Environment : Coral

Coral

Coral

Coral

CORAL

Caribbean coral reefs are warm, clear shallow ocean habitats, comprised of only 8% surface area of the world’s coral reefs and are greatly dominated by Fringing reef’s. A coral reef habitat provides shelter for many aquatic animals, such as sponges, fish, jellyfish, sea anemones, crustaceans, turtles, sea snakes, eels, snails and mollusc’s.

Over the last 30 years Caribbean coral reefs have suffered a decline in the overall coral reef health and the productivity of reef fishes due to deteriorating water quality and the elevation in water temperature from a variety of manmade causes including: pollution, dynamite fishing, tourism, hurricane’s and reef overuse leading to global warming, ocean acidification and large areas of hard coral being overgrown by algae. The study of coral reef decline is a rapid identifier for climate change because it is affected from such a diversity of sources.

Coral is an animal and each individual coral consists of polyps. A polyp has a simple cup shaped body with a single central opening acting as a mouth and anus. This anatomy draws in calcium carbonate (limestone) from seawater and uses it to form a hard coating for their bodies and to attach to firm substrates such as rock.

For a colony to flourish they require several critical environmental factors, water temperature, salinity, clarity water movement for food and oxygen supply, and a firm base for attachment. Sufficient sunlight is a requirement for photosynthesis to occur and therefore most occurs in the uppermost 200ft layer of the ocean. Coral growth is slow, on average less than an inch each year for the majority of species.

Under times of stress E.g. when the temperature is abnormally high or during a hurricane, a process called ” coral bleaching” occurs. This is when the symbiotic algae, zooanthellae is expelled from the polyps changing the corals colour to white. Ultimately the diversity of the reef is affected.

Coral is classified into the following groups:

“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach

en.wikipedia.org/wiki/Coral

Coral Magazine, Nov/Dec 2010 issue, vol 7, no 6, James M Laurence

www.projectnoah.org/missions/6529308

Fire Coral: Millepora alcicornis on "Man on Fire"

Fire Coral: Millepora alcicornis on "Man on Fire"

Fire Coral: Millepora alcicornis on “Man on Fire

Fire Coral: Millepora alcicornis on "La Jardinera"

Fire Coral: Millepora alcicornis on “La Jardinera

Fire Coral: Millepora alcicornis on "La Jardinera" Growth after 9 months

Fire Coral: Millepora alcicornis on “La Jardinera” Growth after 9 months

HYDROCORALS

These are not actually corals but hydroid colonies that secrete hard calcareous skeletons. They are closely related to jelly fish and stinging anemones. There are two types, Fire Coral and Lace Coral.

FIRE CORAL:

Phylum: Cnidaria

Family: Milleporidae

Fire corals are widespread in the marine environment forming colonies on rock and coral. They are important in reef ecosystems producing protective shelter for many reef creatures. The calcareous skeleton of fire coral appears smooth but is actually covered with a sharp yet fuzzy layer produced by tiny hair-like polyps of the colony that extend through small pores. They contain two types of polyps, Sensory polyps which are the stinging part and Feeding polyps. The gastric cavities of these polyps are connected beneath the surface. They have tiny stinging nematocysts on the tentacles of the polyps and are therefore also named “stinging coral” due to the burning sensation felt when touched with bare skin causing welts and a rash. It is a device developed to fend off predators such as parrot fish who normally nibble on coral. They proliferate rapidly due to reproduction from fragmentation or via producing medusea which release sex cells.

Normally fire corals range from brown to yellow in colouration with white tips. There are 3 structures found in the Caribbean: Branching, Plate and Box coral. Most are encrusting colonies. A good example is the type of fire coral planted for “La Jardinera” and propagated into “Man on Fire” They are known for encrusting on top of coral, particularly Gorgonian fan coral.

“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach

en.wikipedia.org/wiki/Fire_coral

www.news.scubatravel.co.uk/2005/11/stinging-fire-coral.html

reefkeeping.com/issues/2002-11/eb/index.php

Staghorn coral: Acropora cervicornis stage at propagation

Staghorn coral: Acropora cervicornis stage at propagation

Staghorn coral: Acropora cervicornis growth after 9 months

Staghorn coral: Acropora cervicornis growth after 9 months

Staghorn coral: Acropora cervicornis growth after 18 months

Staghorn coral: Acropora cervicornis growth after 18 months

Clubtip Finger coral: Porites porites stage at Propagation

Clubtip Finger coral: Porites porites stage at Propagation

Clubtip Finger coral: Porites porites growth after 9 months

Clubtip Finger coral: Porites porites growth after 9 months

 

STONY CORALS / HARD CORALS

Phylum: Cnidaria

Order: Scleractinea

These are the building blocks for tropical coral reefs. The types of Stony coral structures range from Branching corals, Encrusting and boulder corals, Brain corals, Fleshy corals, Leaf or sheet coral to flower or cup corals.

