Sinelobus vanhaareni -

The area of origin is unknown.

First observation in Belgium

In Belgium, S. vanhaareni was observed for the first time on the 19^th of July 2007, in the Verrebroek Dock in the Port of Antwerp. S. vanhaareni was present on an artificial substrate used for glass eel monitoring. This substrate was dominated by other non-indigenous species such as the Tiger scud Gammarus tigrinus, the estuarine mud crab Rhithropanopeus harrisii and the New Zealand mud snail Potamopyrgus antipodarum ^[2].

Spreading in Belgium

In 2007 – a couple of months after the first observation of Sinelobus vanhaareni in the Port of Antwerp – large numbers of this species (up to 4,200 individuals per sample) were found in the Ghent-Terneuzen Canal, near Terneuzen. In the following year, the observation from the Sea Scheldt was confirmed by new sightings and it appeared that S. vanhaareni also occurred more inland, up to the inflow location of the Albert Canal ^[2].

Despite the limited numbers in the Sea Scheldt (Belgium) – always less than 10 individuals per sample – the species is expected to establish itself here and in adjacent channels (both brackish and fresh water) on artificial substrates such as buoys and dock walls ^[2].

Spreading in neighbouring countries

The first European report of S. vanhaareni dates back to the 14^th of September 2006, when it was found in the Old Meuse, near Hoogvliet (Rotterdam, the Netherlands). A couple of days later – due to observations in the ‘Nieuwe Waterweg’ (English translation: ‘New Waterway’) and the Dutch Ijssel – it turned out that the species already occurred in the waterways close to the Port of Rotterdam.

That year, the species was also found more to the north, near the mouth of the North Sea Canal, that connects Amsterdam with the North Sea ^[2].

In 2009 and 2010, S. vanhaareni was found even further to the north, namely in the Wadden Sea near Harlingen (north of the Netherlands), in the ports of Emden (German-Dutch border) and in Brunsbüttel (near the German Elbe) ^[3].

The AquaNIS database indicates that the species was already identified in Estonia in 2010 and reached Finland in 2016 ^[4]. The species has been present in Poland since 2014 ^[5].

Presumably, it spread initially by attaching itself with its tube to the hulls of ships or solid ballast material ^[2]. Later, S. vanhaareni might have further dispersed together with the transport of molluscs for aquaculture purposes and with cargo ships’ ballast water ^[6]. The latter may have led to the relatively recent introduction to port areas along the North Sea ^[2].

Solid substrates are essential for this species because they need this type of substrate for the attachment of their self-made silt tubes. S. vanhaareni benefits from the increasing number of artificial hard substrates in the Scheldt estuary, where naturally mostly soft sediments occur ^[7]. To build the tubes in which they live, they need a certain quantity of silt in the water ^[2]. There is no shortage of silt in the Scheldt estuary.

In contrast to most other tanaids, S. vanhaareni also occurs in fresh water but is mainly found in brackish water and estuaries ^[2]. The species can tolerate the strong fluctuations in salinity that characterise estuaries. In the northwest of Europe, the species can be found in waters with different salt concentrations: from slightly fresh water (1.5 PSU, e.g. in the Scheldt estuary) to nearly salt water (20 PSU, e.g. in the Wadden Sea). To compare, the water of the North Sea has a salinity of about 35 PSU.

The water temperature in which S. vanhaareni occurs in our regions varies between 13-21°C ^[2].

S. vanhaareni is found on shells, barnacles, plants, rocks, artificial constructions, in between stones, in the water column and even in the canal system of sponges ^[8]. Although hard substrates house the largest numbers of this species, they are also found to a lesser extent on softer silt, clay or sandy soils ^[8].

In Belgium and the Netherlands, some native species – like the amphipods Apocorophium lacustre and Corophium multisetosum – also form silt tubes just like S. vanhaareni and feed on similar food. It is expected that these species will compete for space and food, but this hasn’t been demonstrated ^[2]. Other potential effects of this alien species on its environment are unknown ^[3].

Adults of S. vanhaareni can grow 4-7 mm in size ^[2]. Like other tanaids, S. vanhaareni has a cephalothorax with a shell (carapace), a pair of pincers (chelipeds), eyes and two pairs of antennae. It has an abdomen consisting of six segments with little pereopods and a tail ^[9]. In tube-living species, the legs on the abdomen are not used for swimming but rather to create a flow of oxygen-rich water into the tube. Flattened plates on the legs of females form a breeding pouch (marsupium), in which the eggs and later the larvae develop into almost full-grown individuals ^{[10, 11]}.

