Detecting Great Crested Newts with Environmental DNA Testing

24.06.14

REC is pleased to confirm that their Ecology experts are fully trained in conducting Environmental DNA (eDNA) testing, the latest methodology for detecting presence or absence of Great Crested Newts. This is a newly developed, more accurate method that could save developers both time and money.

eDNA is collected from the environment in which an organism lives, rather than directly from the plants or animals themselves. This new method requires the collection of pond water samples, typically at the same time that a Habitat Suitability Index (HSI) assessment of water bodies is conducted.

Reducing sampling effort and increasing accuracy

A recent study published by DEFRA (Department for Environment, Food and Rural Affairs) evaluates whether the presence or absence of Great Crested Newts in ponds can be reliably determined by testing the water for eDNA. The results show that the eDNA tests were accurate for 99.3% of pond samples which were known to have great crested newt present. This is much more effective than traditional bottle trapping (76% accurate), torch survey (74%) and egg searches (44%).

There were no false positives in the study, i.e. eDNA did not record newts where they were believed to be absent. The study found that newt abundance was weakly correlated with the eDNA ‘score’. It highlighted that sites with low eDNA scores consistently had low newt counts, however, sites with higher eDNA scores were not always found to have a larger population of great crested newts.

Survey Timings

eDNA testing is now accepted by Natural England as a legitimate survey method for assessing great crested newt presence but they will only accept surveys carried out in this way between April 15th and June the 30th.

With this in mind however, if the eDNA results show great crested newts to be present, Natural England still require a population size class to be established in order to show the level of mitigation required for a European Protected Species Development Licence. This means that six surveys are needed between March and June, with at least three of these surveys carried out between mid-April and mid-May. As eDNA sampling cannot be reliably undertaken until mid-April, if Great Crested Newts are confirmed present, there may not be enough time to fulfil Natural England’s guidelines for establishing a population size class.

Therefore, eDNA surveys are really only suitable for:

  • Projects large projects with long lead times. eDNA surveys could be undertaken a year in advance to scope in or out, large numbers of waterbodies with potentially considerable savings to the developer;
  • Temporary and low impact developments that may only require presence or absence surveys; and,
  • Small projects with limited risk of great crested newt presence, such as those with low numbers of ponds that are unsuitable for great crested newts.

eDNA samples can also be collected until the 30th June. For comparison, traditional bottle trap surveys need to be started before mid-May and completed by mid-June. Thus, eDNA is not as time constrained as traditional methods and thus slightly increases the available survey window for this species. .

What can REC do for you?

As required by Natural England, REC’s Ecology Team contains a number of surveyors that are trained and licensed to survey for great crested newts using both methods.

REC offer a full range of consultant expertise regarding great crested newt survey and mitigation, and other protected species – please contact us for more information

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