Going, going, gone? Loss of genetic diversity in two critically endangered Australian freshwater fishes, Scaturiginichthys vermeilipinnis and Chlamydogobius squamigenus, from Great Artesian Basin springs at Edgbaston, Queensland, Australia

Abstract

1. Artesian springs are particularly sensitive freshwater ecosystems, characterized by specialized flora and fauna which, owing to their isolation, are often endemic. Thus, protection of spring habitats and endemic spring biota is important for biodiversity conservation, particularly because human impacts such as invasive species, habitat destruction, and fragmentation can have such devastating effects.2. This study investigated the mitochondrial DNA (mtDNA) genetic diversity and structure of two critically endangered (IUCN) freshwater fish species: red-finned blue-eye Scaturiginichthys vermeilipinnis, and Edgbaston goby Chlamydogobius squamigenus, with the aim of assisting management agencies to establish relocated populations that conserve the genetic integrity and evolutionary potential of both species.3. 2862 bp from multiple mtDNA genes were amplified from 111 red-finned blue-eye individuals (17 from the 1990s and 94 from 2010), and a 660 bp segment of mtDNA cytochrome b was amplified from 111 Edgbaston goby individuals (from 2010). In total, 14 concatenated mtDNA haplotypes were identified in red-finned blue-eye and three cytb haplotypes were identified in Edgbaston goby.4. Overall assessment of the genetic diversity and structure of the endemic fish fauna from the Edgbaston springs revealed low levels of diversity in both species and a loss of haplotypes in red-finned blue-eye over time. In addition, both species displayed significant genetic structure: at the spring scale for red-finned blue-eye and at the spring group scale for Edgbaston goby. It is concluded that without the appropriate management of relocated populations, such as considering genetic structure and diversity and selecting high quality habitats, these species are at a severe risk of losing evolutionary potential and becoming extinct. This study provides a valuable example for conservation managers of the contribution that population genetic studies can make regarding the adaptive management of endangered species.

Assessing the benefits and risks of translocations in depauperate species: A theoretical framework with an empirical validation

“…The extinct remnant population was genetically differentiated from all extant populations (Table ; Figure ), although it had low levels of diversity (Table ). The failure to source founder individuals from this population prior to its extinction in 2015 means that, as a species, redfin blue eye have lost a substantial amount of nuclear and mitochondrial diversity (Faulks, Kerezsy, Unmack, Johnson, & Hughes, ). Ensuring all extant populations are represented in translocated populations provides the best opportunity to maintain high levels of genetic diversity in newly established populations.…”

The ecology of narrow-range endemic macro-invertebrates of Great Artesian Basin springs

“…These findings also suggest that the collection of baseline data and ongoing monitoring of springs that are data deficient can be rapid, which they need be as threatening processes persist to the point of causing extinctions (Fairfax et al, 2007;Faulks et al, 2016;Mudd, 2000). A single spring requires no more than 4 samples each in two disparate areas, which can be completed in ~2 hours using scoops.…”

“…Habitat loss that has not led to extinction is still associated with the loss of genetic diversity (Faulks et al, 2016), and the potential loss of cryptic species or clades before they were discovered or described (Mudd, 2000). Despite the unique nature of GAB springs, and the severity of the threats they face, the system has only recently attracted conservation attention.…”

“…The amount of pool area where this species can persist has been severely reduced due to the invasion of the Western Mosquito fish (Gambusia holbrooki), which persists in some springs at very high densities and appears to outcompete or predate upon the endemic. This has led to a significant decline in the already limited number of springs it can persist within (Nicol et al, 2015), resulting in severe population declines, extirpation from all but one of the springs it originally occupied (Fairfax et al, 2007) and a cataclysmic loss of genetic diversity (Faulks et al, 2016). The Mosquito fish also consumes gastropods (Unmack, unpub.…”

“…Twenty-five years of dedicated efforts at a basin-wide scale incorporating conventional taxonomy and molecular methods have resulted in the description of species that are new to science and endemic to GAB springs at a rate of approximately two species per year (Figure 1-3). Additional threatened species listing has been used to provide protection where needed, and guides dedicated science and management that, for some of the systems most vulnerable species like the Red-finned Blue-eye (Wager & Unmack, 2004), guarantees their persistence in the face of critical threats (Faulks et al, 2016;Fensham, et al, 2006;Kerezsy & Fensham, 2013). However, the data presented in this thesis emphasizes that, despite this substantial progress, there are still considerable problems we must engage with to guarantee the conservation of the full diversity in the GAB springs threatened community.…”