Invasion, threat

Results of these inspections have shown that the following insects must definitely be regarded as a casual invasion threat ... 

The Great Lakes have suffered the invasion of numerous exotic species of which the smelt, alewife and sea lamprey are probably the best known. More recently, two more species have entered the lakes probably via ballast water from foreign ships. The ruffe (Gymnocephalus cemuus) a small percid, feeds on the eggs and larvae of other percids and whitefish. The ruffe is currently considered to be a threat to Lake Superior s 5- 10 million whitefish fishery. The zebra mussel (Dreissena polymorpha) was discovered in Lake St. Clair in 1985 (31). It has subsequently been discovered at locations throughout the Great Lakes and is of major concern not only environmentally but economically. It has already colonized numerous industrial and domestic water intakes in sufficient numbers to entirely block water flow and is also an intermediate host to parasites which eventually invade fish. 

Further, the threat of future wars may be diminished if the world is less critically dependent on oil. Competition over oil resources was an important factor in Japan s entry into World War n and in our military response to Iraq s invasion of Kuwait. Nuclear energy can contribute to reducing the urgency of such competition, albeit without eliminating it. 

In the light of history we now know that Hitler had no intention of stopping with the gains he made through the Munich agreement. In order to justify. .. the threat of invasion. .. of Bohemia and Moravia,... 

The Ebro watershed has a large surface area (85,000 km2) and a complex drainage network (a total of 347 streams). The Ebro is a relatively well known river from the point of view of the biological communities composition. Studies exist on the aquatic fauna and flora [3]. However, the functional activity of the river is largely unknown, mostly because of its complexity and associated technical difficulties. This chapter provides a state-of-the art of the who is who in the biological communities in the river, as well as considerations about the threats imposed by habitat deterioration, eutrophication, pollution and species invasions, and indicates the current gaps that still exist in the knowledge of the river. 

Even after the threat of invasion faded away, the British continued heavy production of chemical weapons. Indeed, as Table 4.2 illustrates, by far the biggest expenditure by the British government on research and development in the Second World War was on poison gas. 

Pimentel D., S. McNair, and J. Janecka. 2001. Economic and environmental threats of alien, plant, animal and microbial invasions. Agriculture, Ecosystems and the Environment 84 1—20. 

Konvalinkova, P., Generative and vegetative reproduction of Helianthus tuberosus, an invasive plant in central Europe, in Plant Invasions Ecological Threats and Management Solutions, Child, L.E., Brock, J.H., Brundu, G., Prach, K., Pysek, P., Wade, P.M., and Williamson, M., Backbuys Pub., Leiden, The Netherlands, 2003, pp. 289-299. 

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