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T. `Aulani Wilhelm News Release 03 |
CORAL RESEARCHERS COMPLETE TRANSECT DIVES AT NIHOA AND NECKER AHEAD OF SCHEDULE
Calm seas and light winds enabled marine biologists to complete their sixth and final dive at Necker Island today in Hawaii's Northwestern Hawaiian Islands, one day ahead of schedule. The two teams of research divers also completed seven rapid ecological assessment dives at neighboring Nihoa atoll yesterday.
Although Nihoa and Necker are two of the largest islands in the Northwestern chain, the reefs immediately surrounding the islands are small, especially as compared to the other atolls and islets the teams will be visiting later in the expedition.
According to principle investigator Jim Maragos from the US Fish and Wildlife Service, "because the reefs are small, fewer fish and other species have colonized them and have been able to survive. This doesn't mean that the reefs are unhealthy, just that they cannot support a large variety and number of species."
"Coral at Nihoa and Necker have a tough time surviving," explained Maragos. "They suffer from constant scouring from swells and currents that rush against nearly all sides of these tiny islands, breaking coral and making it very difficult for new corals to grow," said Maragos. "Because of these circumstances, there is little suitable habitat upon which strong coral colonies can flourish."
Around these islands, there are only submerged reefs, no emergent ones. Most are found at depths of 40 feet or below. On the North side of Nihoa, few corals were found until 70 feet. At nearly all sites surveyed, most of the coral found were low growing, encrusting species that have adapted to high energy environments. The researchers didn't see many branching corals, except for cauliflower coral (Pocillopora).
Except for some fishing line and some small marine debris, there was little sign of human disturbance. An unusual find at both Nihoa and Necker, divers found an uncommon soft, leather coral (Sinularia). This coral is rare in the main Hawaiian Islands and only found in small numbers at places like Okala islet off Kalaupapa, Molokai and fronting the blowhole in East Oahu.
"Over the long-term, these reefs have a marginal existence due to Mother Nature," Maragos predicted. "At any time, a 100 year storm or other major weather occurrence could knock out as much as 95% of the current population, forcing them to re-establish themselves over decades.
"Other natural occurrences such as an explosion in population of a species like the crown-of-thorns starfish, which feed on coral, could also seriously impact the small reefs and make survival difficult," Maragos concluded.