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Fieldwork and friendship!

Drøbak 6th till 15th of May 2018

The Norwegian Taxonomy Initiative  funded project Sea slugs of Southern Norway  had its official kick-off with its first expedition to Drøbak, a little village on the east side of the Oslofjord about 40 km south of Oslo. Main goal, start mapping the sea slug species diversity of that area which we will continue to do so along different carefully chosen locations along the Southern Norwegian coast. But besides finding sea slugs, we had another ambition; meeting up with our hard-working collaborators that would help us out during our stay.

Sea slugs of Norway, a love story

Sea slugs are often a diver’s favourite encounter underwater. They are colourful, have an overall attractive appearance, with their little rhinophores exploring their surroundings, gliding slowly through their habitat.

Caronella pellucida, photographed by Anders Schouw

They are exciting to photograph as, besides pretty, it can be technically very challenging to get a good shot of them since they are often just a few millimetres long. Despite being popular animals, relatively little is known about them. Just recently the attention from the scientific community started to grow, and manuscripts with new records and species for Norway become to be published. However, the target areas were often the Northern territories of Norway rather than the South, and this resulted in a huge gap lasting already for about 80 years within the scientific literature for this particular area. About time to do something about it!

The citizens that are scientists

Southern Norway alone has a coastline of about 8000km, which makes it a monstrous task to really get a proper picture of the sea slug biodiversity (let alone cryptic species variation, invasive species etc.). Therefore, we asked for help from the so-called citizen scientists. Citizen scientist are volunteers that help out scientists by providing them with data as a hobby in their spare time. Many of them are not to be considered amateurs though, due to their many years of experience and enthusiasm, they are professionals when it comes to their knowledge of species and their habitats. Such a tight community is also found here in Norway within the dive community, and during this project of our hunt for sea slug species, we heavily rely on their input and willingness in order to make the mission a success.

Back to Drøbak

It was not a blind pick on the map to go to Drøbak as our main starting point. Drøbak is strategically chosen as former literature describes it as a type locality for a variety of the Norwegian sea slug species. Besides, the University of Oslo has its Marine Biology field station, with sleeping facilities, located here. Near the field station, there is also the – all famous – dive centre called Gylte, were many dive enthusiasts rent their gear, fill up their pressure tanks and go diving in the centres’ backyard. Not surprisingly one of the workers of Gylte is big sea slug enthusiast; let me introduce you to Tine Kinn Kvamme

Manuel Malaquias with Tine Kinn Kvamme

There was great excitement from both parties to finally meet in person and she was able to help us get in touch with other citizen scientists and explain in detail about all the species she encountered in the last years. The list was impressive,and a valuable contribution to our project;

Tine’s sea slug species check list for the area

That week we managed to meet up with her several times, and she brought us more sea slugs. We introduced her to the laboratory facilities in the Marine field station, where she had the opportunity to look at her beloved Doto’s in detail with help of a microscope, while telling us more about other possible interesting locations and possibilities to collect different species! This is what it is all about, happy scientists and happy citizen scientists!

Doto fragilis

Two other members of our team that joined us during the length of our stay in Drøbak were the respected divers Anders Schouw (from Bergen) and famous underwater photographer Nils Aukan (from Kristiansund).

Anders Schouw showing his photography skills in the laboratory

It was an honour to be able to work together with them, Anders proved his photography skills both underwater and above water to be of incredible valuable input and Nils great knowledge of Marine life and amazing photography skills made me and Manuel blush on our cheeks more than we would like to admit. They both dived every single day during our stay and brought sea slugs back to the laboratory where we together could identify, photograph, measure and prepare them for transport back to Bergen. Nils Aukan is a known sensation within the Norwegian diving community and ever since the project started we have received many samples from him. He is able to photograph the species in their natural habitat capturing the tiniest details, a valuable asset to later identify the species properly.

Fjordia lineata photographed by Nils Aukan

Anders is the guy every expedition need; he knows everyone, everywhere, and we’re very happy to announce his decision to join us in our next field work trip to Hagesund (in July, facilitated with a blog, obviously).

The gate to grass

At the spot we also met with the citizen scientist Roy Dahl, his son and Heine Jensen

Heine Jensen with Manuel Malaquias

A snapshot of the group, from left to right; A snapshot of the group, from left to right; Roy Dahl’s son, Roy Dahl, Anders Schouw, Cessa Rauch and Nils Aukan

Roy and Heine have been collaborating and sampling for us in the Oslofjord area. They know their favourite diving spots on the back of their hands and shared with us all the details one needs to know about the sea slugs’ habitat. They knew about species diversity, where to find but also when to find them. There is some change in sea slugs’ diversity when it comes to different times of the year, some species thrive just before spring starts, others are more regularly seen throughout the summer. All interesting and valuable information for us in order to see the bigger picture. Most diving spots were easy accessible and well facilitated, but sometimes the hunt for different habitats does not always favour you in a laidback access to the water. Manuel and I were a little obsessed with probing for sea slugs within the seagrass meadows of the Oslofjord. You never know what you can find there! Healthy seagrass meadows are the nursery, hiding, and hunting ground of many marine organisms, and we would not let the opportunity to study this habitat pass by!

