COASTAL ECOSYSTEMS

There can be no doubt that coral reefs are one of the most diverse and productive ecosystems on earth. For their sheer beauty, species richness and numerous biological interactions, coral reefs have few equals in the natural world.

Coral reefs consist of different types of corals and associated organisms such as hundred of fish species, and other invertebrates such as octopus, lobster, shrimp, anemones, sea worms and many others.

Corals may not appear like living things but they are ! They are animals without backbones also known as invertebrates, comprised of a polyp with tentacles and a skeleton. The polyp is the soft part of the organism that resides within a protective limestone skeleton.

There are basically two types of corals : hard and soft. The hard corals are known as reef builders whose protective skeleton is a hard stony structure easily seen in the reef. Thus, the massive coral reefs are actually the dead skeletons of many generations of coral polyps piled on top of each other. Although corals occur throughout the oceans, only the hard corals build reefs in the tropical and subtropical areas. The major reef-building corals are brain corals, small and large star corals, finger corals, elkhorn corals, staghorn corals and the plate corals. The soft corals like the hard corals have a skeleton; however, it is not hard and stony. In Belize, 74 species of hard corals and 36 species of soft coral have been identified.

Coral reefs display beautiful shades of greens, browns and pinks, all due to a large amount of symbiotic microscopic algae called zooxanthellae, growing in the tissue of the coral polyp. The zooxanthellae produce oxygen and other compounds through photosynthesis and they also process the waste materials produced by the coral polyp. The corals, in turn, use the oxygen and compounds to supplement their own feeding. Coral reefs cannot exist in the size and density that they do without the close interdependent relationship with this algae.

Hydrocorals -

These secrete hard calcareous skeletons and include the fire corals which have unusually strong poison in their stinging cells. They are found in a variety of shapes such as tree-like, encrusting, oriental fan or blade-like. For example, Millipora complanata has thin, irregular upright blades.

Octocorals -

These are known as soft corals. Octocorals have a similar appearance to plants. They have flexible, branched stalks that appear to grow from the bottom. Thousands of individual polyps form these colonies. There have been 36 species of octocorals identified in Belize, though there are about 50 known species throughout the Caribbean. They are extremely difficult to differentiate and only a small percentage have been given common names. They can be highly branched, or with a few branches near their base, but the different branches all tend to have similar diameters. They are found in all reef environments. Examples include Plexaura homomalla, Muricea spp. and Briarium spp.

Feather Plumes are soft corals that resemble large feathers which have a long main stalk with smaller side branches that normally oppose each other on a plane. They may grow from a few inches to well over six feet in height. They are also found in all reef environments and an example is Pseudopterogorgin species.

Sea Fans are fan-shaped soft corals growing in a vertical plane. They are highly branched with delicate lace-like patterns. For example, Gorgonia ventalina and Iciligorgia schrammi.

Sea Whips have long, thin stalks resembling whips. If branched, the branches normally occur near the base, such as Ellisellidae species and Pterogorgia species.

Hard corals are the most significant group of corals in terms of reef building. As the coral grows, the polyps secrete a massive external skeleton of calcium carbonate commonly known as limestone. Hard corals can be grouped into the following categories.

Pillar or branching coral -

These corals grow in the form of a cylinder or spiral. The "pillars" can grow to 10 feet. They tend to inhabit the inner fore-reef just in front of the reef crest where huge colonies of elkhorn corals (Acropora palmata) often dominate, or just behind the reef crest where colonies of staghorn corals (Acropora cervicornis) often dominate.

Boulder, mound and knob-shaped corals -

This group is a dominant coral type on the reef and forms the basis of the outer coral reef structure in Belize. Colonies show a variety of growth patterns including huge mountains, domes, boulders, multi-lobed heads or knobs. These corals include Porites asteroides, Montastrea spp. and Madracis spp.

Brain corals -

Brain corals are those corals having ridges and valleys on their surface which resemble the surface of a brain. The colonies are often hemispherical in shape. Brain corals include Colpophyllia natans and Diploria species.

Leaf and plate shaped corals -

These form fragile, thin, leaf-like colonies. They can be a dominant type on some shallow water reefs. Some plate forms are also found in deeper waters. Example includes Agaricia species and Meandrina meandrites.

Fleshy corals -

These corals have polyps that are usually thick and fleshy. The fleshy tissue often hides the coral skeleton, for example, Mycetophylia spp. and Scolymia spp.

Antipatharians -

The skeletons of these "black" corals are often prized as jewelry when hardened by a tanning process. They are generally black in color, uncommon and found mostly in deeper water. Some are plant-like while others are shaped as a single long wire without branches and are called "wire coral", such as Antipathes pennacea.

