Aquatic environment

15N isotope fractionation in an aquatic food chain: Bellamya aeruginosa(Reeve) as an algal control agent

Shiqun Han , Shaohua Yan , Kaining Chen , Zhenhua Zhang , Rengel Zed , Jianqiu Zhang , Wei Song , Haiqin Liu


Received April 01, 2009,Revised November 18, 2009, Accepted , Available online

Volume 22,2010,Pages 242-247

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15N isotope tracer techniques and ecological modeling were adopted to investigate the fractionation of nitrogen, its uptake and transformation in algae and snail (Bellamya aeruginosa Reeve). Di erent algal species were found to di er in their uptake of nitrogen isotopes. Microcystis aeruginisa K¨utz. demonstrated the greatest 15N accumulation capacity, with the natural variation in isotopic ratio ( 15N) and the isotope fractionation factor (",‰) being the highest among the species investigated. The transformation and utilization of 15N by snails di ered depending on the specific algae consumed (highest for Chlorella pyrenoidosa Chick., lowest for M. aeruginisa). When snails was seeded in the experimental pond, the algae population structure changed significantly, and total algal biomass as well as the concentration of all nitrogen species decreased, causing an increase in water transparency. A model, incorporating several chemical and biological parameters, was developed to predict algal biomass in an aquatic system when snails was present. The data collected during this investigation indicated that the gastropods such as snails could significantly impact biological community and water quality of small water bodies, suggesting a role for biological control of noxious algal blooms associated with eutrophication.

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