Coral Reefs

Queen angelfish (NPS image)

"No sea-lover could look unmoved on the blue rollers of the Gulf Stream and the crystal-clear waters of the reef, of every delicate shade of blue and green, and tinged with every color of the spectrum . . . a sort of liquid light, rather than water, so limpid and brilliant is it." - Commodore Ralph Munroe in 1877

Park visitors may experience a kaleidoscope of colors and frenetic movements. Blue neon gobies and yellow striped porkfish punctuate a background of golden-brown elkhorn corals and swaying purple sea fans. A loggerhead sea turtle takes a breath at the surface as a young nurse shark settles to the bottom.

Corals extend tentacles to trap food particles. (NPS image by A. Bourque)

Tiny coral animals, called polyps, obtain calcium from seawater and use it to build cup-like external skeletons around themselves. Generations of polyps create fantastic colonies that appear in the shapes of flowers, mountains or elk antlers. Colonies of different coral species create the living fortresses we call reefs.

Other reef dwellers include sea whips, sea fans and other soft corals that sway in the current and give the whole reef the appearance of movement. Bright sponges filter small plants and animals from the water. Christmas tree worms burrow into stony coral skeletons, adding tufts of red, orange and purple to the grooved surfaces of brain corals. Algae and other plants are important food sources for fish, shrimp, crabs and a myriad of other animals.

 

Nurse shark glides through a coral reef. (NPS image by A. Bourque)

Like a bustling city, the reef is active day and night. Polyps on the soft corals withdraw as hard coral polyps emerge for a night of feeding. Parrotfish and wrasses wrap up in mucous sleeping bags, as octopi and squirrelfish become active. This "shift change" ensures that the reef's plentiful food supply is utilized around the clock.

 

Queen angelfish (NPS image by A. Bourque).

For many, it is the fish that give reefs their magical qualities. The park is home to an incredible array of over 500 species of reef fish. The diversity of colors, shapes, sizes and behaviors is amazing. Inch long damselfish nip at diver facemasks, attempting to chase them away from carefully tended algae gardens. A green moray hovers nearby, mouth agape, at the entrance to its lair. A variety of fish wait at a "cleaning station" where tiny gobies scour their bodies for parasites. A stoplight parrotfish chomps on coral, devouring algae, polyps and stone in bites. A 500 pound goliath grouper peers out from under a ledge. A pair of spotfin butterfly fish float effortlessly through the water.

There are many unique sponges on coral reefs (NPS image by A. Bourque).

Coral reefs are among the most biologically diverse ecosystems on earth. Every crack and crevice seems to be occupied. Knowledge of reefs is constantly growing. This knowledge will be increasingly valuable as reefs around the world experience problems from pollution, overfishing, boat groundings, climate change, marine debris and disease.

The reefs of South Florida are accessible to millions of people who visit and live in the greater Miami area. For this reason, the reefs are also very vulnerable. When diving, snorkeling or boating, please remember the following tips:

• Tiny coral polyps are fragile and easily damaged by the slightest touch.
• Be aware of where your feet are placed and be careful not to cause damage with fins.
• Use proper nautical charts to avoid running aground.
• Use mooring buoys where available and ensure that anchors are not set in corals.

Simple things you can do to make a difference for the health of the reefs include avoiding anchoring on hardbottom, never tossing debris overboard and retrieving fishing gear and line that gets away from you.