Hawaii biologists fight invasive seaweed

Biologists fighting invasive seaweeds taking over Hawaiian reefs are using native sea urchins and fish to help control the aggressive plants. "If people can raise herbivore (plant-eating) stocks quite substantially, I believe it will have a big impact," said coral reef ecologist Ivor Williams of the Hawaii Coral Reef Initiative and the state Division of Aquatic Resources. In tests of weed-infested reefs in Kaneohe Bay, the tactic has been successful and gives hope that the state's coral reefs might be able to battle the plants."We have not had enough urchins to test them out on a whole reef, but in every experiment on a smaller scale, we saw that urchins stop infestations of alien algae to begin with, or prevent the re-growth of existing alien algae," said Eric Conklin, who conducted some of the urchin experiments and is now marine science adviser for The Nature Conservancy's Hawaii Marine Program.One aspect of a larger project will be matching each invasive seaweed species to the creature that enjoys eating them most.Grazing fish, such as manini, for example, are fond of the acanthophora seaweed troubling West Maui. But the fish don't have a taste for Kaneohe Bay's kappaphycus weeds, which are instead a favorite of collector urchins.The noshing sea life are expected to add to an invasive seaweed removal program that includes the mechanical Super Sucker and its smaller progeny Super Sucker Junior."Using the urchins (and herbivorous fish) in conjunction with the Super Sucker, that carries us through the next few years," Conklin said.In order for the project to work, however, officials will need to contend with a certain voracious, two-legged predator. People eat collector urchins, which have been so overharvested they can't keep up with the seaweed.Scientists at the University of Hawaii hope to release large numbers of urchins to restore overfished urchin populations. But they are still learning how to raise the prickly sea creatures in captivity.In other coral reef news, the Bush administration has announced that it has submitted legislation to Congress to reauthorize the Coral Reef Conservation Act of 2000 and to add protections for coral reefs and improving marine debris removal.