Paper Type

Master's Thesis


College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)




Cold temperatures are thought to be among the most important determining factors of geographic distribution for tropical and sub-tropical marine invertebrates. The Asian green mussel, Perna viridis, has been introduced into coastal waters of Florida where its current distribution is hypothesized to be limited by low temperatures during winter. Lethal and sublethal effects (heat shock protein/ Hsp70 expression) of cold water and air temperatures were analyzed in two size classes of P. viridis from Florida in an effort to determine the effects of current and forecasted temperatures on the potential for range expansion. Mussels were exposed to water temperatures of 14, 10, 7 and 3°C for up to 30 days, or to air temperatures of 14, 7, 0 and -10°C for periods of two hours. Mortality was significantly increased at all water and air temperatures ≤ 14°C. No consistent differences in mortality rates were observed between small (15-45mm) and large (75-105mm) size classes after exposure to either cold water or air. Significant increases in Hsp70 expression were observed after a two hour exposure to 10°C water, but Hsp70 expression was not significantly increased at any temperatures in which mortality was not also significant. The temperature threshold for survival in this population appears to be between 10-14°C which suggests that under current conditions, P. viridis may already be at the northern edge of its potential range in the United States. However, if water temperatures increase in association with global climate change, northerly flowing currents may permit range expansion as temperatures allow.

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