McMurdo Dry Valleys LTER
Published on McMurdo Dry Valleys LTER (https://mcm.lternet.edu)


Summary

Abstract: 

Investigation of the effect of long-term variation in soil moisture and soil temperature on nematode anhydrobiosis as part of the McMurdo Dry Valleys Long Term Ecological Research (LTER) project. The percent of anhydrobiotic (coiled) nematodes with relation to season was determined.
 
The study took place on three separate dates during the 1997-1998 austral summer: 21 November 1997, 16 December 1997, and 13 January 1998, samples were gathered at the south side of the Lake Hoare

Date Range: 

November 21, 1997 to January 13, 1998
Dataset(s)

Description: 

Seasonal effects on soil biota data units and spreadsheet column descriptions

Variables (click to expand): 

LOCATION
  • Label:
  • Definition: Name of area where measurement was made
  • Type: Nominal
  • Missing values: None specified
DATE_TIME
  • Label:
  • Definition: Date on which sample was gathered
  • Type: Date/time
  • Date format: MM/DD/YYYY
  • Missing values: None specified
SAMPLE #
  • Label:
  • Definition: ID associated with transect, sampling location
  • Type: Nominal
  • Missing values: None specified
TYPE OF ORGANISM
  • Label:
  • Definition: Family associated with organism
  • Type: Code list
  • Codes:
    • Nematode = Nematode
    • Rotifer = Rotifer
    • Tardigrade = Tardigrade
  • Missing values: None specified
SPECIES
  • Label:
  • Definition: Species found in soil
  • Type: Code list
  • Codes:
    • Scottnema = Scottnema
    • Eudorylaimus = Eudorylaimus
    • Plectus = Plectus
    • Combined = Scottnema, Eudorylaimus and Plectus
    • Unknown = Unknown
  • Missing values: None specified
SEX
  • Label:
  • Definition: Gender of organism (male vs. female)
  • Type: Code list
  • Codes:
    • Female = Female
    • Male = Male
    • Combined = Combined (male and females)
    • Undetermined = Sex Undetermined
  • Missing values: None specified
LIVE/DEAD/COMBINED
  • Label:
  • Definition: Survival Status (living, dead, or both)
  • Type: Code list
  • Codes:
    • Live = Live
    • Dead = Dead
    • Combined = Combined dead and live
    • Undetermined = Undetermined
  • Missing values: None specified
ADULT/JUVENILE/COMBINED
  • Label:
  • Definition: Maturity (adult, juvenile, or both)
  • Type: Code list
  • Codes:
    • Juvenile = Juvenile
    • Adult = Adult
    • Combined = Adult and Juveniles combined
    • Undetermined = Stage undetermined
  • Missing values: None specified
TOTAL (#/KG DRY SOIL)
  • Label:
  • Definition: Number of organisms found in that category per kilo
  • Type: Physical quantity
  • Unit: #/KG DRY SOIL
  • Maximum: Not specified
  • Minimum: Not specified
  • Precision: Not specified
  • Missing values: None specified
Comments
  • Label:
  • Definition: Comments
  • Type: Nominal
  • Missing values: None specified
FILE NAME
  • Label:
  • Definition: Name of file in which data was stored
  • Type: Nominal
  • Missing values: None specified

File: 

sewo.csv (82 KB)

Dataset ID: 

244
People

Principal Investigator(s): 

Diana H. Wall
Ross A. Virginia

Contact: 

McMurdo Dry Valleys LTER

Associated Personnel: 

Field Crew
Byron J. Adams
Field Crew
John "Jeb" E. Barrett
Data Manager
Denise Steigerwald
Data Manager
Inigo San Gil
Related

Related publications: 

The use of anhydrobiosis by soil nematodes in the Antarctic Dry Valleys
Methodology

Methods: 

 Sampling was done by using a clean plastic scoop and collecting soil to a 10-cm depth.  Soil samples were taken for organism enumeration and moisture content analysis as follows: Sampling bags were prepared with one sterile 'Whirlpak' bag and clean plastic scoop per sample. Samples were taken from within the 10 cm diameter circular area of each plot. The location of the sampling was recorded so that areas were not re-sampled. Using the plastic scoop, soil was collected to 10 cm depth. Very large rocks (>20 mm diameter) were excluded from the sample.  
 
