aquatic fauna

Seven new species of whitefish described in Central Switzerland

Biologists at Eawag identified whitefish species in the lakes of the Reuss river system. Of them, seven are described as new to science.

Biologists at Eawag have identified ten species of whitefish in the lakes of the Reuss river system. Of these, seven have been described as distinct species for the first time – although in two cases this required inspection of specimens from historical collections, since eutrophication of lakes in the 20th century also led to the extinction of fish species in Central Switzerland.

These seven whitefish were described as separate species for the first time, including the “Albeli” from Lake Lucerne, which now bears the name Coregonus muelleri in memory of the whitefish expert Rudolf Müller. Image by Eawag

The “Edelfisch” (Coregonus nobilis) was, after the smaller “Albeli”, the second most commonly caught species of whitefish in Lake Lucerne until, in the second half of the 20th century, phosphate from domestic wastewater and nutrient-rich run-off from farmland led to a massive increase in algal blooms. Compared to the lakes of the Central Plateau, nutrient levels in Lake Lucerne were moderate, and eutrophication was short-lived; even so, due to algal decomposition, oxygen was depleted in the deeper layers of the lake. The “Edelfisch”, which reproduces in the late summer at a spawning depth of 80 metres or more, suffered as a result. Shortly before nutrient inputs decreased following the ban on phosphates in detergents and the expansion of wastewater treatment plants, stocks of this species collapsed and it was considered to be extinct in 1980. Only from the late 1990s were individual specimens caught once again, unequivocally identified as C. nobilis in 2000 by the whitefish specialist and Eawag researcher Rudolf Müller.

Coregonus nobilis, Lake Lucerne, Switzerland.

Five whitefish species in Lake Lucerne

As the “Edelfisch” is now a protected species, Lake Lucerne has not lost any of its historically recorded whitefish species. Indeed, in addition to the familiar “Edelfisch”, “Albeli” and “Bodenbalchen”, Eawag scientists have identified two new species – two large whitefish, differing from the previously known species in their habits, morphological characteristics and genetic composition. The pelagic “Schwebbalchen” (Coregonus suspensus) probably lives permanently in the open water, not only for foraging but also for reproduction – a spawning behaviour only previously observed in the “Blaufelchen” (C. wartmanni) of Lake Constance. Occupying a position intermediate to the pelagic “Schwebbalchen” (C. suspensus) and the “Bodenbalchen” (C. litoralis) is the littoral “Schwebbalchen” (C. intermundia).

Lake Zug survivor

Particularly affected by eutrophication in the mid-20th century were whitefish in Lake Zug, which – like other Central Plateau lakes – was exposed to higher nutrient levels, for a longer period, than waterbodies further upstream. As only the uppermost water layers of this 200-metre-deep lake maintained oxygen levels sufficient to support fish, two whitefish species spawning in the depths of the lake died out – the (Lake Zug) “Albeli” (C. zugensis) and “Albock” (C. obliterus). Indeed, the Lake Zug “Albock” would have been completely forgotten if specimens had not been found by Eawag scientists Oliver Selz and Ole Seehausen in the historical Steinmann-Eawag Collection. Its morphology and historical accounts indicate that the Lake Zug “Albock” was a deep‑water specialist – a specialisation only otherwise observed to the same degree in the (likewise extinct) Lake Constance Kilch (C. gutturosus) and the (still extant) Lake Thun Kropfer (C. profundus).

The only whitefish species still found in Lake Zug today, spawning near the shore, is the “Balchen”. Testifying to its survival is its new scientific name – Coregonus supersum (“I have survived”).

Species endemic to each lake

Also new are the scientific names of the Lake Lucerne “Bodenbalchen” (C. litoralis) and “Albeli” (C. muelleri). For the morphological and genetic studies carried out by Oliver Selz and Ole Seehausen in order to revise the taxonomy of whitefish showed that almost every lake in Central Switzerland has its own species of “Albeli” and “Bodenbalchen”.

Previously, the “Albeli” of Lakes Zug and Lucerne had been classified as members of the same species (C. zugensis), while the “Balchen” spawning near the shore of the various Central Swiss lakes were known as C. suidteri. These collective species names have now been inherited by the extinct Lake Zug “Albeli” (C. zugensis) and the Lake Sempach “Balchen” (C. suidteri).

The Lake Lucerne “Albeli” received the new name C. muelleri in honour of the fisheries biologist and whitefish specialist Dr Rudolf Müller (1944–2023).