Facelina bostoniensis on sea grass photographed by Anders Schouw

Anders was able to find an area of seagrass that seemed to be accessible from the Google maps point of view. But was it in real life though? After driving around, back and forwards for almost an hour we sadly realized that the only land access was through a private condo, closed by a gate and inaccessible to us. Whilst driving around a little unsure about what the next plan of action would be, Anders decided to use his communication skills to find out if there was another way. By a matter of luck, chance, sign – you name it – Anders asked the way to a person that happen to live there and to have a remote device that could open the gate giving us access to the park. All together it took us a whole afternoon to figure out how to get to the seagrass meadow and I think we can vote for Heine Jensen as our most patient citizen scientist! As we were driving in many circles to find the sea grass meadows, Heine jokingly mentioned, ‘look, there is grass just next to the road, why don’t we look for our slugs there’. We definitely own him one for his stamina!

You reap what you sow

After 10 days the sea slug teller was on approximately 39 species, and this without the species collected by the citizen scientists before our fieldtrip. All together we have so far assembled 43 species from areas in the Oslofjord. The work has just begun, and as a consequence of our successful actions in Drøbak, we now have to face the mountain of work waiting; structuring our harvest and make some sense of it all in the light of evolution.

For frequent updates, awesome images, and much more information about sea slugs in Norway than you ever imagined encountering, join the projects Facebook group 

Acknowledgments

We would like to thank our collaborators during this project; Torkild Bakken from Trondheim University who was also part of the Drøbak team for a few days, and our dedicated citizen scientists; Anders Schouw, Nils Aukan, Tine Kinn Kvamme, Roy Dahl and Heine Jensen. We hope that during the two years of this project we will have many more chances to meet and that our teamwork continues to be fruitfully!

By Cessa Rauch and Manuel Malaquias

Sognefjorden cruise May 2017

After our week with SponGES on R/V Bonnevie, Luis and I had a night back in Bergen before we headed out on our second spring adventure: a four day cruise (still onboard Bonnevie) of Sognefjorden, the longest (205 km) and (deepest 1308 m) fjord in Norway.

The cruise, led by Prof. Henrik Glenner from the Institute of Biology, UoB,  was a multi-purpose one, with the majority of the projects being linked to the Norwegian Taxonomy Initiative (Artsprosjekt):

We collected material for the ongoing project that is investigating and mapping the barnacle fauna (Crustacea: Cirripedia) in Norway, which a special focus on the strange, parasitic barnacle Anelasma squalicola that is found on the shark Etmopterus spinax (velvet bellied lantern shark/svarthå).

The material we collected will also serve as an addendum to the project on Species inventory and nature type mapping of Sognefjorden, which was recently concluded.

As for the University Museum, Luis was onboard collecting pelagic and benthic Hydrozoa for the HYPNO-project, whilst I was on the hunt for more species for DNA-barcoding through NorBOL (the Norwegian Barcode of Life). We have also re-sampled some polychaete type localities from the 1970’s, and attempted to retrieve more material from stations where we have found new species in more recent material (we need more specimens before we can formally describe them).

In addition, we had two Danish researchers onboard that were studying the bioluminescence and eye development of the starfish family Brisingidae. The story told in images:

We should maybe also add "one of the most gorgeous" to the description of the fjord

We should maybe also add “one of the most gorgeous” to the description of the fjord

Velvet belly lanternshark, Etmopterus spinax

Velvet belly lanternshark, Etmopterus spinax

Henrik and Christoph sorting a shrimp trawl catch on deck

Henrik and Christoph sorting a shrimp trawl catch on deck

Eager pickings in the trawl catch

Eager pickings in the trawl catch

Not all trawl samples go according to plan... this one, taken in the open sea, ended up sampling *a bit* deeper than intended, so we got a lot of benthic animals - and mud. So. much. mud.

Not all trawl samples go according to plan… this one, taken in the open sea, ended up sampling *a bit* deeper than intended, so we got a lot of benthic animals – and mud. So. much. mud.

Most novel sampling gear yet? Collecting velvet belly lanternshark by monkfish!

Most novel sampling gear yet? Collecting velvet belly lanternshark by monkfish! (caught in the “benthic” trawl)

The brisinga sea stars are very fragile - and live deep down.

The brisinga sea stars are very fragile – and live deep down.

