New Zealand's pristine waters face a significant threat from exotic Caulerpa seaweeds. These invasive species, found in areas such as Great Barrier Island (Aotea), Great Mercury Island (Ahuahu), Te Rāwhiti Inlet in the Bay of Islands, Kawau Island, and Waiheke Island in the Hauraki Gulf, are rapidly spreading and posing a risk to native marine ecosystems.
Exotic Caulerpa species, such as Caulerpa brachypus and Caulerpa parvifolia, are difficult to distinguish from native species due to their similar appearance. These seaweeds feature green fronds up to 10 centimetres long, shaped like oar blades, and grow from long runners or roots known as stolons. They thrive below the tideline, at depths between 2 and 30 metres, on both hard and sandy surfaces, forming dense mats that cover large areas of the seafloor.
Why These Caulerpa Seaweeds Are a Concern
The rapid spread of exotic Caulerpa can lead to dense underwater fields that compete with other marine species, including native Caulerpa, for space. This competition can disrupt local ecosystems, affecting recreational, cultural, and commercial marine activities. Detecting and managing these invasive species promptly is crucial for preserving New Zealand's marine biodiversity.
AI-Based Detection of Exotic Caulerpa
Role of AI in Marine Monitoring
Artificial intelligence (AI) plays a pivotal role in enhancing the detection and management of exotic Caulerpa seaweeds. By processing large volumes of visual data, AI algorithms can accurately identify and track the spread of invasive species. Solar-powered marine drones equipped with high-resolution cameras and AI systems can autonomously monitor extensive areas of the ocean, providing real-time insights into marine ecosystems.
Solar-Powered Marine Drones
Solar-powered marine drones, often designed as catamaran-style vessels, are ideal for continuous marine monitoring. Equipped with high-resolution cameras, these drones capture detailed images of the seafloor. The use of solar power allows them to operate autonomously for extended periods, making them perfect for long-term environmental monitoring.
Image Data Collection
High-resolution images collected by the drones provide a comprehensive view of the underwater environment. These images serve as the primary data source for AI algorithms, which analyse the visual information to detect and classify marine species.
AI Algorithms for Species Detection
Training AI Models
Training AI models, particularly convolutional neural networks (CNNs), to recognise exotic Caulerpa species involves feeding the model with extensive datasets of labelled images. This process allows the AI to learn the distinctive features of Caulerpa brachypus and Caulerpa parvifolia. Key characteristics such as the shape, size, and colour of the fronds and stolons are used to differentiate these species from native ones.
Algorithm Optimisation
To ensure high accuracy, the AI algorithms must be continuously optimised. This involves fine-tuning the model parameters and retraining the model with new data. Techniques such as data augmentation, which creates variations of existing images, and transfer learning, which applies knowledge from pre-trained models, enhance the model’s performance.
Real-Time Detection
Once trained, the AI models can process images captured by the marine drones in real-time. The models analyse each image to identify the presence of exotic Caulerpa, classify the species, and assess the extent of the infestation. Real-time detection enables prompt interventions, reducing the risk of widespread ecological damage.
Our Collective Response in New Zealand
In response to the threat posed by exotic Caulerpa, Biosecurity New Zealand, mana whenua, local authorities, and other partners are working tirelessly to control the spread of this invasive species. Since its detection at Aotea Great Barrier Island in 2021, efforts have included trial treatments, legal restrictions on certain boating and fishing activities, and placing rāhui over affected areas.
Exploring Solutions
In June 2023, an advisory group assembled to explore the potential of diver-controlled suction dredging to remove exotic Caulerpa. While challenging, these efforts are crucial for managing the infestation and protecting New Zealand’s marine ecosystems.
Educational Campaigns
Educational campaigns are essential for raising awareness about exotic Caulerpa and preventing its spread. Ongoing surveillance and public engagement are key to understanding and controlling the issue.
Call to Action: Get Involved
For more information and to stay updated on the situation with exotic Caulerpa seaweeds in New Zealand, you can explore the following resources:
Information Hotline:
Reach out to Biosecurity New Zealand at 0800 80 99 66 to report any sightings or for further information.
Key Source: Ministry for Primary Industries
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