aquatic ecosystems

Naturalists can mediate silent plankton invasions

Plankton can easily spread between water bodies on hydrobiological instruments if naturalists use inadequate biosecurity treatments in their work.

Homo sapiens is not only a great (perhaps the best) candidate for the world’s most invasive species award. Humans, due to their actions and technological wonders, are also at the forefront of good vectors for organismal dispersion. Can we break this inglorious streak?

“Because humans will continue to interact with terrestrial and aquatic environments, it is impossible to stop the human-aided dispersal of organisms completely. The best we can do is minimise the risk of human-mediated organism dispersal events by implementing adequate biosecurity methods in our activity” explains Dr Wejnerowski from Adam Mickiewicz University (Poland).

Plankton sampling using net. Photo by Sandra Wejnerowska

“We should be aware that all our activities can affect biodiversity, and adequate biosecurity treatments should be applied whenever the risk of inadvertent spreading of organisms is non-zero” adds Dr Marcin Krzysztof Dziuba from the University of Michigan (United States of America).

Recently, a team of researchers from Adam Mickiewicz University, Istanbul University (Turkey), Åbo Akademi University (Finland), and the University of Michigan empirically proved that plankton net – a basic hydrobiological instrument of almost every aquatic scientist and water manager – is a good vector for the dispersal of various phyto- and zooplankton taxa, including species of high invasive potential. Nuisance, bloom-forming, also toxic filamentous cyanobacteria are efficient hitch-hikers, and they are able to successfully compete with native residents in the new environment.

Instructions for US citizens to avoid spreading invasive species during lake recreation. Photo by Marcin Krzysztof Dziuba

Apart from identifying hitch-hiking plankton on the net and its fate in the new environment, the paper they published in the journal NeoBiota also describes the most commonly used biosecurity treatments that naturalists worldwide use to prevent plankton spread between water bodies via the net.

Their findings sound disturbing: naturalists use inadequate or questionable biosecurity treatments. As revealed by the survey data, only 9% of plankton samplers clean plankton nets using disinfectant liquids after sampling, while a majority of people either rinse the net with distilled or tap water, immerse the net with an open outflow in the water body and let it dry, or do not care about the cleanness of the net after sampling at all.

Exemplary photos of some phyto- (A – Limnothrix redekei, B – Planktothrix agardhii, C – Pseudanabaena limnetica, D – Melosira varians, E – Desmodesmus armatus, F – Asterionella formosa, G – Tetradesmus obliquus) and zooplankton ( H – Keratella cochlearis f. typica) hitch-hikers on the plankton net. Micrograph I shows the plankton biomass on the surface of the plankton net after immersing the net with an open outflow in the water body (inadequate biosecurity treatment). Photos by Tumer Orhun Aykut and Łukasz Wejnerowski. Identification of organisms by Aleksandra Pełechata and Marcin Krzysztof Dziuba.

“Indeed, the reality presented in the paper is unsettling. It worries me when I think of how often I have accidentally facilitated dispersion of nuisance plankton and how much I contributed to the invasion of plankton taxa into new water bodies when using inappropriate biosecurity treatments in my fieldwork,” admits Dr Wejnerowski, and adds: “We do not mean to reinvent the wheel; the problem of aquatic organism dispersal through hydrobiological instruments is already known. For years, it was neglected despite some recalls from the scientific community. It comes back like a bad penny because it needs a complex solution from the society of aquatic naturalists. It should happen. After all, naturalists are a human line of defence, protection and rescue for nature.”

Research article:

Wejnerowski Ł, Aykut TO, Pełechata A, Rybak M, Dulić T, Meriluoto J, Dziuba MK (2022) Plankton hitch-hikers on naturalists’ instruments as silent intruders of aquatic ecosystems: current risks and possible prevention. NeoBiota 73: 193-219. https://doi.org/10.3897/neobiota.73.82636

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.

***

Visit the journal’s website at: https://alpineentomology.pensoft.net/
Follow Alpine Entomology on Twitter and Facebook.

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

Scientists dive into museum collections to reveal the invasion route of a small crustacean

Biological invasions are widely recognised as one of the most significant components of global change. Far-reaching and fast-spreading, they often have harmful effects on biodiversity.

Therefore, acquiring knowledge of potentially invasive non-native species is crucial in current research. In particular, it is important that we enhance our understanding of the impact of such invasions.

To do so, Prof Sabrina Lo Brutto and Dr Davide Iaciofano, both working at the Taxonomy Laboratory of the University of Palermo, Italy, performed research on an invasive alien crustacean (Ptilohyale littoralis) known to have colonised the Atlantic European Coast. Their findings are published in the open access journal ZooKeys.

The studied species belongs to a group of small-sized crustaceans known as amphipods. These creatures range from 1 to 340 mm in length and feed on available organic matter, such as dead animals and plants. Being widely distributed across aquatic environments, amphipods have already been proven as excellent indicators of ecosystem health.

While notable for their adaptability and ecological plasticity, which secure their abundance in various habitats, these features also make amphipods especially dangerous when it comes to playing the role of invaders.

Having analysed specimens stored at the Museum of Natural History of Verona and the Natural History Museum in Paris, the scientists concluded that the species has colonised European waters 24 years prior to the currently available records.

The problem was that, back in 1985, when the amphipod was first collected from European coasts, it was misidentified as a species new to science instead of an invader native to the North American Atlantic coast.

A closer look into misidentified specimens stored in museum collections revealed that the species has been successfully spreading along the European coastlines.

Male of the invasive amphipod species (*Ptilohyale littoralis*), sampled in October 2015, from Bay of Arcachon, France.

Moreover, it was predicted that the amphipod could soon reach the Mediterranean due to the high connectivity between the sea and the eastern Atlantic Ocean through the Straits of Gibraltar – a route already used by invasive marine fauna in the past.

In the event that the invader reaches the Mediterranean, it is highly likely for the crustacean to meet and compete with a closely related “sister species” endemic to the region. To make matters worse, the two amphipods are difficult to distinguish due to their appearance and behaviour both being extremely similar.

However, in their paper, the scientists have also provided additional information on how to distinguish the two amphipods – knowledge which could be essential for the management of the invader and its further spread.

The authors believe that their study demonstrates the importance of taxonomy – the study of organism classification – and the role of natural history collections and museums.

“Studying and monitoring biodiversity can acquire great importance in European aquatic ecosystems and coastal Mediterranean areas, where biodiversity is changing due to climate change and invasions of alien species,” Prof Lo Brutto says. “In this context, specific animal groups play a crucial role in detecting such changes and they, therefore, deserve more attention as fundamental tools in biodiversity monitoring.”

“Regrettably, the steadily diminishing pool of experts capable of accurately identifying species poses a serious threat in this field.”

###

Original source:

Lo Brutto S, Iaciofano D (2018) A taxonomic revision helps to clarify differences between the Atlantic invasive Ptilohyale littoralis and the Mediterranean endemic Parhyale plumicornis(Crustacea: Amphipoda). ZooKeys, 754: 47-62. https://doi.org/10.3897/zookeys.754.22884