Caulerpa

Caulerpa is a fast-growing, coenocytic green algae known for its feather-like structure and ability to dominate marine habitats.

Caulerpa is a genus of green algae known for its unique structure and adaptability. Its resilience and ability to grow rapidly make it a formidable invasive species in non-native habitats.

What is Caulerpa?

A fast-growing type of green algae, Caulerpa is recognisable for its feather-like fronds and long, root-like runners that spread across the seafloor. What makes it especially interesting is that it’s coenocytic. This means that each plant is technically a single cell with multiple nuclei. Despite being unicellular, it grows structures that resemble leaves, stems, and roots. This unique design helps Caulerpa adapt to a wide range of marine environments.

Where Are Caulerpa Species Typically Found?

Species of Caulerpa are commonly found in warm, shallow coastal waters around the world. They grow on sandy or rocky sea bottoms and can form dense mats that cover large underwater areas. Their tolerance for varying light levels and salinity makes them especially resilient in different marine conditions. Because of their fast growth and ability to outcompete native species, Caulerpa species can become invasive in ecosystems where they don’t naturally belong.

Does Caulerpa Have Economic or Practical Uses?

Some species of Caulerpa are used in aquariums, wastewater treatment, and even as a food source. However, while they do have practical applications, their ability to spread rapidly can lead to major environmental and economic problems. This is especially apparent in environments where the algae displaces native species and disrupts coastal industries like fishing and aquaculture.

Why Are Some Caulerpa Species Considered Invasive in New Zealand?

There are Caulerpa species that are native to New Zealand and are generally harmless. However, certain non-native strains are now spreading quickly in coastal areas. Some of these strains can grow up to 3 centimetres per day, and they can easily form mats over the seafloor, alter habitats, and disrupt the natural balance of marine ecosystems.

Because of its speed and resilience, invasive Caulerpa is considered a serious threat that requires close monitoring and early intervention.

Can Human Activities Aid in the Spread of Caulerpa?

Yes, human activities can significantly contribute to the spread of Caulerpa. Tiny fragments of the algae can cling to boat anchors, fishing gear, diving equipment, and even footwear. When these items are moved from one location to another without proper cleaning, they can unintentionally introduce Caulerpa to new areas. The aquarium trade has also played a role in its spread, as some species were once popular for display. Because Caulerpa can regrow from even the smallest pieces, any accidental transport can lead to new infestations.

How Does Caulerpa Affect Local Marine Ecosystems?

The overgrowth of Caulerpa harms ecosystems in several ways:

It forms thick, smothering mats on the seafloor and crowds out native plant species like seagrasses.
It reduces biodiversity by creating monocultures that make it difficult for a variety of species to coexist.
It disrupts the natural balance of the food chain and affects fish and invertebrates that rely on native habitats.
It alters the physical environment by impacting water flow, sediment stability, and nutrient cycling.

What Are the Potential Consequences if Caulerpa Is Left Unmanaged?

If not managed early, Caulerpa infestations can cause:

Severe declines in fish stocks, affecting both commercial and recreational fisheries.
Displacement of native marine species and loss of biodiversity.
Economic damage to marine industries such as aquaculture and tourism.
Long-term habitat degradation, which can make it difficult for ecosystems to recover.

Why Is It Important to Detect Caulerpa Infestations Early?

Early detection is critical to preventing Caulerpa from spreading uncontrollably. Traditionally, detection has relied on divers manually surveying underwater areas. This approach, unfortunately, can be expensive, time-consuming, and limited by weather and visibility. Without early intervention, managing an infestation becomes much more complex and costly.

How Do Remotely Operated Vehicles (ROVs) Aid in Caulerpa Detection?

There’s a growing need for a more efficient, cost-effective way to monitor large marine areas, especially as Caulerpa infestations become more widespread. Engineer and diver Peter Miles offers a practical solution to this challenge by using remotely operated vehicles (ROVs), which can scan an underwater area 3x faster than a SCUBA survey. His project, Detecting Caulerpa, demonstrates how a low-cost ROV can survey the seafloor and capture high-quality images. The images, in turn, are used to create detailed 3D maps of affected areas. This method makes it easier to spot infestations early and take targeted action to help slow the spread of invasive Caulerpa.

On top of offering a faster and more accessible way of detecting infestations, the project empowers local communities—who have already played a key role in spotting Caulerpa—to use the technology themselves. In the future, the goal is to automate these scans and integrate AI into the process of identifying invasive species, making detection even more efficient and accessible.

How Do Projects Like Detecting Caulerpa Empower Communities to Help Manage Caulerpa Invasions?

Initiatives like Detecting Caulerpa are not just about technology, as they are about people, too. Local communities know their marine environments best. By equipping them with tools and training to identify and report Caulerpa, these projects enable faster and more targeted responses. Locals can work alongside experts, contribute sightings, and form part of a frontline defence against invasive marine species. In doing so, they help protect ecosystems while building stronger, more informed communities.