Ssamex

QA/QC

LABORATORY QA/QC PROCEDURES AND SAMPLE ARCHIVING 

Field Quality Control and Safety

Washington State Department of Ecology lists recommended sample sizes, containers, preservation techniques, holding times and safety procedures for all sediment benthos sample collections.  Recent updates and references are included in Sediment Sampling SOPs and Benthos analysis SOPs.  The most critical aspect of all safety and QC procedures is that technicians receive the proper training from experienced field and laboratory personnel.  A description of this training and experience should be included in any QA/QC reports.

Laboratory Sample Receipt and Chain of Custody

Upon receipt, all samples are checked against the client’s chain of custody, if provided. The items checked are listed below. This information should always be provided to the client. 

  • Number of stations and replicates
  • Total number of samples
  • Number of jars per sample
  • Sampling date
  • Consistency of internal and external labeling 
  • Confirmation of processing (e.g. ensure none are meant to be archived without processing)
  • Screen size

If a client’s chain of custody is unavailable, the field technicians should create a sample receipt inventory with the above information. The client must approve this sample receipt inventory before processing commences. Any discrepancies must be resolved before processing commences.

Transfer from Preservative

Because formalin is a carcinogen and an irritant to workers, gloves and eye protection are needed to protect against splashes, and should be considered mandatory safety equipment. If required, all samples are transferred from formalin to ethanol on a finer mesh than on which they were collected, to accommodate the shrinkage of organisms resulting from fixation. 

Formalin is captured and stored for safe disposal (Safety-Kleen Inc.). Samples are rinsed gently with freshwater before being transferred to ethanol for processing.  Rinsing with low pressure ensures no further damage to the organisms is introduced. At this point, all labels (internal and external) must be double-checked to ensure no labeling errors were introduced. Samples are transferred one at a time to ensure no mix up, and the number of jars before and after the transfer are recorded. During transfer, formalin is captured for recycling.

Summary of QA/QC steps for Tier 1 (See Tier 1 document for more detail)

 A sample inventory is constructed, and the destination of these samples is confirmed upon survey completion, and appropriate paperwork drawn up for storage or return. Sorting must include  sample number, date collected (from the sample label), number of vials and estimated counts of sorted specimens in each sample for each of the major taxonomic groups.  Careful and thorough laboratory washing, picking and sorting of samples has been recently proven in comparative studies by Metro Vancouver and Victoria CRD to be critical, and can result in order of magnitude errors in benthos enumerations.  Re-examination of a percentage of picked samples is critical as described in the hyperlinked document, and should be done by experienced personnel other than the original sorter.   Picked sample debris should be kept for at least 2 years in order to allow external re-examination of debris in the event of unusual results.

Sorting QA report includes; A spreadsheet filled out with sample number, date collected, percent of the sample resorted, count of organisms removed during the resorting process, percent of sorting success, and whether the sample passed or failed the sort QA.  The QA procedure includes;

1) Ten percent (10%) of split samples are processed in their entirety (with each split processed separately) to ensure that sub-sampling error, as indicated by variability in total abundance of organisms, is lower than 20%. 

2) Fifty percent (50%) of all samples of a given sorter are spot-checked to ensure sorting efficiency of each particular sample is >90-95%.  Provision should be made for external, arms length re-counts of the picked debris for up to 10% of samples by a recognized (with contact information) external laboratory unconnected to the primary taxonomic laboratory.  

3) 10% of sorted sample debris (after picking) will be retained and made available to the client for external, 3rd party sorting QA (per item 2 above) to maintain status as a viable taxonomic sorting facility.  At the discretion of the client, these samples will be sent to external laboratories approved by the SSAMEx program for checking of sorting efficiency. 

4) Where possible, SSAMEx encourages the collection of extra replicate field samples at 10% of sampling locations in the field study.  These are to be preserved in the field after washing and archived untouched for future full sorting efficiency QA’s in cases where a concern has been noted in either Tier 1 or Tier 2 results.  

