Spatial and temporal variation in DMSP content in the invasive seaweed Codium fragile ssp. fragile:effects of temperature, light and grazing

摘要

The methionine-derived secondary metabolite dimethylsulfoniopropionate (DMSP) is believed to function in cryoprotection, defense against herbivory, and reduction of oxidative stress in some seaweeds. The ability to produce DMSP, and modify its concentration according to environmental conditions, may confer adaptive advantages to these algae. We studied the spatial and temporal distribution of DMSP content in Codium fragile off the Atlantic coast of Nova Scotia. Levels of DMSP in C. fragile were highest in boreal spring (～2 % of total dry wt) and lowest in fall (～1 %), and negatively related to seawater temperature. DMSP content differed among sites and tended to decrease or remain constant with depth. In tide pools, partially bleached algae contained less DMSP than undamaged individuals, consistent with the putative function of DMSP in response to oxidative stress. Results of field- and laboratory-based experiments, designed to examine plasticity in DMSP production by C. fragile, indicate that it increases with light intensity, exposure to sea urchin grazing, and decreasing temperature.