Freshwater

DNA barcoding of Norwegian water mites

Living water mites can look like moving gems in benthic samples from freshwater habitats. What do we know about these fascinating creatures, and how easy is it to barcode them?

Sperchon glandulosusSperchon glandulosus, a common species in low and middle order streams. Photo Reinhard Gerecke.

True water mites are 0.2-5 mm large arachnids that are commonly found in all kinds of freshwater. Under undisturbed conditions, they are particularly frequent and species-rich in lakes, running waters and springs. They are generally recorded also from peat bogs and temporary ponds. Water mites constitute an important element in freshwater ecosystems and many species have specific habitat requirements. This make them suitable for biomonitoring, but extended use is hampered by challenging taxonomies and size. Thus, DNA barcoding would be an excellent tool to increase the use of water mites in freshwater assessments.

This is one of the reasons why we (Elisabeth Stur, Gaute Kjærstad and Torbjørn Ekrem) at the NTNU University Museum started building a reference library of Norwegian water mites. We managed to convince world expert Reinhard Gerecke to collaborate with us to have Norwegian and Greenland water mites identified and barcoded.

The diversity and distribution of Norwegian water mites are poorly known: current unrevised lists comprise about 150 species, mostly recorded from eastern Norway only. At the same time, several species have their type localities in Norway, being first described by the Norwegian priest and arachnologist Sig Thor (1856-1937). This makes knowledge of the Norwegian fauna taxonomically important in a wider perspective, as recently exemplified by Pešić et al. (2017) in their revision of the Hygrobates fluviatilis complex.

When we started our project, there were no records of water mites from Norway and Greenland in the Barcode of Life Data Systems (BOLD). Now there are sequences of 22 identified species from Norway and 3 species from Greenland. Although this only is a very small percentage of the expected fauna, it is a proof of concept for DNA barcoding in Norwegian water mites: DNA barcodes are well suited to identify species and can be used to detect cryptic diversity. One example for this is the species Lebertia porosa, first described by Sig Thor in 1900 and with the high number of 37 junior synonyms. This species has no less than 7 BINs in our dataset and is a good candidate for thorough taxonomic scrutiny.

Lebertia porosaThe water mite Lebertia porosa has seven BINs in Norway. Photo Reinhard Gerecke.

Moreover, we tested two different ways of DNA extraction from sampled tissues: Dissection of legs or non-destructive extraction from whole specimens. Both methods performed equally well with a success rate of 84%. Thus, there are multiple options to preserve vouchers for DNA barcodes.

Given the high diversity and importance of water mites in freshwater ecosystems, the knowledge of the Norwegian fauna would gain much from an inventory project on this group. It is also obvious that a proper representation of identified water mites in the barcode reference library is needed to fully appreciate future environmental barcoding in assessments and management of freshwater ecosystems.

Elisabeth Stur, NTNU University Museum

Report from the Symposium on Biodiversity and DNA Barcoding

The symposium Biodiversity and DNA Barcoding was held at the Scandic Nidelven hotel 11-12 November 2015. Nearly 100 participants from Norway, Sweden, Canada, Finland, Germany, Czech Republic and UK had found their way to Trondheim, making this meeting larger than originally expected. The conference turned out to be a good meeting place for nature managers, barcoders, participants in the Norwegian Taxonomy Initiative and others interested in biodiversity and DNA barcoding.

As the program can confirm, there was a great diversity in the talks, both on topics and organism groups. We were guided through taxonomic challenges in fungi, marine invertebrates and insects, many of which has been detected with the aid of DNA barcodes. We were invited on journeys into the deep oceans and into the “moss forest”, and introduced to the opportunities molecular methods give when studying food webs, pollination and microscopic organisms.  We also learned about the The Planetary Biodiversity Mission, news from BOLD4 and about LifeScanner, a citizen-science initiative where identification of species through DNA barcoding is made available to everyone.

speakers symposiumSpeakers at the symposium. From left: Anders Hobæk, Christiane Todt, Marie Davey, Hans Tore Rapp, Frode Ødegaard, Inger Greve Alsos, Natasha de Vere, Endre Willassen, Kristian Hassel, Sujeevan Ratnasingham, Elisabeth Stur, Christer Erséus, Paul Hebert, Tomas Roslin. Tor Erik Brandrud and Gunn Paulsen were unavailable when the photo was taken. Photo Åge Hojem, NTNU University Museum, CC-BY.

Both organizers and participants seemed very pleased with the conference. Most things went as planned, the food was good, and even if we had music from the neighbouring room accompanying the last presentations on day two, the participants seemed pleased when leaving the venue. Thank you all for coming! More photos are available on Flickr.

participants-biodiv&DNAbarcoding-foto-hojemParticipants at the symposium Biodiversity and DNA barcoding 2015. Photo Åge Hojem, NTNU Vitenskapsmuseet, CC-BY.

Torbjørn Ekrem, NTNU University Museum