KOALA NEWS & SCIENCE
An informative monthly newsletter about successes & important announcements in koala conservation, and the latest scientific publications about koalas.
June 2024
Subscribe here: https://mailchi.mp/808fc4af1ee0/koala-news-science
Updated koala population numbers from CSIRO
The National Koala Monitoring Program released updated koala population numbers in March 2024, for both the listed (QLD, NSW, ACT) and unlisted (VIC, SA) populations.
https://www.nkmp.org.au/populations.php
https://cosmosmagazine.com/nature/koala-numbers-to-be-counted-for-first-time/
CSIRO data reinforces anecdotal reports of koala declines across Victoria 22 May
The drone surveys conducted by the National Koala Monitoring Program in the Moorabool Catchment, Vic, have backed up community and Traditional Owner concerns that koalas have declined in the region.
https://www.abc.net.au/news/science/2024-05-22/citizen-science-national-koala-monitoring-program-conservation/103814822
New analysis shows Forestry NSW targeting Great Koala NP 28 June
Analysis by the Forest Alliance NSW has shown that more than half of northern NSW’s active logging coupes are within the footprint of the GKNP.
https://www.thecooldown.com/outdoors/great-koala-national-park-forestry-corporation-logging-nsw/
https://www.miragenews.com/forestry-corp-targets-great-koala-park-ignoring-1265434/
Koalas allow their temperature to rise with air temperature 18 June
Koalas employ a newly-described adaptive technique to survive hot days: allowing body temperature to fluctuate with ambient temperature, saving ~18% of water. But researcher Dr Valentina Mella says it could prove risky under climate change conditions. https://www.sydney.edu.au/news-opinion/news/2024/06/18/koalas-predict-prepare-hottest-summer-days.html
Rehabilitated orphan koala Kookie has a joey 28 June
Koala Kookie who was raised and released after being orphaned in a vehicle strike in 2022, has been found with a joey. The young female was cared for by IFAW-supported vets and Friends of the Koala at Lismore, NSW.
https://worldanimalnews.com/from-tragedy-to-triumph-rehabilitated-orphaned-koala-seen-with-her-newborn-joey-in-the-wild/
Community takes action to protect koala after thousands of tourists visit 8 June
A google maps pin “koala sleeping in tree” at Kennett River, Vic, has been removed after community concerns. Locals report thousands of tourists flocking to the pin location to view the koala, some attempting to climb the tree, flying drones and throwing rocks. https://timesnewsgroup.com.au/surfcoasttimes/news/google-unpins-sleeping-koala/
Environment groups slam Plibersek’s approval of 151 new gas wells in QLD 26 June
The federal Environment Minister announced the approval of Senex Energy’s Atlas Stage 3 proposed 151 new coal seam gas wells north-west of Brisbane. Many have criticised the decision at a time when Australia should be limiting fossil fuels.
https://www.miragenews.com/greens-condemn-govts-approval-of-151-gas-wells-1263482/
Koalas found at tree planting site, VIC 6 June
Four koalas have been sighted on a property north of Geelong where 3,600 trees were planted in 2023 by IFAW & Koala Clancy Foundation, sparking further tree planting in 2024.
