The importance of fouling in the harbour of Ostend in 1964 GUIDO PERSOONE Biogeografisch Instituut en Laboratorium voor Oekologie, Rijksuniversiteit Gent, Belgium EXTRAIT: L'importance de la salissure dans le port d'Ostende en 1964. D6but juin 1964, plusieurs cadres dot6s de lames de nature diff6rente furent immerg6s dans ie port d'Ostende dans le but de d&ecter des diff6rences 6ventuelles dans la colonisation des substrats. Deux mois plus tard, l'exp6rience dut d65k &re interrompue, les cadres &ant enti~rement recouverts de boue. Ceci rendait toute analyse d'une lame ~ l'autre impossible. Nous avons trouv6 que cet 6norme envahissernent &ait dfi fi l'accumulation progressive d'un polych&e tubuleux: Poly- dora ciliata (JoHNsToN). La liste des organismes pr6sents dans la boue a 6t6 dress&. Fig. 1: Frame with slides at the moment of immersion (June 1, 1964) On June 1, 1964, during our investigations on fouling, we submerged severaI frames with slides (Fig. 1) in the harbour of Ostend, Belgium (Fig. 2), from the termi- nus of the car-ferry Ostend-Dover. These devices, which were suspended by nylon cord from a ratt 1, were submerged to a depth of about 1.5 m. As test substrata we chose slides of glass, wood, iron, and iron coated with an anti- fouling paint. The dimensions of the slides were those of usual glass microscope slides We are indebted to the Administration of the Marine and Interior Navigation who very kindly put the ra~ at our service. Fouling in the harbour of Ostend 445 (7.5 X 2.5 X 0.1 cm). The various materials used would allow the detection of differen- ces in the nature, speed and amount of colonization of substrata of different natures. Aflcer one month, on July 1, 1964, the first frame was taken out and the slides examined normally. North ,_Sea N Bredene f Raft Bass~ de chasse Eede Canal Ostend- Bruge5 Fig. 2: Harbour area of Ostend (Flanders, Belgium), showing the location of the raft from which frames with slides were suspended and submerged into the harbour water When we took out the second frame, on August 1, 1964, we found, greatly to our surprises, that it was entirely covered with a black layer of mud of several centimeters in thickness, which had filled not only the spaces between adjacent slides but also the gap of about 10 cm between slides and the supporting frame plates (Fig. 3). At the moment of immersion the frame and counterpoise weighed about 8 kg, but when we took it out, it weighed more than 30 kg. Although a comparative qualitative and quantitative analysis of single slides was impossible, we nevertheless examined the mud covering the whole frame. In so doing, we found that the main overgrowth was due to the progressive accumulation of the tubes of a sedentary polychaete Polydora ciliata (JoRNsToN 1938). Between these tubes, which were composed of sand, mud particles, diatoms and planktonic detritus, we found a large number of sessile and free- living organisms belonging to several very different groups and constituting innumer- able micro-biocoenoses in the smallest interstices. Below is the list of the organisms which we were able to identify. 