Sensitivity to copper and development of culturing and toxicity test procedures for the Antarctic terrestrial nematode Plectus murrayi
This study describes the development of culturing and aqueous toxicity test procedures for the endemic Antarctic soil nematode Plectus murrayi (Yeates, 1970; Nematoda: Plectidae) and estimates of its sensitivity to aqueous copper (Cu).
Nematode collection details
Plectus murrayi nematodes were isolated from soil and moss samples collected in the austral summer of 2013/14 at Clark Peninsula, Bailey Peninsula and Robinsons Ridge in the Windmill Islands, East Antarctica (AAS 4100). P. murrayi nematodes were transferred to agar plates, then transported to AAD laboratories at Kingston where laboratory cultures were established. Cultures were maintained at 15 degrees C.
Plectus murrayi culturing data
A number of different culturing conditions were trialled to optimise reproductive output in cultures. Data on the abundance of Plectus murrayi nematodes and eggs on agar culture plates. AAS_4100_Pmurrayi_Agar.xlsx
Aqueous exposure
Three solutions were tested to determine the optimum medium for P. murrayi in aqueous exposures. Survival was scored by the numbers of live and dead nematodes counted in each replicate. Hatching success was estimated as percent of eggs that hatched per replicate. Hatched juvenile survival was expressed as percent survival relative to hatching success for each replicate. AAS_4100_Pmurrayi_Aqueous_solution_egg_hatch_juv_adult_surv.xlsx
Sensitivity of Plectus murrayi to aqueous copper
The sensitivity of hatched juveniles to Cu was estimated after a total of 28 d exposure (egg to hatched J2 juvenile). Two tests. Survival was scored by the numbers of live and dead nematodes counted in each replicate. Hatching success was estimated as percent of eggs that hatched per replicate. Hatched juvenile survival was counted in one test and was expressed as percent survival relative to hatching success for each replicate. AAS_4100_Pmurrayi_Cu_egg hatch_juv_survival.xlsx
Juvenile survival in aqueous copper. Two tests. Survival was scored by the numbers of live and dead nematodes counted in each replicate. AAS_4100_Pmurrayi_Cu_juv_survival.xlsx
Aqueous copper concentrations in tests were measured using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (Varian 720-ES). The measured dissolved Cu concentrations (µg/L) used in statistical analyses of sensitivity estimates was the geometric mean of initial and final concentrations for each treatment. Copper concentrations are given in the spreadsheets for tests with copper.
Toxicity of diesel contaminated soil to an Antarctic nematode throughout a laboratory-based ageing experiment
Clean field-collected Antarctic soil was spiked with diesel fuel to a concentration of 40,000 mg/kg soil dry weight and distributed as 110 g subsamples into microcosms (125 mL glass jars). Microscoms were kept in a temperature controlled cabinet at 3°C for up to 45 weeks. This temperature is field-realistic for Antarctic soils during summer. Throughout the 45 week ageing period, microcosms were sampled periodically (at 0, 0.3, 2, 6, 9, 12, 21, 27, 33 and 45 weeks) and used to prepare elutriates for toxicity testing. Preparation of elutriates included mixing soil with ultrapure water (MilliQ) in a 1:1 v/v ratio then centrifuging to separate the aqueous portion (elutriate) to allow it to be collected and filtered to 0.45 μm. A control elutriate was prepared in the same manner using unspiked soil. A dilution series was prepared from each batch of elutriate at: 0, 25, 50, 75 and 100% elutriate for use in toxicity tests with the nematode worm Plectus murrayi, from cultures bred at the Antarctic Division laboratory in Kingston (Tasmania, Australia). Toxicity tests followed protocols developed for this Antarctic species as described by Brown et al. (2020). Elutriate subsamples (undiluted) were analysed for a comprehensive suite of hydrocarbon chemical analytes, with and without silica gel clean up to allow measurement of polar vs non-polar compounds.