May 31, 2012
By Mavis McRae and Kip Evans
|Ann Luskey with Stingray (c) Kip F. Evans/Mission Blue|
Sirenuse headed back into open water on Friday night for the 10-hour journey north from Hawksbill Cay to Conception Island. After a somewhat bouncy night, we awoke to sunshine and gin-clear blue water. The island is home to one of the newer marine protected areas in the region, Conception Island National Park. Covering over 25,000 acres, the park is an important sanctuary for migratory birds, nesting sea birds and green turtles.
As it became evident that the weather was going to hold, we loaded our equipment and boarded the tenders, excited to experience the Bahamian reefs in bright sunlight. The first dive took us to the wall, a stunning drop off with colorful corals, sponges and sea fans. Unfortunately we saw relatively few fish and only one small shark in the area.
|Life Springs from Dead Coral (c) Kip F. Evans/Mission Blue|
The second dive took us to Southhampton Reef, an area dominated by enormous stands of dead, but still intact elkhorn coral. These hard corals, likely hundreds of years old, reached up from the 35 foot sandy sea floor to the surface, forming a maze of valleys and channels.
The Elkhorn coral with their cannon sized branches offer refuge to a wide variety of fish, including parrotfish, grouper, fairy basslets and other tropical beauties. Unfortunately, this old growth forest is nearly dead, covered by several species of algae that choke-out the coral polyps responsible for new growth by secreting calcium carbonate. The algae grew unchecked when the sea urchins that previously inhabited the reef were devastated by disease in the 1970’s. Additionally, a decrease in grazing herbivores, caused by overfishing and other pressures, added to the demise of this intricate marine ecosystem. A few areas of new life have sprouted from some of the dead Elkhorn corals, giving rise to new hope. With continued preservation efforts, this and other breath-taking Bahamian reefs may return to their former beauty. Groups such as the Nature Conservancy are key to working with local governments and scientists working in the area to bring this key Hope Spot back to its healthy natural state.
|Sargassum (c) Kip Evans/Mission Blue|
Today as we headed back from our afternoon dive, Sylvia noticed patches of Sargassum floating on the surface. We had seen several patches during our trip, but this was the first opportunity to collect a few specimens to share with the group. As we pulled a few choice patches on-board, Sylvia quickly pointed to dozens of small animals including a beautiful shrimp and Sargassum frogfish. Excited to see these creatures in more detail, we took a couple of small patches back to the Sirenuse and looked at them in a translucent container. Peering through a thin acrylic window, we saw shrimp in all shapes and sizes and the frogfish Sylvia had seen on the boat. It’s body blended in perfectly with the weed’s floats and blades and it was easy to see that this fish was a master of disguise. After snapping a few images, we carefully returned everyone back to the water where they would continue their drift with the current.
|Tank for Sargassum (c) Christine Guinness|
Sargassum rafts are critical habitat for entire communities of fish and invertebrates, including the endangered Sargassum fish. They are found in offshore areas where calm conditions are allow individual plants to collect and build large mats. There are six species of Sargassum, including Sargasso natans and Sargasso fluitans. Like other algal species that depend on photosynthesis, sargassum plants rely on small gas-filled floats called pneumatocyst to keep them within reach of the sun’s rays. Mission Blue looks forward to mounting a future expedition to the Sargasso Sea, another of Dr. Earle’s Hope Spots in the future. The Sargasso Sea is a colossal subtropical mass of water that slowly turns clockwise in response to movement of the oceanic currents surrounding it. Within this North Atlantic gyre, the free-floating brown algae (Sargassum spp.) aggregates and grows in large floating mats fostering high biological diversity.
|Sylvia Earle with Elkhorn Coral (c) Kip F. Evans/Mission Blue|
|Christine Guiness (c) Kip F. Evans/Mission Blue|
|Lisa Robertson (c) Kip F. Evans/Mission Blue|
|(c) Christine Guinness|
|Floating Sargassum (c) Sylvia Earle |
|(c) Sylvia Earle |
|Eleanor Phillips – TNC with Sargassum (c) Sylvia Earle|
|Expedition members head to dive site (c) Kip F. Evans/Mission Blue|
|(c) Christine Guinness |
|Sargassum Frogfish (c) Kip F. Evans/Mission Blue|
|Sargassum Shrimp (c) Kip F. Evans/Mission Blue|
|M/Y Sirenuse (c) Kip F. Evans/Mission Blue |
|M/Y Sirenuse(c) Kip F. Evans/Mission Blue|