https://www.koalaclancyfoundation.org.au/we-got-the-koalas-back-geelong-advertiser/
https://www.ifaw.org/au/press-releases/koala-trees-planted-historic-grazing-property
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Latest Koala Science:
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Kotzur, I., Moore, B.D., Meakin, C., Evans, M.J. and Youngentob, K.N., 2024. Identifying Habitat Productivity Thresholds to Assess the Effects of Drought on a Specialist Folivore. https://doi.org/10.20944/preprints202406.1532.v1
Climate change has altered the frequency and severity of extreme weather, which can affect vegetation condition and habitat quality for wildlife. Declines in vegetation productivity during droughts and heatwaves can negatively impact animals that depend on vegetation for water and nutrition. The ability to detect such effects on habitat suitability can reveal refugia, which can be prioritised for protection to improve threatened species conservation. We used the normalised difference vegetation index (NDVI) to look at relationships between vegetation productivity and the presence of koalas (Phascolarctos cinereus) in potential habitat throughout much of their range. Using a large, long-term koala presence dataset, we tested the hypothesis that locations where koalas had been observed would exhibit higher NDVI values than a random, representative sample from the same vegetation group (i.e. woodlands, open forests or tall open forests). We also identified the minimum NDVI threshold at which koalas occurred across time for each vegetation group and compared these to the minimum NDVI values observed across potential koala habitat before and during the millennium drought; one of the worst recorded in Australia. Additionally, we investigated whether vegetation above the minimum NDVI thresholds was significantly closer to perennial water than unsuitable vegetation. We found that koalas tend to occur at locations exhibiting higher NDVI than average for all vegetation groups. We also found that 49% of all vegetation groups maintained a minimum NDVI above the koalas’ NDVI threshold before drought, equating to 190,227 km2, which declined to 166,746 km2 during drought (a 12% reduction). We also found that unsuitable vegetation tended to occur farther from perennial water than suitable vegetation for some vegetation groups. Areas that remained above the NDVI thresholds during the drought should be considered potential refugia for populations during an event of similar magnitude and could indicate future core habitat extent.
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Dvorak, P., Hlavac, V., Hanicinec, V., Rao, B.H. and Soucek, P., 2024. Genes divided according to the relative position of the longest intron show increased representation in different KEGG pathways. BMC genomics, 25(1), pp.1-10.
https://bmcgenomics.biomedcentral.com/counter/pdf/10.1186/s12864-024-10558-x.pdf
Despite the fact that introns mean an energy and time burden for eukaryotic cells, they play an irreplaceable role in the diversification and regulation of protein production. As a common feature of eukaryotic genomes, it has been reported that in protein-coding genes, the longest intron is usually one of the first introns. The goal of our work was to find a possible difference in the biological function of genes that fulfill this common feature compared to genes that do not. Data on the lengths of all introns in genes were extracted from the genomes of six vertebrates (human, mouse, koala, chicken, zebrafish and fugu) and two other model organisms (nematode worm and arabidopsis). We showed that more than 40% of protein-coding genes have the relative position of the longest intron located in the second or third tertile of all introns. Genes divided according to the relative position of the longest intron were found to be significantly increased in different KEGG pathways. Genes with the longest intron in the first tertile predominate in a range of pathways for amino acid and lipid metabolism, various signaling, cell junctions or ABC transporters. Genes with the longest intron in the second or third tertile show increased representation in pathways associated with the formation and function of the spliceosome and ribosomes. In the two groups of genes defined in this way, we further demonstrated the difference in the length of the longest introns and the distribution of their absolute positions. We also pointed out other characteristics, namely the positive correlation between the length of the longest intron and the sum of the lengths of all other introns in the gene and the preservation of the exact same absolute and relative position of the longest intron between orthologous genes.
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Watts, E.T., Phalen, D., Greenville, A.C., Donkers, K. and Carver, S., 2024. A retrospective epidemiological study of sarcoptic mange in koalas (Phascolarctos cinereus) using wildlife carer admission records. International Journal for Parasitology: Parasites and Wildlife, p.100955. https://doi.org/10.1016/j.ijppaw.2024.100955
Outbreaks of sarcoptic mange are sporadically reported in koala populations across Australia, but disease characteristics (e.g., distribution across the body) remain poorly understood. In an area of Northern Victoria regular cases coming into care suggest mange may have become enzootic, and here we characterise those koala mange admission records. In 18% (n = 10) of mange affected koala reports that had a recorded outcome (n = 55), the animals died before the carers could locate them, and of the remaining 45 koalas that were alive upon carer arrival, 80% (n = 36) had to be euthanised due to severe mange. The number of admissions varied among years (highest observed in 2019), and over 60% of affected koala admissions were male. Male admissions peaked in austral spring and again in late austral summer-autumn (mating and birthing seasons), with female admissions only exhibiting the latter peak (birthing season). Fissures of the epidermis of the front paws occurred in 100% of admitted koalas, with 70% also showing these signs elsewhere on ventral surfaces or limbs. Only male koalas had signs of mange on the chest and face, and only female koalas had signs of mange on their back. Collectively, this study suggests sarcoptic mange can be a severe disease in koalas, and that male koalas may play an important role in seasonal transmission dynamics. We discuss how these findings may help inform intervention strategies.
