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bio case study - Bio 121 Case Study QuickTimeTM and a...

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Bio 121 12/08/2007 Case Study QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture.
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1. EDC’s cause these effects by disturbing the natural hormonal balance within the alligators. Hormonal imbalance can be directly related to the death of alligator eggs and neonates, as well as adult sterility and deformity. Hormones are necessary for proper egg development in all species, alligators included. When sex hormones in the alligators are at improper levels the eggs can form incorrectly and fail to produce young. Lake Apopka had a greater number of clutches that failed to produce any young than other surrounding lakes. The mother alligator laying the eggs very likely was unable to correctly form the eggs due to EDC intake and thus none of hers could survive. The observed increased neonate death rate from Lake Apopka over Lake Woodruff was much higher (36% to 4%) ( Guillette ) . Hormonal imbalance in hatchlings can cause death in a variety of methods. Too high or low of hormonal levels can cause death by failing to correctly regulate various bodily functions, the hatchlings may have been unable to perform their natural homeostasis. Alternatively the EDCs may have caused organ/developmental defects, which were not severe enough to terminate the hatchling before birth ( Sepulveda ) . Since EDC’s imitate and disrupt sex hormone levels they are highly likely to disrupt the formation of gonadal tissues, which are highly dependant of the correct hormone equilibrium for proper development. The development of gametes is similarly dependant on a very precise process of hormone function, which the article clearly demonstrates has often broken down in alligators originating from Lake Apopka. Improperly formed oocytes, including those with multiple nuclei, and sperm forming structures containing unknown and alien structures are very likely to have been caused by improper levels of hormones (Guillette ) .
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A similar study done on the linkage of organochlorine pesticides (OCPs) to death rates in the American Alligator neonates supported the view of linking pollutants to the deaths of alligator neonates. The article identifies OCPs as having endocrine disrupting effects, which make it an ideal comparison sample. The study looks at the death rates of hatchlings and determines the causes of deaths and attempts to link them to OCP pollutants in the environments. A determination of correlation between the two is confirmed, but the study notes the possibility that the OCPs, and thus EDCs, may not be directly responsible for the deaths of the neonates, but instead may simply make them more vulnerable to natural causes of death ( Sepulveda ) . Studies done on species other than the American Alligator found that EDCs had a very similar effect on the pre- and postnatal development on various forms of wildlife. These studies demonstrate that EDC pollutants can enter a hatchling from its environment, or have come from the mother during egg formation during which time large amounts of fat are mobilized. The fat tissues are often where EDCs are stored by the parent.
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