Thailand still offers some amazing
snorkeling opportunities. Despite many areas being damaged by
anchors, the coral around some of the more southern islands is in very
good shape. We know many secret spots where we've never seen others
snorkeling. Our Trang and Tarutao trips are especially good for
off-the-beaten-path underwater exploration.
Snorkeling in the waters of Thailand is incomparable. There
are at least three times as many reef-dwelling fish and types of coral
than there are in the Caribbean!
Our kayaks allow us to explore reefs from a different vantage
point. A kayak is very easy to pull up on a beach. Once beached,
you can slip out into the water to explore. Not only that, but can you
see almost everything from your kayaks if' the water is calm enough.
That's a special treat. We've had many occasions when we were all
paddling extremely slowly, everyone's heads looking over the sides of
their kayaks.
Our favorite snorkeling destination is Tarutao
Marine National Park. Our
other spots lie in the islands of Trang
province. They offer some pretty good snorkeling opportunities.
Trang's coral is almost all dead thanks to fishemen dropping their anchors
directly on the coral and to tourists walking on the live coral. There
are still a few good patches left however.
These
(below) are the most common fish families.
They make up 60% of
all fish species found in Southeast Asian waters.
| Fish
Wrasses Gobies Butterflyfish Damselfish Snappers Parrotfish Pipefish Surgeonfish Groupers & Anthias Blennies Cardinalfish | Family
Labridae - approximately 170 species Gobidae - approximately over species Chaetodontidae - approximately 60 species Pomacentridae - approximately 150 species Lutjanidae - approximately 50 species Scaridae - approximately 50 species Syngnathidae - approximately 50 species Acanthuridae - approximately 50 species Serrandidae - approximately 100 species Blennidae - approximately 80 species Apogonidae - approximately 100 species |
The Coral Reef System
If you have never had the opportunity to view the coral reefs of Thailand, you have missed a world of mystery and wonder. Over 200 species, belonging to 75 genera, have been recorded in the waters around Phuket alone. 60 species have so far been noted in the gulf of Thailand. There are literally thousands of other inhabitants in, on and around the reefs. Thus the first feelings that one gets of a coral reef is that it is pure chaos. It appears to be evolution gone wild, a madhouse of colors, shapes and patterns. The fact is however, that there is organization to all of this. Just as the mangrove forest and its many inhabitants rely on each other, so do the inhabitants of the reefs.
Definition
Corals are hollow-gutted flower-like animals with hard exoskeletons into which they can retreat when threatened. They could also be described as tentacles at the top of a tube-like body. The polyps (the actual tentacled coral animals) are attached to the hard mass of the reef by basal disks. The corals are protected by the cup-like cells of calcium carbonate (the actual "rock" which makes up the reef) which they secrete and which over time are deposited one atop the other to build up the reef. The reef may be hundreds of meters thick. The living colony itself, however, is only a thin skin of polyps growing on the matrix of the dead substratum (the calcium carbonate which lie beneath and supports further growth -- the foundation).
An interdependent system
The well-being of the coral reef, as a whole, depends upon the
well being of the wide range of different organisms. These organisms in
turn are sustained by the reef itself. The entire reef can be interpreted
as a mass of interdependent creatures. We normally think of the hard coral
as one animal, but in reality it is a colony of mutually dependent organisms.
For example, through a network of connecting stomach extensions, food
is shared out all over the colony, with each polyp both contributing to
and sharing in the general welfare. The reef itself then, can be thought
of as a whole creature with its own ways of capturing food and creating
a suitable environment for future generations of inhabitants.
Corals also have a symbiotic relationship with an algae called
zooxanthella. This algae lives within the tissue of the reef-building
coral. The algae contributes to the calcification capability of corals
by extracting carbon dioxide from the animal's body fluids. This increases
the concentration of the carbonate ion needed for the precipitation of
calcium carbonate. This relationship represents the interdependence of
the system whereby both parties benefit. The coral contributes to the
relationship by providing a supply of nutrients to the zooxanthella.
Corals host a variety of other organisms. These massive formations
also offer protection to a surprising assortment of fish, worms, snails
and shellfish. Some fish benefit from the variety of cleaner shrimp and
cleaner fish that set up cleaning stations on the coral reefs. These are
an essential part of the well being of many larger fish on the reef due
to the fact that they remove parasites and infectious tissue. This, of
course, is added to the other major benefit that larger fish get from
the reef, that being, the direct feeding on smaller prey.