Reef Formations

Not only are there different species of corals, but they are also aggregate to form different shapes and formations. The types of coral reef formations in Belize are :

Barrier -

The Barrier Reef of Belize is unique and is the largest in the Caribbean and in the western hemisphere. The barrier reef is the largest reef type in Belize. It is a continuous reef that extends 220 kilometers from northern Belize to the Sapodilla Cayes in the south. Zonation of the barrier reef is evident as the distribution of several coral types occurs in specific zones. The back reef zone is also termed the landward side of the reef, followed by the reef crest which may be exposed to air at low tide as well as receiving the greatest physical action of the waves. It is followed by the fore reef where many types of corals grow in patches on cliffs of coral rubble.

Atoll -

These are ring-shaped reefs surrounding a central lagoon. Part of the reef's platform emerges as a group of small islands, which occurs in deep water. There are three atolls in Belize namely Glovers Reef, Turneffe Islands and Lighthouse Reef. Glovers Reef represents one of the best and largest atoll formations in the Caribbean. It supports diverse coral species. Lighthouse Reef features the famous Blue Hole, a natural sinkhole with huge stalactites and stalagmites. The third atoll, Turneffe Islands, is home to some of the best mangrove stands in the country.

Fringing -

Reefs are those that form close to the mainland or to islands, for example, the reef between Placencia and Punta Ycacos. These reefs are more tolerant to sedimentation and fresh water due to their proximity to river mouths. Few coral types make up fringing reefs.

Patch -

Patch reefs range in size from a small clump of coral heads to huge reef structures up to 80 meters wide. They are widespread in the central lagoons of Glovers Reef and Lighthouse Reef and in the barrier reef lagoon. There are also numerous patch reefs in the lagoon of north Turneffe.

Faroes -

Faroes are "shelf atolls", sometimes known as "ringed reefs" (these occur mainly in clusters around Victoria Channel, off Stann Creek's coast) and are an unusual reef type in the Caribbean. They resemble miniature atolls and they form in the lagoon, rather than outside the reef.

Cayes -

Belize has over 1000 islands, ranging in size form a small clump of overwashed mangroves to the large Ambergris Caye. There is no separate definition to differentiate between an island and a caye. The latter is generally referred to as an island with sand and vegetation. If we look only at the larger islands, however, approximately 200-300 cayes find shelter within the Belizean coastal zone.

Eleven types of cayes have been distinguished within the Belizean coastal zone. They are categorized based on whether vegetated or not, type of vegetation and location.

For example, an unvegetated sand caye is Curlew Caye, a vegetated sand caye is Tobacco Caye and Harvest Caye is a coastal barrier caye.

Cayes are very fragile areas as they are prime targets for tourism and other recreational development. Remember that with uncontrolled development irreparable damage can occur.

Mangroves

Belize, like other tropical and subtropical countries, has an ideal climate and other environmental factors such as salinity, tidal fluctuation, sedimentation and wave energy in which mangrove forests thrive.

To many of us, mangroves may seem unappealing, so much that these fertile ecosystems have been seen as perfect dumpsites as well as areas to be drained, filled and cleared for development. Fortunately, their ecological importance has been recognised by scientists around the world, and efforts have been made to protect these productive and delicate ecosystems against encroachment and pollution so thay they can be kept as a link for the interchange with those other ecosystems to which they are intimately connected.

Mangroves are a group of woody salt tolerant trees that are adapted to grow in the intertidal zone. They are highly productive ecosystems which provide essential nursery grounds for many marine species such as fish and lobster. They provide food and shelter for many organisms both above and below the water. They also serve as protection against land erosion and storm damage and act as a buffer zone that filters pollutants and prevents them from reaching the sea

There are four species of mangroves in Belize namely :

Red Mangroves -

Red mangroves (Rhizophora mangle) are easily distinguished by their sprawling prop roots with their most interesting feature being the presence of their cigar-shaped propagules which are not seeds but germinated plants.

Black Mangroves -

Black mangroves (Avicennia germinans) have long cabled roots called pnematophores that protrude out of the soil. Its propagules are bean-shaped.

White Mangroves -

White mangroves (laguncularia racemosa) have roots that are not distinctive; therefore this mangrove's distinguishing feature is its oval leaves that are dented at the tip. The propagules are very small.

Buttonwood -

Buttonwood (Conocarpus erectus) is a tree associated with mangrove forests and has a very distinctive silvery-grayish color. They are found mainly along the boundaries of wetlands or swamps.

Although mangroves have basic common characteristics, they vary structurally in species richness, canopy height, tree density and understory vegetation, based on the degree of harshness of the environment conditions in which they grow. It is not uncommon to see dwarf red mangroves in some areas in the Stann Creek District, in contrast to the beautiful, tall majestic red mangorves along the Temash River in the Toledo District.

Littoral Forest

Seagrass Beds

There are five recorded species of seagrass in Belize namely, turtle grass (Thalassia testudinum) manatee seagrass (Syringodium filiforme), duckweed (Halodule wrightii), Halodule filiforme and Halophila englemanii.

There are four distinct zones within seagrass beds where organisms make a home for themselves. These include organisms in the sediment called infauna, epifauna which live on the sediment, organisms on the stems and leaves called epiphytes or organisms swimming above seagrass referred to as nekton.