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Growth Characteristics of Benthic Algae in Gan River
Received:October 24, 2014  
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KeyWord:benthic algae;Gan River basin;biomass;phosphorus forms;water quality
Author NameAffiliationE-mail
WANG Qing College of Life Science, South-Central University for Nationalities, Wuhan 430074, China  
CAO Jin-xiang College of Life Science, South-Central University for Nationalities, Wuhan 430074, China  
PEI Guo-feng College of Life Science, South-Central University for Nationalities, Wuhan 430074, China peigf@mail.scuec.edu.cn 
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Abstract:
      To understand ecosystem health of Gan River, physical and chemical variables of the mainstream and tributaries of Gan River were measured in Spring, 2012. Meanwhile, chlorophyll a(Chl a) and ash-free dry mass(AFDM) of benthic algae at all sites were determined. Phosphorus concentrations and forms in benthic algae in several sites were also measured. Results showed that the water quality of the upper reaches of Gan River was better than that of the lower reaches. Total phosphorus(TP), total nitrogen(TN) and chemical oxygen demand(COD) of water in the upper reaches were 0.014~0.072 mg·L-1, 0.282~1.204 mg·L-1 and 0.77~13.26 mg·L-1, respectively, while those in the lower reaches were respectively 0.214~0.252 mg·L-1, 2.039~2.748 mg·L-1 and 9.09~16.48 mg·L-1. Based on TN and TP, the water quality in sites S1 to S5 belonged to ClassⅡ, while it exceeded ClassⅤ in sites S16 to S20. The contents of Chl a in benthic algae ranged from 6.6 μg·cm-2 to 16.1 μg·cm-2 for all tributaries and from 13.5 μg·cm-2 to 47.3 μg·cm-2 for the mainstream of Gan River. There was a significant correlation between AFDM(645~3050 μg·cm-2) and Chl a. In certain concentration ranges, higher concentrations of nutrients in river water led to higher phosphorus retention by benthic algae. The total phosphorus was up to 82 μg·cm-2 at the lower reaches. Fe-P was a dominant form in benthic algae, accounting for 34%~73% of total phosphorus in all sampling sites. These findings would help assess ecosystem health and improve watershed-scale management of Gan River, China.