Scientists assess herbivorous fishes and coral health off West Maui

In recent weeks, Coral Reef Ecosystem Division (CRED) staff participated in two separate projects for which they conducted surveys and other field work near Kahekili, Maui, in Hawai`i.

Kevin Lino conducts a belt-transect survey of fishes off West Maui in September. NOAA photo by Darla White, Hawai`i Department of Land and Natural Resources

Surveys help evaluate West Maui management area

Ivor Williams and Kevin Lino of CRED and staff from the Hawai`i Department of Land and Natural Resources’ Division of Aquatic Resources (DAR) on Sept. 24–29 conducted the latest in a series of fish, benthic, and urchin surveys at the Kahekili Herbivore Fisheries Management Area (KHFMA) off West Maui.

These surveys are part of a project, funded by NOAA’s Coral Reef Conservation Program (CRCP), through which CRED has been providing survey and analytical support to the DAR to assess the effectiveness of the KHFMA. Current plans are for this collaboration to continue through late 2014, when it will be five years after the establishment of this marine protected area.

Whitebar surgeonfish (Acanthurus leucopareius) and convict surgeonfish (A. triostegus), seen in the above photo, are examples of fishes protected in the Kahekili Herbivore Fisheries Management Area, where regulation prohibits these activities: to injure, kill, possess, or remove any rudderfish, parrotfish, surgeonfish, or sea urchin. NOAA photo by Kevin Lino

Coral reefs now in the KHFMA have been affected by blooms of invasive algae in recent years. In the 10 years prior to establishment of the KHFMA in 2009, three significant algal blooms were documented and coral cover there at the DAR’s long-term monitoring site declined from 55% to 33%. Concern about the rapid decline of the coral reefs along that part of West Maui and the desire to prevent a coral-to-algal “phase shift” (a persistent change of state from coral- to algal-domination), led to the establishment of the KHFMA.

A bluespine unicornfish (Naso unicornis) grazes on algae on a shallow reef off West Maui. NOAA photo by Kevin Lino

Within the KHFMA, herbivorous fishes are protected, but other groups of fishes can still be harvested. This management approach is unusual and differs from full-closure measures. This CRCP-funded series of surveys will provide data that can assist in examination of the KHFMA as a means toward restoration of herbivorous fish populations and prevention of coral-to-algal phase shifts.

Study examines effects of sewage on coral health off West Maui

Erin Looney on Sept. 16–28 participated in a two-week study for a CRCP-funded project focused on examination of the effects of land-based sources of pollution on coral health off West Maui. Led by Cheryl Woodley, PhD, and Lisa May of the Hollings Marine Laboratory in Charleston, S.C., this environmental forensic investigation into causes of coral decline and mortality on nearshore reefs off West Maui will provide baseline data.

At Kahekili, poor water quality, algal blooms, and coral decline are thought to result from sewage effluents seeping into groundwaters from shallow-well injections. The intention of this project is to clarify the role of wastewater injection wells through assessment of porewater toxicity of aquatic life and identification of toxic substances, their sources, and toxicity levels.

During the recent study, water samples were taken to assess the level and identity of fecal-associated bacteria in area waters as evidence of sewage input. This research will provide local resource managers with data to examine potential links between wastewater effluent and adverse biological effects.

Looney helped collect samples, perform microbial assays, and train local managers from the DAR, U.S. Environmental Protection Agency, National Park Service, and NGOs in the methods used for this type of experimentation. She plans to return to Maui this winter to conduct follow-up surveys and microbial analyses.

By Ivor Williams and Erin Looney