1. Marine Alien Species – An Overview

2. What is a Marine Alien Species?
-or Marine Non-Native, Exotic or Non- indigenous Species
Definition of an alien species is “a species introduced (by human action) outside its natural past or present distribution”
When that species starts causing trouble it becomes known as an “invasive” alien species and is defined as “a species that has the ability to spread causing damage to the native environment, the economy, our health and the way we live”
Firstly, they have several different names so you may have come across the terms marine non-natives, exotics or non-indigenous species. For this workshop and project as a whole we are going to call them “Marine Aliens”. By definition a marine alien is a species introduced by human action outside of its natural past or present distribution”. For example this harmless looking seaweed is called Wireweed, it’s thought to have arrived in Britain in the early 70s in the Isle of Wight and spread rapidly, it’s thought it can spread about 30km per year. The problem is is that it fouls man made structures so can block propellers and intakes. It grows in shallow waters so makes things like launching boats difficult, it also smothers other seaweeds. Its now found all along the west coast of Wales and is quite a familiar sight in the shallows.

3. Several factors facilitate a successful invasion, we often only know about the winners and many species arrive but do not take hold.
Resilient
Breed Faster
Grow Faster
High Dispersal
Tolerant to Many Different Conditions
Eats a Variety of Foods

4. £1.7bn spent on control in the UK annually
Invasive species can:
Outcompete native species for space
Outcompete native species for food
Directly predate on native species
Bring disease
Physically damage certain habitats and/or infrastructure
Have huge socio-economic costs
One of the biggest threats to global biodiversity (second only to habitat loss).
Invasive species have caused 40% of animal extinctions in the last 400 years!
£1.7bn spent on control in the UK annually

5. Video
Chinese Mitten Crab

7. How do they get around? Aquaculture Marine Litter Delibrately Released
Shipping & Recreation
Accidental Release

11. 7 of those are considered to be invasive.
In Wales the direct costs of Invasive Species is estimated to be £132,244,000
this doesn’t take into account the indirect costs
In 2011 it was estimated that there are approximately 40 marine alien species in Welsh waters.
7 of those are considered to be invasive.

12. Native to Japan.
The Carpet Sea Squirt (Didemnum vexillum) was first found in the UK in 2008 in Holyhead Marina
It is highly invasive and causes widespread problems out of its native range. It can foul man made structures and smother sea bed habitats.
This is the Carpet Sea Squirt, probably the most famous of Wales’ invasive alien species. You may have heard it being called Didemnum vexillum, this sea squirt is a global problem found in 2008 by a MSc student Kate Griffith, it is huge problem because eit smothers everything it settles on.

14. All of the evidence suggests that the Carpet Sea Squirt is transported by recreational craft.

15. D Vex Video