DNA metabarcoding detects ecological stress within freshwater species

Metabarcoding allows scientists to extract DNA from the environment, in order to rapidly detect species inhabiting a particular habitat. While the method is a great tool that facilitates conservation activities, few studies have looked into its applicability in monitoring species’ populations and their genetic diversity, which could actually be critical to assess negative trends early on. The potential of the method is confirmed in a new study, published in the peer-reviewed scholarly journal Metabarcoding & Metagenomics.

In a new study, German scientists confirm that responses below species level can be inferred with DNA metabarcoding

Metabarcoding allows scientists to extract DNA from the environment (known as environmental DNA or eDNA), for example, river water or, as in the case of the study by the team from the University of Duisburg-Essen (Essen, Germany) within the German Barcode of Life project (GBOL II): Vera Zizka, Dr Martina Weiss and Prof Florian Leese, from individuals in bulk samples. Thus, they are able to detect what species inhabit a particular habitat.

However, while the method has already been known to be of great use in getting an approximate picture of local fauna, hence facilitating conservation prioritisation, few studies have looked into its applicability to infer responses below species level. That is, how the populations of a particular species fare in the environment of interest, also referred to as intraspecific diversity. Meanwhile, the latter could actually be a lot more efficient in ecosystem monitoring and, consequently, biodiversity loss mitigation.

The potential of the method is confirmed in a new study, published in the peer-reviewed scholarly journal Metabarcoding & Metagenomics. To do so, the researchers surveyed the populations of macroinvertebrate species (macrozoobenthos) in three German rivers: Emscher, Ennepe and Sieg, where each is subject to a different level of ecological disturbance. They were looking specifically at species reported at all of the survey sites by studying the number of different haplotypes (a set of DNA variations usually inherited together from the maternal parent) in each sample. The researchers point out that macrozoobenthos play a key role in freshwater ecosystem functionality and include a wide range of taxonomic groups with often narrow and specific demands with respect to habitat conditions.

“As the most basal level of biodiversity, genetic diversity within species is typically the first to decrease, and the last to regenerate, after stressor’s impact. It consequently provides a proxy for environmental impacts on communities long before, or even if never visible on species diversity level,”

explain the scientists.

Emscher is an urban stream in the Ruhr Metropolitan Area that has been used as an open sewage channel for the past hundred years, and is considered to be a very disturbed environment. Ennepe – regarded as moderately stressed – runs through both rural and urban sites, including ones with sewage treatment plant inflow. Meanwhile, Sieg is considered as a stable, near-natural river system with a good ecological and chemical status.

As a result, despite their original assumption that Sieg would support the most prominent diversity within populations of species sensitive to organic pollution, such as mayflies, stoneflies and caddisflies, the scientists reported no significant difference to the medium stressed river Ennepe. This was also true for overall biodiversity. On the other hand, the team discovered higher intraspecific diversity for species resilient to ecological disturbance like small worms and specialised crustaceans in the heavily disturbed Emscher. The latter phenomenon may be explained with low competition pressure for these species, their ability to use organic compounds as resources and, consequently, increased population growth.

“[T]his pioneer study shows that the extraction of intraspecific genetic variation, so-called ‘haplotypes’ from DNA metabarcoding datasets is a promising source of information to assess intraspecific diversity changes in response to environmental impacts for a whole metacommunity simultaneously,”

conclude the scientists.

However, the researchers also note limitations of their study, including the exclusion of specialist species that only occured at single sites. They prompt future studies to also carefully control for the individual number of specimens per species to quantify genetic diversity change specifically.

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Original source:

Zizka VMA, Weiss M, Leese F (2020) Can metabarcoding resolve intraspecific genetic diversity changes to environmental stressors? A test case using river macrozoobenthos. Metabarcoding and Metagenomics 4: e51925. https://doi.org/10.3897/mbmg.4.51925

Integration of Freshwater Biodiversity Information for Decision-Making in Rwanda

Teams from Ghana, Malawi, Namibia and Rwanda during the inception meeting of the African Biodiversity Challenge Project in Kigali, Rwanda. Photo by Yvette Umurungi.

The establishment and implementation of a long-term strategy for freshwater biodiversity data mobilisation, sharing, processing and reporting in Rwanda is to support environment monitoring and the implementation of Rwanda’s National Biodiversity Strategy (NBSAP). In addition, it is to also help us understand how economic transformation and environmental change is affecting freshwater biodiversity and its resulting ecosystem services.

As part of this strategy, the Center of Excellence in Biodiversity and Natural Resource Management (CoEB) at the University of Rwanda, jointly with the Rwanda Environment Management Authority (REMA) and the Albertine Rift Conservation Society (ARCOS), are implementing the African Biodiversity Challenge (ABC) project “Integration of Freshwater Biodiversity Information for Decision-Making in Rwanda.”

The conference abstract for this project has been published in the open access journal Biodiversity Information Science and Standards (BISS). 

The CoEB has a national mandate to lead on biodiversity data mobilisation and implementation of the NBSAP in collaboration with REMA. This includes digitising data from reports, conducting analyses and reporting for policy and research, as indicated in Rwanda’s NBSAP.

The collation of the data will follow the international standards and will be available online, so that they can be accessed and reused from around the world. In fact, CoEB aspires to become a Global Biodiversity Informatics Facility (GBIF) node, thereby strengthening its capacity for biodiversity data mobilisation.

Data use training for the African Biodiversity Challenges at the South African National Biodiversity Institute (SANBI), South Africa. Photo by Yvette Umurungi.

The mobilised data will be organised using GBIF standards, and the project will leverage the tools developed by GBIF to facilitate data publication. Additionally, it will also provide an opportunity for ARCOS to strengthen its collaboration with CoEB as part of its endeavor to establish a regional network for biodiversity data management in the Albertine Rift Region.

The project is expected to conclude with at least six datasets, which will be published through the ARCOS Biodiversity Information System. These are to include three datasets for the Kagera River Basin; one on freshwater macro-invertebrates from the Congo and Nile Basins; one for the Rwanda Development Board archive of research reports from protected areas; and one from thesis reports from master’s and bachelor’s students at the University of Rwanda.

The project will also produce and release the first “Rwandan State of Freshwater Biodiversity”, a document which will describe the status of biodiversity in freshwater ecosystems in Rwanda and present socio-economic conditions affecting human interactions with this biodiversity.

The page of Center of Excellence in Biodiversity and Natural Resource Management (CoEB) at University of Rwanda on the Global Biodiversity Information Facility portal. Image by Yvette Umurungi.

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The ABC project is a competition coordinated by the South African National Biodiversity Institute (SANBI) and funded by the JRS Biodiversity Foundation. The competition is part of the JRS-funded project, “Mobilising Policy and Decision-making Relevant Biodiversity Data,” and supports the Biodiversity Information Management activities of the GBIF Africa network.

 

Original source:

Umurungi Y, Kanyamibwa S, Gashakamba F, Kaplin B (2018) African Biodiversity Challenge: Integrating Freshwater Biodiversity Information to Guide Informed Decision-Making in Rwanda. Biodiversity Information Science and Standards 2: e26367. https://doi.org/10.3897/biss.2.26367