Toxins suspected as cause of seal attack

RethinkTheStink NPC says the recent seal attack at Clifton may have been caused by pollution.

On Tuesday, January 3, a seal pup attacked and bit two bathers at Clifton Beach, raising concerns about the toxicity of the Atlantic coast's beaches and seas.

According to Caroline Marx, the director of RethinkTheStink NPC, studies show that chemicals are accumulating in marine life, including seaweed, sea urchins, black mussels, and fish.

“Harmful algae can release toxins such including domoic acid which is suspected to have caused mass cape fur seal die-offs on the west coast. It is also known to cause neurological damage and changed behaviour including aggression, perhaps this seal was suffering from such poisoning,” Ms Marx said.

“Not only has the volume of raw sewage pumped into the ocean increased, but sewage these days includes many chemicals and human medications which did not exist 60 years ago,” she said.

Ms Marx adds that contact with untreated sewage poses a serious health risk and recommends the implementation of modern sewage treatment systems.

“Knowing the risks, should pumping raw sewage into a marine reserve such as Camps Bay and Green Point continue in a city very dependent on international tourism?”

Jean Tresfon, a marine conservation photographer since 2009, agrees with Ms Marx about domoic acid's impact on marine animals.

“I’ve heard about five or six incidents of seals attacking people since last July. So we have algal blooms, normal and harmful algal blooms and the harmful blooms produce domoic acid which gets into the fish that the seals eat and this is toxic to them (seals), and in the last couple of years we had masses of seals dying and the prevailing theory is that it is linked to this domoic acid,” said Mr Tresfon.

“Sometimes a seal does not get a full dose of this domoic acid and it’s suspected that it affects them neurologically and we suspect the seals that have attacked people have this domoic poisoning. It’s not proven as you would have to kill a seal and do an autopsy and no one wants to kill a seal, so it’s not conclusive but it is the prevailing theory that it (domoic acid) is causing this heightened aggression” he said.

He adds that that wild animals generally avoid humans but people should avoid wildlife that exhibits unusual behaviour.

The NSRI too are appealing to bathers and paddlers to stay clear of seals and avoid marine animals in their environment.

“Bite wounds from seals become severely infected and require thorough cleaning. Wounds of this nature should not immediately be stitched closed and the patient should be prescribed broad spectrum antibiotics. Without professional medical care results in significant infection,” said NSRI CEO Dr Cleeve Robertson.

During the holiday season, Bakoven beach was temporarily closed as a precautionary measure on December 22 due to a pump station failure caused by load-shedding. No other beaches along the Atlantic seaboard were closed according to the City of Cape Town.

An Uninterrupted Power Supply (UPS) was successfully installed at the pump station in Bakoven to reduce the impact of load-shedding, and it was confirmed to be effective during load-shedding.

“There is a risk of further pollution incidents as the City’s infrastructure is taking strain due to illegal dumping, but also the ongoing load-shedding especially the extended hours,” said the City's deputy mayor Eddie Andrews.

“Permanent generators have been fitted at all wastewater treatment plants and larger priority sewer pump stations were fitted with permanent generators as a measure to increase the resilience of sanitation supply systems,” he said.

Mr Andrews adds that the City has a multi-departmental response team that handles any pollution incidents.

“There are no additional costs associated with having staff on standby to deal with incidents as the water and sanitation directorate operates on a 24-hour basis already,” he said.