title: Effects of deposit-feeding tubificid worms and filter-feeding bivalves on benthic-pelagic coupling: implications for the restoration of eutrophic shallow lakes.
abstract: Benthic-pelagic coupling is a key factor in the dynamics of shallow lakes. A 12-week mesocosm experiment tested the hypothesis that deposit-feeding tubificid worms stimulate the growth of pelagic algae while filter-feeding bivalves promote the growth of benthic algae, using the deposit-feeding tubificid Limnodrilus hoffmeisteri and the filter-feeding bivalve Anodonta woodiana. A tube-microcosm experiment using a (32)P radiotracer tested for differential effects of tubificids and bivalves on the release of sediment phosphorus (P). In this experiment A. woodiana was replaced by Corbicula fluminea, a smaller bivalve from the same functional group whose size was more appropriate to the experimental tubes needed for the tracer study. The first experiment recorded greater nutrient concentrations in the overlying water, higher biomass of pelagic algae as measured by chlorophyll a (Chl a), lower light intensity at the sediment and lower biomass of benthic algae in the worm treatments than in the controls, while nutrients and Chl a of pelagic algae were lower and the light intensity and Chl a of benthic algae were higher in the bivalve treatments than in the controls. In the second experiment, (32)P activity in the overlying water was higher in both treatments than in the controls, but highest in the worm treatment indicating that both animals accelerated P release from the sediment, with the biggest effect associated with the presence of worms. Our study demonstrates that worms promote pelagic algal growth by enhancing the release of sediment nutrients, while bivalves, likely through their grazing on pelagic algae increasing available light levels, stimulate benthic algal growth despite enhanced P release from the sediment and thus aid the establishment of clear water states. The rehabilitation of native bivalve populations may therefore enhance the recovery of eutrophic shallow lakes.
authors.affiliation: Department of Ecology and Institute of Hydrobiology, Tropical and Subtropical Aquatic Ecological Engineering Center of the Ministry of Education of China, Jinan University, Guangzhou 510632, China; State Key Laboratory of Lake Science and Environment, Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Ecology and Institute of Hydrobiology, Tropical and Subtropical Aquatic Ecological Engineering Center of the Ministry of Education of China, Jinan University, Guangzhou 510632, China; State Key Laboratory of Lake Science and Environment, Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: zliu@niglas.ac.cn.
authors.forename: Zhengwen
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Bioscience and the Arctic Centre (ARC), Aarhus University, DK-8600 Silkeborg, Denmark; Sino-Danish Centre for Education and Research (SDC), Beijing, China.
authors.forename: Erik
authors.initials: E
authors.lastname: Jeppesen
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
authors.forename: William D
authors.initials: WD
authors.lastname: Taylor
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000502:physiology*; D002681:China; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D003247:Conservation of Natural Resources; D017753:Ecosystem; D005068:Eutrophication; D005247:Feeding Behavior; D005374:Filtration; D005843:Geography; D019015:Geologic Sediments / Q000469:parasitology*; D006376:Helminths / Q000502:physiology*; D060106:Lakes / Q000469:parasitology*; D008027:Light; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010759:Phosphorus Isotopes; D013696:Temperature
chemical_list: D010759:Phosphorus Isotopes; D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: Benthic algae; Benthos; Coupling; Pelagic algae; Phosphorus