Page 77 - CB1.3 Genetic Varation sciPAD

PHOTOCOPYING PROHIBITED
© Silverback Academic Media 77
CB 1.3 GENETIC VARIATION
USING KNOWLEDGE OF GENETICS
eDNA and Invasive Marine Pests
New Zealand’s Polynesian and European settlers brought with them many types of animals and
plants from their homelands. Later introductions were made to support farming, horticulture and
forestry. Inevitably, some introduced species (possums, rabbits, stoats, weasels, etc.) established
feral populations and became pests, out-competing, out-breeding and preying upon native
animals and plants. Marine pests are less obvious than terrestrial ones, simply because they are
harder to observe.
Invasive marine pests can cause a range of negative environmental impacts. They often
compete with native species for space and food, and some introduced species appear to be
more aggressive competitors than native ones. By smothering areas of sea floor, some pests
fundamentally change habitats. A major pathway for the introduction of marine pests into New
Zealand waters is the movement and discharge of ballast water.
Ballast tank full Ballast tank empty
Cargo hold empty Cargo hold full
When cargo is removed from a ship, it takes on
ballast water to stabilise itself. As the cargo hold is
emptied, the ballast tanks are filled. This water will
contain many different marine species.
When cargo is loaded onto the ship, ballast water
is expelled, releasing the exotic marine species
into a new environment.
The ship travels to another port
to pick up cargo. This may be
an international destination.
1
2
3
How Ballast Water Spreads Marine Pests
A marine species that is not present in New Zealand waters, but is rapidly
spreading around the world, is the Chinese mitten crab (Eriocheir sinensis). It
could arrive in ballast water, and would have devastating consequences
for our inshore marine ecosystems.
As a biosecurity advisor to the government, you have been tasked with
establishing a ballast water monitoring program to try and keep mitten
crabs out of New Zealand. You have decided to use eDNA monitoring
technology to assist with this.
1. Describe what genetic information you would require before you can use eDNA monitoring
technology. 

2. Explain how you could use eDNA testing of ships to identify if they are carrying mitten
crabs (or their larvae) in their ballast water. 









Unchecked Sample Pages
For Review Purposes Only - Photocopying Prohibited
www.scipad.co.nz