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Mighty Mangroves |
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 ral history tells of the arrival of the first
humans on Pohnpei. Upon seeing a mangrove tree, a man cried 'Ahk!' in
his surprise. Thus, the mangrove was named ahk, which derived the
more specific names, akalel(1)
and akapah(2).
One of Pohnpei's most interesting biological zones, the naniak
(na·nee·yak)
or coastal
swamp forest, covers an area of more than twenty-one square
miles. Classifying the naniak as either land or sea is difficult, for it
is a bridge between the two. Here, sea meets shore in a complex intertwining
of animal and plant life. The
bulk of the naniak is composed of woody shrubs and trees, such as the
mangroves, xylocarpus, and others,
that have adapted to life in soft, oxygen-poor, waterlogged sediment. This lack of oxygen in the soil is combated by
unique root
systems above ground. All mangrove species have varying types of
aerial roots (bow-like or knee-like), which arch away from the trunk sometimes several feet above high tide level.
As well as helping to support the tree and keep it upright, the roots serve the function of providing oxygen to the plant. Some species also have spike-like
pneumatophores ---vertical extensions of the shallow
roots---that stick up from the soil to access oxygen above the water level. As much as 24% of the total biomass of a
mangrove tree might be made up of aerial roots.
Pohnpei’s naniak has three
zones, based on the conditions and types of species found; the landward
zone, the inter-tidal
zone and the outer seaward fringe. The seaward fringe is made up almost exclusively of the more-hardy
Rhizophora cousins, that can survive in nearly pure seawater. The inter-tidal zone is predominately koatoa and
weingal with small stands of
oriental mangrove and nipa
palm. The landward zone is the most diverse by far. It contains all the species of the other regions as well as
trees less tolerant to salt, like the cannon-ball mangrove, the looking glass tree,
hibiscus and a host of lianas and creepers.
The naniak plays an essential part in the
ecological system on Pohnpei. Ancient Pohnpeians called
mangroves the stabilizers of the shore, because they protected the land from erosion.
The forests also trap sediment and freshwater run-off that would foul
coral reefs further out. Additionally, they serve as nurseries for a myriad of
finfish, shellfish and birds.
Mangrove crabs(3) are common in the silty water beneath the twisting and
knotted trees. Snappers(4), shrimp, worms, snails and other small crabs all make these
forests their home. Ants and spiders dwell in the forest canopy and termites
nest in the trunks of some trees. The swampy, still water is a paradise for mosquito larvae, which also help to feed small fish like the mudskipper. Transient birds,
such as herons and kingfishers, stalk the shallows, searching for tasty
morsels. Terns, broadbills, noddies and starlings are also to be
found. The high, tangled canopy is a prime roosting location for
giant fruit bats.
Mangroves
are
themselves a valuable resource to Pohnpeians. The
hard wood of the trees, which can grow as tall as 100 feet, is
used in construction, for decorative carving and as a source of charcoal, resins
and fuel. The leaves of certain trees are utilized as traditional
medicines.
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Agriculture & Agroforestry
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The
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Plants
& Their Uses
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Examined
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 (1)
AKALEL (a·ka·lel) Rhizophora mucronata is a variety of mangrove with looped prop roots.
(2) AKAPAH
(a·ka·pah) Rhizophora apiculata is another mangrove species similar to
akalel.
AMAZING
ADAPTATIONS
Many
mangrove species deal with seawater by depositing the salts on
their leaves and bark, which are eventually shed. To avoid the loss of
precious moisture, leaves also tend to be small.
 Mangroves germinate through pod-like
propagules, that fall from the branches into the water below. The propagules often float for some time before anchoring themselves in the sediment. They can float viably for up to a year. Because different species produce different size
propagules, a process of segregation tends to occur in the naniak. Species with smaller propagules tend to thrive closer to shore, while those with large propagules grow further out in deeper water.
 (3)
MANGROVE
CRAB (Scylla serrata) is a large species, abundant in the naniak and prized for its meat. It dines on the leaves of Rhizophora
and the Oriental Mangrove. Pohnpeians call it elimoang
(e·lee·mahwng).
(4) SNAPPERS are a reddish fish species that often inhabits the coastal shallows. The
Pohnpeian name is asimel
(a·see·mel).
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- Text
by Alex Zuccarelli 2003.
- Picture credits:
R. mucronata roots, R. apiculata
leaves, R. mucronata (akalel) propagule photos
courtesy of Ria Tan, originally published on Mangrove and Wetland Wildlife of
Sungei Buloh Wetlands Reserve and Guide to the Mangroves of
Singapore. Oriental
mangrove propagule photo courtesy of Gary Carr
of University of Hawaii ©G. Carr. Mangrove crab
photo source unknown. Xylocarpus
roots photo courtesy of Robert Roberts of the
Micronesia Zone ©1993.
Koatoa & Oriental mangrove blossom photos (pop-up
window) courtesy of Gary Carr ©Lani
Stemmermann. Gallery; 1 courtesy of Darvin Bothe ©1999, 2 courtesy of Anthony Jones
©1997-2000.
All other photos, images, and maps property of Alex
Zuccarelli.
- All photographs
on this page were used with the written permission of
their perspective owners, except where otherwise
indicated.
Primary
Sources
- Ashby, Gene
1993. Pohnpei: Island Argosy. Rainy Day Press: Eugene.
- Bernart, Luelen, John L. Fischer, Saul H. Riesenberg and Marjorie G. Whiting, translators and editors
1977. The Book of Luelen. National University Press: Canberra.
- Castro, Peter & Michael E. Huber
2000. Marine Biology, 3rd Edition. McGraw Hill.
- Duxbury, Alyn C., Alison B. Duxbury & Keith A.
Sverdrop.
2000. An Introduction to the World's Oceans, 6th Ed. McGraw-Hill Companies, Inc.
- Fischer, John L.
1957. The Eastern Carolines. Pacific Science Board: New Haven.
- Glassman, S. F.
1952. Flora of Ponape. Bernice P. Bishop Museum, Honolulu.
- Hogarth, Peter J.
1999. The Biology of Mangroves. Oxford University Press: Oxford.
- Levy, Neil M.
1996. Micronesia Handbook. Moon Publications, Inc.: Chico.
- Merlin, M., D. Jano, W.
Raynor, T. Keene, J. Juvik & B. Sebastian
1992. Tuhke en Pohnpei (Plants of Pohnpei). Department of Education, Pohnpei State, Office of Historic Preservation, FSM & Environment and Policy Institute, East-West Center, University of Hawaii.
- O’Connell, James F., Saul H.
Riesenberg, Ed.
1972. A Residence of Eleven Years in New Holland and the Caroline Islands (1820’s). Australian National University Press,
Canberra
On-Line Resources (in no particular order)
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