Eutrophication conditions and ecological status in typical bays of Lake Taihu in China

Sampling was conducted at three site groups, group E (in East Taihu Bay), G (in Gonghu Bay) and M (in Meiliang Bay) in Lake Taihu. TN and TP concentrations among site groups was in the increasing order of E < G < M. TP level at G sites is at the critical threshold for loss of submersed macrophytes. Mean values of DO and Transparence showed different trend, i.e., E > G > M. The mean phytoplankton fresh-weight biomass at M sites was 5.81 mg/l, higher than that at E sites (4.96 mg/l) and G sites (5.18 mg/l). Mean zooplankton fresh-weight biomass was in the decreasing order of M (6.4 mg/l) > G (4.9 mg/l) > E (2.7 mg/l). However, Rotifera density was in the sequence of E > G > M. Both zooplankton biomass and phytoplankton biomass increased with the rise of TN and TP concentrations. Relationships between zooplankton biomass and phytoplankton biomass showed that zooplankton played a limited role in the control of algae in eutrophic lakes. Nutrient availability is much more important than zooplankton grazing pressure in controlling phytoplankton growth in lakes. For most sites in Lake Taihu, reduction of nutrient loading, as well as macrophyte conservation, zappears to be especially important in maintaining high water quality and regulating lake biological structure, but for M sites, it’s urgent to control nutrient inputs rather than to restore macrophyte community.

[1]  L. Miranda,et al.  Hydrologic and climatic regimes limit phytoplankton biomass in reservoirs of the Upper Paraná River Basin, Brazil , 2001, Hydrobiologia.

[2]  Wolf M. Mooij,et al.  The Effect of Atmospheric Carbon Dioxide Elevation on Plant Growth in Freshwater Ecosystems , 2004, Ecosystems.

[3]  M. Moustaka-Gouni,et al.  Seasonal variation in phytoplankton composition and physical-chemical features of the shallow Lake Doïrani, Macedonia, Greece , 2000 .

[4]  Marten Scheffer,et al.  Dynamics and stability of Chara sp. and Potamogeton pectinatus in a shallow lake changing in eutrophication level , 1999 .

[5]  J. Vermaat,et al.  Water flow across and sediment trapping in submerged macrophyte beds of contrasting growth form. , 2000 .

[6]  Maria Rosa Miracle,et al.  Mesocosm experiments on nutrient and fish effects on shallow lake food webs in a Mediterranean climate , 2004 .

[7]  K. Havens.  Submerged aquatic vegetation correlations with depth and light attenuating materials in a shallow subtropical lake , 2003, Hydrobiologia.

[8]  T. Nõges.  Zooplankton—phytoplankton interactions in lakes Võrtsjärv, Peipsi (Estonia) and Yaskhan (Turkmenia) , 1997 .

[9]  Shu Tao,et al.  The restoration of riparian wetlands and macrophytes in Lake Chao, an eutrophic Chinese lake: possibilities and effects , 1999, Hydrobiologia.

[10]  E. Phlips,et al.  Dynamics of the Plankton Community in Submerged Plant Dominated Regions of Lake Okeechobee, Florida, USA , 1993 .

[11]  Marten Scheffer,et al.  THE ROLE OF CHARACEAN ALGAE IN THE MANAGEMENT OF EUTROPHIC SHALLOW LAKES , 1998 .

[12]  A. Ghadouani,et al.  Relationships between zooplankton community structure and phytoplankton in two lime-treated eutrophic hardwater lakes , 1998 .

[13]  I. Holopainen,et al.  Littoral species diversity and biomass: concordance among organismal groups and the effects of environmental variables , 2005, Biodiversity & Conservation.

[14]  Jong-min Oh,et al.  Grazing effects of a freshwater bivalve (Corbicula leana Prime) and large zooplankton on phytoplankton communities in two Korean lakes , 2004, Hydrobiologia.

[15]  Role of nutrients and zooplankton in regulation of phytoplankton in Flathead Lake (Montana, U.S.A.), a large oligotrophic lake , 1998 .

[16]  M. A. Rodrigo,et al.  Controlling factors of phytoplankton assemblages in wetlands: an experimental approach , 2003 .

[17]  A. Belay,et al.  Seasonal variation in phytoplankton primary production in relation to light and nutrients in Lake Awasa, Ethiopia , 1990, Hydrobiologia.

[18]  P. Domingos,et al.  Phytoplankton species composition is more sensitive than OECD criteria to the trophic status of three Brazilian tropical lakes , 1998, Hydrobiologia.

[19]  Luigi Naselli-Flores,et al.  Phytoplankton assemblages in twenty-one Sicilian reservoirs: relationships between species composition and environmental factors , 2000, Hydrobiologia.

[20]  W. Vyverman,et al.  Zooplankton, phytoplankton and the microbial food web in two turbid and two clearwater shallow lakes in Belgium , 2003, Aquatic Ecology.

[21]  Rebecca Zammit,et al.  Influence of nutrient availability on phytoplankton growth and community structure in the Port Adelaide River, Australia: [2pt] bioassay assessment of potential nutrient limitation , 2000, Hydrobiologia.