Knysna sees red over es­tu­ary threat

Sunday Times - - NEWS - SHANAAZ EG­GING­TON

A RED tide that has spread to the Gar­den Route is just the lat­est marine headache for Knysna, where res­i­dents have ex­pressed alarm over the de­te­ri­o­ra­tion of their once pris­tine es­tu­ary.

Chem­i­cals en­ter­ing the wa­ter are to blame for the ram­pant growth of al­gae and sea let­tuce in the es­tu­ary — of­ten in­cor­rectly re­ferred to as a la­goon — de­spite R55.5-mil­lion be­ing spent on pol­lu­tion preven­tion mea­sures.

The salt-wa­ter es­tu­ary is the big­gest and most eco­log­i­cally im­por­tant in the coun­try, act­ing as a line­fish nurs­ery and host­ing 43% of the coun­try’s es­tu­ar­ine life.

“The es­tu­ary is con­tin­u­ing to de­te­ri­o­rate due to a con­tin­ual al­gal bloom caused by too many chem­i­cals en­ter­ing the wa­ter,” said Mike Hamp­ton, a blog­ger and com­mu­nity ac­tivist.

Pro­fes­sor Brian Al­lan­son, who started the Knysna Basin Project, an NGO that mon­i­tors the es­tu­ary, agreed that sea let­tuce was a prob­lem but said this year’s “bloom” was not as se­ri­ous as be­fore.

A red tide oc­curs when al­gal blooms de­plete oxy­gen and as they die off, dis­colour wa­ter. It is harm­ful to fil­ter feed­ers such as mus­sels, oys­ters and shell­fish, but this week­end’s Ro­tary Splash fes­ti­val and the La­goon Mile swim would go ahead, a com­mit­tee rep­re­sent­ing SAN-Parks, the Knysna Basin Project, Knysna Mu­nic­i­pal­ity and the Eden Dis­trict Mu­nic­i­pal­ity’s health di­vi­sion has de­cided.

Greg Vogt, head of Knysna Tourism, said the area was hit reg­u­larly by red tides. “Con­ser­va­tion agen­cies pro­vide the usual alerts that one should not eat shell­fish dur­ing this time and they warn against eat­ing dead fish.”

Al­lan­son ex­pressed con­cern about Knysna’s de­vel­op­ment and ex­pand­ing pop­u­la­tion, which he said were plac­ing strain on in­fra­struc­ture, in turn lead­ing to wa­ter con­tam­i­na­tion.

“If we didn’t have mil­lions of cu­bic me­tres of wa­ter flood­ing the es­tu­ary ev­ery day, we would be in se­ri­ous trou­ble,” he said.

“The sea let­tuce is one of the big­gest prob­lems, be­cause it causes shad­ing that is killing off the or­gan­isms that grow in the lower strata of the wa­ter and that form the ba­sis of the food chain.”

A res­i­dent, who did not want to be named, said the sea let­tuce was be­com­ing a prob­lem for boaters. “It got caught up in the in­take of my out­board mo­tor re­cently, caus­ing it to burn out,” he said.

Mu­nic­i­pal man­ager Grant Eas­ton said Knysna Mu­nic­i­pal­ity had spent R48-mil­lion on waste­water works up­grades, and R6.5-mil­lion on in­stalling restau­rant fat traps.

De­vel­op­ment and ex­pand­ing pop­u­la­tion are plac­ing strain on in­fra­struc­ture

Pic­ture: ESA ALEXAN­DER

BLOOMING AW­FUL: A blan­ket of al­gae cov­ers part of a Knysna es­tu­ary beach

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