DOI: 10.5061/dryad.dz08kprxf
title: Data from: Snail communities increase submerged macrophyte growth by grazing epiphytic algae and phytoplankton in a mesocosm experiment

description: The relationships between producers (e.g., macrophytes, phytoplankton and
 epiphytic algae) and snails play an important role in maintaining the
 function and stability of shallow ecosystems. Complex relationships exist
 among macrophytes, epiphytic algae, phytoplankton and snails. We studied
 the effects of snail communities (consisting of Radix
 swinhoei, Hippeutis cantori, Bellamya
 aeruginosa and Parafossarulus striatulus) on the biomass
 of phytoplankton and epiphytic algae as well as on the growth of three
 species of submerged macrophytes (Hydrilla
 verticillata, Vallisneria natans and one exotic
 submerged plant, Elodea nuttallii) in a 90-day outdoor mesocosm
 experiment conducted on the shore of subtropical Lake Liangzihu, China.
 This dataset including morphological data of three group
 organisms: freshwater snails, macrophytes and epiphytic algae. In
 addition, the environmental parameters were
 included. Morphological data of snails is including biomass (g)
 and number (ind.). Morphological data of macrophytes is including biomass
 (g). Epiphytic algae data is including abundance (N,
 cells). Phytoplankton data is including biomass (Chl-a, μg/L).
description: Snail: All snail individuals
 (adults and offspring) were collected from the aquariums and the quantity
 and fresh mass were determined. Before weighing, the snails were drained
 and allowed to dry on absorbent paper for 5 min (wiping the surface of
 snails and letting the liquid drain from their body) and then gently
 blotting until the surface was dry to ensure consistency among the
 samples Macrophytes: The macrophyte samples were carefully washed
 with distilled water at least three times. Then, the number of leaves in
 each sample was quantified (including the selected leaf for area
 measurement and algae collection). All samples were then dried to a
 constant weight in a drying oven at 60°C. The dry weight of biomass of the
 submerged macrophytes was determined using an electronic
 scale. Epiphytic algae: Fifty leaves of <em>H.
 verticillata</em>, 50 leaves of <em>E. nuttallii</em> and 5 leaves of <em>V.
 natans </em>were carefully selected to ensure uniformity in growth
 state and size before placing each into a wide-mouth plastic bottle with
 200 ml of pure water in the respective aquarium. Periphyton were removed with a banister brush
 in water and preserved in a well-labelled plastic container, with 2 mL
 of Lugol’s solution to fix them. The area of selected leaves was measured
 with an area meter (LI-3100C, LI-COR, USA). The epiphytic algae sample was centrifuged at
 4000 rpm for 10 min, and the supernatant was discarded. Then, the volume
 was adjusted to 30 mL and mixed. The number and species of epiphytic algae
 were counted using a counting plate at 400× under an optical microscope.
 For each sample, 50 microscopic fields of vision were examined and
 counted. Species richness
 (S) of each sample was quantified as the number of species in the sample,
 and the abundance (N, cells). Phytoplankton biomass: chlorophyll a (Chl-a) was
 measured with a handheld chlorophyll fluorometer probe (HYDROLAB DS5,
 HACH, United States) in the field tests.
 Environmental parameters: For
 each aquarium, the water temperature (T), dissolved oxygen (DO),
 conductivity (Cond) and pH of the water were measured with a portable
 water quality monitor (PROPLUS, YSI, United States) in the field tests.
 Turbidity (Turb) was measured with a chromometer (DR900, HACH, USA). We
 collected 1 L water samples from each aquarium with depth integration
 (under water 30 cm) for chemical analysis and stored them on ice. Then,
 TN, TP and ammonia nitrogen (NH3-N) were analysed with a flow injection
 analyser (QC8500, LACHAT, USA). Chemical oxygen demand (COD) was analysed
 with a digestion solution for each corresponding parameter and landscape
 photometry (DR900, HACH, USA).
description: This dataset including
 morphological data of three group organisms: freshwater snails,
 macrophytes and epiphytic algae. In addition, the environmental parameters
 were included. There are no missing values in this
 dataset.