This DATSETNAMEreadme.txt file was generated on 2020-12-20 by James O'Dwyer 1. Title of Dataset: Long term environmental stability drives reduced stress tolerance in salt lake invertebrates 2. Author Information A. Principal Investigator Contact Information Name: James O'Dwyer Institution: La Trobe University Address: Plenty Rd &, Kingsbury Dr, Bundoora VIC 3086 Email: 18088076@students.latrobe.edu.au B. Associate or Co-investigator Contact Information Name: Nicholas Murphy Institution: La Trobe University Address: Plenty Rd &, Kingsbury Dr, Bundoora VIC 3086 Email: NA C. Alternate Contact Information Name: Institution: Address: Email: 3. Date of data collection; 30/4/2017-30/8/2017 4. Geographic location of data collection: 4-1: Lake Bullen Merri -38.237680, 143.105852 4-2: Lake Struan -38.019373, 143.418475 4-3: Lake Bolac -37.720898, 142.858117 4-4: Lake Bookar -38.145135, 143.109618 Funding sources: Murray Darling Freshwater Research Centre SHARING/ACCESS INFORMATION 1. No the publication using this data is currently in copy editing for publication (21/12/2020) 2. For citations of the data please cite the accompanying publication once published Data and file overfiews 1. amphipid_controls 2. acute_trials first and second tests together.xlsx 3. C_striata_controls.xlsx 4. decreasing salinity death points and number of days since freshwater.xlsx 5. decreasing salinity death points and number of days since freshwater amphipods.csv 6.proportional die off for grad salinity increase group.csv 7. proportional die off for grad salinity increase group amphipods.xlsx 8. Proportional die off for temperature group.xlsx Each file contains the counts and deaths/proportions of living individuals during each day of each salinity test. In order, each file has 7 columns: proportion survived, Lake, number_alive, number_dead, trial condition( e.g. salinity, temperature, depending on the trial), trial condition change, and day of trial. Additional columns 8-9 are in some documents representing the longterm lake mean and lake standard deviation salinity, however were not used in the analysis of the data. Missing data is written as NA in each file. The variables used in the generation of generalised linear models for files 4-8 were, lake, number_alive, number_dead, trial condition, and trial condition change. The variables used in the generation of generalised linear models for files 1-4 were lake, number_alive, number_dead, trial condition, and day of trial. Variables number_alive, number_dead, trial condition, trial condition change, and day of trial are continuous positive whole numbers. Variable lake is a categorical variable with four discreat values representing each lake studied. For each file the number of rows varies depending on trial length from 60 to 120. The units for salinity are measured as parts per thousand NaCl. The units for temperature are measured as degrees celsius Methodological information Collection of data and experimental conditions Collection of individuals was undertake by James O'Dwyer and a team of volunteers. Experimental testing was undertaken by James O'Dwyer Approximately 200 snails and 100 amphipods were collected from each lake for physiological stress testing. Samples were collected using dip nets between one and three metres from the shoreline lake and at a depth between 50cm and 1 metre. Salinity and water temperature measurements were taken at the time of collection. Samples from each lake were placed into separate 20 L aquariums adjusted to the salinity recorded at collection, using Red Sea Salt© to approximate major ionic levels found across each lake (Leahy 2010). pH was maintained with APITM pH increasing solution, and aquaria kept at a 12-hour day-night cycle at 17°C. Snails and amphipods were fed daily with algae, goldfish flakes, and algal wafers. All samples were acclimatised for 14 days before physical trials commenced. All lake populations were tested simultaneously, with different individuals used for each test, and controls run (conditions of acclimation salinity and temperature) undertaken with the same handling as each test. Salinity tolerance trials We measured the impact of both gradual salinity change and prolonged salinity exposure on individual survival. To test gradual salinity change, 30 to 40 individuals of either species from each lake were placed into separate plastic bags containing 1 L of water (within aquaria to maintain temperature). Both increasing and decreasing salinities (from acclimation salinity) were tested; NaCl was added to increase salinity and known volumes of saline water replaced by fresh to decrease salinity. Individual snails were probed daily and observed for a response; non-responsive individuals were placed on their backs and if after five minutes had not righted themselves were considered dead and removed and the salinity recorded. Individual amphipods were considered dead if they had fallen to the bottom of the bag and were not responsive to water currents blown through an eyedropper. To test the effect of prolonged salinity exposure, 15 snails from each lake were placed into individual bags at salinity concentrations of 0 ppt, 40 ppt, and 70 ppt. Individual death was examined daily, with time to death recorded for each individual. Amphipods were not included in prolonged salinity exposure tests due to insufficient individuals being successfully collected. For all salinity tests, individuals were fed daily and an eyedropper was used to aerate bags daily. Thermal Tolerance trials To test thermal tolerance, 30 individuals from each species/lake were placed in separate 1 L bags under acclimation salinities. Each bag was then placed inside a larger water bath, which underwent a daily temperature increase of 3°C, starting at 17°C until 32°C, where the temperature was then raised by 1.5°C daily. Individual death was examined daily, using the same methods described in the salinity trials. Analysis of data: 1. For all stress trials, proportional survival rates were measured at each salinity or temperature increment (or each day for the prolonged exposure test). For each trial, a Generalised Linear Model (GLM) was created with “proportion survived” as the dependent variable, and “lake of origin” and “trial condition” as the interacting, independent variables. GLMs were run both with raw data and with a log transformation of the trial condition. The best fit model for each trial was chosen based on lower Akaike Information Criterion values, allowing for the best model under the conditions tested to be chosen for each dataset (Akaike 1974). The overall fit of the data with each model was then calculated as the D2 value of the model ((null deviance – deviance)/null deviance), and the model was used to generate mean predicted values and confidence intervals around each data point for each lake, using the R package boot v 1.3 (Davison and Hinkley 1997). For models which required log transformation of trial condition, all condition values of 0 were changed to 0.1 to allow for a log transformation of the data. The results obtained for each trial were plotted alongside the generated confidence intervals using the R package ggplot2 v 3.2.0 (Wickham 2016), and significant differences between proportion survived from each lake under each condition inferred through non-overlapping confidence intervals (p < 0.05).