Exemplary Introduction Draft 1
Author: Bradley Potter
Contents
Introduction
Significance of the Problem
The native oyster population in the Chesapeake Bay has historically been a robust species, tolerating a wide range of salt concentrations and water temperatures, but it has still fallen victim to pollution, disease, and over-harvesting.[1] As a result, the population size has dropped to as low as 1% of its prior levels.[1][2] The population of native oysters in the bay dropped from roughly 615,000 to just 12,000 from 1884 to 1992. Human activity has played a significant role in the degradation of these reefs: a combination of pollution, over-harvesting, destruction of the reefs by fisherman which lowers the reef profile, and work on the land increasing sediment flow into the bay which has slowed the reproduction and increased the death rate due largely to choking out the population by covering it with sediment deposits.[2][3][4] The heavier sediment flow combined with the lower reef profile is especially detrimental as the slower water flow at greater depths also increases sediment deposition rate, again choking out the oysters and increasing mortality rates.[3][4] This is a major problem not only for the oyster industry and for conservation of the species, but the native oyster species also plays an important role in the construction of the underwater ecosystem on which many other species depend.[5]
Many restoration efforts have been made, especially starting in the 1990s, driven largely by the formation of the Oyster Recovery Partnership in 1993 whose primary goal is the recovery of the Chesapeake Bay oyster population by providing knowledge, resources, funding, and personnel to support the recovery.[6] Unfortunately, many of these efforts have found only minimal success.[7] An experiment performed by the Army Corps of Engineers in 2004 used oyster reefs that were constructed at two different heights, and results suggested that the taller reefs favored successful restoration far more than the short, low-relief reefs.[8] This experiment provides the fundamental basis for the model reconstruction we will pursue.
Background and Hypothesis
It has been seen in various natural habitats that minor external changes can cause a drastic change in the stability of the ecosystem.[9] This is the phenomenon of bi-stability. By changing the conditions of an ecosystem slowly can result in a drastic change, yet returning to the original conditions externally does not force the system to revert back to its previous state. Other mollusk populations have exhibited this bi-stability, including the horse mussel is New Zealand and the blue mussel along the Atlantic Coast of North America.[10][11] Combining this awareness of bi-stability with the experiment by the Army Corps of Engineers[8], we will be developing a model of oyster populations and analyzing these mathematical models for bi-stable equilibrium points with varying initial conditions and parameters. The hypothesis we wish to test using this model is that reefs of greater height are more likely to have stable, living populations of oysters due to an offset of heavy sedimentation and improved disease resistance relative to lower height reefs which will degrade and die in just a few years. This model reconstruction is based on the paper "Bistability in a differential equation model of oyster reef height and sediment accumulation" by William C. Jordan-Cooley, Romuald N. Lipcius, Leah B. Shaw, Jian Shen, and Junping Shi, published in the Journal of Theoretical Biology in 2011.
Final paper will include brief results and model extension
References
- ↑ 1.0 1.1 "Oyster Restoration." National Oceanic and Atmospheric Administration. Chesapeake Bay Office. March 26, 2012. http://chesapeakebay.noaa.gov/oysters/oyster-restoration
- ↑ 2.0 2.1 Rothschild, B., Ault, J., Goulletquer, P., Heral, M., 1994. Decline of the chesapeake bay oyster population: a century of habitat destruction and overfishing. Mar. Ecol. Prog. Ser. 111, 29–39.
- ↑ 3.0 3.1 Newell, R.I.E., 1988. Ecological changes in chesapeake bay: are they the result of overharvesting the eastern oyster(Crassostreavirginica)? In: Lynch, M., Krome, E. (Eds.), Understanding the Estuary, Advances in Chesapeake Bay Research - Chesapeake Research Consortium, Gloucester Point, VA, pp.536–546.
- ↑ 4.0 4.1 Lenihan, H.S., Micheli, F., Shelton, S., Peterson, C.H., 1999 b. The influence of multiple environmental stressors on susceptibility to parasites: an experimental determination with oysters. Limnol. Oceanogr. 44, 910–924.
- ↑ Cerco, C., Noel, M., 2007. "Can Oyster Restoration Reverse Cultural Eutrophication in Chesapeake Bay? Estuar.Coasts30(2), 331–343.
- ↑ "History." Oyster Recovery Partnership. March 26, 2012. http://www.oysterrecovery.org/Content/ContentDisplay.aspx?ContentID=47
- ↑ Ruesink, J., Lenihan, H., Trimble, A., Heiman, K., Micheli, F., Byers, J., Kay, M., 2005. Introduction of non-native oysters: ecosystem effects and restoration implications. Ann. Rev. Ecol. Evol. Syst. 36(1), 643.
- ↑ 8.0 8.1 Schulte, D.M., Burke, R.P., Lipcius, R.N., 2009. Unprecedented restoration of a native oyster metapopulation. Science 325, 1124–1128.
- ↑ Scheffer, M., Carpenter, S.R., Foley, J.A., Folke, C., Walkerk, B., 2001. Catastrophic shifts in ecosystems. Nature 413, 591–596.
- ↑ Coco, G., Thrush, S., Green, M., Hewitt, J., 2006. Feedbacks between bivalve density, flow, and suspended sediment concentration on patch stable states. Ecology 87 (11), 2862–2870.
- ↑ Petraitis, P., Methratta, E., Rhile, E., Vidargas, N., Dudgeon, S., 2009. Experimental confirmation of multiple community states in a marine ecosystem. Oecologia 161 (1),139–148.
