The artsprosjekt: Diversity mapping of Norwegian gyrodactylid flatworms - mining natural history collections

DSC02431-c.jpgNew parasites from old fish

The biodiversity of invertebrate parasites is an important factor in ecosystem health. This project targets the Norwegian gyrodactylid fauna. This group of ectoparasites of fish and cephalopod molluscs includes the major pathogen Gyrodactylus salaris on salmon and the emerging pathogen Gyrodactylus marinus on cod. Overall the genus Gyrodactylus is poorly known and many species and parasite strains await proper description. This is particularly true for the gyrodactylids on Norwegian marine fishes, where perhaps up to 50 species remain to be catalogued, and several species new to science are to be expected. This project adopts a novel approach, screening the fish collection of the Natural History Museum Oslo that has a comprehensive representation of the Norwegian fish fauna for gyrodactylids. These parasites will then be described using advanced morphometric and molecular approaches. We aim at developing towards a comprehensive picture of the Norwegian gyrodactylid fauna of both freshwater and marine fishes, and expect to add morphometric and molecular descriptions of some 30-50 species (including some new to science) to the Norwegian fauna lists.

 

 

The project was funded for 2011-2012 by the artsprosjektet managed by ARTSDATABANKEN
(The Norwegian Biodiversity Information Centre).

 

 

 

 


Active researchers on the project were:

Lutz Bachmann (PI)
Eve Zeyl (technician)

 

May 2011: Paula Marcotegui from University of La Plata, Argentina, received an Yggdrasil fellowship (International Mobility Stipend) from the Research Council of Norway.

Paulal joined the project from 1. August 2011 - 31. January 2012. She focused on the foreign fish in the NHM fish collection and checked them for gyrodactylids.

 

 

 

The project delivered the following results:

Summary:
Natural history collections are not only useful for documentation of biodiversity but provide a treasure for new discoveries. The Norwegian fish fauna is well documented in the scientific collection of the Natural History Museum, University of Oslo. Collection material was screened for monogenean ectoparasitic flatworms of the genus Gyrodactylus that were (unintendedly) collected along with the fish. The recovered flatworm specimen were identified by means of morphological analyses of the hard parts of the opisthaptor, i.e. the structures used for attaching to the skin of the host. In the course of the project 13 flatworm species were identified that are new to science, and an additional seven parasite species were recorded as new to Norway. Three Gyrodactylus species were also recorded from new fish hosts, and in particular Gyrodactylus pterygialis appeared to have a broad range of host species.​

 

 

The project targeted 4 major objectives:

1. To comprehensively screen the Norwegian fish holdings of the scientic collections of the Natural History Museum Oslo for gyrodactylid monogeneans

The scientific fish collection at the Natural History Museum Oslo comprehensively documents the Norwegian fish fauna. However, the representation of the species and the quality of the samples varies largely, both in age, geographic coverage and number of specimens. A major issue for the project turned out in the level of preservation of the fish, which is also largely dependent on the samples age and the way of preservation. The project aimed at identifying the ectoparasitic Gyrodactylus parasites. These flatworms are first of all expected to occur on the skin, preferentially on the fins, and the gills of the fish. Quite a number of fish specimens - in particular of the larger species - were obviously  "cleaned" by the collectors/curators in order to look nicer; this means that the mucus had been removed and the skin appeared "polished". On such specimens no gyrodactylids could be detected on the skin, and only the gills could be inspected. For many samples the accumulated "debris" on the bottom of the sample vials were inspected as well, and a number of parasites could be identified that obviously fell of the skin.
In the course of the project more than 300 samples from the fish collection covering 33 fish families were analyzed. The selection of the samples was slightly biased as salmonid fish were not considered in detail; the gyrodactylids on salmonids in Norway have attracted significant attention due to the severe ecological and economic damage caused by Gyrodactylus salaris on Atlantic salmon and Rainbow trout. Most salmonid species have therefore been studied for the presence of Gyrodactylus in numerous earlier projects.

2. To undertake morphometric analysis of collection material and DNA barcoding using methodologies appropriate to degraded DNA

Many Gyrodactylus specimens of species new to science were subjected to morphometric measurements. Morphological species description relies first of all on the hard parts of the opisthaptor, a structure that is used by the parasite to attach to the skin of the host. These measurements will be the basis for the pending species descriptions. In the course of the project it turned out that the screening of the fish from the collection were very time demanding. Molecular attempts for barcoding of the specimens were therefore postponed as such approaches are on their own very time consuming.

