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Source-sink Dynamics Affect on Trophic Cascades

Source-sink Dynamics Affect on Trophic Cascades. By Group A33: Rachel Conforto Thomas Fontana Jason Malia Domingo Uceda Martin Yeh. http://wwf.panda.org/what_we_do/where_we_work/baltic/?uNewsID=199972. http://www.maretarium.fi/mare/kala_uk.php?id=203. Source Sink Dynamics.

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Source-sink Dynamics Affect on Trophic Cascades

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  1. Source-sink Dynamics Affect on Trophic Cascades By Group A33: Rachel Conforto Thomas Fontana Jason Malia Domingo Uceda Martin Yeh http://wwf.panda.org/what_we_do/where_we_work/baltic/?uNewsID=199972 http://www.maretarium.fi/mare/kala_uk.php?id=203

  2. Source Sink Dynamics • Theoretical model that ecologists use. • Model accounts for the fact that habitats are not perfectly designed for a specific organism. • “source” - high quality spots of the habitat that allows the population size to increase • "sink” - low quality spots of the habitat that on its own would not be able to support the population.

  3. Trophic Cascades • Occurs as a result of the food chain and predation. • Introduction or removal of a part of the chain can alter the whole cascade. • Can alter both the abundance and the habits of the organisms at different trophic levels. • When a predator limits its prey's population, the system is under top down control. • Humans can affect Trophic Cascades through removal of predators

  4. Case Overview • Favorable breeding conditions and low rates of  fishing in the late 1970’s  led to over abundance of the species Cod in the Baltic Main Basin. • “Spillover effect” or migration of Cod into the Gulf of Riga. • In the mid 1980’s over-fishing in the Baltic Main Basin decreased abundance in the source habitat of Cod. • The Cod retracted back into Main Basin from the Gulf of Riga sink habitat.

  5. Case Overview • Data was collected analyzing the source-sink dynamics between the Baltic Main Basin and Gulf of Riga. • Trophic cascades caused by top-down effects • Led to fluctuations in biomass & population size of herring and zooplankton in Gulf of Riga.

  6. Discussion • Migration and disappearance of cod paralleled by decrease and increase in the population size of herring. • Variation in herring population inversely reflected in zooplankton populations. • Variations were observed in phytoplankton populations.

  7. Conclusion • Humans can have a dramatic impact on ecosystems via human exploitation of organisms/resources. • Key species role in ecosystems and how the flow of organisms across systems affects food-web dynamics.

  8. Literature Cited • Freeman, Scott. Biological Science, 4th ed.; Benjamin Cummings, 2011: pg 1083-87. • Casini, Michele et al. "Predator transitory spillover induces trophic cascades in ecological sinks." PNAS vol. 109 no. 21 (2012): pg 8185-89. • Fox, Jeremy W. "Testing The Mechanisms By Which Source-Sink Dynamics Alter Competitive Outcomes In A Model System." American Naturalist 170.3 (2007): 396-408.    

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