Nutritional status of the sessile algal community as a primary producer in the Yahagi River ecosystem, central Japan

The nutritional status of the sessile algal community in the Yahagi River located in central Japan was examined based on the ratios between particulate carbon (PC), nitrogen (PN) and phosphorus (PP) proposed by Hillebrand and Sommer (1999). The survey was conducted at five stations from August 2008 to September 2009. The concentration of Chlorophyll a of the sessile algal community ranged from 5.0 to 193.7 mg m-2. The composition of the community changed seasonally from blue-green algae dominated by Homoeothrix janthina in May-November to diatoms dominated by Cymbella and Gomphonema in December-April. The PC: PN and PN: PP ratios were 7.2 and 22.3, respectively, which were close to the reference ratios. Our results indicate that the sessile algal community in the Yahagi River was not exposed to severe deficiency in nitrogen or phosphorus.