Nyk Aphrodite approaching Port of Rotterdam, Holland.
Key points:
- Researchers found a surprising number of live bacteria, fungi, worms, seeds and insects in soil aboard sea freight.
- The team recovered various regulated biosecurity organisms from the samples, including species never recorded as being present in New Zealand.
- Overall, the study suggests contaminated sea freight is an important introduction pathway for exotic species.
A research team from AgResearch and Better Border Biosecurity (B3) investigated the biological risk posed by soil on the external surfaces of sea freight such as shipping containers or used machinery at sea ports in New Zealand. With their work, the researchers hope to facilitate the assessment of relative biosecurity risks between different introduction pathways and contribute to the development of more efficient measures against them.
The team found soil on most types of sea freight, irrespective of origin—with all soil likely to vector microbes, including plant pathogens. The amount of soil recovered from a single sea container was 5.3 kg, while the overall mean weight collected from sea freight was 417g, with most of the soil found on the underside of sea freight.
According to the findings published in the journal NeoBiota, while the presence of soil was not surprising, the researchers were concerned with the amount of live bacteria, fungi, worms, seeds and insects. The team recovered various regulated biosecurity organisms from the samples, including plant-parasitic worms, seeds, insects and spiders that were not recorded as being present in New Zealand.
“Not only does the spread of exotic species through these networks represent significant environmental, economic and social costs to natural and agricultural environments if invasive alien species were to establish, a loss of biodiversity is also an expected consequence of invasive alien species establishment,” said Mark McNeill of AgResearch, who led the study. “For islands, the implications can be significant, as they have high levels of endemism and invasive alien species establishment can lead to extinction of species as well as biodiversity declines.”
Compared with a previous study on contaminated footwear carried in luggage by international airline passengers, the number and diversity in soil on sea freight was smaller than soil transported in more protected environments. This showed that biosecurity risk can vary with pathway. However, prioritizing one soil pathway over another is problematic since the relative risk is dynamic, dictated by factors such as new pests or diseases.
Even so, the researchers suggest contaminated sea freight is an important introduction pathway for exotic species.