Stocking of herbivorous fish in eutrophic shallow clear-water lakes to reduce standing height of submerged macrophytes while maintaining their biomass

TY - JOUR

T1 - Stocking of herbivorous fish in eutrophic shallow clear-water lakes to reduce standing height of submerged macrophytes while maintaining their biomass

AU - Zhen, Wei

AU - Zhang, Xiumei

AU - Guan, Baohua

AU - Yin, Chunyu

AU - Yu, Jinlei

AU - Jeppesen, Erik

AU - Zhao, Xuefeng

AU - Liu, Zhengwen

PY - 2018/4/1

Y1 - 2018/4/1

N2 - To balance the conservation value versus recreational use of shallow lakes, moderate herbivory may be needed in eutrophic lakes to avoid near surface growth while maintaining high vegetation biomass close to the sediment. However, over-grazing or even complete elimination of macrophytes by grass carp (Ctenopharyngodon idella) commonly used for control purposes has often been observed, leading to a shift from a clear to a turbid phytoplankton-dominated state. We hypothesized that slow-growing and smaller-sized herbivorous fish species might be more suitable than grass carp to obtain the desired moderate control because they consume the top part of the vegetation without severely affecting the lower plant parts. To test the hypothesis, the effects of Wuchang bream (Megalobrama amblycephala), an endemic medium-sized herbivorous cyprinid, and grass carp on the biomass, density and trait of the macrophyte Vallisneria denseserrulata were compared in an enclosure experiment. We found that V. denseserrulata grew less tall but did not lose biomass under moderate herbivory by Wuchang bream due to increased plant density and leaf weight per length, whereas excessive herbivory by grass carp had strong negative effects on the plant biomass. Moreover, the plant had more and thicker leaves in the fish treatments than in the fishless controls. The growth of grass carp was much faster than that of Wuchang bream. Our findings suggest that stocking of Wuchang bream in proper densities may be more useful than grass carp for the management of V. denseserrulata and likely also other macrophyte species. More tests, especially at different fish densities are, however, needed to draw any firm conclusions regarding this hypothesis.

AB - To balance the conservation value versus recreational use of shallow lakes, moderate herbivory may be needed in eutrophic lakes to avoid near surface growth while maintaining high vegetation biomass close to the sediment. However, over-grazing or even complete elimination of macrophytes by grass carp (Ctenopharyngodon idella) commonly used for control purposes has often been observed, leading to a shift from a clear to a turbid phytoplankton-dominated state. We hypothesized that slow-growing and smaller-sized herbivorous fish species might be more suitable than grass carp to obtain the desired moderate control because they consume the top part of the vegetation without severely affecting the lower plant parts. To test the hypothesis, the effects of Wuchang bream (Megalobrama amblycephala), an endemic medium-sized herbivorous cyprinid, and grass carp on the biomass, density and trait of the macrophyte Vallisneria denseserrulata were compared in an enclosure experiment. We found that V. denseserrulata grew less tall but did not lose biomass under moderate herbivory by Wuchang bream due to increased plant density and leaf weight per length, whereas excessive herbivory by grass carp had strong negative effects on the plant biomass. Moreover, the plant had more and thicker leaves in the fish treatments than in the fishless controls. The growth of grass carp was much faster than that of Wuchang bream. Our findings suggest that stocking of Wuchang bream in proper densities may be more useful than grass carp for the management of V. denseserrulata and likely also other macrophyte species. More tests, especially at different fish densities are, however, needed to draw any firm conclusions regarding this hypothesis.

KW - Submerged macrophytes

KW - Moderate herbivory

KW - Grass carp

KW - Wuchang bream

KW - Vallisneria denseserrulata

KW - TRIPLOID GRASS CARP

KW - AQUATIC PLANTS

KW - GROWTH

KW - BIOMANIPULATION

KW - RESTORATION

KW - MANAGEMENT

KW - DYNAMICS

KW - FLORIDA

KW - STATE

U2 - 10.1016/j.ecoleng.2017.10.011

DO - 10.1016/j.ecoleng.2017.10.011

M3 - Journal article

SN - 0925-8574

VL - 113

SP - 61

EP - 64

JO - Ecological Engineering

JF - Ecological Engineering

ER -