Real Time qPCR Assessed Macroalgal Bloom Formation Patterns within the Genus Ulva (U. rigida & U. compressa) in Response to Temperature Thresholds

Narragansett Bay, RI is home to a vast and diverse population of estuarine species. Green algae of the genus Ulva inhabit Narragansett Bay and, under certain environmental conditions, can form harmful macroalgal blooms that cause serious negative ecological and economic impacts. As the climate changes, the magnitude and duration of these blooms are predicted to increase. In order to determine the harmful effects of the macroalgal blooms and link their growth dynamics with global environmental changes, more information about the life history and genetic makeup of these macroalgae must be explored. At present, the genus Ulva includes more than 100 species, which are widely distributed in estuarine and marine environments worldwide. Their abundance is particularly due to their high tolerance of variable salinity and water temperatures, along with high growth rate. The primary focus of this study is to observe expression patterns of a specific gene (LhcSR) known to play an important role in the photo-protective mechanisms of green algae. Real Time qPCR was performed on Ulva rigida and Ulva compressa tissue samples collected from Narragansett Bay from 2012 through 2013 during pre-bloom, bloom, and post bloom periods. In previous studies, the LhcSR gene was found more highly expressed at higher temperature ranges. Two housekeeping genes (Histone 2 and 18S) were used as controls for the normalized expression of the target gene. Expression patterns were compared between three different bloom periods (May, July, and September) in three different U. rigida and U. compressa populations in Narragansett Bay (Chepiwanoxet, Sandy Point, and Oakland Beach) and in both tidal levels (intertidal and subtidal). Normalized LhcSR gene expressions in U. rigida and U. compressa demonstrated that the target gene (LhcSR) was being upregulated during the warmer time periods (July and September) for all the populations studied.