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Smith, A.P. and Pile, J., 2024. Koala density, habitat, conservation, and response to logging in eucalyptus forest; a review and critical evaluation of call monitoring. Australian Zoologist. https://doi.org/10.7882/AZ.2024.023
This study is the second in a series that examines the habitat requirements and response to logging of koalas (Phascolarctos cinereus) inhabiting tall eucalypt forests of north-east NSW. It presents the findings of koala population and habitat monitoring surveys in Pine Creek State Forest and Bongil Bongil National Park using a combination of call-counting and direct observation (spotlighting). The 6400 ha study area was mapped into 6 zones of increasing koala habitat quality by ground survey of forest structure and floristics on a 200 m grid. The accuracy of habitat definition and mapping was tested by stratified transect counts of koala calls and sightings over two consecutive years (1997–98). Average koala density increased steeply and significantly, from 0.02 – 0.20 koalas/hectare, with increasing mapped habitat quality based on increasing forest age, structural complexity, local food tree species diversity, history of prior koala occurrence and decreased past logging intensity. This relationship was driven primarily by breeding females, with the number of male koala calls weakly or uncorrelated with koala sightings and mapped habitat quality. Male koalas were more widely and uniformly distributed than females, including areas of low quality, plantation, and intensively logged forest. This finding explains the discrepancy between our results and those of other recent studies which concluded that koalas are tolerant of intensive logging based on modelling of calling male koalas and reliance on an untested assumption that male calling is indicative of female breeding success. Koala density in a subset of the highest quality habitat was relatively stable at 0.28 koalas/ha (3 hectares/koala) over the long term (1997–98 and 2012–2023). Key characteristics of the forest koala population, including low stable density, large home ranges, preference for high food tree diversity and locally unique food trees (including Allocasuarina torulosa and Syncarpia glomulifera), are not adequately explained by existing koala habitat models.
We present a new paradigm to explain regional variation in koala distribution, habitat and foraging preferences based on variations in foliage chemistry (toxicity and nutritional value) determined by the duration and stability of local plant-koala interactions in response to past fire, hunting, predation and logging disturbance history. We hypothesize that koala density in stable forest populations is regulated at low levels by a combination of selected and induced increases in leaf toxicity and decreases in leaf nutrition that limit koala browsing to benign levels of about 1-2% of annual leaf production. Large home ranges, complex mature forest structure, high food tree diversity and a specialized or diverse gut microbiome may be essential to allow females to rotate and change food trees frequently to minimize induced toxicity and select individual leaves with sufficient nutrients to support breeding and lactation with minimal risk of predation. High density koala populations (> 0.6/ha) occur primarily in areas where koalas have been introduced or re-introduced to planted habitats and natural areas where aboriginal hunters and dingoes were historically present but are now absent, and where food trees have not been selected for resistance to koala browsing pressure.
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Newton, H.P., Higgins, D.P., Casteriano, A., Wright, B.R., Krockenberger, M.B. and Miranda, L.H., 2024. The CARD9 Gene in Koalas (Phascolarctos cinereus): Does It Play a Role in the Cryptococcus–Koala Interaction?. Journal of Fungi, 10(6), p.409. https://doi.org/10.3390/jof10060409
Cryptococcus is a genus of fungal pathogens that can infect and cause disease in a range of host species and is particularly prominent in koalas (Phascolarctos cinereus). Like other host species, koalas display a range of outcomes upon exposure to environmental Cryptococcus, from external nasal colonization to asymptomatic invasive infection and, in rare cases, severe clinical disease resulting in death. Host factors contributing to these varied outcomes are poorly understood. Due to their close relationship with eucalypt trees (a key environmental niche for Cryptococcus gattii) and suspected continual exposure to the pathogen, koalas provide a unique opportunity to examine host susceptibility in natural infections. Caspase recruitment domain-containing protein 9 (CARD9) is a key intracellular signaling protein in the fungal innate immune response. Humans with mutations in CARD9 succumb to several different severe and chronic fungal infections. This study is the first to sequence and explore CARD9 variation in multiple koalas using Sanger sequencing. Four CARD9 exons were successfully sequenced in 22 koalas from a New South Wales, Australia population. We found minimal variation between koalas across all four exons, an observation that was also made when CARD9 sequences were compared between koalas and six other species, including humans and mice. Ten single-nucleotide polymorphisms (SNP) were identified in this study and explored in the context of cryptococcal exposure outcomes. While we did not find any significant association with variation in cryptococcal outcomes, we found a high degree of conservation between species at several SNP loci that requires further investigation. The findings from this study lay the groundwork for further investigations of CARD9 and Cryptococcus both in koalas and other species, and highlight several considerations for future studies.
