Coral polyps may not need to be genetically modified to become lethal. Toxins from coral spores are already deadly. This was demonstrated recently when a family of seven were poisoned by toxins from coral spores released from an aquarium in their house.
A family of seven living just south of Adelaide is in hospital because of suspected poisoning from spores released by coral from a
household aquarium which was scrubbed with a cleaning brush.
Ambulance crews were called to the house on Sunday Parade at Aldinga
Beach, about 2:30am, when the residents fell ill.
They were taken to Flinders Medical Centre and remain in a stable
Decontamination crews have worked at the home throughout the day.
The Country Fire Service (CFS) and police were then called to the
scene, which has been cordoned off.
The CFS said it traced the problem to the aquarium because of what the
family members had said and the symptoms they were displaying — mainly
"Those two together [we] worked out that it was the spores [from the
coral]," CFS regional officer Peter Phillips said.
"It would appear that in trying to clean the coral, they've taken it
out of the aquarium and scrubbed it with a brush and that's liberated
To give an indication of how dangerous this situation was: --
Three hazardous materials removal teams are on site, wearing
protective suits and breathing gear, each working in 20-minute shifts.
Marine ecologist Ivan Nagelkerken said coral products sold in aquarium
shops could contain toxins which could be life threatening.
"When people start cleaning their aquaria and damaging these flower
corals that's when the toxicants are released," he said.
"For example if people have a cut in their hand or if there was one
case of somebody cleaning their tank with boiling water and the toxins
entered the water vapour, then the effects can be really harmful."
The mechanism employed by coral spores is explained thus:
Aquaculture farmer Peter Fullerton told ABC Radio Adelaide's Drive
program that certain corals released toxins as a defence mechanism.
"You can have desirable corals that are colourful and ones that are
less colourful, so sometimes people decide to clean out the
He said some of the most toxic coral was found in the zoanthids genus.
The toxin is called palytoxin (PTX) and can cause severe respiratory
reaction, haemorrhaging and death to humans if ingested.
Mr Fullerton said he had known of a few aquaculture farmers who
suffered bad reactions after being squirted in the eye by the juice of
He recommended aquarium owners wear eye and hand protection when
handling coral to ensure toxins were not transferred.
This means that there are coral genus that produce deadly toxins. If genetic modification is required, then it should be of a kind that enables the coral spores and organisms is expel their defensive poisons to attack people and other creatures that feed on the corals.
Assuming many more corals could be equipped with similar toxic defense mechanisms could make reefs into hazardous and lethal environments. The basic mechanisms are there, if they can adapted and transplanted into the majority of corals then this could achieve the result you want in making corals deadly. This may not be what you had in mind when you wanted to make corals pathogenic.