New & Noteworthy: Reefs, NWHI, and Snakes

posted in: May 2007 | 0

A Beautiful Reef — Gone: Last fall took a tremendous toll on three miles of coral reef off the Kohala Coast. The culprit, according to Bill Walsh, a biologist with the state Division of Aquatic Resources, was most likely a combination of natural drainage patterns being screwed up by development and heavy rainfalls on either side of the earthquakes that occurred October 15.

While surveying the reef last December, Walsh saw nothing unusual — just “beautiful reef” as far as the eye could see — until suddenly, “there was mud all over. The sedimentation was very extensive.” The mud covered the sea floor out to depths of at least 80 feet, and it could have been more, Walsh said, but the limits of his equipment didn’t allow him to track it further than that.

In localized squalls before the earthquake, swimming pools in the Kohala Ranch development were reported to have filled with mud, and the gulches carried much of it to the coast. The earthquakes may have contributed to later waves of sedimentation, though, since some of the walls along Honokoa Gulch were reported to have collapsed following the tremors. Other contributing factors could be the Department of Transportation, which was working on an earthquake-damaged bridge without silt curtains, roads and hard surfaces associated with Kohala Ranch interrupting natural drainage ways, and residents of new developments dumping debris and yard waste into the gulches.

Walsh was hopeful that winter swells would clean much of the reef. When he returned at the end of January, he saw no improvement. “There was a lot of dying coral, covered with filamentous algae. The bottom was anoxic.” The mud was up to 15 inches deep in places.

Walsh says the extent of the damage to coral far outstrips what occurred at Pila`a, on Kauai`’s North Shore in November 2001, and at Hokuli`a, near Kealakekua Bay, in 2000.

New NWHI Protections: The National Oceanic and Atmospheric Administration has applied to the International Maritime Organization for designation of the Papahanaumokuakea Marine National Monument as a Particuarly Sensitive Sea Area. Designation, if approved, would expand IMO-designated Areas To Be Avoided (IBTAs) and would establish a reporting system for transiting ships.

“We believe that the burden on international shipping by the proposed PSSA and its associated protective measures is minimal,” says Linda Johnson of NOAA, “while the objectives for establishing it — increased maritime safety, protection of the fragile environment, preservation of cultural resources and areas of cultural importance significant to Native Hawaiians, and facilitation of the ability to respond to developing maritime emergencies — are significantly furthered.”

The IMO will take up the application at its fall meeting.

A New Tree Snake Terror: Hawaii lives in fear — and rightly so — of the brown tree snake. A new report on the snake’s reproductive strategies, published in the April 2007 issue of Pacific Science, suggests the threat that a reproducing population of Boiga irregularis might become established here may be even greater than was previously thought.

According to the report’s authors, Julie Savidge, Fiona Qualls, and Gordon Rodda, a female from a closely related species, Boiga multomaculati, was reported to have produced fertile eggs after 9 months in isolation, while a female Boiga dendrophila produced young after two years in isolation. Another female snake from a different but closely related genus, Leptodeira annulata, was reported to have produced viable young after being isolated for six years.

The ability to store sperm may account for the long interval between the last known encounter with a suitor and the hatching of offspring. But the authors suggest another possibility: parthenogenesis, or asexual reproduction. They write: “[I]t is possible that B. irregularis can reproduce asexually. If so, this would further reduce the minimum requirements for establishing … populations of brown tree snakes.”

In other words, with parthenogenesis, it wouldn’t necessarily take a breeding pair to establish a new population of the snakes, or even an impregnated female. All it would take is a single juvenile female, “or even one egg.”

 

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