Community, Creeks & Critters

Using eDNA technology to connect people, place and science


A project that focuses on creek critters and biodiversity and encourages local community members to become volunteer citizen scientists and work together in collecting eDNA water samples. It’s also about sharing results within our catchment communities and building partnerships and networks.

An innovative “Data Dashboard” has been developed by the project team in order to present our eDNA sampling results.

View the Data Dashboard

“Community, creeks and critters - using eDNA technology to connect people, place and science” is a 2023/24 project aimed at encouraging local community members to become volunteer citizen scientists. It is funded by the NSW Department of Premier and Cabinet as part of their NSW Social Cohesion Grants Round 2 – Unsung Heroes – Innovation in Volunteering program.

This project builds upon the success of a 2022 citizen science pilot project initiative (funded by the Sydney Water Community Grants program) called "Using Hornsby Platypus eDNA as a Catalyst for Healthy Waterways".

While the pilot project focused specifically on detecting platypus DNA in several rural Hornsby Shire creeklines, the “Creeks & Critters” project utilises broader focus environmental DNA (eDNA) metabarcoding techniques that can detect a wider range of species beyond just platypus. It also expanded eDNA water sampling efforts to a wider selection of Hornsby Shire creeks. To capture seasonal variation, eDNA sampling is scheduled for Spring (2023) and Autumn (2024).

eDNA, or environmental DNA, is a cutting-edge technology used for wildlife detection and monitoring. It is a non-invasive sampling technique that is gaining popularity due to its effectiveness and cost-efficiency.

All animals release DNA into their surroundings, such as through mucus, faeces, urine, gametes, and skin cells. Scientists can now extract and analyse DNA from water, air, or soil samples to trace the presence of various species. For instance, a water sample can capture evidence of a platypus being in a creek within the past 24-48 hours.

How does eDNA work?

There are two methods for identifying sources of eDNA – Barcoding & Metabarcoding:

  • eDNA Barcoding: This method targets a specific gene to detect a single species. It was utilised in the Hornsby platypus eDNA pilot project.
  • eDNA Metabarcoding: This is the analysis method used in Creeks & Critters and allows for the simultaneous identification of many taxa within the same sample. The main difference between barcoding and metabarcoding is that metabarcoding does not focus on one specific organism, but instead aims to determine species composition within a sample.
Limitations of eDNA monitoring

Environmental DNA (eDNA) analysis has become a powerful tool in ecology and conservation biology for detecting the presence of species in aquatic environments. However, it does come with limitations:

  1. Sampling Bias: eDNA analysis of our local waterways relies on filtering a sample of water (generally 400mL to 2000mL during our Creeks & Critters sampling) in order to capture fragments of DNA (e.g. mucus, faeces, urine, gametes, and skin cells). This means that capture of the DNA is subject to the limitations of sampling, including where and when samples are collected. The method will only detect DNA that happens to be in the volume of water sampled. Therefore, it's possible to miss species that are present in the area but not in the sampled water.
  2. Temporal and Spatial Variability: Environmental conditions, such as water flow, temperature, and the presence of inhibitors, can affect the distribution and degradation of DNA in the environment. Consequently, eDNA detection can vary temporally and spatially, leading to inconsistent results.
  3. Sensitivity to Detection: The sensitivity of eDNA detection can vary depending on the target species, their abundance, and their behaviour. Rare or elusive species may not shed enough DNA into the environment for detection, leading to false negatives.
  4. Community Composition: The diversity and abundance of species in a given area can affect the likelihood of detecting their DNA in a water sample.
    Species with higher biomass or shedding more DNA are more likely to be detected compared to rare or less abundant species.
  5. DNA Persistence: DNA can degrade over time due to environmental factors such as sunlight, microbial activity, and water chemistry. This degradation can reduce the detectability of DNA, especially in certain environments.
  6. Cross-contamination: There is a risk of cross-contamination between samples, which can lead to false positives if proper precautions are not taken during sample collection, processing, and analysis.
  7. Reference Databases: The accuracy of species identification in eDNA analysis depends on the availability and quality of reference databases. Incomplete or inaccurate databases can lead to misidentification of species or failure to detect species not represented in the database.

