382 Monitoring Threatened Species and Ecological Communities
NW90n) have since been lost to gambusia infestation; red-finned blue-eye remain
in NW30 (the type locality spring and the largest naturally occurring population);
and in NW70 which is adjacent to NW30 and intermittently coalesces with NW30
depending on discharge (Fig. 30.2). Of the four populations that were translocated
in 2009, a large, robust and self-sustaining population has established in spring
NW72. The other three populations perished for a variety of reasons, including
cessation of discharge into the spring (dynamism is an inherent feature of the
spring complex), and for other reasons that remain unclear – possibly unsuitable
habitat, the small size of receiving springs or population f luctuations associated
with small founder populations. It is salient that all three populations persisted for
between 1 and 4 years, albeit in low (<100) numbers. It is also notable that
gambusia was not implicated in the demise of any of these three populations,
indicating that multiple factors inf luence survival, and naturally occurring
extinction and colonisation events were, and are, relatively common at the spring
level, characteristic of a meta-population dynamic (Levins 1969; Hanski 1994).
The populations translocated in 2011 have fared better, with all three extant
more than 5 years later (Fig. 30.3). The population in E518 appeared to disappear
in early 2012, but subsequently recovered and now appears robust. Later
translocations to NW80 (September 2012) also appear stable, but the population
translocated to E509 is declining and was not detected during the last monitoring
event (gambusia are now present). Spring E508 is adjacent to E509 and a single
red-finned blue-eye was observed in this spring once following natural
colonisation after rainfall.
Thus, by late 2016, red-finned blue-eye occur naturally in one spring (NW30
and NW70 joined outf lows in March 2016), and through managed translocation
now occupy a further six springs (NW72, NW80, E504, E509, E518, E524) although
there is recent decline and gambusia infestation in one of those (E509).
Establishing new populations from one or a small number of source
populations using relatively small founder populations can have profound genetic
Fig. 30.3. Status of red-finned blue-eye at Edgbaston Reserve, 2009–2016.