Benthivorous fish dominance in some subtropical lakes may alter submerged plant growth, reproduction, and progeny germination by changing water-submerged plant-algae interactions. We conducted mesocosm experiments to examine the effects of three densities of benthivorous fish, Misgurnus anguillicaudatus, on the water properties, the growth, asexual reproduction, and the germination of turions of Potamogeton crispus L.

The dataset includes water environment characteristics, macrophyte traits, algae traits, and sediment nutrient characteristics. Macrophyte traits include morphological, stoichiometric, turion traits, and germination traits.

Macrophytes and sediment samples: All plants were harvested and carefully washed with tap water for later measurements. The branching number of P. crispus in each tank was counted. Measuring shoot length and root length with a straightedge (cm). All the plants were divided into leaf, root, stem, and turion. To determine the dry weight (DW), all leaves, roots, and stems were dried with bibulous paper, weighed, oven-dried at 70 °C to constant weight, and weighed (g). Twenty turions of each tank were randomly selected, oven-dried at 70 °C to constant weight, and weighed to determine the dry weight (DW). The remaining biomass was calculated according to the relative proportion. In each tank, the total biomass of each species was the sum of the DW of each plant organ. The dried plant and sediment samples were meticulously ground into a fine powder to determine C, N, and P. An elemental analyzer (UNICUBE, Elementar, Germany) was then used to analyze the N and C content in both plant tissues and sediment. The P content of the macrophyte and sediment was determined using a sulfuric acid-hydrogen peroxide digestion and ammonium molybdate–antimony potassium tartrate–ascorbic acid spectrophotometric method. The leaf chlorophyll concentration was assessed from 0.5 g fresh and ripe leaves plucked from the petiole on the final sampling day; the samples were put in 10 mL of 80 percent acetone in the dark for 48 hours at 25 C and then quantified by colorimetric analysis using a spectrophotometer.

Periphyton biomass: The PE board was carefully removed by hand from each mesocosm and placed in a zip-lock plastic bag to analyze periphyton biomass in the laboratory. The periphyton (a mixture of algae, bacteria, and residue, but primarily algae) attached to the board was rinsed with distilled water and filtered through pre-combusted and pre-weighed GF/C filters, and subsequently dried in the oven at 70 °C for 48 hours.

Phytoplankton biomass: Chlorophyll a (Chl-a) was measured with a handheld chlorophyll fluorometer probe (HYDROLAB DS5, HACH, United States) in the field tests.

Water properties: We collected 1 L water samples from each tank with depth integration for chemical analysis. Total phosphorus (TP) was analyzed by the Total Phosphorus Analyzer (IL500P, HACH, USA). The colorimetric method was used to measure TN by following digestion with K2S2O8 and NaOH solution. The colorimetric method using Nessler's reagent was used to determine ammonia nitrogen (NH4-N), while the UV spectrophotometric method was used to assess nitrate nitrogen (NO3-N)  (Moss et al., 1996). PO4-P was determined by the molybdenum blue method (Gaudet, 1971). Photosynthetic active radiation (PAR) was measured at the water depth of 0 and 0.5 m (PAR1 and PAR2) using an underwater radiation sensor (UWQ-192S) connected to a data logger (Li-1400; Li-Cor Company, Lincoln, NE, U.S.A). 

Germination traits: At the end of the experiment, all turions were harvested and were considered to have sprouted if at least one bud body appeared (>1cm).

Moss, B., J. Stansfield, K. Irvine, M. Perrow, and G. Phillips (1996) Progressive restoration of a shallow lake: A 12-year experiment in isolation, sediment removal and biomanipulation. Journal of Applied Ecology 33:71-86. https://doi.org/10.2307/2405017

Gaudet, J. J. (1971) Methods for chemical analysis of fresh waters. H. L. Golterman. The Quarterly Review of Biology.