Algae bloom along Kona
Water tests show no sewage or discharge, but some residents remain concerned
KAILUA-KONA » Smelly, brown waters along the Big Island's Kona coast recently alarmed residents concerned that their shores had been polluted.
Tests of the waters over the last two months by the state haven't found any raw sewage from land-based leaks or cruise ship discharges, but some West Hawaii residents remain unconvinced about the source of the two mysterious algae blooms in Kailua Bay and Keauhou Bay.
"I know they said the water samples tested clean," said Paul Aguirre, a Keauhou resident and canoe paddler. "But what is it clean of? The algae must be feeding on something. ... That bay usually is bell clear. You can see the bottom, but no one has seen the bottom in some months now."
The mystery of the two incidents hasn't been solved and likely will need much more testing.
But scientists and state officials are not ready to sound any alarms.
Algae appear seasonally -- typically in late summer in Keauhou Bay, for example -- and responds to higher water temperatures, circulation patterns and changing nutrients in the water.
Nutrient levels change naturally and seasonally, but some also point to man-made causes such as development along the shoreline that creates more opportunities for runoff and leaching.
The state has not conducted any studies to determine whether this is a natural or seasonal occurrence, and it has no plans to do so unless there's a serious threat to the marine environment or people, said Nancy Nakata, environmental health specialist with the Department of Health's Clean Water Branch, Kona office.
Linda Preskitt, a Kula Naia Wild Dolphin Research Foundation marine botanist, said any algae bloom is a sign of changing conditions, which is not a concern by itself.
"Generally, blooms happen, changes happen. There are constant fluctuations. You can see changes in just 15 minutes," she said.
One year of unusual algae activity is not a cause for concern, Preskitt said, as it could be the result of an El Nino year or some other spike in one area.
It's also possible, though, that the algae are a first signal of a more serious, long-term threat to reefs and ocean ecosystems.
"Blooms can be a real problem if they are of a persistent nature," she said.
Preskitt said she tested a recent algae sample from along the Kona Coast, although not specifically in response to the blooms in either bay. The sample showed her nothing unusual.
"It's the kind of thing you will see in warmer waters," she said. "You cannot tell from one test. You'd need a whole water quality study."
Preskitt spoke yesterday morning to residents, visitors and Girl Scouts at Kahaluu Beach Park, which is situated between Kailua Bay and Keauhou Bay, during the regular monthly ReefTeach educational program.
"We need to be aware that it is a limited resource," said Preskitt, a 15-year Big Island resident. "The more locals and visitors realize their impact on our reefs, the more it's going to help."