The Safe Use of Chlorine in Marine Biosecurity

Here are some FAQ's on the safe use of chlorine in Marine Biosecurity practices

Isn’t chlorine harmful to marine life?

When used irresponsibly, yes—but the Rehabitat system is different. It uses chlorine within a sealed treatment chamber, so the chemical is contained and does not enter the surrounding ocean. After treatment, the chlorine is neutralised.

Is chlorine even appropriate to use in the ocean?

Chlorine is already present in our oceans. Seawater naturally contains chloride ions—making up about 1.9% of the ocean by weight. The use of chlorine in a controlled, temporary, and targeted way builds on what is already a natural part of the marine ecosystem.

What else is chlorine used for in marine contexts?

Chlorine is commonly used worldwide in marine biosecurity and ballast water treatment to prevent the spread of invasive species. It’s also used to disinfect potable water and is approved for sanitising ship hulls, aquaculture gear, and marine research equipment.

What’s the international precedent for using chlorine against Caulerpa?

California—one of the most environmentally progressive jurisdictions in the world—uses chlorine as its primary method for treating invasive Caulerpa species. Their success has helped inform best practice globally, and the Rehabitat system takes this even further by containing the chlorine.

How much chlorine is used in the Rehabitat system?

The concentration is only about twice that of a standard swimming pool and is applied directly to the affected seabed within a sealed dome. It’s a precise and localised approach that uses far less chlorine than traditional benthic mat treatments.

Does chlorine leave any residue in the ocean?

Nothing noticeable. Because Rehabitat contains and removes the chlorine post-treatment, minimal residual chlorine is left in the water. Even if trace amounts did remain, chlorine rapidly dilutes in seawater and does not persist in the environment.

Is this method safe for long-term use?

Yes. Research and early testing show that the seabed recovers quickly after treatment, and there’s no evidence of harmful long-term effects when used this way. In fact, the Rehabitat approach is one of the most environmentally responsible tools available for marine invasive species management.

How does this compare to traditional methods?

Rehabitat improves on traditional chlorine treatments by:

• Containing the chemical in a sealed chamber.

• Minimising dispersal into surrounding water.

• Requiring much lower chlorine volumes.

• Reducing risk of fragmentation and spread of Caulerpa as it kills it.