Editor’s Page AL Resurrection of Paradise


I’ve been studying the Kahekili reef on the west shore of Maui since the 1970s. It is a dynamic ecosystem fraught with natural and anthropogenic challenges. Over the last 20 years, science-based remediation programs have resurrected the reef. Similar programs around the island have worked in other locations also. So, amid attacks on science and science- based regulation, Kahekili reef is living evidence that programs deliver.


Seaweed near the shoreline in the 1980s and ’90s was attributed to agri- cultural runoff from the upslope sugarcane and pineapple fields. A basin was built to catch the runoff, and successfully starved the green slime. By 2000, water quality improved dramatically.


Coral bleaching recovery


In November 2015, I was shocked to see that the coral garden looked like it had been hammered by a snowstorm. Many small coral heads were snow-white, bringing to mind that the color white is associated with death in many Asian cultures.


Good news: last fall, the “snow” had been replaced with signs of re- colonization of the coral. The colors of the blue crust, green cauliflower, and white finger coral were coming back. Color intensity was muted, however. But my dives in April 2017 showed a significant improvement. The coral is recovering, at least for now.


Turtle tumors recede This past May, I encountered more than 20 green sea turtles while snor-


keling from Kahekili beach to Honolua Bay on the west shore of Maui. Notably, I saw no signs of tumors—10 years ago, more than half the turtles I encountered had visible fibropapillomatosis tumors (see https:// en.wikipedia.org/wiki/Fibropapillomatosis). These are attributed to a herpes virus that correlates with high nitrogen content in the water.


Decreased farming in Western Maui and improved sewage treatment processes are possible reasons for reduction in tumors. Today, sugarcane growth has ceased and the mill has closed. Pineapple farming has been curtailed as well.


“Boiling” sand pots explained In 2002, I found a series of sand pots where warm water and gas bubbles


were upwelling through the sand at the surf line at the north end of the Westin Villas. The subsurface sand was warm to the touch, which is unusual, since other groundwater springs on the west shore of Maui are frigid. The West Maui volcano is one of the wettest spots on earth, with rainfall at over 300 inches per year. Cold rainwater rushes through the porous volcanic formations to empty into the ocean.


A recent paper1


from the lab of Professor Craig R. Glenn, Department of Geology, University of Hawaii, Manoa, used radioisotopes and


AMERICAN LABORATORY 4


Bleached coral. Image reproduced with permission from Maui Ocean Center, The Aquarium of Hawai‘I, Wailuku, HI.


JUNE/JULY 2017 by Robert L. Stevenson


fluorescent dyes to characterize the vent. The water temperature is about 25–27 °C, which is noticeably warmer than the water in the surf line (~20 °C). The gas bubbles emanating from the vents are enriched in nitrogen compared to atmospheric composition.


I’d attributed the warm water to magmatic heating, but Professor Glenn advises the warmth comes from solar heating of wastewater for low- temperature nitrate removal with anaerobic enzymes.2


This releases


nitrogen gas, which is seen in the bubbles. The activity of the enzymes increases with water temperatures up to about 40 °C. Thus, Maui uses solar heating to increase the temperature of the wastewater prior to treatment—truly an example of wastewater management adapted to the tropics.


Coral is not common in the surf zone, but the area around the most active part of the vents has a dark brown dead zone extending ra- dially about 50 meters. There is little sign of life, such as urchins or nudibranchs, but a few fish do swim through. The dead zone is attrib- uted to further oxidation of iron and molybdenum salts to form insoluble higher hydrous oxides.


During the last year, I’ve noticed new gas bubble emissions extending into the coral garden about 100 meters south of the original vent. These were particularly evident during early-morning swims when the tide was low. The last year has been unusually wet for Maui, which might increase runoff and hence SGD.


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