Invertebrate and Macroinvertebrate Survey Design Advice | Post-Survey Interpretation

Habitat Management for Invertebrate Conservation

EMS have been leaders in the field of environmental entomology and the assessment of site conservation value using invertebrates since 1988. Our expertise in this field is unrivalled (see EMS Academic Publications and EMS Client Portfolio). As a consequence, we are able to offer professional advice on a variety of subjects where invertebrates are employed. This advice is offered at various levels, ranging from rebuttal statements to recommendations, guidance or suggestions concerning invertebrate surveys.

The use of invertebrates in environmental assessment suffers from considerable problems (see Key Concerns, Problems and Solutions in Environmental Entomology). The majority of these problems stem from the fact that the foundations of invertebrate work in the environment is rooted in an 'ad hoc' amalgamation of disparate 'amateur philosophies'. These include a number of spurious assumptions, mainly related to thinking that insect collecting is adequate for environmental monitoring. These approaches do not offer reproducible or standardised routes within the decision making process.

As a consequence many organisations requiring definitive answers from invertebrate work, employ entomologists to produce reports or management prescriptions. However, due to the technical and specialised nature of the discipline, decision-makers are unable to assess the veracity of the produced work, much of which is inappropriate, inaccurate or sub-standard.

Inadequate or inappropriate invertebrate assessments are often accepted at 'face-value'. This is mainly due to difficulty of interpretation, (for example, see National Rarity and Scarcity Statuses in Key Concerns, Problems and Solutions in Environmental Entomology). In the past the questioning of invertebrate work was a rare event. However, there is an increasing tendency for inappropriate invertebrate work to be subjected to scrutiny, where the quality of the work is often exposed as 'suspect'.

EMS's team of associates has a proven track record in all aspects of the subject and is in a position to comment on invertebrate work in an authoritative and professional manner. For example, EMS were recently asked by a public enquiry to assess work carried out on an open-cast project near Wakefield where a number terrestrial and aquatic habitats was surveyed by an entomologist working for the developer. EMS were able to show that inappropriate sampling procedures and inaccurate interpretation negated the original work. In particular, the 'surveys' of the terrestrial sites were based on flying insects; it is difficult to find a correlation between flying insects and land cover. The assessment of the wetland sites was based on a 'survey' without any aquatic sampling of macroinvertebrates.

An important component of an EIA is the ecological assessment. This component covers many disciplines and is increasingly including invertebrate and macroinvertebrate assessments.

EMS can offer professional advice on general invertebrate survey design or on the appropriate sampling method for a particular survey. It is important to understand that many so called invertebrate and macroinvertebrate surveys conducted by entomologists are either inappropriate or not in fact surveys at all but sometimes just insect collecting. Below are some examples of survey design difficulties or contentious issues often applied within the invertebrate component of an EIA.

Butterfly transects - this technique gives an estimate of butterfly activity. In the assessment of habitat manageent it may be very limited since the source of the insects may not be the site being investigated. Furthermore, it is highly weather dependent and is subject to sampler differences. It cannot be used to assess site quality value.

General insect collecting techniques - sweep-netting, beating and hand searching are techniques used for collecting terrestrial invertebrates. These methods are very weather and sampler dependent and those species recorded one day will be totally different to those recorded on another, especially when year-on-year monitoring is employed.

Dragonflies - reliance on flying dragonflies should be avoided, as where they fly may not be the breeding habitat. They do not occur in a lot of aquatic habitat types and there are too few species in the UK for use in habitat definition.

Kick sampling and stone-turning - for freshwater macroinvertebrates is appropriate only if there is sufficient flow and stones. However, in headwaters, mud and silt substrate streams and down-stream sections of rivers it has very limited use and is of no use in pond and other static water sites.

The key to successful invertebrate and macroinvertebrate surveys and monitoring is the use of appropriate techniques in a reproducible and standardised way.

EMS is able to offer advice on the most appropriate methods to produce meaningful results.

Conducting invertebrate surveys is only part of the process; understanding and offering the results up to public scrutiny is also required. EMS can offer advice on analysis and interpretation of survey results.

Analysis - once survey results have been collated it may be necessary to analyse them. EMS can offer advice on choosing appropriate statistical techniques. For example, if the survey is large and covers many habitat types then the use of multivariate statistics (ordination or classification) may be required, but if the survey is limited then simple, descriptive interpretation may suffice.

Interpretation - the estimation of site quality using invertebrates tends to be based on the use of the National Rarity and Scarcity Statuses, derived from the JNCC Reviews. However, the increase in invertebrate survey work using standardised methods has called into question the accuracy of these statuses (see Key Concerns, Problems and Solutions in Environmental Entomology) and considerable experience is required in correctly interpreting lists of these species.

Public Scrutiny - invertebrate data will increasingly come before public enquiries as more invertebrate work is carried out. EMS can offer advice on the quality and interpretation of the invertebrate part of EIA's and conservation assessments.

EMS can advise on the construction, development and management of invertebrate habitat types. It is important to understand that invertebrate habitat types are different, particularly in terms of scale, from those associated with plants and animals. EMS's considerable experience in the field can be called upon to advise on any matters relating to either maintaining or increasing invertebrate biodiversity.