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Liang-Yu Pan, Harsh Pahuja, Tim Portas, Edward Narayan 2024 Testing the application of plasma glucocorticoids and their ratios as biomarkers of acute and chronic stress in rescued wild koala patients: a pilot study bioRxiv 2024.05.24.595853; doi: https://doi.org/10.1101/2024.05.24.595853
Koalas (Phascolarctos cinereus) are one of the most iconic marsupial species endemic to Australia. However, their population is declining due to threats including habitat loss, disease, dog attacks, and vehicle collisions. These threats also serve as acute or chronic stressors that impact koala welfare and conservation. Cortisol is widely used as a biomarker to study stress in koalas. However, plasma cortisol concentration is less studied due to its limited ability to assess chronic stress and welfare concerns. Dehydroepiandrosterone sulphate (DHEAS) and dihydrotestosterone (DHT) are biomarkers that could potentially detect chronic stress due to their antagonising and inhibitory effects on cortisol. In this study, we used plasma cortisol and the ratio of DHEAS and DHT to cortisol to assess stress in rescued koalas (n = 10) admitted to RSPCA Queensland. Although no significant differences were found between koalas across all biomarkers and the ratios failed to detect chronic stressors, similar trends were found consistently, suggesting the potential use of the biomarkers to assess stress. Across all biomarkers, the highest medians were found in koalas with Chlamydia-related reproductive disease and oxalate nephrosis and the lowest medians were found in koalas with Chlamydia-related conjunctivitis. Higher medians were also found consistently in females (n = 3) and adult koalas. In addition, insignificant negative correlations were found across all biomarkers between age, weight, and body conditioning scores, except for the positive correlation between weight and cortisol and cortisol:DHT. Overall, the consistency of trends and the insignificant differences found across biomarkers in our study suggested that using a single biomarker to assess chronic stress is insufficient, especially for hospital-based studies limited by sample population. Thus, this pilot study provides first step towards developing a koala-specific allostatic load index based on multiple stress biomarkers to understand chronic stress in rescued koalas.
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Koala Science In Brief:
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Tchatchouang, S., Mikangue, C.A.M., Kenmoe, S., Bowo-Ngandji, A., Mahamat, G., Ebogo-Belobo, J.T., Mbaga, D.S., Taya-Fokou, J.B., Zemnou-Tepap, C., Yéngué, J.F. and Magoudjou-Pekam, J.N., 2024. Systematic review: Global host range, case fatality and detection rates of Mycobacterium ulcerans in humans and potential environmental sources. Journal of Clinical Tuberculosis and Other Mycobacterial Diseases, 36, p.100457. https://www.researchgate.net/profile/Mahamat-Gadji/publication/381629998_Systematic_review_Global_host_range_case_fatality_and_detection_rates_of_Mycobacterium_ulcerans_in_humans_and_potential_environmental_sources/links/6677d9041dec0c3c6f9bc5ae/Systematic-review-Global-host-range-case-fatality-and-detection-rates-of-Mycobacterium-ulcerans-in-humans-and-potential-environmental-sources.pdf
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Previous Koala News & Science here: https://www.wildkoaladay.com.au/koala-news-science/koala-news-science-may-2024/
Written by Janine Duffy President, Koala Clancy Foundation.
with support from Cheryl Egan, Organiser, Wild Koala Day.
Please send your positive, important news & publications to president@koalaclancyfoundation.org.au before 29th of each month for possible inclusion.