Ruedi Müller with the then Lucerne fisheries and hunting administrator, Josef Muggli, catching whitefish. Photo by Robert Muggli, Archive

A reflection of Switzerland

The lakes of the Reuss river system are a reflection of Switzerland as a whole. Since the last ice age, at least 35 whitefish species evolved in the pre-alpine lakes, usually two or more in each lake. Switzerland lost a third of these species during the period of lake eutrophication around the middle of the 20th century. Many of the lost species are known to researchers only thanks to historical collections, such as that created before the eutrophication period by the naturalist Paul Steinmann and currently curated by the Natural History Museum of Bern.

Original source:

Selz OM, Seehausen O (2023) A taxonomic revision of ten whitefish species from the lakes Lucerne, Sarnen, Sempach and Zug, Switzerland, with descriptions of seven new species (Teleostei, Coregonidae). ZooKeys 1144: 95-169. https://doi.org/10.3897/zookeys.1144.67747

Journal Alpine Entomology calls for contributions in a new topical collection

“Trends in Arthropods of Alpine Aquatic Ecosystems” is the first topical collection for the journal of the Swiss Entomological Society

The open-access, peer-reviewed scholarly journal Alpine Entomology, published by Pensoft on behalf of the Swiss Entomological Society, announced its very first topical collection of articles, which will be focusing on arthropods associated with aquatic ecosystems in mountainous regions.

The journal is currently inviting scientists, working on aquatic fauna from alpine habitats, to openly publish their research articles and short notices that provide evidence how arthropods’ biogeography, species communities, distribution, behaviour and morphology have changed in recent times.

“Aquatic invertebrates are key indicators of global or local changes. Furthermore, many aquatic ecosystems are closely linked to mountains because they originate in them. Many valuable unpublished datasets on aquatic arthropod fauna may therefore be available from mountainous regions,”
explain the rationale behind the newly opened topical article collection guest editors Dr. Jean-Luc Gattolliat (Museum of Zoology, Lausanne and University of Lausanne, Switzerland) and Dr. David Muranyi (Eszterházy Károly Catholic University, Hungary).

The aim of the “Trends in Arthropods of Alpine Aquatic Ecosystems” collection is to bring together data and findings about what many agree is the most impacted type of environment on Earth: aquatic ecosystems, especially running waters.

The collection will remain open for submissions for the next two years. In the meantime, the accepted manuscripts will be published on a rolling basis, as soon as they are ready for publication.

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One water bucket to find them all: Detecting fish, mammals, and birds from a single sample

Revolutionary environmental DNA analysis holds great potential for the future of biodiversity monitoring, concludes a new study.

Revolutionary environmental DNA analysis holds great potential for the future of biodiversity monitoring, concludes a new study

Collection of water samples for eDNA metabarcoding bioassessment.
*Photo by Till-Hendrik Macher.*

In times of exacerbating biodiversity loss, reliable data on species occurrence are 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, scientists progressively agree that we need a more comprehensive and holistic method to assess freshwater biodiversity.

Meanwhile, recent studies have continuously been demonstrating that eDNA metabarcoding analyses, where DNA traces found in the water are used to identify what 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.

Furthermore, as eDNA metabarcoding assessments use samples from water, often streams, located at the lowest point, one such sample usually contains not only traces of specimens that come into direct contact with water, for example, by swimming or drinking, but also collects traces of terrestrial species indirectly via rainfalls, snowmelt, groundwaters etc.

In standard fish eDNA metabarcoding assessments, these ‘bycatch data’ are typically left aside. Yet, from a viewpoint of a more holistic biodiversity monitoring, they hold 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 scholarly 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 litres of water from across a two-kilometre stretch along the river Mulde.

After water filtration the eDNA filter is preserved in ethanol until further processing in the lab.
*Photo by Till-Hendrik Macher.*

In fact, it took only one day for the team, led by Till-Hendrik Macher, PhD student in the German Federal Environmental Agency-funded GeDNA project, to collect the samples. Using metabarcoding to analyse the DNA from the samples, the researchers identified as much 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 litres 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 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.

Original source:

Macher T-H, Schütz R, Arle J, Beermann AJ, Koschorreck J, Leese F (2021) Beyond fish eDNA metabarcoding: Field replicates disproportionately improve the detection of stream associated vertebrate species. Metabarcoding and Metagenomics 5: e66557. https://doi.org/10.3897/mbmg.5.66557

Zorro, the new Latin American fish species, takes off the mask to show its true identity

Unidentified since its discovery in 2007, a large fish species from Amazonia has failed to give out enough information about itself, leaving only insufficient hints about its genus. Nevertheless, three scientists have now recovered the missing pieces to puzzle out its mysterious identity. In their study, published in the open-access journal ZooKeys, they describe the fish as a new species and name it after the fictional secretive Latin American character Zorro.