3. To provide state-of-the-art descriptions of newly discovered species and parasite strains

In the course of the project 13 Gyrodactylus species new to science were detected. The proper state-of-the-art description of these species is underway.

4. To establish a comprehensive overview on the biodiversity of the Norwegian gyrodactylid fauna including collection based and fieldwork validated range estimates

Given the biases listed above, the species list delivered by the project cannot be considered a complete list of Gyrodactylus species for Norway. Such list will be compiled at a later stage. Nevertheless, the project revealed a much greater biodiversity of Gyrodactylus species in Norway than previously known. This may to some extent meet the expectation as the biodiversity of Gyrodactylus is considered heavily underestimated on a global scale. Usually, scientist focus on these parasites once severe problems are reported. This usually refers only to parasites on fish species that are important for fishery and/or aquaculture. Most other species descriptions appear occasional rather than from systematic surveys. In this respect, the project was innovative as it attempted to investigate the occurrence of Gyrodactylus parasites on a very broad spectrum of potential hosts.

 

Methodology:

Taxa: The project focused on the Norwegian Gyrodactylus fauna. Gyrodactylus species are monogenean ectoparasite infecting mainly bony fish. In order to screen for the Norwegian Gyrodactylus biodiversity the scientific fish collection of the Natural History Museum, University of Oslo was used. Here, the Norwegian fish fauna is comprehensively represented by hundreds of specimens that were collected over the years. Gyrodactylus salaris was introduced into Norway in the 1970ies and has since caused severe damage in many Norwegian Atlantic salmon stocks. This as attracted great attention, and the gyrodactylid fauna of salmonid host fish has been addressed in many earlier studies. The current project, therefore, focussed mainly on on fish species belonging to other fish families than Salmonidae.

Geographic focus: The current project focussed mainly on fish species occurring in Norwegian waters. Particular geografic focus depended on where fish had been collected earlier and deposited in the fish collection of the Natural History Museum Oslo.

Sample collection: The current project made use of the fish samples earlier collected and registered into the Fish Collection at the Natural History Museum, University of Oslo, Norway. The samples are all stored in ethanol. However, many samples were stored earlier in other fixatives such as formalin but this was not always recorded in the collection journals. To some extent various marine fish species were also collected with nets in the Oslofjord area in order to provide reference material for molecular analyses

Species identification: The samples of the fish collection at the Natural History Museum, University of Oslo, were already determined earlier to species level by taxonomic experts. The respective information about the samples could be obtained from the collection's journals and an electronic database available at NHM. To some minor extent species names needed to be revised according to the latest literature. The species determination of the detected Gyrodactylus specimens relied on a variety of reference material. Most important was a morphological approach, i.e. microscopic inspection of the opisthaptor, i.e. the hard parts that the parasite uses for attaching to the host. Of particular importance is the GyroDb (http://www.gyrodb.net/) database that compiles taxonomic information on gyrodactylids. Original literature and illustrations and references therein were also used. A particular challenge is seen in the often very short and superficial original descriptions that are frequently only poorly illustrated. This resulted to some extent in a host-based classification system in the literature, an approach that was avoided in the current study.

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Here is a table that summarizes the detected Gyrodactylus species

Species Host species Fish family
New to science
New to Europe
New to Norway
Comments
G. alexanderi Gasterosteus aculeatus Gasterosteidae        
G. arcuatus Gasterosteus aculeatus Gasterosteidae        
G. branchicus/rarus Gasterosteus aculeatus Gasterosteidae        
G. sp. 1 Pungitus pungitus Gasterosteidae
uncertain
uncertain
uncertain
 
G. arcuatus Pungitus pungitus Gasterosteidae        
G. branchicus/rarus Pungitus pungitus Gasterosteidae        
G. sp. 2 Spinachia spinachia Gasterosteidae
yes
yes
yes
 
G. arcuatus Spinachia spinachia Gasterosteidae        
G. branchicus/rarus Spinachia spinachia Gasterosteidae        
G. sp. 3 Artediellus atlanticus Cottidae
yes
yes
yes
 
G. sp. 13 Taurulus bubalis Cottidae
yes
yes
yes
resembles G. groenlandicus
G. groenlandicus Myoxocephalus scorpius Cottidae        
G. sp. 4 Triglops nybelini Cottidae
yes
yes
yes
 
