| dc.description.abstract | Freshwater systems and fish communities face many anthropogenic threats
such as climate change, pollution, and invasive species, causing a rapid loss of
biodiversity. To protect freshwater fish basic knowledge of their numbers,
distribution, and habitat is required, but can be difficult to obtain. Remote freshwater
systems can experience human impacts but are even less understood due to lack of
access and potential hazards. Patagonia (the southern tip of South America) is
sparsely populated but contains many freshwater systems that can be indirectly
impacted by human activities. The introduction and subsequent naturalization of
several invasive salmonid species in rivers and lakes. Despite the potential for
adverse effects on these ecosystems, they are generally under researched and
uncharacterized. One such freshwater environment is the rivers draining from the
stratovolcano Melimoyu in northern Chilean Patagonia, where limited access, high
flows and considerable river debris makes traditional sampling from boats or wading
impractical or dangerous.
New biomonitoring techniques such as environmental DNA (eDNA) detection
can be used to sensitively and non-invasively obtain data of species presence or
even community structure through analysis of water samples and may provide an
avenue for obtaining data about freshwater communities in remote systems such as
Melimoyu. Applying eDNA barcoding or metabarcoding techniques in remote
systems may allow researchers to gain knowledge about the biota in these
environments where traditional sampling may be limited or impossible.
Environmental DNA barcoding was used for the detection of three different fish
species: invasive brown trout (Salmo trutta) and Atlantic salmon (Salmo salar), and
native puye (Galaxias maculatus) in the rivers draining Volcán Melimoyu. Brown
trout eDNA was detected at seven sites across four rivers, Atlantic salmon eDNA
was not detected at any sample sites, and puye eDNA was detected in one river with
high certainty. At several sites eDNA detection techniques were accompanied by backpack electrofishing. The detection of brown trout eDNA was potentially
influenced by differing environmental conditions (e.g., flow) between sampling
events. Puye was not always detected by eDNA despite being collected during
electrofishing.
eDNA can be a powerful biomonitoring tool for detection of fish in remote
systems, especially if applied with consideration of controls for contamination,
transport, and storage of samples. Samples for eDNA barcoding can be collected
under less-than-ideal conditions, and with an appropriate sampling regime, applied
to remote systems to obtain valuable data on distributions of individual fish species.
However, in future studies eDNA metabarcoding (i.e., simultaneous detection of all
fish eDNA present using universal primers) may be a more powerful tool for use in
remote freshwater environments to gain an understanding of entire communities.
Collections of supplementary data could be used to inform occupancy models for a
better understanding of the eDNA and presence of fish in these freshwater systems.
This study demonstrates the potential application of eDNA for informing resource
managers about fisheries resources, even in areas where traditional fisheries
techniques are difficult or impractical to complete. | en |
