Lo­cal finds ma­rine pest in is­land bay

Waiheke Marketplace - - Front Page - ROSE DAVIS

A de­struc­tive Aus­tralian ma­rine pest has been found in a Wai­heke Is­land bay, so boat­ies are be­ing warned to check their hulls.

An is­land res­i­dent re­ported an in­fes­ta­tion of the Aus­tralian droplet tu­ni­cate, Eud­is­toma elon­ga­tum, at Oakura Bay off Te Whau penin­sula on the western coast of Wai­heke in May last year.

The Min­istry for Pri­mary In­dus­tries has con­firmed the pest, which breeds in clus­ters of slimy white tubes, is present in the bay.

Auck­land Coun­cil ma­rine biose­cu­rity ad­vi­sor Sa­man­tha Happy said Eud­is­toma posed a se­ri­ous dan­ger to the ma­rine en­vi­ron­ment.

It couldsmother beaches, rocks and ti­dal pools and posed a threat to ma­rine farms.

‘‘The pest will change our beau­ti­ful fore­shores as we know it, for­ever, and is nearly im­pos­si­ble to con­trol once it’s es­tab­lished,’’ Happy said.

‘‘Pre­vent­ing the pest spread­ing is some­thing every Kiwi, es­pe­cially sea far­ers and boat own­ers, needs to be part of, so we can keep our trea­sured ma­rine play­ground pest-free for fu­ture gen­er­a­tions.’’

The clus­ters of white or cream cylin­dri­cal tubes die back in win­ter, so the coun­cil planned to as­sess the prob­lem this sum­mer.

The Min­istry for Pri­mary In­dus­tries tried to re­move Eud­is­toma from North­land in 2007 and 2008, un­til the tubes dis­ap­peared af­ter a flood. The pest is vul­ner­a­ble to salin­ity changes due to rain­fall.

‘‘Any at­tempts to smother or treat pop­u­la­tions will also have an im­pact on non-tar­get species, and Eud­is­toma can frag­ment eas­ily, fa­cil­i­tat­ing its spread,’’ Happy said.

The pest, which can grow from five cen­time­tres to more than a me­tre long and from five mil­lime­tres to two cen­time­tres thick, has been spread­ing through­out the North Is­land.

The first Auck­land bay where Eud­is­toma was found was Sand­spit in 2010 and it has since been spot­ted in Mahu­rangi Har­bour.

The tu­ni­cate re­pro­duces quickly and spreads eas­ily, be­cause it has a free-swim­ming lar­val stage and each ‘‘slimy saus- age’’ con­tains nu­mer­ous in­di­vid­ual or­gan­isms that can break away and form new colonies.

It looks sim­i­lar to the na­tive colo­nial sea squirt, Didem­num spp., but the na­tive species forms mats, while Eud­is­toma re­mains in sep­a­rate tubes and some­times has or­ange flecks from its lar­vae.

The ma­rine pest Eud­is­toma elon­ga­tum has been found in a Wai­heke Is­land bay. SUPPLIED

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