Presentation on theme: "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."— Presentation transcript:
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: 1.Be introduced to biological invasions 2.Know several examples of invasive species 3.Learn what you can do to stop the spread of invasive species
BBC 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.
Laurentian Great Lakes www1.ncdc.noaa.gov/pub/data/images/ great-lakes-ice-avhrr.gi Superior Michigan Huron Erie Ontario Mills et al 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 Canals Bait buckets, live wells and gear Ballast water
Sea Lamprey (Petromyzon marinus) Invaded the Great Lakes after the opening of the Welland Canal Devastated native fish stocks, especially lake trout
ZEBRA MUSSEL — Dreissena polymorpha Found in 1988 in Lake St. Clair (Lake between Huron and Erie, just off of Detroit, MI). Likely came to North America in ballast water Up to 70,000 individuals per m 2
Also attaches to boat hulls, docks, locks, breakwaters and navigation aids, increasing maintenance costs and impeding waterborne transport. One of the most expensive exotic species Will biofoul and restrict the flow of water through intake pipes (drinking, cooling, processing and irrigating water)
They have a free-living planktonic larval stage— veliger Characteristics of zebra mussels: Can attach to hard surfaces 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
Negative effects on native clams Zebra mussels cover them and prevent them from feeding and moving
How to prevent the spread of aquatic nuisance species? Empty all water before leaving site Never dump bait buckets!! Before leaving site, inspect gear, boats and trailers for exotics Let equipment dry for several days (does not work for species with resting eggs) Rinse your boat and equipment with high pressure hot water, especially if moored for more than a day
Lake Victoria More than 30 million people depend on the lake for survival z max = 100m
Lake Victoria Cichlids Haplochromis obliquidens Rock scraper Plant scraper Crab eater Rock-reef low-foraging zooplanktivore Parasite picker Snail crusherEgg snatcher Scale eater Over 300 endemic species described from Lake Victoria
The traditional fishery was dominated by hundreds of native species. 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 Oreochromis niloticus Nile tilapia eats zooplankton Lates niloticus Nile perch eats fish
One major life-history difference between the native and exotics: Many cichlids brood a relatively small number (5 to 100) of large eggs The exotics have much higher birthrates and no parental care All cichlids provide parental care
Before 1980, Haplocromines contributed about 80% of the biomass and Nile perch less than 2% Most rapid vertebrate mass extinction in recent history Figure from Kaufman 1992
What had been a fishery of > 400 species now was dominated by three: 80% Nile perch20% Nile tilapia and omena As the native fish species declined, Nile perch shifted to feeding on the native shrimp Cardina nilotica
Other problems with Nile perch: Destroys gear Cannot be sun-dried Can be smoked, but smoking required wood Favors large-scale fishing operations, which results in malnutrition, unemployment and poverty
What kind of ants are “pests” Both native and introduced species can become problematic –Leaf cutting ants, “sugar ants”, fire ants Most damaging species are introduced Biggest problems may occur on islands that have no native ant species.
Why worry about introduced ants? Agricultural –Some direct damage to crops –Tend and protect aphids –Disrupt biological control programs Urban pests –Mostly nuisance but can spread bacteria (in hospitals) Ecological pests - ecosystem level effects
Phrynosoma coronatum Declining throughout its range. A “sit and wait” ant specialist.
Argentine ants disrupt ant-mediated seed dispersal. Dendromecon rigida - tree poppy (Papaveraceae)
How do we control invasive species? In urban and agricultural areas pesticide use still common Natural enemies - Biological Control Manage the landscape to minimize disturbance –Turn off the water; landscape with native plants
Results of pesticide use Killed native competitors May select for resistance Health risks for people
Biological Control: 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.
Priorities for future research: Comparisons of native & introduced populations (determining native range) More experimental, large-scale & long-term studies Better estimates of density & biomass Prevention & control
Prevention Education is key Research is still needed - generalities? Monitoring programs - early detection Prevent establishment - quarantine Increased communication among agencies Increase regulations
What can you do to stop the spread of exotics?
Points to know, Oct. 2-4 Name two reasons we should be concerned about exotic, invasive species. How are they often introduced? Why are some exotic species so successful? Why are certain ecosystems more vulnerable to exotic species? Be able to recognize the exotic species from these lectures by name. Additionally, know the Lake Victoria and Laurentian Great Lakes stories in detail. Know how individual people can help prevent the spread of invasive species.