The Maui News
Sunday, May 27, 2007 11:06 AM
Invasive algae blooms, hurts isle reefs
By MELISSA TANJI, Staff Writer
KIHEI - When state aquatics biologist Russell Sparks goes diving in Maalaea he sees a slippery, slimy invasive algae growing on the reef that was once healthy coral.
Gone is the coral ecosystem that is a habitat for a variety of reef fish.
Sparks said a reason for the overgrowth of invasive algae is an increase in nutrients from land-based sources. Research data indicate there is a "correspondence" between algae blooms and wastewater injection wells pumping treated effluent deep into the ground, from where the nutrient-rich water is seeping out into the ocean.
A specialist with the county wastewater program agreed, saying the county would want to reduce its use of wastewater injection wells and use the treated effluent elsewhere.
But it requires public support.
"We will always need some type of alternate disposal, even if we could use all of the effluent for beneficial reuse," said Steve Parabicoli, water recycling program coordinator for the county.
"Because we feel that algae blooms, ocean water quality and effluent disposal is a community issue, the entire community should take some responsibility in helping reduce the use of injection wells through increasing recycled water reuse."
A co-chairman of the County Council public works committee, Mike Victorino, said he understands the benefits of reusing treated effluent, and not only because it would reduce the impact on the ocean.
But there is a cost, and council members need to convince taxpayers that their money is being used wisely.
"Whoís going to pay for it?" Victorino said.
Sparks and Parabicoli presented the data on the apparent impact of wastewater injection wells on the nearshore reefs during a recent Kihei Community Association meeting, hoping to educate the public on the benefits of effluent reuse with information on the cost to the reefs.
Parabicoli said in order to reduce the use of injection wells, the county wastewater division will need "significant funding" to construct distribution infrastructure for the treated wastewater.
As an example, he estimated it could cost $30 million to $40 million to install a transmission pipe to carry treated wastewater from the Kihei treatment plant to Wailea golf courses.
"This is the largest hurdle or obstacle preventing more recycled water from being utilized," he said.
The county policy has been to have users pay for the costs of effluent-transmission lines, which has limited the demand for effluent for irrigation purposes. But the alternative would be for taxpayers or rate payers to cover the costs.
Three county wastewater treatment plants on Maui rely on injection wells to dispose of treated effluent. There are three wells at the Kihei facility, four at Lahaina and eight at Kahului.
Plants countywide treat 15 million gallons of wastewater a day. Although there is some reuse for irrigation, including at the Elleair Golf Course in Kihei; at Kalama Park and at Kanaha Beach Park, most of the treated effluent is pumped into the ground.
Sparks said he acknowledges that the causes of coral reef decline are complex and vary among locations. But he said there are strong indications that injection wells contribute nutrients to the nearshore waters, feeding the bloom of invasive algae.
Off Maalaea, where condominiums and the Maalaea Harbor Village commercial complex have private sewage treatment and injection wells, coral cover Ė the amount of reef covered by living coral Ė-is down to 8 percent, Sparks said.
In 1993, he said, estimated coral cover was 50 percent to 75 percent off Maalaea.
Three primary non-native algae have been proliferating on the reefs off Kihei and Maalaea where there are injection wells. The invasive algae also are blooming off Kahului and West Maui. They are:
Acanthophora spicifera, a red seaweed with cylindrical branches covered with small spinelike branches. It varies in height between 1 and 8 inches.
Hypnea musciformis, a brown seaweed that was first brought in for possible commercial use and "escaped" into island waters, has cylindrical branches and grows in clumps or is loosely intertwined. It can grow up to 8 inches tall and is about a quarter-inch in diameter.
Sparks said Hypnea can double in size in two days. During heavy blooms, thousands of pounds wash up on beaches where Maui County has had to contract for regular cleanups.
Ulva, or sea lettuce, is a thin green seaweed with wide blades. It is 4 to 6 inches wide at its base, tapering upward to less than an inch wide at its tip. It can grow nearly a yard long.
By comparison, Sparks cited the condition of the reefs at Molokini Crater, a state marine life conservation district far away from any human nutrient sources. They provide an example of a thriving coral reef ecosystem, with coral cover at around 80 percent, Sparks said.
Because it is a marine life conservation district, Molokiniís reefs also may benefit because the fish are protected and thriving schools of algae-eating fish could be keeping down the invasive algae.
Heavy fishing pressure could be a factor in the deterioration of the reefs off Maui.
In addition to seeking to reduce the use of wastewater injection wells, Sparks said the state is looking to control fishing on herbivore species.
Three families of herbivore fishes the state would like to protect are: surgeonfishes, manini, kala, and palani; parrotfishes, or uhu; and rudderfish, or nenue.
By protecting the fish, the state hopes the increased schools will be better able to control the invasive algae on the reefs. As a pilot project, Sparks said, the state is looking at establishing a controlled fishing area off North Kaanapali at Kahekili Beach Park.
The goal would be to increase the number of fish that feed on algae such as Acanthophora. That would also mean discouraging snorkelers from feeding the fish, Sparks said, to encourage the fish to eat the less-desirable algae rather than bread, peas or other foods that people might offer.
The nutrient enrichment offshore from injection wells has been documented, he said.
In a study conducted along the North Kihei coastline by researchers Celia Smith and Chip Hunt, Sparks said research showed that a chemical tracer added to the treated effluent pumped into the ground was showing up in the offshore waters. The levels of the tracer, a nitrogen isotope, was elevated in the water where Hunt's model showed an injection plume would be seeping out.
Although there isnít an algae bloom in every area in proximity to an injection well, Sparks said the research showed that if the habitat is appropriate for algae growth, the algae will use the nutrients in the effluent plume to grow.
In an effort to address concerns that injection wells were contributing to algae blooms, Parabicoli said, the county incorporated biological nutrient removal systems at its plants that reduced nitrogen discharges by 60 percent.
The systems have been place for about 10 years at the Lahaina and Kihei plants and at the Kahului plants for two years.
But the prime option would be to eliminate the need for injection wells.
Victorino said council members understand that the costs to reduce use of injection wells are high, but are willing to listen.
No one has to sell him on the benefits of reusing treated effluent, he said. It would be a good idea to get more golf courses, parks and agriculture-based businesses hooked up to systems providing treated wastewater for irrigation.
Having more effluent go to irrigation would reduce the use of precious potable water for landscaping, he said.
"The hard sell is the public."
When the county expands or make improvements to its wastewater systems, itís the taxpayers who foot the bill, he said. Then council members need to monitor the departmentís work to be sure the funding is used appropriately, he said, because itís the council members who are answerable to voters.
Even if the county funds project with bonds or loans, he said, the taxpayers pay back the money thatís borrowed. Residents need to be willing to pay for an improved system, he said.
"What we use is what we pay for. When you are talking mass infrastructure improvements, then you have to pay now for the future," he said.
Melissa Tanji can be reached at email@example.com.
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