IMIS - Marine Onderzoeksgroepen

This website presents the information gathered by Hans De Blauwe about medusa and invasive species from the harbour of Zeebrugge (Belgium). A comprehensive photogallery illustrates the species involved as well as some remarkable observations. Furthermore, this website should inform you about Bryozoans from the southern coasts of the North Sea.

Medusae. During five years (1999-2003), medusae and their sessile stage were investigated in the environment of Zeebrugge. Two species of Ctenophora, 4 species of Scyphozoa and 17 species of hydromedusae were collected. The hydroid has been reared from the medusae in 7 species: Nemopsis bachei, Eucheilota maculata, Eutonina indicans, Sarsia tubulosa, Rathkea octopunctata, Aequorea vitrina and Margelopsis haeckeli. The Ctenostome Mnemiopsis leidyi was found in Zeebrugge (and Belgium) since 2007.

Invasive species. Since a first visit to the pontoons of the marina in the Zeebrugge outer harbour area on 7 July 1999, Hans De Blauwe started to study the marine fauna and flora of this locality, together with Emmanuel Dumoulin and Marco Faasse. A survey was made of the organisms (for the algae only partly) living as fouling-species on the pontoons, or the occurrence in the surrounding water column, in the latter case often between growth of algae. Numerous visits and sampling during the past ten years resulted in a comprehensive list of mainly macro-species. We found 101 species of marine invertebrates of which 18 species are exotic.

Bryozoa. All information gathered by Hans De Blauwe about Bryozoa of the southern Bight of the North sea is brought together in a book in Dutch. This website offers information and updates from the book in English. The book was meant to replace the identification key of Lacourt. It has become a virtually complete inventory of a group of animals that have been the object of very few studies so far. As many as 179 species are discussed, all of which were found on beaches, in ports and in marine habitats between Cap Gris Nez (Northern France) and the Dutch-German border. The sandy substrate that is predominant in this area is usually poor in moss animal species.

This book is the result of an in-depth study of recent observation and of the review of historical collections:

• tide mark material: 75 species on objects washed ashore, of which 46 have not been found anywhere else in the area
• on breakwaters and port structures: 20 species
• on shells and stones near sandbanks : 80 species
• in the past 15 years: 7 exotic species have settled

For convenience's sake a double page has been created for each species: a tekst on the left-hand side and a set of unique photographs, made especially for this book, on the right-hand side. The photographs include a caption (in English) indicating the abundance of the species among objects washed ashore (B), on hard substrate (S) or as found in historical collections. Thanks to the different determination keys in the book and a 20-30x magnifying glass it is possible to recognise most of the moss animals in the study area.