, the difficulties of enforcement allow illegal fishing in Fagatele Bay to occur; this appears to have caused declines in some grouper, wrasse, and snapper populations. At present, fish populations are dominated by surgeonfish and parrotfish. While continued fishing may cause further declines, populations currently do not appear to be changing.
What is the status of non-indigenous species and how is it changing?
Taxonomic studies of marine species present in American Samoa (including Fagatele Bay) have found non-indigenous and cryptogenic (of uncertain origin) invertebrate and algae species, but these mainly occur in Pago Pago Harbor and are not considered to significantly impact Fagatele Bay sanctuary. Certain invertebrates, such as zoanthids, have been known to rapidly colonize disturbed reef surfaces, slowing the recovery of coral populations.
What is the status of key species and how is it changing?
Fishing has reduced the size and number of predatory fish species, particularly grouper and snapper, to the extent that large individuals are rarely seen; at present, their population levels do not appear to be changing.
What is the condition or health of key species and how is it changing?
Disease has increasingly afflicted some corals and coralline algae and there is concern that these additional stressors could reduce the reef's ability to recover from natural disturbances. In addition, abundant herbivorous fishes keep fleshy algae populations low.
What are the levels of human activities that may influence living resource quality and how are they changing?
Illegal and legal fishing, including primarily subsistence and artisanal fishing, continues to remove large fish. Even though subsistence fishing appears to be developing, population recovery has not been observed. It is unclear what other factors, including illegal fishing. may be hampering recovery.
Living Resources and Trends
Status: Good Good/Fair Fair Fair/Poor Poor Undet.
Trends:
▲ Conditions appear to be improving.
- Conditions do not appear to be changing.
▼ Conditions appear to be declining.
? Undeterminted trend.
N/A Question not applicable.
| # |
Status |
Rating |
Basis For Judgement |
| 9. |
Biodiversity |
|
All species present but some in low numbers |
| 10. |
Extracted Species |
|
Fishing has removed large fish |
| 11. |
Invasive Species |
|
Some non-indigenous algae and invertebrates may be present |
| 12. |
Key Species |
|
Reduced number and size of certain predatory fish species |
| 13. |
Health of Key Species |
|
Coral and coraline algae diseases
|
| 14. |
Human Activities |
?
|
Illegal and legal fishing continues to remove large fish |
Maritime Archaeological Resources
No marine archaeological artifacts have been found in Fagatele Bay National Marine Sanctuary.
Maritime Archaeological Resources and Trends
Status: Good Good/Fair Fair Fair/Poor Poor Undet.
Trends:
▲ Conditions appear to be improving.
- Conditions do not appear to be changing.
▼ Conditions appear to be declining.
? Undeterminted trend.
N/A Question not applicable.
| # |
Status |
Rating |
Basis For Judgement |
| 15. |
Integrity |
N/A
|
No documented underwater archaeological sites |
| 16. |
Threat to Environment |
N/A
|
No documented underwater archaeological sites |
| 17. |
Human Activities |
N/A
|
No documented underwater archaeological sites |