Reproduction & Growth
Coral may
sexually reproduce continuously or once a year. Some may only spawn
during the lunar period. Fertilized eggs develop into the free-swimming
plankton called planula larvae. With further development, the larvae settle,
attach to the bottom and change into young adults with 6 tentacles and
a basal disc for attaching to the substrate.
Growth comes about as the coral colony expands in size by the budding
of new polyps. Budding may occur at the base or at the oral disc of old
polyps.
Feeding
Although
there are many exceptions, most corals feed at night and contract
during the day. Corals feed like sea anemones. The prey size ranges from
small fish down to small zooplankton, depending on the size of the polyps.
Corals continuously feed at night in correspondence to the vertical migration
of plankton. Digestion is rapid. Corals store their food in the form of
fat and glycogen. Armed with stinging cells, or nematocysts (spring-loaded
capsules containing harpoon-shaped barbs on filaments), the tentacles
are employed first to trap, incapacitate, and finally convey zooplankton
to the mouth. Fish dart in to feed on the exposed polyps when the polyps
are feeding on the plankton.
Communication
Each polyp is able to communicate with neighboring polyps. This can be seen by touching one polyp in a coral colony, and watching its neighboring polyps contract. This may reflect an interconnecting nerve network within the coral colony.
Light
Various colors appear in coral. This is due to the intensity of the light in the coral reef. Sometimes, corals of the same species differ in color. If you dive deep enough, beyond the range where there is enough light to support photosynthesis, you cease to find living hard corals. The greatest depth at which coral growth can take place is 150 meters. The upper seaward slopes are usually the most productive parts of the system, with most of the basic food production and deposition of the limestone skeleton taking place here. Bytheway, as an interesting little side note, red reef fish are camouflage at night.
Mangrove's role in reef preservation
Corals
are acutely sensitive to changes in their environment. Mangrove destruction
for charcoal or building material adds sediment to the waters. Coral is
extremely sensitive to sediment. Mangrove forests collect the sediments
in the water. Scientists are just now beginning to realize how the mangroves
do this. They have come to realize that the flood tide (incoming or rising)
brings in the sediment. The mangled roots of the trees create areas of
water turbulence. The sediment comes in on the rising tide and the sediment
is trapped. The settled sediment is not re-entrained at ebb (outgoing
or falling) because the high vegetation density (mangled root systems)
inhibits currents which are too sluggish to erode the sediment. In other
words, the sediment comes in with the tide, is trapped in the root systems,
but the ebbing tide is not capable of taking all of the sediment back
out to sea. Thus the mangrove forest is an important part of the coral
reef by ways of sediment entrapment. Furthermore, the removal of mangrove
trees increases the amount of sediment in the sea. All of the sediment
that has been trapped by the mangrove in forming the mudflats is then
washed into the sea. If you want to see the pretty coral and obtain food
from the seas, then protect the mangroves.
An Ending... or the Chance for a New Beginning?
The reef is an amazing interdependent system of living organisms.
Each creature has its place and, as we saw, corals actually act for the
betterment of the entire by sharing food and contributing to the growth
of the reef itself. There is however, one creature which is capable of
destroying this underwater wonderland -- humans. Much of what was once
a virgin underwater jungle has been exploited to the point of nearly complete
destruction. This is a global problem. Longtail boats take tourist to
beautiful beaches then drop their anchor directly on the coral that the
tourists are coming to see. Souvenir collecting tourists then forage for
goodies to take home. Run-off from hotels disperse tons of chemicals and
waste into reefs. Various damaging fishing methods such as dynamiting
and poisoning have destroyed more than just the fish population. Vast
areas of brightly colored coral have all but disappeared from many reefs.
It is possible for a reef to returning. However, if the original
causes of the reef's destruction are still taking place, there is little
likelihood that a healthy reef will return.
Responsible tourists can have a big impact, a positive impact,
on the future of Thailand's reefs. Unfortunately, natural treasures are
only important if they generate income for a country. PaddleAsia tours
practice low-impact touring. We don't alter anything... we just
look and appreciate the wonders that are still available to us. Help us
preserve what is left.
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Contact
us
9/71
Moo 3 Thanon Rasdanusorn, Ban Kuku, Phuket 83000
Tel/fax: +66 76 216145 tel: +66 76 240952
Dave's mobile: 01 8936558
Tanya's mobile: 01 7974775
Related web sites: PaddleAsia.com
| Birding in Thailand | Thailand
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March 6, 2008
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