Macroinvertebrates
Examining the diversity and relative abundance of macroinvertebrates within a waterbody be it a stream, river, lake or estuary is a commonly employed technique to grade the biological water quality of that system. Well-developed procedures for the collection and analysis of macroinvertebrate samples have long been in place and sufficient identification keys mean that the major groups are routinely identified to the taxonomic level of family and even species. However in order to achieve results of consistently high quality it is necessary to train staff to meet strict quality control procedures thus ensuring that any changes observed between sites or over time are a result of responses to environmental change and not to sorter anomalies.
APEM Macroinvertebrate Services
With over 30 years experience of processing invertebrate samples between them APEM's laboratory staff are capable of identifying organisms to both the taxonomic level of family and species.
APEM's macroinvertebrate biologists undergo a comprehensive training programme and operate within stringent quality control procedures. These procedures are fully compatible with the Environment Agency's own protocols, and as such APEM provides a macroinvertebrate analysis service widely acknowledged as being one of the best in the UK.
Our clients have the option of not only utilising APEM's Biolabs service but also the service of our experienced field scientists who undertake a range of sampling techniques, encompassing both qualitative and quantitative strategies. For freshwaters, kick-heel, surber, sweep, naturalist dredge, airlift, standard colonisation units and cylinder sampling can all be considered whilst for estuarine and marine systems, surface trawls, dredges and grabs of various descriptions are more commonly used.
Our scientists also perform comprehensive data analysis, which include calculation of biotic indices, multivariate statistical analysis, RIVPACS analysis and statements of the conservation status of rare and protected species, together with a thorough assessment and expert interpretative report writing service.
APEM's AQC statistics for the latest audit results as provided by CEH.
Quality Assurance
When interpreting macroinvertebrate data it is important that every effort is made to minimise and account for the errors that are attributable to field sampling and laboratory analysis. We achieve this by:
- Rigorous training of staff and strict adherence to standard protocols;
- 6 full-time APEM taxonomists are accredited with the Natural History Museum IdQ E062 Freshwater Macroinvertebrate Species (>90% pass);
- Stringent internal Analytical Quality Control (AQC) that exceeds industry standards;
- Regular external audit of laboratory analysis.
Internal AQC Industry standards formally require an internal AQC system for the analysis of macroinvertebrate samples. APEM is one of the few independent laboratories in the UK that can genuinely meet this requirement to the standards set by the UK environmental regulators, which are detailed in the Environment Agency’s technical manuals (Environment Agency, 1999 & 2007).
External Audit APEM’s macroinvertebrate analysis is also subject to rigorous independent audit by UK environmental regulators. The audit is based entirely on measuring the discrepancies found between the primary analyst and the auditor who both process the same sample and assumes that the auditor’s experience exceeds that of the primary analyst. Quality is measured by 'gains' which is the number of extra scoring invertebrate families that the auditor finds in addition to those recorded by APEM biologists. This could be due to a failure to note invertebrates in the sample, misidentifying invertebrates or due to errors in data recording. The regulator demands a performance target of
a mean of no more than two gains per 20 externally audited samples. Our audit results for the last 5 years are summarised below and have always far exceeded the regulator’s quality standards. The external audit has been performed by Centre for Ecology and Hydrology (CEH) on contracts undertaken for both the Environment Agency and the private sector.
APEM audit results for the past five years
| Year |
No. samples audited |
Mean No. gains per sample |
| 2007 |
5 |
0.40 |
| 2007 |
17 |
0.47 |
| 2006 |
18 |
0.78 |
| 2006 |
10 |
1.40 |
| 2005 |
20 |
0.95 |
| 2004 |
20 |
1.05 |
| 2003 |
20 |
0.65 |