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The unique semi-diurnal tide system of Southern California suspends beach wrack along the beaches for approximately six hour periods before being washed back into the ocean. It has been noted in prior research that beach wrack is an essential part of Southern California's costal ecology but not much research has been done to learn about the viability of beach wrack as it dehydrates on the beach. To better understand the viability of wrack as it travels through these hydration changes, this study tested the effect of dehydration and rehydration on the fronds of Macrocystis pyrifera as they have been partially dehydrated and re-hydrated. This was tested by measuring the Fv/Fm, using a pulse-modulated fluorometer, and the change in water mass of selected fronds over a six hour dehydration period, and three hour re-hydration period. It was found that there was a significant increase of Fv/Fm and water mass after rehydration. However our studies showed that Fv/Fm surprisingly continued to increase as the plant was dehydrated and a chi-square test verified that the values of the rehydrated plants were not independent of the dehydrated values.

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