Breaching the dispersal barrier to invasion: quantification and management.

Area of Science:

• Ecology
• Biogeography
• Conservation Biology

Background:

• Globalization drives increased movement of species globally, leading to biological invasions.
• Research often overlooks propagule pressure due to measurement difficulties, focusing instead on post-dispersal processes.
• The Antarctic's isolation and limited entry points make it an ideal model for studying propagule movement and introduction.

Purpose of the Study:

• To investigate the logistics operations of the South African National Antarctic Programme (SANAP).
• To quantify the initial dispersal of alien species into the Antarctic via these operations.
• To assess the potential for human movements to facilitate intra-regional homogenization of native species.

Main Methods:

• Analysis of logistics operations, including passenger luggage and cargo, associated with the South African National Antarctic Programme (SANAP).
• Quantification of the number and diversity of seeds transported into the Antarctic.
• Assessment of propagule drop-off rates to estimate entry into the recipient Antarctic environment.

Main Results:

• Over 1400 seeds from 99 different taxa are transported into the Antarctic each field season via SANAP logistics.
• An estimated 30-50% of these transported propagules successfully enter the Antarctic environment.
• Many introduced taxa are cosmopolitan weeds or known Antarctic aliens, indicating a cycle of global species movement linked to human disturbance.

Conclusions:

• Antarctic logistics operations are a significant pathway for the introduction of alien species.
• Human movements may also contribute to the homogenization of native Antarctic species within the region.
• Implementing simple biosecurity policy changes can substantially mitigate the risk of nonnative species introductions into the Antarctic.