麻豆淫院

In times of exacerbating biodiversity loss, reliable data on species occurrence is essential, in order for prompt and adequate conservation actions to be initiated. This is especially true for freshwater ecosystems, which are particularly vulnerable and threatened by anthropogenic impacts. Their ecological status has already been highlighted as a top priority by multiple national and international directives, such as the European Water Framework Directive.

However, traditional monitoring methods, such as electrofishing, trapping methods, or observation-based assessments, which are the current status quo in fish monitoring, are often time- and cost-consuming. As a result, over the last decade, more and more scientists have come to agree that we need a more comprehensive and holistic method to assess freshwater biodiversity.

Meanwhile, recent studies have continuously been demonstrating that eDNA metabarcoding analysis, where DNA traces found in the water are used to identify which organisms live there, is an efficient method to capture aquatic biodiversity in a fast, reliable, non-invasive and relatively low-cost manner. In such metabarcoding studies, scientists sample, collect, and sequence DNA, so that they can compare it with existing databases and identify the source organisms.

The eDNA metabarcoding assessments use samples from water鈥攐ften streams鈥攃ollected at the lowest point. One such sample usually contains not only traces of specimens that come into direct contact with water鈥攆or example, by swimming or drinking鈥攂ut also collects traces of terrestrial species indirectly via rainfalls, snowmelt, groundwaters, etc.

In standard fish eDNA metabarcoding assessments, this "bycatch data" is typically left aside. Yet, from a viewpoint of more holistic biodiversity monitoring, it holds immense potential to also detect the presence of terrestrial and semi-terrestrial species in the catchment.

In their new study, reported in the open-access journal Metabarcoding and Metagenomics, German researchers from the University of Duisburg-Essen and the German Environment Agency successfully detected an astonishing quantity of the local mammals and birds native to the Saxony-Anhalt state by collecting as much as 18 liters of water from across a two-kilometer stretch along the river Mulde.

In fact, it took only one day for the team, led by Till-Hendrik Macher, Ph.D. student in the German Federal Environmental Agency-funded GeDNA project, to collect the samples. Using metabarcoding to analyze the DNA from the samples, the researchers identified as many as 50% of the fishes, 22% of the mammal species, and 7.4% of the breeding bird species in the region.

However, the team also concluded that while it would normally take only 10 liters of water to assess the aquatic and semi-terrestrial fauna, terrestrial species required significantly more sampling.

Unlocking data from the increasingly available fish eDNA metabarcoding information enables synergies among terrestrial and aquatic biodiversity monitoring programs, adding further important information on species diversity in space and time.

"We thus encourage [researchers] to exploit fish eDNA metabarcoding biodiversity monitoring data to inform other conservation programs," says lead author Till-Hendrik Macher.

"For that purpose, however, it is essential that eDNA data is jointly stored and accessible for different biodiversity monitoring and biodiversity assessment campaigns, either at state, federal, or international level," concludes Florian Leese, who coordinates the project.