Background & Aims: Biological monitoring is a core component of
biodiversity conservation, and an important tool for assessing the progress of
conservation efforts. Traditional aquatic monitoring methods are often based on
specimen collection and morphological identification, which are time-consuming
and ineffective practices. Additionally, these methods are unable to conduct
the type of large-scale, continuous ecological surveys that are required for
many conservation initiatives. There is therefore an urgent need to find a new
approach to monitoring to meet today’s growing biodiversity surveillance needs.
Progresses & Challenges: As molecular biology tools have improved,
environmental RNA technology has been introduced into the field of aquatic
biomonitoring and applied to species monitoring, biodiversity assessment, and
pathogen detection, showing significant potential to meet conservation needs. However,
the development of environmental RNA technology is still at the
proof-of-concept stage, and there are many technical drawbacks, including
limited understanding of environmental RNA ecological processes, the
inconsistent application of the technology and, the lack of a transcriptome
database that limits its ability to be used in aquatic biomonitoring.
Review Results: In this review, we first
give a brief introduction to environmental RNA technology. We then introduce
the analysis process of environmental RNA technology and discuss in detail what
information should be noted in the sample collection and preservation process,
the environmental RNA extraction and cDNA synthesis process, PCR amplification
and sequencing, and analysis of results. Next, we present the current status of
the application of environmental RNA technology in three areas: species
monitoring, biodiversity assessment, and pathogen detection. Further, we also
discuss problems associated with environmental RNA technology in practical applications.
Finally, we summarize the strengths and weaknesses of environmental RNA
technology. We identify two primary advantages of environmental RNA technology:
(1) environmental RNA technology can further improve the accuracy of
biomonitoring; and (2) environmental RNA technology can reveal additional
relevant information, such as the structural composition of populations, the
physiological status of organisms, and the health of ecosystems. The
shortcomings of environmental RNA technology are as follows: (1) the ecological
processes of eRNAs released into the environment are unclear, which may lead to
false positive and false negative errors; (2) the application of environmental
RNA technology is not standardized, which makes it impossible to compare the
results between different studies; and (3) the lack of a transcriptome database
will limit the further development of environmental RNA technology in aquatic
biomonitoring. In order to make full use of environmental RNA technology, these
shortcomings must be addressed as soon as possible.
Going Forward: In the future, in order to
properly apply environmental RNA technology in the field of aquatic
biomonitoring, researchers should focus on the following aspects in their
research: (1) to clarify the ecological processes of environmental RNA in the
aquatic environment to reduce the probability of false positive and false
negative errors; (2) to develop a standardized analysis process for
environmental RNA technology so that the data obtained from aquatic biomonitoring
using these approaches are accurate, reproducible and comparable; (3) to
continuously improve the transcriptome database so that environmental RNA
technology can be used for more biological assessments; and (4) to further
expand the application of environmental RNA technology in aquatic
biomonitoring, such as the use of environmental RNA technology to conduct
research on the physiological conditions of aquatic organisms, population
ecology and ecosystem health evaluation.