Invasive alien species, often inadvertently introduced by human activities, pose a significant threat to native flora and fauna, disrupting ecosystems and driving species to the brink of extinction. Understanding how and why these species establish themselves in new locations is crucial for effective mitigation. A research team from AgResearch and Better Border Biosecurity (B3) has delved into the biological risk posed by soil on the external surfaces of sea freight, such as shipping containers and used machinery at New Zealand’s sea ports. Their work aims to aid the assessment of biosecurity risks and contribute to the development of more efficient measures to combat these invasive species.
The researchers discovered soil on various types of sea freight, regardless of its origin, all of which could potentially carry microbes, including plant pathogens. Notably, a single sea container yielded a substantial 5.3 kilograms of soil, while the overall average weight collected from sea freight was 417 grams. Most of this soil was found on the underside of sea freight.
Mark McNeill of AgResearch, who led the study, expressed concern over the presence of live bacteria, fungi, worms, seeds, and insects associated with the soil. The samples also contained regulated biosecurity organisms, including plant-parasitic worms, seeds, insects, and spiders not native to New Zealand.
The researchers emphasized that the spread of exotic species through these networks carries significant environmental, economic, and social costs and can lead to a loss of biodiversity. On islands, where endemism is high, invasive alien species can result in species extinction and a decline in biodiversity.
Comparing their findings to a previous study on contaminated footwear carried by international airline passengers, the researchers noted that the number and diversity of soil on sea freight were smaller than that transported in more protected environments, such as footwear in luggage. This highlights the variation in biosecurity risk among pathways.
While prioritizing one soil pathway over another is challenging due to the dynamic nature of relative risk, the researchers assert that contaminated sea freight is a crucial pathway for the introduction of exotic species. Preventive measures include cleaning containers before departure, border inspections, and further cleaning when necessary.
This research underlines the importance of understanding and managing the risks associated with soil on sea freight, a pathway that can significantly impact ecosystems and biodiversity. By addressing these concerns and implementing effective measures, we can better protect our environments from the threats posed by invasive alien species.