Chapter 9 Tropical and Subtropical Shallow Seas Coral

Chapter 9 Tropical and Subtropical Shallow Seas Coral reefs, mangrove stands, and seagrass meadows provide homes and attachment sites for countless marine organisms in shallow tropical oceans. Copyright © 2004 Jones and Bartlett Publishers

Chapter 9 Coral Reefs • Anatomy and Growth – Coral reefs are created by many species of colonial cnidarians. These anemone-like polyps produce a Ca. CO 3 skeleton in a great variety of sizes and shapes.

Chapter 9 Coral Reefs • Anatomy and Growth Fig. 9. 1 Extended polyps of a coral colony. The numerous light-colored spots on the tentacles are batteries of cnidocytes (Courtesy of T. Phillipp) Fig. 9. 2 Cross section of a coral polyp and a calcareous corallite skeleton. The living coral tissue forms a thin interconnection, the cenosarc, over the surface of the

Coral Reefs • Anatomy and Growth Fig. 9. 3 Coral exhibit a large variety of growth forms. Chapter 9

Chapter 9 Coral Reefs • Coral Distribution – Living coral reefs usually are located • within 30º latitude of the equator • in water that averages at least 20ºC • on the eastern sides of most continents • within the photic zone

Chapter 9 Coral Reefs • Coral Distribution Fig. 9. 5 Distribution of reef-forming corals, by number of genera. Black lines indicate continental barrier reefs. Light blue <20 genera Medium blue 20 -40 genera Dark blue > 40 genera

Chapter 9 Coral Reefs • Coral Ecology – Reef-building corals contain a mutualistic single -celled dinophyte that provides photosynthetic products to the coral to aid in its survival and growth.

Chapter 9 Coral Reefs • Coral Ecology Fig. 9. 6 Exchange of materials between zooxanthellae and their coral host.

Chapter 9 Coral Reefs • Coral-Reef Formation – Charles Darwin was the first to suggest that coral reefs are sequential developmental stages in the life cycle of a single reef: • fringing reefs • barrier reefs • atolls

Chapter 9 Coral Reefs Fig. 9. 8 The developmental sequence of coral reefs, from young fringing reefs (left), to barrier reefs (center), and finally to atolls (right).

Coral Reefs Chapter 9 • Coral-Reef Formation Fig. 9. 9 Volcano chains along the Hawaiian Island-Emperor Seamount are carried, in a conveyer-belt fashion, north into deeper water by the movement of the Pacific Plate.

Chapter 9 Coral Reefs • Reproduction in Corals – Corals reproduce in a great variety of ways, both asexually and sexually. Most sexually reproducing corals are hermaphroditic spawners.

Chapter 9 Coral Reefs • Zonation on Coral Reefs – Wave force, water depth, temperature, salinity, and a host of biologic factors vary greatly across a reef and result in both horizontal and vertical zonation of the species that form the reef.

Coral Reefs Chapter 9 • Zonation on Coral Reefs Fig. 9. 12 Cross-sectional zonation of an atoll.

Chapter 9 Coral Reefs • Zonation on Coral Reefs (a) plate coral, Acropora (b) brain coral, Diploria (c) staghorn coral, Acropora Fig. 9. 15 Variations in coral growth forms from the Solomon Islands.

Chapter 9 Coral Reefs • Coral Diversity and Catastrophic Mortality – Reefs worldwide are threatened by human activities, succumbing to pollution, destructive fishing practices, bleaching, and a host of diseases.

Chapter 9 Coral Reefs • Coral Diversity and Catastrophic Mortality. Fig. 9. 17 External symptoms of black-band disease on coral. Fig. 9. 18 Effect of coral bleaching on a Caribbean coral head.

Coral-Reef Fishes Fig. 9. 19 General habitats of some common reef fishes on a tropical Caribbean reef. Chapter 9

Chapter 9 Coral-Reef Fishes • Coral-Reef Sharks and Rays – Reefs worldwide are dominated by • benthic orectolobid sharks (nurses, wobbegongs, and bamboosharks) • and more typical pelagic carcharhinid sharks (blacktips, whitetips, tigers, and reefs sharks).

Coral-Reef Fishes Chapter 9 • Coral-Reef Sharks and Rays Fig. 9. 20 Dermal flaps around the mouth of a wobbegong, a benthic shark.

Chapter 9 Coral-Reef Fishes • Coral-Reef Teleosts – About 50% of all living vertebrates are teleost fishes, and many of these fishes inhabit coral reefs. Fig. 9. 21 Close-up of a small coral head with some of its many associated fish species.

Chapter 9 Coral-Reef Fishes • Coral-Reef Teleosts – The great diversity of fishes have evolved numerous symbiotic relationships such as inquilinism and cleaning behaviors.

Coral-Reef Fishes Chapter 9 Fig. 9. 27 a A well-camouflaged scorpionfish, Scorpaena (Courtesy of T. Phillipp).

Chapter 9 Coral-Reef Fishes • Coral-Reef Teleosts Fig. 9. 24 Clownfishes, Amphiprion, hovering near their host anemone (Courtesy of T. Phillipp). Fig. 9. 26 A small wrasse, Labroides, cleaning external parasites from a lionfish, Pterois (Courtesy of C. Farwell).

Chapter 9 Coral-Reef Fishes • Coral-Reef Teleosts – The brightly colored patterns of coral-reef fishes illustrate the advertisement, disguise, and concealment roles of brilliant coloration in a coral-reef environment.

Coral-Reef Fishes Chapter 9 • Coral-Reef Teleosts (a) (b) Fig. 9. 28 Disruptive coloration pattern of two species of butterflyfish, Chaetodon (a. courtesy of T. Phillipp).

Chapter 9 Coral-Reef Fishes • Coral-Reef Teleosts – About one fourth of all reef-fish species place sticky benthic eggs in a guarded nest on the reef.

Chapter 9 Coral-Reef Fishes • Coral-Reef Teleosts – The great diversity of reef fishes results in sexual systems that range from species with separate sexes to simultaneous and sequential hermaphrodites.

Coral-Reef Fishes Chapter 9 • Coral-Reef Teleosts Fig. 9. 35 Male and female “bluehead” wrasses in their initial yellow phase. Fig. 9. 36 Terminal-phase bluehead male.

Some Tropical Marine Tetrapods Chapter 9 • Tropical Marine Reptiles – The 100 or so species of sea snakes are closely related to the highly venomous cobras, coral snakes, and kraits. Most sea snakes are highly derived and are able to complete their entire life cycle at sea, remaining underwater for 8 hours or more.

Some Tropical Marine Tetrapods Chapter 9 • Tropical Marine Reptiles – Most sea turtles (seven species are known) frequent coral reefs and seagrass meadows, often navigating over great distances to return to preferred nesting beaches.

Some Tropical Marine Tetrapods Chapter 9 • Tropical Marine Reptiles Fig. 9. 41 The leatherback sea turtle, Dermochelys coriacea.

Some Tropical Marine Tetrapods Chapter 9 • Mammalian Grazers of Seagrasses – Manatees and dugongs are the only herbivorous marine mammals. They use their prehensile snouts to graze on a wide variety of sea grasses and other plants.

Some Tropical Marine Tetrapods Chapter 9 • Mammalian Grazers of Seagrasses Fig. 9. 43 The Caribbean manatee manipulating plant food with its snout vibrissae and flippers.