G. pterygialis Ciliata mustela Lotidae       new host;
perhaps two species on this host
G. sp. 5 Ciliata septentrionalis Lotidae
yes
yes
yes
 
G. cyclopteri Cyclopterus lumpus Cyclopteridae    
yes
 
G. sp. 6 Limanda limanda Pleuronectidae
yes
yes
yes
resembles G. groenlandicus
G. flesi Pleuronectes platessa Pleuronectidae    
yes
 
G. pterygialis Pleuronectes platessa Pleuronectidae    
new host
G. flesi Platichthys flesus Pleuronectidae    
yes
 
G. errabundus Zoarces vivipares Zoarcidae        
G. sp. 7 Phrynorhombus norvegicus Scophthalmida
yes
yes
yes
resembles G. pterygialis
G. sp. 8 Phrynorhombus norvegicus Scophthalmida
yes
yes
yes
resembles G. flesi
G. ostendicus Pomatoschistus microps Gobidae    
yes
 
G. sp. 9 Gobiusculus flavescens Gobidae
yes
yes
yes
 
G. sp.10 Gobiusculus flavescens Gobidae
yes
yes
yes
resembles G. groenlandicus
G. sp. 11 Callionymus lyra Callionymidae
yes
yes
yes
resembles G. pterygialis
G. pterygialis Pollachius pollachius Gadidae       new host
G. pterygialis Pollachius virens Gadidae        
G. alviga Merlangius merlangius Gadidae    
yes
 
G. pterygialis Trisopterus minutus Gadidae       new host
G. callariatis Gadus gadus Gadidae        
G. sp. 12 Pholis gunnellus Pholidae
yes
yes
yes
resembles G. pterygialis
G. harengi Sprattus sprattus Clupeidae    
yes
 
G. harengi Clupea harengus Clupeidae    
yes
 
G. anarhichatis Anarhichas lupus Anarhichidae        
G. osmeri Osmerus eperlanus Osmeridae    
yes
 
G. petruschewskii Mallotus villosus Osmeridae    
yes
 
G. harengi Mallotus villosus Osmeridae    
yes
new host
G. ammodyti Ammodytes tobianus Ammodytidae    
yes
 
G. alviga Ammodytes tobianus Ammodytidae    
yes
new host

 

 

Sticklebacks (Gasterosteidae):

Three-spined stickleback (Gasterosteus aculeatus):
Several Gyrodactylus species have been recorded earlier from the G. aculeatus. A survey* of reports and papers revieled that so far G. arcuatus and G. branchicus were reported from the three-spined stickleback from Norway.

Several fish specimens collected 1977 in the Oslofjord area were screened, and as expected many gyrodactylids were found. They were mounted for microscopic inspection. The majority of parasites was identified as Gyrodactylus arcuatus. There may be also some other Gyrodactylus species as well, but proper identification of the mounted parasites is pending.

On one three-spined stickleback sample from Surnadal, near Trondheim, G. alexanderi was detected. It has been suggested to be present in Western Norway, but without precise locality data. This species is an important addition to the Norwegian fauna because it is a Pacific species, found mainly on the West Coast of North America and in Japan and the Pacific coast of Siberia. In Europe, there is an unconfirmed record from Germany near Berlin (Glaser, 1987) and a number of authenticated records from the UK (Harris, 2008), where the species is thought to be a glacial relict. The working hypothesis is that this species was brought to the Atlantic basin with the initial expansion of the sticklebacks from the Pacific over 100 000 years ago (Orti et al. 1994). Recolonisation of rivers from the sea by sticklebacks after glaciation has principally led to colonisation by G. arcuatus and G. branchicus. How then did G. alexanderi persist in Norway and the UK during the last ice age? 


G. alexanderi
 from G. aculeatus (IHL 42/90, fish collection NHM Oslo) collected 13.09.1990 at Surnadal, near Trondheim. 
Photo: Eve Zeyl

 

Ninespine stickleback (Pungitius pungitius):

Sea stickleback (Spinachia spinachia):

 

Lumpfishes (Cyclopteridae):

Lumpfish (Cyclopterus lumpus):
For the lumpfish (Cyclopterus lumpus) the GyroDb database lists only one Gyrodactylus species, G. cyclopteri. To our knowledge the species has not been reported from Norwegian lumpsuckers yet.

