The distance separating the Caribbean and the eastern Pacific in time and space is short, as little as 50 km and around 3.5 million years. This separation has resulted in very different oceanographic settings and coral reefs on both sides of the Central American isthmus. On our Central America cruise we focus on the Pacific coasts of Panama and Costa Rica where there are opportunities for seeing some of the corals during snorkeling outings.
Eastern Pacific reefs are smaller and more dispersed than their Caribbean counterparts. The absence of fossil reefs on the Pacific coast of the Americas may have been due to several factors such as changes in temperature and cooling due to intensified upwelling and warming during El Nino events. In Central America's past geologic history, there was also a period of large shifts in sea level, and so most eastern Pacific coral reefs are late starters (with growth beginning less than 2,000 years ago).
Corals themselves are small marine animals related to jellyfish and anemones which feed on plankton (microscopic plants and animals) and other suspended food particles with arm-like tentacles feeding a centrally located mouth. Most hard corals also host symbiotic algae, in a long-standing and successful partnership. Algae provide the corals with food through photosynthesis, and in turn, corals secrete hard calcareous (aragonite) exoskeletons, giving them structural rigidity. These colonial "hard corals" form elaborate finger-shaped, branching, or moundshaped structures and can create masses of limestone that stretch for tens or even hundreds of miles.
Coral reefs have been termed the "rainforests" of the ocean and are typically restricted to relatively shallow, warm tropical waters between latitudes 30 north and 30 south and require constant temperatures (77- 85° F/25 – 29° C), water clarity (for photosynthesis to take place) and minimal sea level change; all three of these requirements are difficult to find on the Pacific side of the Central American isthmus because the water in the Eastern Pacific is rich in nutrients that have been brought up to the surface from the deep sea, is often very green with algae and has variable water temperatures. Off Costa Rica there is a strong tropical thermocline (temperature gradient), and in Panama, episodic upwelling is caused by winds blowing across the Panama Isthmus from the Caribbean side. However, there are protected pockets where corals thrive, and some of the areas with coral reefs are on our Central America cruise itinerary; we know where to find them.
Reefs are ecologically important ecosystems and have a high biodiversity that serves as a storage bank of rich genetic resources, and none know better than researchers working around the island of Coiba, Panama. Coiba’s unique location has given rise to an extraordinary biodiversity in its marine life. In the past, this area had an ancient connection with the Caribbean Ocean, as evidenced by related species found in both bodies of water; it is presently situated where several ocean currents mix, both warm and cool, consequently harboring life forms from both, and is home to corals, tunicates, sponges, bacteria, and fungi that are proving to be rich sources of information about natural chemicals. The cyanobacteria—also known as blue-green algae—have yielded Coibamide A, a compound extremely active against cancer cells, named for Coiba. Veraguamide A, an anti-cancer compound named after the Panamanian province of Veraguas and Santacruzmate, an anti-parasitic compound named after the island, Santa Cruz. Recently, scientists from Panama and the U.S. working together have discovered a total of 45 new chemicals that show great promise as cures for cancer and a wide range of tropical diseases.
The undersea life off the shores of Coiba are unparalleled, and on our Panama and Costa Rica cruise we make time to explore the undersea world, one of the world's most fragile and endangered ecosystems.
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