1. To establish a baseline for comparison: The control sample acts as a reference point to distinguish between genuine bighead carp DNA and any potential contamination or background noise in the environment. By analyzing the control, scientists can identify any false positives that might arise from the sampling or analysis process itself.
2. To confirm the accuracy and specificity of the eDNA detection method: A control sample helps ensure that the eDNA test accurately detects bighead carp DNA and doesn't mistakenly identify other fish species or environmental factors as positive results. It confirms the specificity and sensitivity of the chosen detection method.
3. To identify potential sources of contamination: By analyzing the control, researchers can pinpoint potential sources of contamination in their sampling or laboratory processes. This could be anything from using equipment that was previously used with bighead carp samples or even the presence of bighead carp DNA in reagents or laboratory supplies. Identifying these sources helps ensure the reliability and accuracy of the eDNA results.
4. To assess the effectiveness of the eDNA method: Control samples are essential for assessing the overall effectiveness of the eDNA method. By comparing the results from control samples with samples taken from water bodies where bighead carp are known to be present, scientists can evaluate the sensitivity and accuracy of the eDNA approach.
Types of Control Samples:
There are several types of control samples commonly used:
* Negative Control: This is a sample that should contain no target DNA (bighead carp DNA in this case). It is used to ensure that no contamination occurred during the sampling or analysis process.
* Positive Control: This is a sample that is known to contain the target DNA. It serves as a positive reference to confirm that the detection method is working properly and can identify the target DNA.
* Field Blank: This is a sample of distilled water or a sterile solution that is collected and processed along with the environmental samples. It helps identify contamination that may occur during the sampling process.
In conclusion: Control samples are an indispensable part of eDNA surveillance. They help scientists ensure the accuracy, reliability, and effectiveness of the eDNA method, leading to more robust and accurate results for detecting invasive species like bighead carp.
