Turtles in trouble. Conservation ecology and priorities for Australian freshwater turtles

Abstract

The Australian freshwater turtle fauna is dominated by species in the family Chelidae. The extant fauna comprises a series of distinct lineages, each of considerable antiquity, relicts of a more extensive and perhaps diverse fauna that existed when wetter climes prevailed. Several phylogenetically distinctive species are restricted to single, often small, drainage basins, which presents challenges for their conservation. Specific threats include water resource development, which alters the magnitude, frequency, and timing of flows and converts lentic to lotic habitat via dams and weirs, fragmentation of habitat, sedimentation, nutrification, and a reduction in the frequency and extent of floodplain flooding. Drainage of wetlands and altered land use are of particular concern for some species that are now very restricted in range and critically endangered. The introduced European red fox is a devastatingly efficient predator of turtle nests and can have a major impact on recruitment. In the north, species such as the northern snake‐necked turtle are heavily depredated by feral pigs. Other invasive animals and aquatic weeds dramatically alter freshwater habitats, with consequential impacts on freshwater turtles. Novel pathogens such as viruses have brought at least one species to the brink of extinction. Species that routinely migrate across land are impacted by structural simplification of habitat, reduction in availability of terrestrial refugia, fencing (including conservation fencing), and in some areas, by high levels of road mortality. We report on the listing process and challenges for listing freshwater turtles under the Australian Environment Protection and Biodiversity Conservation Act, summarize the state of knowledge relevant to listing decisions, identify the key threatening processes impacting turtles, and identify key knowledge gaps that impede the setting of priorities. We also focus on how to best incorporate First Nations Knowledge into decisions on listing and discuss opportunities to engage Indigenous communities in on‐ground work to achieve conservation outcomes.

Opportunities for research and conservation of freshwater turtles in Australia

“…While research has unravelled much of the biology and conservation needs of Australian freshwater turtles, there remains much to be learned. With many species recommended for an upgrade to more severe listings in the Special Assessment Expert Panel process in 2022 (Petrov et al, This issue), the trend in declines for Australian freshwater turtles highlights the need for increasing conservation efforts. A heavy bias exists between some well‐studied species compared with others for which no information is published.…”

“…Symposium discussions on the primary gaps in research identified the lack of baseline data to inform population modelling as a key deficiency (Petrov et al, This issue). This lack of data includes relationships for fertility, hatching rates, sex ratios, age of maturity, maximum age, and age‐dependent survival rates.…”

“…For many northern species, there is little published information on basic ecology, such as nesting location and timing, reproductive output, or habitat use. Excluding subspecies, six of the seven species excluded from the Special Expert Assessment Panel owing to data deficiency were species from northern Australia (Petrov et al, This issue). Many species live in remote parts of northern Australia (e.g., Elseya flaviventralis , Emydura tanybaraga ), are recently described ( Myuchelys purvisi ), or are rare or sympatric with crocodiles, and therefore difficult to study (e.g., Emydura subglobosa subglobosa ).…”