When mining the habitat of a rare carnivorous landsnail leads to a wealth of knowledge gain for the whole genus

Abstract

Powelliphanta is a genus of large land snails endemic to New Zealand. The twelve recognised species and numerous sub-species in that genus are known for their bright and colourful shells as well as their carnivorous habits. Although they are found in a variety of habitat types, several species and sub-species are in danger of extinction. In 2006, a new species (Powelliphanta augusta) was discovered on the footprint of New Zealand's largest opencast coalmine. Most of this snail natural habitat had been lost already and an ambitious conservation programme was established to save the species.

Before conservation work began on P. augusta, little was known about the behaviour, the diet, the population structure, the life cycle, of most species in the genus. Only two peer-reviewed publications on Powelliphanta can be found on web of knowledge prior to 2007. Since then, 13 additional papers have been published, attracting 113 citations. The conservation programme around P. augusta also breathed new life in research on native earthworms, upon which the snails prey. The direct knowledge gained and the research emulation generated by the conservation programme of P. augusta had far-reaching repercussions on the ecology and conservation of New Zealand fauna and constitutes a long-term scientific compensation for the mining activities.

For example, the method routinely used by the NZ Department of Conservation for estimating abundance of Powelliphanta had never been proven to be accurate. In fact, we show that on average, only 30% of snails are observed during a standard monitoring event, while the proportion of snails overlooked at each monitoring plot ranges from 10% to over 50%. We propose an alternative mark-recapture technique, which was developed to monitor the critically endangered snail P. augusta (1). Our proposed monitoring method is reliable and a practical alternative to the standard method for monitoring Powelliphanta snails. Another example lies in the detailed description of the diet of P. augusta and the development of a molecular diet analysis method later applied to another species in the genus (2). Knowledge on the diet of these species supported their successful rearing in captivity with the aim of releasing new populations in protected predator controlled areas.

In this talk we will present our findings and summarise the knowledge gained on the ecology, development, captive rearing and translocation of Powelliphanta snails, which directly arose from P. augusta conservation programme.

(1) Hamilton M (2015) Monitoring Powelliphanta land snails: an assessment of the current technique and the development of a new mark-recapture technique (Doctoral dissertation, Lincoln University).

(2) Boyer S, Wratten SD, Holyoake A, Abdelkrim J, Cruickshank RH (2013) Using next-generation sequencing to analyse the diet of a highly endangered land snail (Powelliphanta augusta) feeding on endemic earthworms. PLoS One, 8(9), e75962