Monday, December 3, 2001

Kaneohe targeted for
fight against 5 alien,
2 local algae species

The growth of algae threatens coral reefs
and other nearshore marine ecosystems

By Diana Leone

You could call algae the feral pig of Hawaii's marine environment.

Overgrowth of the seemingly benign plant threatens coral reefs, fish, other sea life and the natural beauty and tourism draw of nearshore waters.

Come January, Kaneohe Bay will be the battleground against five alien algae and two overgrown local species.

On the front line will be University of Hawaii doctoral students Jennifer Smith and Eric Conklin, working under the guidance of Waikiki Aquarium curator Cindy Hunter.

"Hawaii has a really big problem with alien marine plants," said Smith, a botanist who has been studying the interaction between plants and corals for four years.

The team will be wading, snorkeling and diving, trying different methods to banish the unwelcome guests.

A $60,000 grant from the Hawaii Coral Reef Initiative will help the team figure out the best methods to get the bad algae out. They hope ultimately to pass on what they learn to volunteers, who then can help weed Hawaii's underwater garden.

Removal of alien species from coral reefs is a top priority for the Hawaii Coral Reef Initiative, said its director, Mike Hamnett.

"Our biggest hope is to remove algae in ways that don't make the situation worse," Hamnett said. "It's going to be very carefully controlled and monitored."

Most algae can regenerate from tiny broken pieces of plant. Unless the removal is done carefully, you could end up with a bigger problem than you started with.

The yearlong research could have long-term effects for all the Hawaiian Islands, Hamnett said. "It's pretty significant because we've never done this."

Kaneohe Bay was chosen as the proving ground because it hosts all of Hawaii's worst algae offenders in a variety of habitats, including both fringing and patch reefs, in varying depths and conditions of sea water.

"We hope to get techniques in place before we get (volunteer) people out there. We don't know how much manpower it's going to take to clear even a small patch of reef in Kaneohe," Smith said.

"We're doing this to make a difference," Smith said. "It's my hope that eradication of some species may be possible. ... I have a feeling we're never going to actually completely get rid of them. But by reducing their abundance, we can at least give the natural ecosystem a chance to come back."

In the meantime, she said, "We need more state and federal help through public education, better land use management practices, more interaction between land and water resource management, and ... more regulation of the aquarium trade, aquaculture, ship ballast waters and boat hulls."

If you'd like to volunteer to help with algae removal in 2002, contact Jennifer Smith at or 956-3943.

The 7 most harmful near-shore weeds

These are the algae cited as problems in Hawaii:

Acanthophora spicifera: This most common alien algae is yellowish to dark brown and has lots of short spikes coming off cylindrical branches. It's very abundant in Kaneohe Bay, and fish like it; probably too late for complete eradication.

Hypnea musciformis: This dark maroon algae has cylindrical branches, with large hooks on end of branches that it uses to wrap around other plants. This alien species is blamed for massive blooms in the Kihei area of Maui.

Avrainvillea amadelpha: This alien algae anchors on sandy or muddy bottoms, appearing as upright little paddles, olive green to almost dark brownish black. It is feltlike in texture, often has other things growing on top of it and is common at Kahala's shallow reef flats and in 30 or more feet of water at Portlock and Kahe Point. Believed to compete with native sea grass.

Gracilaria salicornia: Dense, three-dimensional mats of this dark brown to bright orange alien algae can be found covering the reef in front of the Waikiki Natatorium. It's "crispy" -- and is showing up in some poke mixes.

Kappaphycus spp.: This alien algae is only found in Kaneohe Bay. Its large branches can be more than a centimeter wide, with short little spines covering it; color ranges from light tan to purple. Very competitive and may be killing coral.

Dictyosphaeria cavernosa, or bubble algae: A local algae that has been a pest in Kaneohe Bay since the 1970s.

Cladophora sericea: This local algae has troubled West Maui with summertime blooms from Lahaina to Kahana in recent years. It has bright green, soft filaments and forms long green tufts.

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