UH scientists study algal bloom off Maui
By Timothy Hurley
Advertiser Maui County Bureau
Two University of Hawai'i scientists who specialize in the study of algal blooms have launched an investigation into what's causing the proliferation of seaweed this summer in the waters off West Maui.
Jennifer Smith of the UH botany department and John Runcie of the Institute of Marine Biology spent a couple of days diving and collecting samples on Maui last month and plan to return next week — and for as long as the bloom lasts.
Smith said the pair surveyed popular dive sites near Ka'anapali and Honokowai and found acres of the wispy green Cladophora sericea, some of it tangled on reefs and smothering coral heads.
Cladophora sericea is thought to be a native species that normally exists in relatively low concentrations.
"But something is driving it to go crazy,'' Smith said.
Experiments in their Honolulu lab already have eliminated nitrogen by itself as the primary cause of the algal bloom. However, nitrogen could still play a part, perhaps in combination with phosphorus, another nutrient, or with trace amounts of heavy metals. Those experiments are still to come, she said.
Smith said the Hawai'i Sea Grant-financed research will focus on finding the source of the bloom. A prime suspect is a coastal sewage treatment plant with injection wells, she said, but there are also theories that the algae is growing in much deeper water and being pushed to shore by currents.
"That would eliminate anything man is doing,'' she said.
Smith said that she may seek to obtain a larger research grant that would allow her to take a submarine into deeper waters.
Meanwhile, Skippy Hau, aquatic biologist with the state Department of Land and Natural Resources, said Thursday that this summer's algal bloom doesn't appear to be growing any worse.
The bloom apparently started at about the beginning of May and has been seen primarily in waters from Kapalua to Ka'anapali but also off Lana'i and South Maui.
In the summers of 1989 and 1991, Cladophora sericea exploded off West Maui. Those episodes fueled fears about the degradation of Maui's near shore waters and prompted Congress to allocate more than $1 million for algal bloom research.
A dozen major investigations were unable to pinpoint the cause of the West Maui algae episodes, but they did indicate the blooms are driven not only by nutrients, such as those from fertilizers and surface runoff, but by changes in climate, currents and precipitation.
Smith said she and Runcie may be able to give the issue a fresh perspective because of their expertise in phycology, the study of algae, kelp and related plants.
