title: 15N isotope fractionation in an aquatic food chain: Bellamya aeruginosa (Reeve) as an algal control agent.
abstract: 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). Different algal species were found to differ in their uptake of nitrogen isotopes. Microcystis aeruginisa Kütz. demonstrated the greatest 15N accumulation capacity, with the natural variation in isotopic ratio (delta 15N) and the isotope fractionation factor (epsilon, % per hundred) being the highest among the species investigated. The transformation and utilization of 15N by snails differed 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.
authors.affiliation: Institute of Agricultural Resources and Environments, Jiangsu Academy ofAgricultural Sciences, Nanjing 210014, China. shqunh@yahoo.com.cn
authors.forename: Shiqun
authors.initials: S
authors.lastname: Han
authors.forename: Shaohua
authors.initials: S
authors.lastname: Yan
authors.forename: Kaining
authors.initials: K
authors.lastname: Chen
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Zhang
authors.forename: Rengel
authors.initials: R
authors.lastname: Zed
authors.forename: Jianqiu
authors.initials: J
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Song
authors.forename: Haiqin
authors.initials: H
authors.lastname: Liu
mesh_terms: D000818:Animals; D056890:Eukaryota / Q000502:physiology*; D005247:Feeding Behavior; D020387:Food Chain; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010572:Pest Control, Biological; D012908:Snails / Q000502:physiology*; D013997:Time Factors; D018508:Water Purification; D014881:Water Supply
chemical_list: D009587:Nitrogen Isotopes; D009584:Nitrogen