We amanged to get some not-too-damaged specimens with a small trawl

We manged to get some not-too-damaged specimens with a small trawl

The plankton net going our for collecting

The plankton net going our for collecting

Luis an Marie studying a plankton sample

Luis an Marie studying a plankton sample

Plankton

Plankton

For some reason, my samples seems to involve inordinate amounts of mud - good thing I had good helpers to work through it all!

For some reason, my samples seems to involve inordinate amounts of mud – good thing I had good helpers to work through it all!

Cruising in a postcard!

Cruising in a postcard!

Sadly, plastic pollution was prevalent in Sognefjorden as well - here's a soda bottle from a sample taken at 911 m depth

Sadly, plastic pollution was prevalent in Sognefjorden as well – here’s a soda bottle from a sample taken at 911 m depth

And here are som eof the plastic that we ended up with from our sampling, most of it from over 1000 meters depth.

Here is some of the plastic that we ended up with from our sampling, most of it recovered from over 1000 meters depth.

Our final night of the cruise was spent in the mud and the sunset - it's starting to become a recurring theme!

Our final night of the cruise was spent in the mud and the sunset – it’s starting to become a recurring theme!

Once again, thank you so much to the crew on Bonnevie for all their help!

Once again, thank you so much to the crew on Bonnevie for all their help!

-Katrine

Door #11: Just a white blob?

Colobocephalus costellatus repainted from M. Sars (T.R. Oskars)

Colobocephalus costellatus repainted from M. Sars (T.R. Oskars)

When researching small, obscure sea slugs you are bound to run into surprises. Partly because it often takes a long time between discovery and identification, and also because a lot of the really interesting stuff is first revealed when new methods become widely available.

In 2011 a team of researchers from the Invertebrates collection were sampling specimens in Aurlandsfjorden for the Invertebrate collections and range data for the Norwegian Biodiversity Information Centre (Artsdatabanken). Among other interesting critters they found a 2 mm long white blob. While not initially impressive this small blob turned out to be the enigmatic cephalaspidean sea slug Colobocephalus costellatus (Cephalaspidea: Heterobranchia) described by Michael Sars from Drøbak in 1870. At the time of its re-discovery it was thought that this species, which is unique for Norway, had not been seen or collected since M. Sars first laid hands on it 145 years ago (more (in Norwegian) here). However, you continuously discover more information in the course of scientific work. During their work on the enigmatic slug Lena Ohnheiser and Manuel Malaquias found in the literature that the species had in fact been discovered a couple of times since 1870, first by Georg Ossian Sars in Haugesund some years after his father, and more recently by Tore Høisæter of Bio UIB in Korsfjorden outside Bergen.

Still, no in-depth analyses have been done on this species since M. Sars until Nils Hjalmar Odhner of the Swedish Natural History Museum drew the animal from the side showing some of the organs of the mantle cavity.

Most authors have had real difficulties to place this slug within the cephalaspids, and M. Sars even thought is possible that the slug might not be an opisthobranch. Some placed it within Diaphanidae based only on the globular shell, a family that has been poorly defined and often used as a “dump taxon” for species that hare hard to place. Yet others thought it might even be the same as the equally enigmatic Colpodaspis pusilla, which has been suggested to be a philinid sea slug (flat slugs digging around in mud and sand).

What was unique about the most recent find was that this was the first time it was collected alive and photographed with high magnification. The material was also so fresh that Lena and Manuel could dissect the animal and study its internal organs. In their 2014 paper “The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species Colobocephalus costellatus M. Sars, 1870” they tried to resolve the relationships between these globe shelled slugs. What they found was that Diaphanidae was likely not a real grouping of species, containing at least three distinct groups, where one group was Colobocephalus and Colpodaspis, which were closely related to each other, but also quite distinct.

Colobocephalus costellatus M. Sars, 1870. Photo Lena Ohnheiser, CC-BY-SA. Also featured on http://www.artsdatabanken.no/File/1292

Colobocephalus costellatus M. Sars, 1870. Photo: Lena Ohnheiser, CC-BY-SA. Also featured on http://www.artsdatabanken.no/File/1292

Another new development with the sampling in Aurlandsfjorden was that the slugs were preserved in alcohol rather than formalin. Formalin is good for preserving the morphology of animals, but it destroys DNA. On the other hand, alcohol is perfect for preserving DNA. This lead to C. costellatus to be included in a 2015 DNA based phylogenetic analysis of cephalaspidean sea slugs.

Modified Tree from Oskars et al. (2015)

Modified Tree from Oskars et al. (2015)

This resulted in that the slug was found to be indeed an Opisthobranchia, and as Lena and Manuel thought, Colobocephalus and Colpodaspis were placed in their own family, Colpodaspididae. Whereas the traditional “Diaphanidae” was split apart. Even weirder was the sea slugs that were shown to be the closest relatives of Colpodaspididae, which were neither the philinids or the diaphanids. The closest relatives turned out to be slugs that are equally as weird and unique as Colpodaspididae, namely the swimming and brightly colored Gastropteridae (sometimes called Flapping dingbats) and the Philinoglossidae, which are tiny wormlike slugs that live in between sand grains.