An important goal of the “Creeks & Critters” project is to encourage the local community to get involved and learn more about creek critters while picking up citizen science-based eDNA sampling and survey skills. By volunteers sharing this knowledge with local networks, the project aims to deepen understanding of aquatic biodiversity, foster community connections, and contribute to the promotion of healthy waterways.

Citizen scientists participate in field work by collecting water samples from creeks using special, easy to use eDNA sampling kits. Samples are then sent off for laboratory analysis where a DNA reference library detects genetic traces (such as skin particles, mucus, faeces, and urine) left by different species in our local creeks.

The collection of this valuable eDNA data will not only facilitate a baseline assessment of creek biodiversity across the Shire, but also offer insights into our local aquatic wildlife and provide crucial knowledge in the event of a natural disaster.

DNA data of this kind has never been gathered within the Bushland Shire, making this the most significant citizen science and creek biodiversity research project in Hornsby’s history.

The “Creeks & Critters” project will allow citizen scientists to detect DNA fragments from a variety of Vertebrate species, which could include fish, frogs, lizards, birds, rakali, eels, turtles and, who knows, maybe even platypus, foxes and feral cats. The project’s eDNA analysis also includes detection of Decapods (i.e., critters with 10 legs such as freshwater shrimp and yabbies).

July/August 2023 – Project promotion
  • Call out to Citizen Scientists in local print & social media.
August/September 2023 – Project registration and eDNA sampling site nomination
  • Participants were asked to register an expression of interest in being a “Creeks & Critters” citizen scientist and provide relevant details via a Hornsby Council Yoursay project webpage.
  • Participants were asked to nominate a specific creek, dam or waterhole location (where they would like to sample for eDNA) by placing a pin on an online mapping tool and providing a relevant comment. Most proposed sampling locations were either a participant’s local creek or a favoured bushwalking spot. Some participants also shared local knowledge of their preferred location.
September/October 2023 – Finalise eDNA sampling site locations
  • The project team & scientific experts reviewed 91 creek sampling site locations submitted as part of the nomination process.
  • Based on a selection criterion, 40 sampling sites spread across Hornsby Shire were selected.
    • All sites selected were either a freshwater creek, waterhole, or dam within Hornsby LGA.
    • Creekline sampling sites were located downstream of upper catchment stormwater pipes to maximise natural habitat sampling.
    • Participants were informed that the project budget allows for the laboratory analysis of 40 eDNA samples in Spring 2023 and 40 eDNA samples in Autumn 2024. For this project, the significant cost of eDNA technology currently equates to approximately $500/site.
October 2023 – SPRING eDNA training workshops and field sampling Saturdays
  • The project requires each citizen scientist to undertake a short, in person training workshop to learn how to use an eDNA sampling kit and to be available to collect water samples on sampling Saturday field days. Workshops include a presentation from a local platypus expert and eDNA sampling kit pick-up.
  • Workshop locations & dates
    • Hornsby Library – Thursday 5 October
    • Galston Community Centre – Saturday 14 October
  • Sampling Saturdays include a base camp scenario where project team members are on hand for eDNA sampling kit pick-up/drop-off and general assistance.
    • Hornsby Council Chambers (Federation Room) – Saturday 7 October
    • Galston Community Centre – Saturday 14 October
April 2024 – AUTUMN eDNA training workshop and field sampling Saturdays
  • Saturday 6 April – eDNA Sampling Training Workshop & Sampling Saturday (Base camp at Hornsby Council Chambers)
  • Saturday 13 April – Sampling Saturday (Base camp at Galston Community Centre)
  • Thursday, 25 July 2024, 6.30pm – Hornsby Library (to be confirmed)

eDNA Sampling Results

Useful links