title: Stable isotopes as a useful tool for revealing the environmental fate and trophic effect of open-sea-cage fish farm wastes on marine benthic organisms with different feeding guilds.
abstract: Environmental fate of fish farm wastes (FFW) released from an open-sea-cage farm at Kat O, Hong Kong was examined by measuring carbon and nitrogen stable isotope (SI) ratios in selected benthic organisms collected along a 2000 m transect from the farm. Our results showed that FFW significantly influenced the energy utilization profile of consumers near the fish farm. Although nitrogen enrichment effect on δ15N was anticipated in biota near the farm, the predicted patterns did not consistently occur in all feeding guilds. Two species of suspension-feeders, which relied on naturally δ15N-depleted sources, were δ15N-enriched near the fish farm. In contrast, both species of benthic grazer and deposit-feeder, which relied on naturally δ15N-enriched algal sources, were δ15N-depleted under the influence of FFW. The SI signatures of biota can, therefore, serve as feasible biomarkers for FFW discharges only when the trophic structure of the receiving environment is fully elucidated.
authors.affiliation: The Swire Institute of Marine Science and School of Biological Sciences, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China. waitakcheung@hotmail.com
authors.forename: Tak-Cheung
authors.initials: TC
authors.lastname: Wai
authors.forename: Kenneth M Y
authors.initials: KM
authors.lastname: Leung
authors.forename: Rudolf S S
authors.initials: RS
authors.lastname: Wu
authors.forename: Paul K S
authors.initials: PK
authors.lastname: Shin
authors.forename: S G
authors.initials: SG
authors.lastname: Cheung
authors.forename: X Y
authors.initials: XY
authors.lastname: Li
authors.forename: Joseph H W
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D017756:Aquaculture; D044822:Biodiversity; D002247:Carbon Isotopes / Q000032:analysis / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods*; D005399:Fishes / Q000378:metabolism*; D020387:Food Chain; D007554:Isotopes / Q000032:analysis; D009587:Nitrogen Isotopes / Q000032:analysis / Q000378:metabolism; D017747:Seafood / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D007554:Isotopes; D009587:Nitrogen Isotopes; D014874:Water Pollutants, Chemical