Announcements Oct. 4, 2006. Key on course web site (link on lectures page) click on “Test 1 (key)” after Sept. 20 You can pick up error sheets after class today. Invasive Species II. Lecture Objectives: Be introduced to biological invasions Know several examples of invasive species
Key on course web site (link on lectures page)
click on “Test 1 (key)” after Sept. 20
You can pick up error sheets after class today.
5 October, 2004
Deadly ladybird' sighted in UK
A ladybird which has already caused havoc to native insects in America has been spotted near a pub in Essex. Harmonia axyridis posed a "deadly threat" to butterflies, lacewings and many other ladybirds. The ladybird is an Asian species which was introduced into North America 25 years ago to fight aphids. It has since spread to Europe and last month was discovered in the gardens of the White Lion pub in Sible Hedingham. It is critical to monitor this ladybird now, before it gets out of control and starts to annihilate our own British ladybirds. H. axyridis is still sold in North America as a pest control. "It is now the commonest ladybird in North America.
Mills et al. 1993
Over 140 exotic species
Many fish species were (and continue to be) released intentionally
Many other exotics have entered the lake accidentally:
Escape from captivity
Bait buckets, live wells and gear
Invaded the Great Lakes after the opening of the Welland Canal
Devastated native fish stocks, especially lake trout
Round goby (1990)
Chinook salmon (1873)
Coho salmon (1933)
Bythotrephes cederstromi (1984)
Cercopagis pengoi (1998)
Quagga mussel (1990s)
Asiatic clam (1980)
Found in 1988 in Lake St. Clair (Lake between Huron and Erie, just off of Detroit, MI).
Up to 70,000 individuals per m2
Likely came to North America in ballast water
Will biofoul and restrict the flow of water through intake pipes (drinking, cooling, processing and irrigating water)
Also attaches to boat hulls, docks, locks, breakwaters and navigation aids, increasing maintenance costs and impeding waterborne transport.
Can attach to hard surfaces
They have a free-living planktonic larval stage— veliger
Females can produce 40,000 veligers
These are typical characteristic of marine species
Veligers are easily transported in bait buckets and livewells and anywhere else water collects
Adults can attach to hulls and survive outside of water for several days.
Cover most hard surfaces
Zebra mussels cover them and prevent them from feeding and moving
Purple Loosestrife (early 1800s)
Eurasian Watermilfoil (1881)
Never dump bait buckets!!
Before leaving site, inspect gear, boats and trailers for exotics
Empty all water before leaving site
Rinse your boat and equipment with high pressure hot water, especially if moored for more than a day
Let equipment dry for several days (does not work for species with resting eggs)
zmax = 100m
More than 30 million people depend on the lake for survival
Over 300 endemic species described from Lake Victoria
Rock-reef low-foraging zooplanktivore
But the introduction of gill nets and other gear by the British in the early 1900s resulted in over-fishing
In the 1950s, several new species were introduced to Lake Victoria to compensate for the declining stock of native species
All cichlids provide parental care
Many cichlids brood a relatively small number (5 to 100) of large eggs
The exotics have much higher birthrates and no parental care
Before 1980, Haplocromines contributed about 80% of the biomass and Nile perch less than 2%
Figure from Kaufman 1992
Most rapid vertebrate mass extinction in recent history
80% Nile perch
20% Nile tilapia and omena
As the native fish species declined, Nile perch shifted to feeding on the native shrimp Cardina nilotica
Cannot be sun-dried
Can be smoked, but smoking required wood
Favors large-scale fishing operations, which results in malnutrition, unemployment and poverty
on islands that have no native ant species.
Declining throughout its range.
A “sit and wait” ant specialist.
Dendromecon rigida - tree poppy (Papaveraceae)
The use of one species to control another.
Usually a specialist predator or parasite of an invasive species.
Needs to be species specific or could cause even worse problems.