Seaweed on beaches

Seaweed accumulation is a naturally occurring process and is vital to the sustainability of beach and marine environments. It provides a source of recycled nutrients, food source and habitat for other living organisms and acts as a barrier against coastal erosion.

Seaweed abundance is largely dependent upon prevailing conditions with wind, wave and tidal action the key determining factors in the natural movement of seaweed. The process is generally seasonal but can occur at any time throughout the year and build-up of seaweed and natural removal can occur very rapidly.

Accumulations of seaweed on beaches and boat ramps can occasionally impact recreational use and amenity. The accumulations can also have adverse impacts upon access and egress for emergency services and commercial activities.

In respect of the important ecological values of seaweed accumulations, the preferred option for the City in relation to seaweed accumulation and management is to not intervene and to leave seaweed in-situ to be broken down and/or removed by natural processes. Where practicable, every attempt should be made to retain the material within the immediate coastal ecological system.

However, there may be some exceptional circumstances where the City may take targeted action to relocate seaweed accumulations to restore access at high use beaches including Arrawarra Beach, Woolgoolga Beach, Park Beach, Jetty Beach and Sawtell Beach. 

Frequently asked questions

Why does seaweed sometimes accumulate on the beach?

Seaweed naturally washes ashore due to tides, currents, and storms. It’s a normal part of coastal ecosystems and varies seasonally.

Is seaweed a sign of pollution or poor beach health?

Not at all. Seaweed is a natural and healthy part of the marine environment. Its presence often indicates a healthy offshore underwater ecosystem.

What normally happens to seaweed when it accumulates on beaches?

In many cases, depending on the weather and ocean conditions, the natural tides and waves will wash seaweed back into the ocean. Otherwise, the seaweed will break down and decompose naturally. Natural decomposition of seaweed on NSW beaches can take weeks to several months, depending on the species of seaweed, temperature, moisture, and exposure to sunlight.

Why don’t we remove the seaweed from the beach?

Removing seaweed can disrupt important ecological processes. Some of the key environmental benefits of seaweed on beaches include:

• Habitat for wildlife: Washed-up seaweed provides shelter and habitat for invertebrates, insects, and shorebirds, supporting coastal biodiversity.
• Nutrient cycling: As seaweed decomposes, it releases nutrients back into the sand and nearby ecosystems, enriching vegetation and microbial communities.
• Sand stabilisation: Seaweed helps trap and hold sand, reducing erosion and contributing to the formation and maintenance of dunes.
• Food source: Many coastal species, including amphipods and crustaceans, feed on decaying seaweed, forming the base of a rich food web.
• Carbon sequestration: Seaweed stores carbon, and even when washed ashore, it continues to play a role in long-term carbon cycling.
• Buffer against wave energy: Accumulated seaweed can act as a natural barrier, dampening wave impact and protecting the shoreline.

 

Does seaweed smell or attract pests?

While decomposing seaweed can produce a smell, it’s a natural process. Most seaweed breaks down quickly and does not pose a health risk.

Can seaweed affect beach enjoyment?

We understand that some people prefer clean, sandy beaches. However, balancing human use with environmental health is key. In some cases, limited removal may occur for safety or access, but our general approach is to let nature take its course.

Is seaweed removal ever considered?

Yes, but only under exceptional circumstances—such as:

• Public health concerns.
• Obstruction of access for emergency services.
• Events or activities requiring temporary clearance, where no other viable alternative exists.