By Erin Looney
Erin Looney of the PIFSC Coral Reef Ecosystem Division (CRED) recently worked with Darla White of the Division of Aquatic Resources of the Hawai`i Department of Land and Natural Resources to collect water samples off West Maui. This effort continued a study that began last fall: “Environmental investigation into impacts of land-based sources of pollution on coral health in West Maui, HI.” This research is funded by NOAA’s Coral Reef Conservation Program and led by Cheryl Woodley, PhD, of Hollings Marine Laboratory in Charleston, S.C.
Water samples were collected on Jan. 26–Feb. 4 at 15 sites from La Perouse to Kapalua Bay. The samples were taken to a temporary lab where Looney filtered samples onto selective media to isolate fecal coliforms, Staphylococcus, Enterococcus, and Serratia marcescens. Water samples also were shipped on dry ice to Hollings Marine Laboratory for further toxicological processing.
Examples of the dilution of water samples used to assess the level and identity of fecal-associated bacteria in waters off West Maui. (a) Duplicate plates with filtered samples from a site called Sand Channel on the following media (top to bottom): mannitol salt agar (MSA), a medium that encourages the growth of Staphylococcus, 1 mL; MSA, 10 mL; membrane-Enterococcus Indoxyl-β-D- glucoside (mEI), which is used to culture Enterococcus; deoxyribonuclease-toluidine blue-cephalothin (DTC), which is used to grow Serratia marcescens, and membrane filtration fecal coliform (mFC), which is used to grow fecal coliforms. (b) A set of duplicate plates with a 10-mL dilution on MSA. Each dot represents a colony, and the average number of colonies on these plates is ~140. Thus, in 10 mL of water taken at Sand Channel, there were 140 colonies of Staphylococcus. (c) A set of duplicate plates of filtered samples on mFC media. NOAA photos by Erin Looney