Co­ral reef woes linked to bio­ero­sion, waste­water wells

Honolulu Star-Advertiser - - VIEWS & VOICES - By Rus­sell Sparks

Re­cently, a sci­en­tific pub­li­ca­tion ti­tled, “Vul­ner­a­bil­ity of Co­ral Reefs to Bio­ero­sion From Land-Based Sources of Pol­lu­tion,” was re­ported on by sev­eral lo­cal news out­lets. Bio­ero­sion de­scribes the ero­sion — grad­ual de­struc­tion or dis­in­te­gra­tion — of hard ocean sub­strates such as co­ral reefs, by liv­ing or­gan­isms, and this re­search ef­fort led by the U.S. Ge­o­log­i­cal Sur­vey (USGS) is part of nu­mer­ous sci­en­tific peer-re­viewed pub­li­ca­tions con­sis­tently demon­strat­ing con­cerns with the dis­posal of treated waste­water into coastal in­jec­tion wells.

The Kaana­pali area in West Maui is one of the U.S. Co­ral Reef Task Force’s des­ig­nated pri­or­ity wa­ter­sheds. With this des­ig­na­tion, many agen­cies have part­nered with the state De­part­ment of Land and Nat­u­ral Re­sources (DLNR) to study threats to the area’s co­ral reefs and iden­tify man­age­ment ap­proaches to help corals sur­vive. The work re­cently re­ported on by the USGS is part of this part­ner­ship.

A key find­ing of this study was that bio­ero­sion rates on corals next to seafloor ground­wa­ter vents off Ka­hek­ili Beach Park are up to eight times greater than ex­pected for corals grow­ing away from pol­lu­tion. In an­other in­de­pen­dent study, Ka­hek­ili had the high­est av­er­age co­ral bio­ero­sion rates when com­pared to other sites in the state. The ground­wa­ter vent sites at Ka­hek­ili are com­posed pri­mar­ily of waste­water ef­flu­ent from the in­jec­tion wells at the treat­ment plant.

Water qual­ity stud­ies and dye tracer work have demon­strated that the ground­wa­ter dis­charg­ing at Ka­hek­ili is con­tam­i­nated by in­jected, treated waste­water with ni­trate con­cen­tra­tions 50 times higher than back­ground sea­wa­ter con­cen­tra­tions. This fact has been con­clu­sively shown and is cur­rently un­der­go­ing le­gal lit­i­ga­tion.

In a re­cent ar­ti­cle in a La­haina pub­li­ca­tion, I re­ported on some early signs of par­rot­fish and sur­geon fish re­cov­ery and con­cur­rent im­prove­ments in co­ral health off­shore of the Ka­hek­ili Beach Park. The changes in the reef ecosys­tem health ap­pear to be the re­sult of her­bi­vore fish­eries man­age­ment ac­tions taken by the state in 2009 — ad­min­is­tra­tive rules pro­hibit­ing the har­vest of im­por­tant seaweed graz­ing fishes. Re­sults are en­cour­ag­ing with changes to­ward a reef ecosys­tem bet­ter suited for new co­ral re­cruit­ment and growth.

Co­ral reefs may rise up many feet above the ocean bot­tom, but the ac­tual live co­ral tis­sue is only the out­er­most skin of this structure. It is, there­fore, im­por­tant to un­der­stand that although we are see­ing im­prove­ments in the liv­ing layer of the corals at Ka­hek­ili, the ac­cel­er­ated bio­ero­sion rates re­ported on by the USGS can re­sult in the col­lapse of the un­der­ly­ing reef structure.

As a re­sult, this reef may lose its abil­ity to con­tinue to sup­port fish pop­u­la­tions and to serve as a nat­u­ral bar­rier pro­tect­ing the shore­line from coastal haz­ards such as storms, and waves.

The best avail­able sci­ence sug­gests that the ac­cel­er­ated bio­ero­sion of the co­ral reef structure at Ka­hek­ili is the di­rect re­sult of the con­stant ex­po­sure to con­tam­i­nated wa­ters from the La­haina waste­water in­jec­tion wells.

While we await the fi­nal judg­ment of the courts and hope for an in­creased pri­or­i­ti­za­tion of waste­water re­cy­cling within the county, we must take other proac­tive re­source man­age­ment ac­tions to re­duce the loss of co­ral structure and the over­all col­lapse of the co­ral reefs. The her­bi­vore man­age­ment ac­tions taken by DLNR at Ka­hek­ili were de­signed to help buy us some time.

How­ever, for the long-term sur­vival of this reef, we must find other al­ter­na­tives to the in­jec­tion of treated waste­water, and we must all work to­gether to re­duce other land-based im­pacts to our coastal wa­ters. More in­for­ma­tion on the sci­en­tific re­search from this area and sug­ges­tions on how to re­duce land-based pol­lu­tion im­pacts is on www.west­

Rus­sell Sparks is with the state De­part­ment of Land and Nat­u­ral Re­sources, Di­vi­sion of Aquatic Re­sources.

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