Biomass reports should include bulk taxonomic group wet weights for each sorted group and sample along with abundance counts for that group.  This is only done when no Tier 2 analyses are being done. Weighed group samples must be labelled by station, group identification and measured weight, stored in ethanol and retained for at least 5 years or until it is determined that no further information will be required from the samples.

Summary of QA/QC procedures for Tier 2 benthos

The taxonomy report includes an electronic copy of identifications and counts, size classes and all mean wet weights for each taxon and size class, weights and sample IDs for individual megafauna (>2 g).  New weights (for existing reference collections) of dominant biomass fauna and those with suspected size class shifts should be identified in the report. Also included in the report will be the bibliography of taxonomic literature used to identify specimens found in the samples.  A reference collection (size class and species) should be provided or existing one identified, with new specimens to be added for new taxa and/or size groups. 

Taxonomic QA reports include a list of the original taxa identifications for the project, any changes to the identifications proposed by the external QA taxonomist, and, where appropriate, comments on the suggested changes. The external verifying taxonomist(s) must be fully identified, with full contact information, affiliation, description of experience and dates of verification.  This procedure includes;

1. Re-identification of 5% of samples for each survey should be done by a different, qualified QC taxonomist (trained as described in section 1.1), who also double-checks any new species which have not been externally verified.  Any taxonomic changes or discrepancies should be reported, with the resulting survey report corrected. New and unusual taxa should always be sent for external verification. 

2. One to two percent of all marine benthic samples from a given taxonomic laboratory may be sent for bulk re-identification by a second accredited laboratory every year to both assess  percent agreement, and inform professional development needs.  Results of these inter-calibrations should be available upon request through the SSAMEx program.

3. Bench sheets (hand-notes of taxonomists) must be retained for ten years at a minimum to check for anomalies or transcription errors.

4.  During identification bulk specimens and voucher/reference specimens are placed in tightly-sealed vialswith appropriate internal labelling, and organized into labelled boxes (specimens) or Cornell trays (voucher/reference specimens). One to two mL of glycerin is added to each vial to prevent complete desiccation, and topped up with clean 70-80% ethanol. Each vial is sealed with parafilm around the cap.  

5. The sorted, preserved and identified samples from each survey should be retained in an appropriate storage facility for at least 5 years, or until it is determined that no further information will be required from the samples.

 

Summary of QA/QC procedures for Tier 3 benthos

QA/QC methods for meiofauna sampling and processing have not yet been described, since this is typically the objective of focused studies for which there are not standardized protocols.  Meiofauna sampling is not at present a recommended harmonization and data sharing component of the SSAMEx monitoring protocols.   Methods and cautions are described in the Tier 3 benthos document.  Several issues are critical if this level of benthos analysis is to be done;

1) Different mesh sizes capture different components of the interstitial meiofauna.  This must be taken into account in the study objectives.  If the purpose is to obtain more juvenile macrobenthos, it is recommended that a stacked set of 0.5 mm and 1 mm screens be used for field and laboratory washing of samples.  In this way, the 1 mm fraction can be used to compare with the broader SSAMEx data, with the 0.5mm fraction used to enhance understanding of recruitment patterns.

2) If most of the biomass and production of interstitial invertebrate biota are required, the use of stacked 0.5 mm, 0.25mm and 0.125 mm screens are recommended for laboratory processing of the smaller volume samples collected and preserved whole in the field.  

3) Care must be taken to determine as accurately as possible the sample volume prior to screening in the laboratory.  This is critical to scale up quantitative measurements to the original grab sample size. 

4) Meiofaunal samples are very fragile and effective processing requires great care in screening, washing and handling.  Enumeration methods need to be consistent, but are not prescribed. Staining is vital for sample enumeration.

3) Methods for microbial (non-invertebrate) production are not included in the SSAMEx protocols.