We have checked four fish collected in 1903, 1912, and 1983, respectively, and found G. cyclopteri on three of them. The parasite occurs on fish from the Oslofjord as well as from Troms (Northern Norway).


G. cyclopteri
from C. lumpus (J4258, fish collection NHM Oslo) collected 03.04.1903 at Onsø, Oslofjord.
Photo: Eve Zeyl

 

Righteye flounders (Pleuronectidae):

American plaice (Hippoglossoides platessoides):
Three fish have so far been screened for Gyrodactylus, two from the Oslofjord and one from the Barent Sea. No gyrodactylids were detected.

 

 

 

Presentation of the project:

The artsprosjekt was presented as an invited contribution to the workshop "Species discovery amongst parasitic groups" held on 20. June 2011 under The IVth Conference of the Scandinavian-Baltic Society for Parasitology, Oslo, Norway.
Flyer for the workshop (pdf)

It was also mentioned in further conference papers:

Hahn C., Zeyl E., Bakke T.A., Harris P.D. & Bachmann L. Museomics for ectoparasites recovered from historical fish collections – lessons from Gyrodactylus. 8th Biennial Conference of the Systematics Association, Queen`s University Belfast, July 4th-8th 2011.
Hahn C., Zeyl E., Bakke T.A., Harris P.D. & Bachmann L. Museomics of ectoparasites – chasing the origin of Gyrodactylus salaris. 4th Conference of the Scandinavian-Baltic Society for Parasitology, Oslo, June 19th-22nd 2011.
Hahn C., Bakke T.A., Harris P.D., Weiss S. & Bachmann L. The Gyrodactylus fauna of the 19th century – Museomics for ectoparasites recovered from historical fish collections. ForBio Annual meeting, Bergen, 1st-2nd February 2011.
Hahn C., Zeyl E., Bakke T.A., Harris P.D., Bachmann L. Museomics for ectoparasites recovered from historical fish collections - lessons from Gyrodactylus. EMOP XI, European Multicolloquium of Parasitology, Cluj-Napoca, Romania, July 25th – 29th 2012.

 

A popular science article entitled "Nye parasitter fra gamle fisk" by Zeyl et al was published in Naturen 136, 274-280 (2012).
Abstract:
De store samlingene av preserverte dyr og skjeletter er de naturhistoriske museenes fundament. Driften av disse samlingene medfører imidlertid høye kostnader, og spørsmålet blir da: Er de naturhistoriske samlingene berettiget i dagens verden? Våre undersøkelser viser at fiskesamlingen ved Naturhistorisk museum, UiO, er et skattekammer for å øke vår kunnskap om artsmangfoldet av fiskeparasitter, i dette tilfelle haptormarker i slekten Gyrodactylus. Til sammen 3 til 4 Gyrodactylus arter på norske fiskearter har vi så langt i bare flyndrefamilien; der i hvert fall 2 av artene aldri før er påvist fra norske farvann. I tillegg påviste vi Gyrodactylus på 3 av de 29 utenlandske flyndrefisk-artene vi undersøkte i samlingen.
Full text



*The survey for Norwegian gyrodactylids included information extracted from the following reports and papers:

Appleby, C. & Sterud, E. 1996. Parasites of white bream (Blicca bjoerkna), burbot (Lota lota) and ruffe (Gymnocephalus cernua) from the River Glomma, South-Eastern Norway. Bulletin of the Scandinavian Society for Parasitology 6: 18-24.
Malmberg, G. 1970. The excretory system and marginal hooks as a basis for the systematics of Gyrodactylus (Trematoda, Monogenea). Archiv für Zoologie, 23: 1–237.
Malmberg, G. 1993. Gyrodactylidae and gyrodactylosis of Salmonidae. Bulletin Francais de Peche et de la Pisciculture. Boves 328: 5-46.
Sterud, E. & Appleby, C. 1996. Parasites of common asp (Aspius aspius), bream (Abramis brama) and zander (Stizostedion lucioperca) from the river Nitelva.' Bulletin of the Scandinavian Society for Parasitology 6: 134-138.
Sterud, E. 1999. Parasitter hos norske ferskvannsfisk. Norsk Zoologist Forening. Rapport. Oslo. 7: 22 pp.
Thoen, E., Haugland, O., Sterud, E. 1998. Parasites of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) from the River Akerselva, Oslo, Norway. Bulletin of the Scandinavian Society for Parasitology 8: 92-96.