Relative Influences of Riverine and Macroalgal Phenolic Materials on UV Absorbance in Temperate Coastal Waters

Abstract

Seasonal changes in profiles of both UV absorbance and phenolic material versus salinity were observed in some estuarine and coastal waters of the Gulf of Maine. Profiles of riverine UV-absorbent and phenolic materials were seasonally invariant, with slight losses from high molecular weight fractions during estuarine mixing. In estuaries containing significant populations of fucoid macroalgae, exudation by the macroalgae increased levels of these parameters by as much as threefold. These increases showed a strong seasonal pulsing, following water temperature. This pulsing was detectable in seasonal transects of adjacent shelf waters.