The soil was shoveled into the 'Whirlpak' bag until three quarters full (about 1.5 kg soil). The soil was mixed well in the bag, then the bag was closed tightly, expelling as much air as possible. The soil samples were stored in a cooler for transportation. On return to the laboratory (within 8 hours of sampling), the soils were stored at 4C until further processing.  In the laboratory, soil samples were handled in a laminar flow hood to prevent contamination. The Whirlpak bags of soil were mixed thoroughly prior to opening. Approximately 200cm3 of soil was placed in a pre-weighed 800mL plastic beaker. Rocks greater than 3-4mm in diameter were removed from the sample. A sub-sample of approximately 50g was removed and placed in a pre-weighed aluminum dish, and weighed on a balance accurate to 0.01g. This sample was dried at 105C for 24 hours. The sample was removed, placed in desiccator to cool down, and re-weighed. These data were used to calculate water content of the soil and to express data as numbers of soil organisms per unit dry weight of soil.  The remaining soil in the plastic beaker was weighed. Cold tap water was added up to 650 mL. The soil suspension was stirred carefully (star stir or figure of 8) for 30 seconds, using a spatula. Immediately the liquid was poured into wet screens - a stack of 40 mesh on top of a 400 mesh. The screens were rinsed gently with ice cold tap water (from a wash bottle) through the top of the stack, keeping the screens at an angle as the water filtered through. The water was kept on ice at all times. The top screen was removed, and the lower screen rinsed top down, never directly on top of the soil, but at the top of the screen and from behind. The water was allowed to cascade down and carry the particles into the bottom wedge of the angled screen. The side of the screen was tapped gently to filter all the water through. The suspension was rinsed from the front and the back, keeping the screen at an angle and not allowing the water to overflow the edge of the screen. The soil particles were backwashed into a 50mL plastic centrifuge tube, tipping the screen into the funnel above the tube and rinsing the funnel gently. The suspension was centrifuged for five minutes at 1744 RPM. The liquid was decanted, leaving a few mL on top of the soil particles. The tube was filled with sucrose solution (454g sucrose per liter of tap water, kept refrigerated) up to 45mL. This was stirred gently with a spatula until the pellet was broken up and suspended. The suspension was centrifuged for one minute at 1744 RPM, decanted into a wet 500 mesh screen, rinsed well with ice cold tap water and backwashed into a centrifuge tube. Samples were refrigerated at 5C until counted.
 
Samples were washed in to a counting dish and examined under a microscope at x10 or x20 magnification. Rotifers and tardigrades were identified and counted.  Nematodes were identified to species and sex, and counted. Total numbers in each sample were recorded on data sheets. All species of nematode, and all rotifers and tardigrades found in the sample were recorded. Data were entered in to Excel files, printed, and checked for errors.
 

Maintenance: 

San Gil completes metadata in 2016

This file was created by Pilar Tillberg on 10 May 2001, using raw data from the Excel workbook '9711sewo.raw'. The file format was suggested by the LTER data manager, to conform with the relational database structure. [PT 10 May 2001]. data will be appended.

Additional information: 

Categories

Research Section: 

  • Soils
  • Soil Biology

LTER Core Areas: 

  • population dynamics

MCM Keywords: 

  • Antarctica
  • biomass
  • Eudorylaimus
  • LTER
  • nematodes
  • Plectus
  • rotifers
  • soil
  • soil biota
  • tardigrade
  • Taylor Valley

Keywords: 

  • biomass
  • nematodes
  • rotifers
  • soil
  • soil disturbance

Source URL: https://mcm.lternet.edu/content/seasonal-effects-soil-biota