David Morgan

Adverse fire regimes threaten biodiversity, potentially leading to population declines and increased extinction risk. Understanding how varying fire regimes affect threatened species is essential for effective ecosystem management, including in Western Australia where diverse ecosystems are exposed to wildfires, Indigenous burning, and prescribed fire. We compiled and synthesised data on the threat of adverse fire regimes to threatened animal taxa in Western Australia. Using a threat classification scheme, we ranked adverse fire regimes as having either no, low, medium, high, or unknown impact on each taxon. A total of 212 taxa were reviewed, 153 (72%) of which are considered fire-threatened: 29 high, 67 medium, 43 low, and 14 unknown impact. This includes 100% of threatened amphibians (3 taxa), 91% of threatened mammals (29), 71% of threatened invertebrates (85), 67% of threatened fish (6), 63% of threatened reptiles (10) and 61% of threatened birds (20). Only some bird (6), mammal (5), and invertebrate (18) taxa received a ranking of ‘high’. Across all fire-threatened taxa, we synthesised 330 fire response cases from 169 studies. Most taxa (75%) are considered fire-threatened due to small ranges and limited dispersal (primarily invertebrates and island taxa), with much smaller numbers reliant on long-unburnt vegetation (>10–40 years; 7%) or habitat features that take decades to form (e.g. tree hollows; 7%). Many taxa should be considered putatively fire-threatened until further information on their fire responses and the nature of fire regimes within their ranges is collected. We identify key research priorities to inform fire management and threatened species conservation.

Anthropogenic climate change is forecast to drive regional climate disruption and instability across the globe. These impacts are likely to be exacerbated within biodiversity hotspots, both due to the greater potential for species loss but also to the possibility that endemic lineages might not have experienced significant climatic variation in the past, limiting their evolutionary potential to respond to rapid climate change. We assessed the role of climatic stability on the accumulation and persistence of lineages in an obligate freshwater fish group endemic to the southwest Western Australia (SWWA) biodiversity hotspot. Using 19,426 genomic (ddRAD-seq) markers and species distribution modelling, we explored the phylogeographic history of western (Nannoperca vittata) and little (Nannoperca pygmaea) pygmy perches, assessing population divergence and phylogenetic relationships, delimiting species and estimating changes in species distributions from the Pliocene to 2100. We identified two deep phylogroups comprising three divergent clusters, which showed no historical connectivity since the Pliocene. We conservatively suggest these represent three isolated species with additional intraspecific structure within one widespread species. All lineages showed long-term patterns of isolation and persistence owing to climatic stability but with significant range contractions likely under future climate change. Our results highlighted the role of climatic stability in allowing the persistence of isolated lineages in the SWWA. This biodiversity hotspot is under compounding threat from ongoing climate change and habitat modification, which may further threaten previously undetected cryptic diversity across the region.

Context
Obtaining a source of genetic data is a key constraint in population genomic research.

Aims
In this study, single-nucleotide polymorphisms (SNPs) were generated from oblong turtle (Chelodina oblonga) cadavers, to ascertain whether decomposed tissue could be used as a source of genetic data and to investigate genetic variation.

Methods
Tissue was opportunistically collected from 47 cadavers following a mass mortality event during April 2024 at Bibra Lake, Western Australia. Genotyping was performed using a Chelodina DArTseq platform, with a high-density assay of 2.5 million sequence reads.

Key results
Genetic diversity and inbreeding were investigated for 39 individual C. oblonga, using 8053 SNPs retained from data filtering. Observed and expected heterozygosities (HO = 0.26, HE = 0.31) for C. oblonga were relatively low compared with other freshwater turtle species within Australia. A high inbreeding coefficient (FIS = 0.17) was also detected, suggesting that inbreeding may threaten C. oblonga population viability at Bibra Lake.

Conclusions
This study highlights the utility of decomposed turtle cadavers as a viable source of DNA.

Implications
Management plans should implement strategies to improve gene flow between Bibra Lake and adjacent populations, such as establishing wildlife corridors to encourage migration between populations.

Context
The south-western corner of Australia is a biodiversity hotspot that includes a freshwater fauna with a high proportion of endemic species. The temperate perches comprise nearly half of the obligate freshwater fishes of the region, representing important components of local ecosystems and are of significant conservation concern.

Aims
Provide a spatially comprehensive molecular genetic assessment of species boundaries and major substructure for all local members of the family to better understand the interplay of ecology and environment across a common landscape.

Methods
Nuclear markers (allozymes) and matrilineal (cytb) datasets were generated to infer genetic groupings and any instances of hybridisation or introgression in relation to the current taxonomy, regional geography and ecological understanding.

Key results
There were contrasting patterns of diversification across genera, with Nannoperca housing four likely species-level splits, Nannatherina having three distinct geographically and ecologically separated subpopulations, and Bostockia comprising several refugial subpopulations that appear partially introgressed. Repeated genetic patterns were identified across particular biogeographic features, most notably the Margaret River and Shannon River.

Conclusions
This study highlighted the value of comparative range-wide molecular studies to inform taxonomy, ecology and conservation planning.

Implications
These analyses pave the way for taxonomic revision, management of key habitat refuges, and other conservation actions.