*Cousin Meeting*  - "You sure we are related?"  - "Well, the scientists seem to think so. I see no reason to waste a good party!"

*Cousin Meeting*
– “You sure we are related?”
– “Well, the scientists seem to think so. I see no reason to waste a good party!”

So it took 145 years from its discovery before Colobocephalus became properly studied and its family ties revealed, but it is still mysterious as we do not know much about their ecology or diet.

Suggested reading:

Colobocephalus costellatus: http://www.biodiversity.no/Pages/149747

Colpodaspis pusilla: http://www.biodiversity.no/Pages/149766

Philinoglossa helgolandica: http://www.biodiversity.no/Pages/149915

Høisæter, T. (2009). Distribution of marine, benthic, shell bearing gastropods along the Norwegian coast. Fauna norvegica, 28.

Gosliner, T. M. (1989). Revision of the Gastropteridae (Opisthobranchia: Cephalaspidea) with descriptions of a new genus and six new species. The Veliger, 32(4), 333-381.

Odhner, N.H. (1939) Opisthobranchiate Mollusca from the western and northern coasts of Norway. Kongelige Norske Videnskabers Selskabs Skrifter, 1939, 1–92.

Ohnheiser, L. T., & Malaquias, M. A. E. (2014). The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species Colobocephalus costellatus M. Sars, 1870. Zootaxa, 3774(6), 501-522.

Oskars, T. R., Bouchet, P., & Malaquias, M. A. E. (2015). A new phylogeny of the Cephalaspidea (Gastropoda: Heterobranchia) based on expanded taxon sampling and gene markers. Molecular phylogenetics and evolution, 89, 130-150.

Sars, M. (1870) Bidrag til Kundskab om Christianiafjordens fauna. II. Nyt Magazin for Naturvidenkaberne, 172–225.

-Trond

Door #3: Prepare to be HYPNOtized

One of this year’s new projects at the Invertebrate collections is HYPNO – Hydrozoan pelagic diversity in Norway, funded by the Norwegian Taxonomy Initiative.

A selection of photos depicting some of the species encountered so far in the project

A selection of photos depicting some of the species encountered so far in the project

Hydrozoa are a class of cnidarians, the pelagic representatives of which include hydromedusae as well as colonial siphonophores and porpitids. They are thus “cousins” to the more familiar larger scyphozoan jellyfish such as the moon jelly or the lion’s mane jelly. The size of pelagic hydrozoans ranges from small medusae of less than 1 mm to siphonophore colonies reaching several meters in length. They are mostly predators that use their tentacles and stinging cells to catch other zooplankton or even fish larvae. Most of the time they go largely unnoticed by the public, but at times they can form blooms and deplete zooplankton as well as cause problems for aquaculture and fisheries or sting bathers.

The aim of HYPNO is to chart, document and DNA-barcode the diversity of hydromedusae and siphonophores occurring in Norway. Gelatinous zooplankton, including hydrozoans, has been generally less studied than their crustacean counterparts, and we know less about their diversity. This is due to several challenges in studying them. First of all, many pelagic hydrozoans, particularly the colonial siphonophores, are very fragile and often damaged during sampling with standard plankton nets. This can make it difficult to identify them. Secondly, preserving hydromedusae and siphonophores for later work is problematic. For morphological studies, they are best preserved in formalin, since most other fixatives used for zooplankton -including ethanol- cause distortion and shrinkage of their gelatinous bodies, rendering the animals impossible to identify. Formalin fixation, however, hinders further genetic work.

To overcome these practical problems, HYPNO uses gentle collection methods to obtain specimens in good condition. Collected samples are immediately examined for hydrozoans, and the live animals are identified and documented with photos before they are fixed in ethanol for DNA barcoding of CO1 and 16S sequences.

So far, HYPNO has participated on two cruises by the Institute of Marine Research: to the North Sea and Skagerrak on RV Johan Hjort 24 Apr – 4 May 2015 and to the Arctic Ocean and Fram Strait on RV Helmer Hanssen 17 Aug – 7 Sep 2015. So far, 34 species have been photographed and sampled for DNA. Here is a selection of pictures depicting some of the species encountered during these surveys.

You can read more about HYPNO at http://data.artsdatabanken.no/Pages/168312.

-Aino

Bubble snails in “Species online”

The Norwegian Taxonomy Initiative has an ongoing effort to present species in a scientific but user friendly context in their concept “Species online”. Yesterday the first marine group of animals was released, the Cephalaspidean gastropods. These pretty creatures are also known as “bubble snails”. This is the work of the malacologists at the University Museum of Bergen, go and have a look! 

arter på nett_boble