Ecology Population Ecology Part 3

New York: European Starling From the New York Times, 1990 (cont.) Today the starling is ubiquitous, with its purple and green iridescent plumage and its rasping, insistent call. It has distinguished itself as one of the costliest and most noxious birds on our continent. Roosting in hordes of up to a million, starlings can devour vast stores of seed and fruit, offsetting whatever benefit they confer by eating insects. In a single day, a cloud of omnivorous starlings can gobble up 20 tons of potatoes. 2

3 Zebra Mussels The native distribution of the species is in the Black Sea and Caspian Sea in Eurasia. Zebra mussels have become an invasive species in North America, Great Britain, Ireland, Italy, Spain, and Sweden. They disrupt the ecosystems by monotypic (one type) colonization, and damage harbors and waterways, ships and boats, and water treatment and power plants.

4 Zebra Mussels Water treatment plants are most impacted because the water intakes bring the microscopic free-swimming larvae directly into the facilities. The Zebra Mussels also cling on to pipes under the water and clog them. This shopping cart was left in zebra mussel-infested waters for a few months. The mussels have colonized every available surface on the cart. (J. Lubner, Wisconsin Sea Grant, Milwaukee, Wisconsin.)

5 Zebra Mussel Range

Snakehead Fish During all life stages, snakeheads compete with native species for food and habitat. As juveniles, they eat zooplankton, insect larvae, small crustaceans, and the young of other fishes. As adults, they feed on other fishes, crustaceans, frogs, small reptiles, and sometimes birds and small mammals. Their predatory behavior could drastically disrupt food webs and ecological conditions, thus forever changing native aquatic systems by modifying the array of native species. 7

INQUIRY: Does feeding by sea urchins limit seaweed distribution? W. J. Fletcher of the University of Sydney, Australia reasoned that if sea urchins are a limiting biotic factor in a particular ecosystem, then more seaweeds should invade an area from which sea urchins have been removed. 8

INQUIRY: Does feeding by sea urchins limit seaweed distribution? Seems reasonable and a tad obvious, but the area is also occupied by seaweed-eating mollusc called limpets. What to do? Formulate an experimental design aimed at answering the inquiry question. 9

Predator Removal 10

Predator Removal 11 Removing both limpets and urchins or removing only urchins increased seaweed cover dramatically

Predator Removal 12 Almost no seaweed grew in areas where both urchins and limpets were present (red line), OR where only limpets were removed (blue line)

Relationship Between Temperature and Precipitation 13

Created by: Susan Ramsey Virginia Advanced Study Strategies Notable contributions by S.Meister