James Michael Furse

Distribution and population genetics of the threatened freshwater crayfish genus Tenuibranchiurus (Decapoda : Parastacidae)

Very high rates of extinction are recorded in freshwater ecosystems, with coastally distributed species threatened by urban development, pollution and climate change. One example, the world’s second smallest freshwater crayfish (genus Tenuibranchiurus), inhabits coastal swamps in central-eastern Australia. Although only one species is described (Tenuibranchiurus glypticus), it was expected that populations isolated through habitat fragmentation would be highly divergent. The aims of this study were to determine if populations of Tenuibranchiurus are genetically distinct, and if ancient divergence, as indicated in other species in the region, was evident. Tenuibranchiurus were collected at seven sites, extending the known geographical distribution ∼260 km south to Wooli, New South Wales. Analysis of two mitochondrial DNA gene regions indicated two highly divergent clades, with numerous additional subclades. Both clades and subclades were strongly congruent with geographical location, and were estimated to have diverged from each other during the Miocene or Pliocene era. Little sharing of haplotypes between subpopulations was evident, indicating negligible gene flow, and genetic differentiation between subclades possibly indicates distinct species. The coastal distribution of Tenuibranchiurus, severe habitat fragmentation and clear differences between subclades suggest that they should be recognised as evolutionarily significant units, and be treated as such if conservation and management initiatives are warranted.

Thermal limit of Euastacus sulcatus (Decapoda: Parastacidae), a freshwater crayfish from the highlands of central eastern Australia

Increased temperature as a potentially threatening process, and the need to investigate the thermal tolerance of the ‘highland-rainforest’ Euastacus were first identified 20 years ago; however, the thermal repertoire of Euastacus has still not been explored. Euastacus is the largest of Australia’s 10 freshwater crayfish genera with 52 species, and includes many of the largest, slowest-growing and longest-lived species (some >35 years) in the World. Several species have distributions consistent with being ‘climate refugees’, namely, being closely associated with cool, damp conditions and restricted to isolated mountain-top refuges. The present study investigated the critical thermal limit of a well known abundant species, Euastacus sulcatus, from central eastern Australia. Thermal limit was assessed using chronic, ongoing exposure to steadily increasing temperature, with the breakdown of physiological function tested by righting response. Distress was clearly evident in the crayfish at ~23°C (e.g. sluggish, lack of aggression), and the test criterion was met at ~27°C, with animals effectively incapacitated and unable to right themselves. Field water temperatures rarely exceed 21°C; however, any increases in environmental temperature may expose this species to temperatures where physiological stress may become problematic.

CONSERVATION OF IMPERILED CRAYFISH - EUASTACUS BINDAL (DECAPODA: PARASTACIDAE), A HIGHLAND CRAYFISH FROM FAR NORTH QUEENSLAND, AUSTRALIA

1 Environmental Futures Centre and Griffith School of Environment, Gold Coast campus, Griffith University, Queensland 4222, Australia 2 Environmental Futures Centre and Griffith School of Environment, Gold Coast campus, Griffith University, Queensland 4222, Australia; and Marine Ecology Research Centre, Southern Cross University, Lismore, NSW 2480, Australia 3 Environmental Futures Centre and Griffith School of Environment, Gold Coast campus, Griffith University, Queensland 4222, Australia; and, Outback Ecology, 1/73 Troy Terrace, Jolimont, Western Australia, 6014, Australia

The freshwater crayfish fauna of Australia: update on conservation status and threats

The Australian Continent is home to one of the most diverse freshwater crayfish faunas in the world, and includes many of the world’s largest species of freshwater crayfish (including the largest species at ~1 m overall length), but also some of the smallest. The Australian fauna is almost entirely endemic and features some of the world’s rarest, slowest growing and longest lived species (over 30 years in some cases), the most highly endangered, but also the most iconic, charismatic and in some cases, most bizarre looking freshwater crayfish. Some species are among the hardiest, most ecologically aggressive, highly fecund, and fastest growing in the world. Due to traits desirable for fisheries and aquaculture, some species have been extensively translocated over large distances. With the exception of the arid zone, the freshwater crayfish of Australia occupy all habitat types and climatic zones on the Continent. A few species are widely distributed habitat generalists that can tolerate extremes in environmental conditions, while many other species have far smaller distributions (≪10 km2 in a number of cases) and are very closely associated with specific habitat types and rely on particular environmental conditions. The widely distributed nature of the Australian fauna exposes the Australian fauna to a broad array of very serious existing and emerging threats, all of which are mainly anthropogenic in nature. A 2010 conservation assessment of the world’s freshwater crayfish versus IUCN Red List criteria indicated that the Australian freshwater crayfish fauna was the world’s most endangered. This paper, 1) provides a review of earlier conservation reports and outlines our understanding of the situation to date, 2) presents the current conservation status of the Australian fauna, 3) provides updates on well-known and emerging threats, and 4) discusses recent discoveries and progress towards conservation of the Australian fauna.

Conservation of Imperiled Crayfish—Euastacus jagara (Decapoda: Parastacidae), a Highland Crayfish from the Main Range, South-Eastern Queensland, Australia

Conservation Status.—Euastacus jagara Morgan, 1988 (Fig. 1) is currently listed as ‘Endangered’ on the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species (Crandall, 1996). A recent assessment and revision of the conservation status of the genus Euastacus (the ‘spiny crayfish’) considered that a listing of ‘Critically Endangered’ is now appropriate under current IUCN criteria (Coughran and Furse, 2010; Furse and Coughran, in press a, b, c). The conservation assessment noted that further information is urgently required on the species, in order to both refine its conservation status and enable specific conservation and management programs. The species is not currently listed under any State or Federal conservation legislation.

A novel genus and cryptic species harboured within the monotypic freshwater crayfish genus Tenuibranchiurus Riek, 1951 (Decapoda: Parastacidae)

Identifying species groups is an important yet difficult task, with there being no single accepted definition as to what constitutes a species, nor a set of criteria by which they should be delineated. Employing the General Lineage Concept somewhat circumvents these issues, as this concept allows multiple concordant lines of evidence to be used as support for species delimitation, where a species is defined as any independently evolving lineage. Genetically diverse groups have previously been identified within the monotypic parastacid genus Tenuibranchiurus Riek, 1951, but no further investigation of this diversity has previously been undertaken. Analysis of two mitochondrial DNA gene regions has previously identified two highly divergent groups within this taxon, representing populations from Queensland (Qld) and New South Wales (NSW), respectively. Additional testing within this study of both mitochondrial and nuclear DNA through species discovery analyses identified genetically diverse groups within these regions, which were further supported by lineage validation methods. The degree of genetic differentiation between Qld and NSW populations supports the recognition of two genera; with Qld retaining the original genus name Tenuibranchiurus, and NSW designated as Gen. nov. until a formal description is completed. Concordance between the species discovery and lineage validation methods supports the presence of six species within Tenuibranchiurus and two within Gen. nov. The recognition of additional species removes the monotypy of the genus, and the methods used can improve species identification within groups of organisms with taxonomic problems and cryptic diversity.