In contrast to other tanaids, Sinelobus species have a clear difference in morphology between the male and female individuals. In male individuals, the cephalothorax is noticeably slimmer, and the pincers are larger than those of females ^{[2, 10]}.

S. vanhaareni mainly occurs in shallow water, but many related tanaid species can occur up to 200-9,000 metres deep. In some of these deep-water habitats, tanaids are among the most numerous and diverse fauna ^[12].

[1]          World Register of Marine Species (WoRMS) (2020). Sinelobus vanhaareni Bamber, 2014. [http://www.marinespecies.org/aphia.php?p=taxdetails&id=798772] (2020-11-17).

[2]          Van Haaren, T.; Soors, J. (2009). Sinelobus stanfordi (Richardson, 1901): A new crustacean invader in Europe. Aquat. Invasions 4(4): 703-711. [http://www.vliz.be/imis/imis.php?module=ref&refid=203907]

[3]          Gittenberger, A.; Rensing, M.; Stegenga, H.; Hoeksema, B. (2010). Native and non-native species of hard substrata in the Dutch Wadden Sea. Ned. Faunist. Meded. 33: 21-76. [http://www.vliz.be/en/imis?module=ref&refid=206549]

[4]          AquaNIS - Information system on aquatic non-indiginous and cryptogenic species (2019). Public domain: Introduction events' accounts [http://www.corpi.ku.lt/databases/index.php/aquanis/introductions/open/fl/S] (2019-07-09).

[5]          Brzana, R.; Marszewska, L.; Normant-Saremba, M.; Błażewicz, M. (2019). Non-indigenous tanaid Sinelobus vanhaareni Bamber, 2014 in the Polish coastal waters – an example of a successful invader. Oceanological and Hydrobiological Studies 48(1): 76-84. [http://www.vliz.be/en/imis?module=ref&refid=311036]

[6]          Sytsma, M.D.; Cordell, J.R.; Chapman, J.W.; Drabeim, R. (2004). Lower Columbia River aquatic nonindigenous species survey 2001-2004: final technical report. Portland State University: Portland. 69 pp. [http://www.vliz.be/imis/imis.php?module=ref&refid=206971]

[7]          Soors, J.; Faasse, M.; Stevens, M.; Verbessem, I.; De Regge, N.; Van den Bergh, E. (2010). New crustacean invaders in the Schelde estuary (Belgium). Belg. J. Zool. 140(1): 3-10. [http://www.vliz.be/en/imis?module=ref&refid=145536]

[8]          Gardiner, L.F. (1975). A fresh- and brackish-water Tanaidacean, Tanais stanfordi Richardson, 1901, from a hypersaline lake in the Galapagos Archipelago, with a report on West Indian specimens. Crustaceana 29(2): 127-140. [http://www.vliz.be/imis/imis.php?module=ref&refid=206825]

[9]          Heard, R.W.; Hansknecht, T.; Larsen, K. (2003). An illustrated identification guide to Florida Tanaidacea (Crustacea; Pericarida) occuring in depths of less than 200 m. Annual Report for DEP Contract Number WM828. State of Florida - Department of Environmental Protection: Tallahassee. 163 pp. [http://www.vliz.be/imis/imis.php?module=ref&refid=206969]

[10]        Hayward, P.J.; Ryland, J.S. (2017). Handbook of the marine fauna of North-West Europe. Second Edition. Oxford University Press: Oxford. ISBN 978-0-19-954944-3. xiii, 785 pp. [http://www.vliz.be/nl/catalogus?module=ref&refid=284804]

[11]        Sieg, J. (1988). Tanaidacea, in: Higgins, R.P. et al. Introduction to the study of meiofauna. Smithsonian Institution Press: Washington D.C.: pp. 402-408. [http://www.vliz.be/en/imis?refid=34491]

[12]        Drumm, D.; Heard, R. (2018). Tanaidacea Home Page. [http://gcrl.usm.edu/tanaids/] (2018-09-07).

VLIZ Alien Species Consortium (2020). Sinelobus vanhaareni. Non-indigenous species in the Belgian part of the North Sea and adjacent estuaries anno 2020. Flanders Marine Institute (VLIZ). 5 pp.