Lecture 3 – Take Home Points
Vectors and pathways
Vector – the mechanism of conveyance of the invasive species (ship, plane, etc.)
Pathway – the route that the vector moves the invasive species (e.g., China to the USA)
Our transportation system underlies all biological invasions
When we move ourselves or our goods and services, we inadvertently or deliberately move
species from where they are native to where they are not.
Not a new phenomenon – we’ve been doing this since humanity evolved and started to
expand our geographic range.
What has changed is the volume, the efficiency, the speed, and the distances that we move
species across.
Consider the old sailing ships of the 1600-1800’s that helped in the colonization of
Australia, North and South America and islands throughout the world. They were small
and slow but still managed to offload all sorts of species. In contrast, a modern container
ship can move the equivalent of a 1000 sailing ships in one voyage that takes 9-10 days to
go from Shanghai to Long beach, CA.
Vectors and pathways change through time as technology evolves and trading partners
change. As they change, so to do the types of organisms moved.
Leading Vectors:
Shipping (marine / freshwater), Canals, Raw Wood, Living Industries
Containerized shipping: Containers move the world!! From humble beginnings, the
standard shipping container now moves most of the World’s finished goods.
This type of shipping led to fundamental changes in invasive species introductions
(1) Eliminated the old ‘break-bulk’ labor intensive load/unload
(2) Changed points of destination from just coastal port cities, to a distributed network
of terminals where containers can be moved anywhere in the country, and thus
introductions are more diffuse.
(3) Increased the speed with which organisms can be moved
(4) Changed the kinds of organism entrained in the transport system.
Ballast water: Used to achieve ideal buoyancy in ships by compensating for displacement
by cargo. Tanks are filled through a series of pumps by uptaking water from wherever the
ship is and discharging water when it is not needed.
Huge source of aquatic invasions as many organisms are sucked up with the water and
dumped out with the water. Allows significant movement of water (and aquatic
organisms) from one region to another