The new fish, called Myloplus zorroi, is commonly known among the Brazilians as ‘pacu’ and is a relative to the piranha. The research team, led by Marcelo C. Andrade, Universidade Federal do Para, Brazil, recognised in a fish, collected by sport fishermen from Rio Madeira basin, Brazil, a previously found, yet undescribed species. Following their analysis, it turned out that its discoverers had assumed an incorrect genus for it.

Among the distinctive features of the new fish, which helped its rightful placement, are its characteristic teeth, specialised to crush seeds.

The new pacu species is quite large, growing up to 47,5 cm. It dwells in moderately to rapidly flowing clear rivers, running over rocky or sandy bottoms, and ranging from about 2 to 8 metres in depth. Its basis colour is reddish silver with darker markings running along the upper side of the body. The head is dark and the belly – pale yellow.

Curiously enough, although the name of the new fish is chosen as a tribute to Mauricio Camargo-Zorro, a researcher at the Instituto Federal de Educacao, Ciencia e Tecnologia, in recognition of his invaluable contribution to the fish fauna inventory from the Marmelos Conservation Area, zorroi is also a playful reference to the Latin American fictional character Don Diego de la Vega and his secret identity hidden behind the nickname of Zorro.

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Original source:

Andrade MC, Jegu M, Giarrizzo T (2016) A new large species of Myloplus (Characiformes, Serrasalmidae) from the Rio Madeira basin, Brazil. ZooKeys 571: 153-167. doi: http://doi.org/10.3897/zookeys.571.5983.

‘Hidden fish’ genus described for 2 new weakly electric mormyrid species from Gabon

A new weakly electric mormyrid fish genus of two new species has been described from only three specimens collected over a period of 13 years in the rivers of the Central African country of Gabon. The genus has been named Cryptomyrus, meaning ‘hidden fish’ in Greek, and is the first new genus to be described within the family Mormyridae since 1977.

The study, authored by Dr. John Sullivan and Prof. Carl Hopkins of Cornell University, Ithaca, New York, and Sebastien Lavoue of the Institute of Oceanography at the National Taiwan University in Taipei, Taiwan, is published in the open-access journal ZooKeys.

“It’s odd we have only three specimens, given how much fish collection effort there’s been in Gabon over the past years,” says lead author Dr. John Sullivan. “Not having more made the descriptions difficult, but it was important to bring this discovery to light without further delay.” Sullivan added that he does not know if these fish are rare throughout their range or if specialists simply have not sampled localities or habitats where they are common, yet. “It shows that we still have a very incomplete picture of fish diversity in Gabon,” says Dr. Sullivan.

The last of the three specimens was found on an expedition to Gabon’s Ogooue River in September 2014, jointly sponsored by CENAREST and The Nature Conservancy. It was after nightfall on the Ogooue, beside Doume Falls, when Sullivan and the other team members caught the one odd fish in a plastic fish trap baited with earthworms. Reflecting its river of origin, the species now bares the name Cryptomyrus ogoouensis, while the second – Cryptomyrus ona, is named after Gabonese environmental activist Marc Ona Essangui.

Puzzled over the identity of the fish, back home at the Cornell University Museum of Vertebrates Dr. Sullivan remembered two somewhat similar specimens collected in Gabon and sent to him for identification by his colleagues Sebastien Lavoue and Yves Fermon, 11 years apart. “This is why we need natural history collections,” said Dr. Sullivan, “to keep these specimens and their DNA samples in good condition, because it can take years or even decades to connect the dots.”

Analyses of the DNA from the three specimens conducted at Cornell University showed they were close relatives and did not belong within any recognized genus. “That left us no choice but to describe them as a new genus, and Cryptomyrus, which means “hidden fish,” seemed an appropriate name given how hard they are to find,” said Dr. Sullivan.

Over 200 species of mormyrid fish live in fresh waters across Africa where they orient to their environment and communicate using electric pulses, too weak to be felt by humans, in combination with highly sensitive electroreceptor cells embedded in their skin.

The Nature Conservancy, a global conservation organization that works in more than 35 countries around the world, funded the 2014 expedition of the Ogooue. “We were thrilled to have contributed to this discovery,” said Marie-Claire Paiz, Gabon Program Director for The Nature Conservancy. “Our goal is to help Gabon acquire better baseline knowledge about the state of their fish and rivers which will enable them make science-guided choices about where and how to use their resources wisely for both people and nature.”

“The Nature Conservancy deserves a lot of credit,” commented Sullivan. “It’s a great example of how a conservation organization can promote the discovery of biodiversity by partnering with taxonomists and natural history museums.”

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Original Source:

Citation: Sullivan JP, Lavoue S, Hopkins CD (2016) Cryptomyrus: a new genus of Mormyridae (Teleostei, Osteoglossomorpha) with two new species from Gabon, West-Central Africa.ZooKeys 561: 117-150. doi: 10.3897/zookeys.561.7137