frog conservation taronga zoo aus wildlife lec 5

Introduction by Host

  • Introduction of Michael McFadden from Taronga Zoo, who runs the Reptile and Amphibian Conservation Unit.
  • Michael's group has done significant work conserving endangered Australian frogs.

Michael McFadden's Background

  • Supervisor at Taronga Zoo for over 20 years (since 2005).
  • Current role: Wildlife Conservation Officer, focusing on frog conservation programs.
  • Taronga Zoo has insurance colonies for seven threatened herpetofauna species: one turtle, two lizards, and four frog species.

Overview of Presentation

  • Ex situ conservation programs: why and how they are implemented.
  • Case studies of frog conservation efforts.

Southern Gastric Brooding Frog: An Extinct Case Study

  • Unique reproductive strategy: female swallows fertilized eggs, developing them into tadpoles in her stomach, and then regurgitates the young frogs.
  • Lived in streams of the Conondale Ranges, Southeastern Australia.
  • Disappeared in 1981, along with the Southern Day Frog (disappeared two years earlier).
  • The species could have been used for human medicine (shutting down or slowing down digestive acids).
  • Northern Gastric Brooding Frog discovered in 1984, but extinct the following year.
  • Cause of disappearance was unknown at the time.
  • Six frog species extinct in Australia (potentially seven).
  • Gradual spread of extinctions north and south from Southeast Queensland since the late 1970s.

Current Status of Frogs in Australia

  • Three species declared extinct.
  • Six species disappeared.
  • 15 species currently endangered.
  • Species on the brink of extinction, such as the Southern Corroboree Frog, Yellow-spotted Bell Frog, and Booroolong Frog.

Threats to Frogs

  • Frogs are sensitive to various factors due to their permeable skin and aquatic environment.
  • Habitat fragmentation and loss.
  • Introduced predators.
  • Chytridiomycosis: Disease caused by chytrid fungus (Batrachochytrium dendrobatidis) is the primary threat.
    • Implicated in the decline of approximately 500 amphibian species worldwide.
    • Conservative estimate of 90 species extinctions.

Chytrid Fungus

  • Waterborne fungus affecting the outer layer of amphibian skin (epidermis).
  • Frogs get it through contact with other frogs or through aquatic environments.
  • Zoox sporangia release spores into the waterway, infecting other frogs.
  • The fungus disrupts electrolyte balance (sodium and potassium levels drop), leading to cardiac arrest.
  • First records in Australia: 1978 (dainty tree frog museum specimen) but disease not described until the late 1990s (1998-1999).
  • Spread north and south from Southeast Queensland at approximately 100 kilometers per year.
  • Found in every continent except Antarctica.
  • African clawed frog may have contributed to its spread; immune to the fungus but carries it.
  • Genomic technology reveals the fungus originated on the Korean Peninsula.

Impact in Central America

  • In 1987-88, the Golden Toad disappeared from Monteverde Cloud Forests.
  • Moved eastward, wiping out about 50% of amphibian species and 80% of amphibians in total in parts of Panama as it passed through.
  • Drastic decline in amphibian biomass affects the entire ecosystem.
  • Amphibians consume invertebrates, maintaining balance in ecosystem; their decline has flow-on effects on the food web.

Diagnosis and Signs of Chytrid Fungus

  • Frogs often show no signs until later stages of infection (within 48 hours of death).
  • Clinical signs: reddening, excess skin sloughing, neurological behaviors (quiet, head down), skin lesions.
  • Diagnosis through swabbing the ventral surface of the skin and PCR testing.
  • PCR testing indicates if the frog is positive and provides a rough zoospore count.

Ex Situ Conservation

  • Definition: Conserving animals outside their natural environment, typically in zoos and wildlife parks.
  • Textbook examples: black-footed ferret and Californian condor.
  • Becoming an increasingly used tool in conservation.
  • If conservation could occur in situ it would be preferable; however this is not always enough to save the species in time.

Purpose of Ex Situ Conservation

  • Establishing insurance colonies.
  • Providing animals for reintroduction.
  • Establishing husbandry protocols.
  • Conservation research to abate threats.
  • Conservation education.
  • Fundraising for in situ conservation.

Establishing Insurance Colonies

  • Rescue species against imminent extinction.
  • Example: Southern Corroboree Frog.
  • Population trajectory was heading toward extinction.

Research

  • Almost all ex situ activities has an element of research.
  • Alpine Tree Frog was brought into Zoos yo examine innate immunity to Citric fungus to compared past exposed populations verus currently exposed.

Education

  • Burrowing Frog example: conservation education regarding human impact, sedimentation and siltation of streams, and the impact of willow trees.

Reintroduction and Translocation

  • Reintroducing species to former habitats.
  • Population augmentation.
  • Assisted colonization.

Considerations Before Setting Up an Ex Situ Conservation Program

  • Species prioritization.
  • Establishing analog species.
  • Founder collection.

