Identifying marine invasion threats and management priorities through
introduction pathway analysis in a remote sub-Antarctic ecosystem
Abstract
The threat from novel marine species introductions is a global issue.
When Non-native marine species are introduced to novel environments and
become invasive, they can affect biodiversity, industry, ecosystem
function, and both human and wildlife health. Isolated areas with
sensitive or highly specialised endemic species can be particularly
impacted. The global increase in the scope of tourism activities
together with a rapidly changing climate, now put these remote
ecosystems under threat. In this context, we analyse invasion pathways
into South Georgia & the South Sandwich Islands (SGSSI) for marine
non-native species via vessel biofouling. The SGSSI archipelago has high
biodiversity and endemism, and has historically been highly isolated
from the South American mainland. The islands sit just below the Polar
Front temperature boundary, affording some protection against
introductions. However, the region is now warming and SGSSI increasingly
acts as a gateway port for vessel traffic into the wider Antarctic,
amplifying invasion likelihood. We use remote AIS vessel-tracking data
over a two-year period to map vessel movement and behaviour around South
Georgia, and across the ‘Scotia Sea’, ‘Magellanic’, and northern
‘Continental High Antarctic’ ecoregions. We find multiple vessel types
from locations across the globe frequently now enter shallow inshore
waters and stop for prolonged periods (weeks/months) at anchor. Vessels
are active throughout the year and stop at multiple port hubs,
frequently crossing international waters and ecoregions. Management
recommendations to reduce marine invasion likelihood within SGSSI
include initiating benthic and hull monitoring at the identified
activity/dispersion hubs of King Edward Point, Bay of Isles, Gold
Harbour, St Andrews Bay and Stromness Bay. More broadly, regional
collaboration and coordination is necessary at neighbouring
international ports. Here vessels need increased pre- and post-arrival
biosecurity assessment following set protocols, and improved monitoring
of hulls for biofouling to pre-emptively mitigate this threat.