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View the final Pohnpei postcard
View photos of Pohnpei |
Day 2: Threats to Pohnpei's Corals
Crown of Thorns and Deforestation Adversely Affect Corals
Unfortunately, it’s not all good news for the reefs of Pohnpei. Emre Turak and Lyndon DeVantier have found that while corals on some reefs are in good condition, many reefs inside Pohnpei’s lagoon are stressed by silt and sediment that is washing off the land. They have also found lots of the coral-eating starfish, called crown-of-thorns starfish.
Emre and Lyndon believe that the crown-of-thorns starfish were present here in low numbers for a long time, but recently have been changing Pohnpei’s coral communities, making some coral species disappear, while other coral species become more common. They believe that the starfish populations have become chronic, which may be due to the sediment and nutrient runoff from the land.
Pohnpei is one of the wettest places on Earth with almost 26 feet of rain a year in the highlands! With such enormous volumes of rain and a high elevation, any vegetation loss and deforestation has significant effects on the land’s ability to hold soil in the catchment areas. This means that a lot of silt and sediment washes off the land and into the beautiful lagoon that rings the island. This extra sediment in the water makes it difficult for some corals to survive.
Emre and Lyndon also think that there are extra nutrients washing off the land with the sediment, that help tiny plants in the water to grow and in turn, provide extra food for young crown-of-thorns starfish. This means that more starfish than usual are growing to become adults. Some fish, such as the lethrinid or snappers (known as medi or kasapal in Pohnpei), will eat young crown-of-thorns starfish and help control starfish populations. "Unfortunately, we haven’t seen many lethrinid fishes on Pohnpei’s reefs," notes Lyndon.
The poor water quality and low numbers of fish mean that there are thriving communities of crown-of-thorns starfish eating many of the corals. This combined with the effects of sedimentation, is magnifying the damage to the reefs.
Many of the native forests have been cleared to grow sakau, since the 1970s, the intact forests of Pohnpei have dropped from about 45% of the land area to only about 14% by 2002. Sakau is made into a narcotic drink which is an important part of the Pohnpeian culture.
The clearing of land for sakau farming has recently subsided. This has resulted from the Conservation Society of Pohnpei’s educational awareness and the community volunteers’ monitoring programs focused on the preservation of the upland forests, and a concerted effort by the farmers to halt new agricultural site clearing activities.
Unfortunately, there are other activities which are still causing destructive sedimentation loads to be released onto the reefs. Land clearing and construction for roads, buildings and development remain the major threat to the reef and the fish populations. The numerous dredge sites and continued land development remain the foremost concerns for Pohnpei’s reefs, fisheries and its outlook for the future in general.
In a few places along Pohnpei’s west coast, the scientists have found rich communities of corals which include corals such as Acropora pichoni. They believe that these communities may have been more common in Pohnpei before the immense land clearing caused high loads of sediment to flow into the lagoon.
Fortunately, Pohnpei has established 11 Marine Protected Areas (MPA) to help preserve its coral reefs. These MPAs will boost fish numbers in some areas of Pohnpei and, in turn, may help to reduce the numbers of crown-of-thorns starfish. However, MPAs alone will not be enough to stop the shift in Pohnpei’s reef communities. Better land management is needed to really make a difference to Pohnpei’s coral reefs.
Next: New coral species?
For more information about our work in the Federated States of Micronesia:
- The Nature Conservancy in the Federated States of Micronesia
Scattered across a million square miles of the Pacific Ocean, the Federated States of Micronesia is comprised of 607 tropical islands. - How You Can Help: Donate Online
Support conservation by helping to save the last great places in the Federated States of Micronesia. - How We Work: Global Marine Initiative
Learn more about The Nature Conservancy's marine conservation efforts. Currently we have over 100 marine projects in 21 countries and 22 U.S. states.
