Ka Wai Ola - Office of Hawaiian Affairs, Volume 26, Number 9, 1 September 2009 — Palmyra Atoll study shows shipwrecks harm coral reefs [ARTICLE]

Palmyra Atoll study shows shipwrecks harm coral reefs

New research conducted at Pahnyra Atoll by three Hawai'i-based scientists indicates that shipwrecks and other man-made structures increase the likelihood that coral reefs - even relatively pristine ones - will be overtaken and even destroyed by invasive species. The coral reefs that were studied underwent fast changes in their dominant life forms, a phenom-

enon known as phase shift. Scientists have observed the longterm reduction in the diversity of marine hfe from phase shift, but prior to this study, they have not fully understood the cause well enough to identify remediation measures. Research on a 100-foot vessel that wrecked in 1991 on isolated Pahnyra Atoh in the central Pacific Oeean highlights the unportance of rapid removal of shipwrecks on corals reefs to prevent the take over by invasive species. Results of the justreleased research was begun two years ago by Dr. Thierry Work of the U.S. Geological Survey, Dr. Greta Aeby of the Hawai'i Institute of Marine Biology and Dr. Iames Maragos from U.S. Fish and Wildlife Service. They found a concentration of invasive Rhodactis howesh near the shipwreck site. The density of this species progressivefy decreased with distance from the ship and was rare or absent in other parts of the atoh. The researchers also conhnned high densihes of the invasive species around several buoys installed ontheatohin2001. Scientists say elhninating organisms responsible for phase shifts ean be difficult, particularfy if they cover a large area. Yet to be explained is why this phase shift occurs. One possibihty is that iron leeching associated with the man-made structures eomhine with environmental factors to promote the growth of the invasive species.