Queensland Spiny Crayfish and Friends: Using Genetic Techniques to Guide Conservation
Charlotte Hurry, Australian Rivers Institute, Griffith University – October 2015
Charlotte received a grant from WPSQ to assist in her study of three Queensland crayfish species. The crayfish she studied were:
- Roberts Spiny Crayfish (Euastacus robertsi )is found on three mountaintops in four creeks in the Daintree area. It is listed as critically endangered. Charlotte used data from previous studies to investigate the genetic distribution of these crayfish.
- Maleny Spiny Crayfish (Euastacus urospinosus) is a dwarf crayfish found between 250-750 metres above sea level in and around the Mary River near Maleny.
- Conondale Spiny Crayfish (Euastacus histricosus) is a giant crayfish (though most Charlotte found were small). They occur in the Conondale Ranges above 400 metres. It is listed as endangered because of its fragmented habitat.
Each of these crayfish has its own flatworm, which will also go extinct if its host becomes extinct.
Charlotte’s studies are based around the DNA of these crayfish. She looked at the genetic diversity of the various populations, the extent of fragmentation and their effective population sizes. Fragmentation leads to reduced gene flow, which leads to reduced genetic diversity, which results in more frequent inbreeding and increased likelihood of extinction. Conservation might be achieved by translocation (resulting in more genetic diversity) and restoration of habitat. Crayfish are thought to live 15 – 30 years.
The Roberts Spiny Crayfish from the Daintree consisted of 2 separate strains in 3 separate locations (Mt Finnegan, Mt Pieter Botte and Thornton Peak). Charlotte studied the genetic relationship between each group and found that there was genetic movement to Thornton Peak from both Mt Finnegan and Mt Pieter Botte, but not between the latter two sites over 2.6 million years.
The Maleny Spiny Crayfish showed mutational differences and each sanctuary was different (Conondale, Kondalilla, Mapleton Maleny, Bellthorpe National Parks and Mary Cairncross Reserve). These changes took place in the last 2.1 million years.
The Conondale Spiny Crayfish was found to have three extremely distinct populations with very little gene flow. There was low genetic diversity in each population, likely to lead to inbreeding. There is no reason to remove their endangered status from the ICUN Red List. Of the 800 crayfish she caught, only three were over 15 cm though, historically, the Conondale crayfish grows very large.
Crayfish natural predators include water rats, eels, platypus and possibly cane toads. Charlotte told people who watched her work at the study sites that she was investigating water bugs so they did not prey on the crayfish for the cooking pot.