Although the red fox (Vulpes vulpes) is considered one of the most damaging and adaptive invasive carnivorous mammals that consumes a wide variety of vertebrate and invertebrate taxa, there are surprisingly few reports of red foxes hunting fish. We observed evidence of an attempted predation event by a red fox on a neonate green sawfish (Pristis zijsron) within a deltaic island in the Ashburton River estuary, a remote desert river in Western Australia. The site is a globally important nursery where newborn sawfish arrive annually in spring. Injuries to the sawfish included paw/claw marks on the head, damage to the rostrum, which is a formidable tool that is used for both defence against predators and for detecting and attacking prey, as well as a major hole in the head and damage to the gills, which are vital for respiration, osmoregulation, nitrogenous waste excretion, pH regulation, and hormone production. A series of tracks suggests at least one fox parades the shallow tidally influenced banks, with evidence of a green mud crab (Scylla serrata) having also been predated on. There have also been reports of red fox predation of sea turtle nests nearby. This is the first record of a red fox hunting in marine waters and one of the few identifying fish as prey. We suggest that a monitoring program for foxes, and possibly a control program, is warranted prior to the annual seasonal colonisation of this habitat by neonate green sawfish and nesting turtles, which may in turn reduce predation of sympatric species.

Fishes exhibit a range of feeding modes and strategies to forage in and on sand habitat. Here, we describe a novel feeding mode, whereby small juvenile baldchin groper, Choerodon rubescens (⁓65–100 mm TL), vigorously forward sweeps the benthos with a single pectoral fin to reveal small benthic prey and visually scans the immediate benthos on the swept side of the body. The behaviour was not exhibited by larger conspecifics (140–180 mm TL) presumably because they had progressed to larger and hard‐shelled benthic prey and/or perhaps because the small juveniles foraged more or less continuously to obtain enough very small prey. These records confirm yet another mode of prey capture in the evolution of the highly variable feeding repertoire of the Labridae.

Collection description
Full mitochondrial genomes of 384 Northern River Sharks, Glyphis garricki, and their associated metadata are stored here. The genetic data was produced to investigate the sex-specific dispersal behaviour of the species in Northern Australia and Papua New Guinea.

Start date
2012-01-22

End date
2016-10-12

Access
The metadata and files (if any) are available to the public.

Lineage
The full mitochondrial genomes were amplified with two primer pairs. The amplicons were fragmented and barcoded with the Nextera XT DNA Sample Preparation kits and 96 sample Nextera Index kits. Libraries were then pooled and sequenced on a Miseq desktop sequencer using the 2x250 bp paired-end reads MiSeq reagent kit v2.

The SNP data were created by Feutry et al. (2020), following the DArTseq protocol (Diversity Arrays Technologies, Canberra).

For globally threatened species, patchy data pose challenges in both establishing historical baselines and assessing current distributions. In the case of saw-fishes, much previous research has relied on amputated trophy rostra or historical photographs to fill data gaps in distribution and population estimates. However, the established morphometric models that allow the estimation of total length from rostra are restricted by the data available to generate them, with many constructed solely from juvenile morphometric data, and robust error testing rarely performed. This study generates an independent dataset from citizen science photographs and field measurements, incorporating sawfishes of all life history stages, to test the robustness of previously proposed models for the four Indo-Pacific sawfish species. Rostrum-to-length morphometric models (RLMs) were confirmed for Pristis clavata and Pristis pristis, and a new model was proposed for Pristis zijsron. A key source of error in previous RLMs for Anoxypristis cuspidata was identified as changing rostrum morphology with body size, but there were insufficient measurements in the present dataset to propose a new robust model for this species. This study highlights the problems associated with extrapolating total lengths of animals beyond the size bounds used to produce the original model. For historically exploited species like sawfishes, which are often represented in collections by trophies alone, these methods outline a critical step prior to use in further ecological study.

Tidal-exclusion barriers have routinely been constructed within estuaries throughout the world to moderate the risk of flooding by marine incursions. These barriers have been shown to impact ecological connectivity, however, their impact on the movement patterns of obligate estuarine fishes is poorly understood. We aimed to determine the environmental drivers of movements through a fish passage gate within a tidal exclusion barrier by the temperate sparid Black Bream (Acanthopagrus butcheri), which occasionally suffers from large-scale mortality events that predominantly occur in the adjacent habitat upstream of the barrier. Fish were fitted with passive integrated transponder (PIT) tags and their fine-scale passage was recorded using a monitoring system that acted as a gate at either end of the barrier over 14 months. Hydrological and environmental predictor variables were included in generalised additive mixed models to determine the drivers of upstream and downstream passages through the gate on an hourly and daily basis. Successful upstream and downstream passages were associated with times of minimal flow velocity within the fish gate that occurred when water levels equalised on both sides of the barrier. Downstream passages were also associated with declines in dissolved oxygen concentrations upstream of the barrier; suggesting that fish were seeking to escape poor water quality. However, as passage opportunities to avoid unfavourable conditions were influenced by tides that equalised the water levels, periodic mass fish mortality events can occur upstream of the barrier. As climate change will increase saltwater incursion and storm-related flooding risks, there will be a greater need for tidal exclusion barriers in many regions. This study underscores the need to understand the movement patterns of fishes in estuaries to maintain the connectivity of populations.
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•Tidal-exclusion barriers can deleteriously impact ecological connectivity.•Movements of an estuarine-resident sparid fish through a fish passage gate investigated.•Passages occurred at times of minimal flow velocity within the fish gate.•Passage opportunities to avoid poor water quality limited by tides.