Top-down effects of filter-feeding fish and bivalves moderate bottom-up effects of nutrients on phytoplankton in subtropical shallow lakes: An outdoor mesocosm study.

Biomanipulation has been widely used in the ecological restoration of eutrophic lakes for decades. However, biomanipulation is prone to failure if external nutrient loads are not reduced. In order to explore the importance of filter-feeding fish and bivalves on algal control, an outdoor mesocosm experiment was conducted using different nutrient concentrations.

Simultaneous increases of filter-feeding fish and bivalves are key for controlling cyanobacterial blooms in a shallow eutrophic lake.

Eutrophication and cyanobacterial blooms have severely affected many freshwater ecosystems. We studied the effects of filter-feeding fish and bivalves on algal populations using a mesocosm experiment and long-term monitoring data from Lake Taihu (China). The mesocosm study, comprised of a two-way factorial design with the clam Corbicula fluminea and the fish Aristichthys nobilis at three biomass levels, resulted in lower chlorophyll a (Chl a) in high fish treatments, but no significant differences in the low and medium fish treatments.

Piscivore stocking significantly suppresses small fish but does not facilitate a clear-water state in subtropical shallow mesocosms: A biomanipulation experiment.

Biomanipulation by piscivore stocking has been widely used to combat eutrophication in north temperate lakes, but its applicability in warm lakes has not yet been well elucidated. Here, we used experimental mesocosms to test the effects of a native benthi-piscivore (snakehead, Channa argus Cantor) on water clarity under subtropical conditions where small omni-benthivorous fish like crucian carp (Carassius carassius L.) prevail.

Reducing nutrient increases diatom biomass in a subtropical eutrophic lake, China-Do the ammonium concentration and nitrate to ammonium ratio play a role?

Response of aquatic organisms to eutrophication have been well reported, while less studies are available for the recovery of eutrophic lakes following a reduction in the external loading, especially for systems where nitrogen is reduced but the phosphorus concentration is maintained high due to internal loading. Diatoms are nitrate (NO-N) opportunists but can also use ammonium (NH-N). They may, therefore, be more sensitive to nitrogen reduction than other algae that typically prefer NH-N.

Impacts of nutrient reduction on temporal β-diversity of rotifers: A 19-year limnology case study on Lake Wuli, China.

There have been many studies on the effects of eutrophication on beta diversity (β-diversity) of species assemblages. However, few studies have focused on the effects of nutrient reduction on β-diversity and community structure, and long-time series analyses are particularly scarce. We conducted a 19-year case study on the impacts of management intervention on the temporal β-diversity of aquatic grazers in a lake at the Yangtze River Basin.

Co-occurrence of multiple cyanotoxins and taste-and-odor compounds in the large eutrophic Lake Taihu, China: Dynamics, driving factors, and challenges for risk assessment.

Cyanobacterial blooms producing toxic metabolites occur frequently in freshwater, yet the environmental behaviors of complex cyanobacterial metabolites remain largely unknown. In this study, the seasonal and spatial variations of several classes of cyanotoxins (microcystins, cylindrospermopsins, saxitoxins) and taste-and-odor (T&O) compounds (β-cyclocitral, β-ionone, geosmin, 2-methylisoborneol) in Lake Taihu were simultaneously investigated for the first time. The total cyanotoxins were dominated by microcystins with concentrations highest in November (mean 2209 ng/L) and lowest in February (mean 48.

Combining bivalve (Corbicula fluminea) and filter-feeding fish (Aristichthys nobilis) enhances the bioremediation effect of algae: An outdoor mesocosm study.

In outdoor mesocosms, we experimentally studied the effect of combining two native filter feeders, bighead carp (Aristichthys nobilis) and Asian clam (Corbicula fluminea), to control nuisance cyanobacterial blooms. Four treatments - clam-only, fish-only, combined and controls - were used. In combination, bighead carp (80 g m) and Asian clam (260 g m), had a remarkable controlling effect on phytoplankton biomass and improved water quality.

Effects of juvenile crucian carp (Carassius carassius) removal on submerged macrophyte growth-implications for subtropical shallow lake restoration.

Rapid expansion of juvenile fish after biomanipulation can delay the successful restoration of submerged macrophytes, leading to a turbid water status in subtropical shallow lakes. Aimed to test the effects of direct removal of juvenile crucian carp (Carassius carassius) on water quality and growth of two submerged macrophytes Vallisneria natans and Hydrilla verticillate, a short-term outdoor mesocosm experiment was conducted in the Taihu Laboratory for Lake Ecosystem Research (TLLER). The results indicated that the concentrations of TN, TP, suspended solids, and chlorophyll a decreased significantly with increasing removal density of juvenile crucian carp, thus resulting in a clear status of the water.

[Seasonal Difference in Water Quality Between Lake and Inflow/Outflow Rivers of Lake Taihu, China].

The seasonal and spatial variation of external nutrient loading from rivers and their impact on lake water quality were analyzed in Lake Taihu, China, using the monthly monitoring data from 16 major inflow/outflow rivers and 32 observation sites in the lake. The results showed:① The average monthly values of total nitrogen (TN), dissolved total nitrogen (DTN), total phosphorus (TP), and dissolved total phosphorus (DTP) in rivers were all higher than the corresponding areas in the lake. Significant positive correlations were found between nutrient concentrations in the inflow rivers and the corresponding areas in the lake, indicating the pronounced impact of external loading on lake water.

[Insertion efficiency of Tgf2 transposon in the genome of Megalo-brama amblycephala].

To study insertion efficiency of goldfish Tgf2 transposon in the genome of Megalobrama amblycephala, we built Tgf2-Mlyz2-RFP donor plasmid with goldfish Tgf2 transposon left and right arms, and then co-injected with goldfish Tgf2 transposase mRNA into the 1-2 cell stage fertilized eggs of M. amblycephala. In 30 d- and 180 d-stage larval, RFP fluorescence can be observed in back and side muscle of the fish.

Goldfish transposase Tgf2 presumably from recent horizontal transfer is active.

Hobo/Activator/Tam3 (hAT) superfamily transposons occur in plants and animals and play a role in genomic evolution. Certain hAT transposons are active and have been developed as incisive genetic tools. Active vertebrate elements are rarely discovered; however, Tgf2 transposon was recently discovered in goldfish (Carassius auratus).

HIF-1alpha and -2alpha genes in a hypoxia-sensitive teleost species Megalobrama amblycephala: cDNA cloning, expression and different responses to hypoxia.

Transcriptional responses to hypoxia are primarily mediated by hypoxia-inducible factor (HIF) alpha subunits, i.e. HIF-1alpha, -2alpha and -3alpha.