They use the calcium carbonate each polyp produces to form structures called “corallites” as protection for their bodies. These are laid down in radiating ridges called “septa” and these septa project above the overall colony forming distinctive rims. Each polyp consists of bunches of six tentacles surrounding the mouth while the central axis of the polyp is beneath. The polyps are generally small from 1-3mm in diameter. The polyps are interconnected via horizontal sheets of tissue external to the skeleton, therefore allowing continual circulation of nutrition within the colony members. The corallites grow to form colonies and each colony reproduces by asexual budding, adding more polyps therefore continually increasing in size over time. A variety of sizes shapes and design can be seen depending on the individual species. Normally Caribbean hard corals consist of polyps which retract into their protective coating during the day and at night they extend out their body and tentacles to feed.

The colour of a hermatypic (containing zooanthellate symbiotic algae) colony is typically from a symbiotic relationship with a single-celled algae called zooxanthellae that lives within the polyp’s. The algae assist to stimulate the secretion of calcium carbonate from the polyp’s. Without the algae the coral grows colourless and a white skeleton is seen beneath. Hermatypic colonial corals contribute substantial amounts of calcium carbonate to the reef, and therefore are termed “reef-building corals.” Coral with the endosymbiant grows three times faster than the ahermatypic (without zooanthellate) colonies. However it does mean that they are restricted to shallow well light water with a narrow temperature range of 17-34 degrees Centigrade.

Examples of Hard corals propagated on La Jardinera and their rapid growth:

Elkhorn coral, Family: Acroporidae, a complex structure with many large branches resembling antlers. They grow on average 5-10cm per year and are one of the major contributors to reef structures as well as producing refuge for several species of fish and crustaceans.

Staghorn coral, Family: Acroporidae, a Branching coral with cylindrical branches found in waters up to 30meters deep. It is one of the three most important corals in the Caribbean ocean for reef growth and fish habitat. Branches can break off and reattach to a new surface have the ability to start a new colony.-

Finger coral, Family: Poritidae, the third most important reef building contributors when found in large colonies however growth is much slower.

en.wikipedia.org/wiki/Elkhorn_coral

“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach

en.wikipedia.org/wiki/Scleractinia

en.wikipedia.org/wiki/Staghorn_coral

Propagated Gorgonian Fan coral in competition with Fire Coral at the base on "La Jardinera"

Propagated Gorgonian Fan coral in competition with Fire Coral at the base on “La Jardinera

Propagated Gorgonian Fan coral in competition with Fire Coral at the base on "La Jardinera"

Propagated Gorgonian Fan coral: Gorgonia ventalina on "La Jardinera"

Propagated Gorgonian Fan coral: Gorgonia ventalina on “La Jardinera

SOFT CORALS / OCTOCORALLIANS

Phylum: Cnidaria

Order: Gorgongacea

This group of corals are commonly called Gorgonians and include Sea rods, Sea whips, Sea plumes and Sea fans. They are termed “soft” due to the lack of a hard rigid skeleton and instead they have a central skeleton composed of fused calcareous spicules. The skeleton is surrounded by a gelatinous material and to this the polyps are embedded within. They are termed “Octocorallians” because their polyps have eight tentacles, each have tiny feather-like projections called pinnules that are extended out to feed and give the colony a bushy appearance. The polyps carryout their task of filter-feeding when the fan faces into the prevailing current, maximising the food supply Octocorals also have a symbiotic relationship with the algae zooxanthellae or occasionally with colouring minerals in the calcareous spicules of the colony. They range in various colours, often purple, yellow or red and their structures can be whip-like, bushy or encrusting. The anatomical attachment to a base is often the distinctive factor in determining the species present. Normally this anchorage is to stable unmoving surfaces such as rock rock but it can be mud or sand and are usually in shallow waters. Many organisms take refuge within the fans, including Brittlestars, Hydrozoa and in particular the Pygmy Seahorse will camouflage itself to the fans colouring. However there are a few species of slugs and snails that will predate on Gorgonian Fan corals.

La Jardinera” contains some pots with propagated Gorgonian Fan corals alongside the patio which are to be used for a future propagation sculpture. One pot shown in the photographs adjacent was broken gorgonian fan coral found in the ocean after a bad storm, it was re-potted to grow for future propagation projects. From the image you can see where there is a clear delineation between the gorgonian coral above and fire coral below trying to engulf and colonise on top taking on the shape. This is a common trait of Fire coral.

“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach

en.wikipedia.org/wiki/Gorgonian

www.thesea.org/gorgonian/gorgonian_fan.htm