freshwater ecology

freshwater ecology - Source: Florida Integrated Science...

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Unformatted text preview: Source: Florida Integrated Science Center - Gainesville Expansion of intergrades by 1980. Current intergrade zone. Entire southern portion of native Largemouth Bass range at risk of being innundated With M. s. floridanus genes. Natural hybridization and human caused mixing (pre-1980) Invasion of nonnative species Probably one of the most permanent forms of “pollution” Once established – eradication is almost impossible. A few things we have learned: 1) Most invaders fail to establish and are never documented – success rate not well known. 1) High variability regarding the effects of successful invaders. 1) All aquatic ecosystems can be invaded. 1) Community effects are most often observed in low diversity systems. 1) Top predator invaders are more likely to have strong community effects. 1) To be successful, invaders must have adaptations suited for the new enviroment 1) Invaders are most likely to become established in disturbed communities 1) The greater the number of individuals and number of times introduced, the greater the success. 1) Species with a history of being invasive are likely to have continued success. Threats to Freshwater Species •20% of freshwater fishes extinct or in serious decline •Extinct/at-risk salmon/steelhead runs outnumber healthy by 3:1 •In CA, 57% of fish species are extinct or declining (Moyle and Williams) •Aquatic species worse-off than terrestrial •Top 6 stressors (most aquatic species face multiple threats): 1)Habitat removal/damage 2)Invasive species 3)Altered sediment loads 4)Altered hydrologic regime (flow, depth, temperature) 5)Altered nutrient inputs 6)Toxic contaminants Agricultural non-point pollution perceived as bigger threat in East; invasive species and loss of surface water bigger in West THE VALUE OF DIVERSITY...
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This note was uploaded on 11/09/2010 for the course NRM 2305 taught by Professor Staff during the Spring '08 term at Texas Tech.

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freshwater ecology - Source: Florida Integrated Science...

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