Species Prioritization

  • Limited resources mean prioritizing species is critical.
  • Factors include:
    • How endangered the species is.
    • The likelihood that conservation efforts will help.
    • Cultural or socioeconomic significance.
    • Threats to species.
    • Phylogenetic significance.
  • Amphibian Ark has developed a species prioritization tool.

Establishing Analog Species

  • Beneficial for inexperienced institutions.
  • Example: Kruman Sanctuary worked with Angular Tinker Frog before working with the more endangered Kruman Tinker Frog.

Collecting Founders

  • Impact on wild population.
  • Number of founders to collect.
  • Number of families.
  • Whether to collect eggs, tadpoles, or frogs.
  • Location of founders to maximize genetic diversity.
  • Amphibian Ark has calculator tools to work out numbers of founders.

Biosecurity

  • Preventing the introduction of diseases or pathogens that could impact the species.
  • Quarantine protocols.
  • Disease screening to understand existing wild diseases.
  • Resourcing is also essential, primarily staffing and facilities costs.

Translocations and Reintroduction Biology

  • It is still relatively young science.
  • Translocation, where, what life stage and how many. All have effects on release success and will often vary between species.

Post Release Monitoring

  • Essential for understanding the success or failure of releases.
  • New South Wales has a strict process for releases.
  • Monitoring includes survey protocols, marking individuals, and tracking groups.

Australian Zoo Response

  • Increased participation in frog conservation programs across Australia.
  • Twelve species being studied for experimental translocations and reintroductions.
  • Programs typically focus on species within the zoo's home region.

Case Study 1: Southern Corroboree Frog

  • Iconic Australian frog species found only in Kosciuszko National Park.
  • Small frog species (2.5-3 cm).
  • Brightly colored and toxic, containing phenolic alkaloids.

Distribution and Habitat

  • Historically found only within Kosciuszko National Park.
  • Inhabits sphagnum bogs and pools.
  • Habitat example: large fragment bog surrounded by forest; sphagnum moss is a spongy moss that absorbs moisture and the pools allow the species to breed.

Monitoring

  • Surveyed through a shout response technique.
  • Dr. David Hunter monitors the populations.

Decline

  • Population crashed in the 1980s due to Chytrid fungus.

Threats

  • Primary threat is Chytrid fungus.
  • Drought can also impact populations.
  • Reservoir host species can amplify the virus. An example is the common eastern frog bird.

Long Term Recovery

  • Establish self-sustaining populations that coexist with Batrachochytrium dendrobatidis (BD).
  • Establish large holding colonies.
  • Research how the species can survive with or become immune to chytrid fungus.

Ex Situ Program

  • Established through egg collections over seven years.
  • Located at Taronga Zoo, Melbourne Zoo, and Healesville Sanctuary.
  • Held in quarantined, biosecure, climate-controlled facilities (refrigeration).
  • Facilities include backup thermostats and back-to-base alarms.
  • Large populations produce approximately 3,000-3,500 eggs per year.

Enclosures

  • Large disease-free enclosures have been constructed in Kosciuszko National Park, in the form of former snowy hydro sites and revegetation.
  • Smaller disease-free enclosures are established at a few locations.
  • Egg releases occur into artificial pools.

Further Studies

  • Continue translocation techniques and specimens for research.
  • Collaboration with the University of Melbourne to develop Chytrid resistance technologies.

Case Study 2: Booroolong Frog

  • Insurance colony established to maintain genetic diversity, protocols, species reintroduction, offspring release, and education.

Former range

  • Used to be more widespread, but the distribution has decreased to the Southern and Central Area.

Genetic Differentiation

  • Genetic work showed that the northern population is very different.

Breeding Protocols

  • Frogs from the Southern area were bred and rescued to maintain the genetics from the water.

Rearing Trials

  • The species was bred and various densitites were used, to see what could produce large numbers for releases.

Education

  • An education campaign was set up to tell children about the species.

Immune Trials

  • Set as testing to ensure a quiter immunity was done on the species.

The La Nina affect 02/1112

  • Populations expanded and recreated, taking pressure off the ex situ program.

Drought 02/1920

  • Severe drought where many streems dried out and resulted in frog populations locally extinct.

Emergency collect

  • A team urgently collected 60 frogs, and maintained at the zoo, within the facility

Liquid Nitrogen

  • Sperm was collected and stored incase for genetic reinvigoration from liquid nitrogen.

Reintroduction trials

  • Reintroduction trials done for over 3 years, that is working in collaboration with various parties.
  • Released frogs succefully bred, is collaborative by local land services, locals, threatening species experts and Taronga Zoo.
  • Phil Spark is environmental consultant involved in raising awareness.

Question About Frog Lifespan

  • Lifespan varies significantly between species.
  • Example: burrralong: 2-3 in the wild, and up to 6-8 in the zoo. Corroboree Frogs can live up to 21.
  • Chytrid does impace shortens the frog life span in the wild.

Question About Frog Resistance

  • Several labs looking at it.