446 G. PERSOONE Fig. 3: The same frame as shown in Figure 1 with counterpoise, two months later (August 1, 1964) Protophyta. Schizophyceae: Microcystis sp., Oscillatoria sp. Schizomy- c etes (filamentous forms only): Beggiatoa alba (VAUCHER), Beggiatoa arachnoidea (AGARDH), Beggiatoa Ieptomitiformis TREVISAN, Gallionella [erruginea EHRENBERG, Leucothrix rnucor OERSTED, Microscilla marina PRINCSHEIM, Sphaerotilus natans KUT- ZINC, Thiothrix marina MOLISCH, VitreoscilIa sp., sp. div. Thallophyta. C h 1o r o p h y c e a e : Ankistrodesmus falcatus (CoI~DA) RALFS, En- teromorpha intestinalis LINK vat. compressa, Pediastrum duplex MEYEN, Scenedesmus acurninatus (LAGERHelM) CHODAT, Scenedesmus opoliensis RICHTEI~, Scenedesmus qua- drlcauda (TuRwN) DE BREBISSON. Bacillariophyceae: Achnanthes brevipes AGARDI~, Achnanthes Hauckiana GRUNOW, Actinocyclus Ehrenbergi RALFS, Actino- cyclus Ehrenbergi RALFS vat. Ralfsii, Actinoptychus splendens (SHAI)~3OLT) RALVS, Actinoptychus undulatus (BAILEY) RALFS, Amphora sp., Anomoeoneis sculpta (EHr.EN- BERG) CLEVE,Asterionella )aponica CLEVE, Aulacodiscus argus (EHRENBERG)SCHMIDT, A., Biddulphia aurita (LYNGBYE) BREBISSON-GODEY, Biddulphia granulata RowR, Biddulphia regia (ScHuLTZE) OSTENFELB,Biddulphia rhombus (EHRENB~RG) SCHMITH, W., Biddulphia sinensis GREWLLE, Campylosira cymbelliformis (ScHMII)T, A.) GRu- NOW, Cerataulus Smithii RA~Fs, Cocconeis ctandestina SCHMIDT, A., Cocconeis scutel- lure EHRENS~r.G, Coscinodiseus cinctus KUTZlNG, Coscinodiscus excentricus EHREN- BERG, Coscinodiscus Iineatus EHr.ENBERG, Coscinodiscus nitidus GREGORY, Coscino- discus oculis iridis EHRENBEI~G, Coscinodiscus radiatus EHRENBERG, CyclotelIa striata (KuTZlNO) GRtSNOXV, Cymatopleura elliptica (BI~EmSSON) SMITH, W., Cymatosira bel- gica GRUNOW, Cymbella clstula H~MVR., Cymbella sp., Diatoma vulgare BoRY, Di- ploneis bombus EHR~NBERG, Diploneis Crabro Em~ENBERG, Diploneis didyma EH~EN- Fouling in the harbour of Ostend 447 BERG, DipIoneis Smithi (BREBISSON) CLEVE, Diploneis splendida (GREGORY) CLEVE, Gomphonema constrictum EHRENBERG, Grammatophora hamulifera KUTZIN~, Gram- matophora oceanica (EI~R~N~rRC) GRuNow, Grammatophora serpentina (RALrS) E~t- REN13rRG, Melosira arenaria MooR~, Melosira islandica MULLER, Melosira Juergensi AGARDH, Melosira sulcata (E~tRENBERO)KUTZING, Melosira westii S~azTH,W., Navicu[a AGARDI~, MeIosira sucata (EI-~RENBZRG)KUTZINC, Melosira westii SMm~, W., Navicula anglica RALrS, Navicula cuspidata KUTZINC, Navicula distans (SMIT~, W.) VAN H~URCX, Navicula forcipata GREVILLE,Navicula monilifera CLrw, Navicula pere- grina (EHRENBERO) KiJTZINC, Navicula rhynchocephala KUTZING, Navicula specta- bilis GREGORY, Navicula viridula KUTZIN~, Navicula sp., Nitzschia apiculata (GRE- GORY) GRUNOW, Nitzschia constricta (KrJTZHqG)RALrS, Nitzschia lanceolata SMITH,W., Nitzschia navicularis (BREBISSON)GRUNOW, Nitzschia punctata (SMIT~, W.) GRUNOW, Nitzschia sigma SMITH, W., Nitzschia sp., Plagiogramma leve (GREGORY) RALFS, Pla- giogramma Van Heurckii GRiJNOW, Pleurosigma angulatum (Qu~) SMITH,W., Pleuro- sigma naviculaceum I)E BREBISSON, Pleurosgima sp., Podosira stelliger (BAILEY)MANN, Raphoneis amphiceros EHRENB~RG, Raphoneis belgica GRUNOW, Raphoneis surirella (EHRrNBEI<G) GRUNOW, Rhizosolenia imbricata BP,IGHTW~LL var. shrubsolei, Rhizo- solenia setigera BRIGrrrwELL, Rhizosolenia styliformis BRIG~TWrLL, Sceletonema costa- turn (GREWLL~) CI~VE, Stauroneis parvula GRUNOW, Stauroneis phoenicenteron EH- REN~Re, Surirella ovata KUTZ~NG, Synedra tabulata (AaARDH) KUTZING, Synedra ulna (NITzSCH.) EIqREN~rRG, Tabellaria fenestra (LY~o~xr) KUTZING, Thalassionema nitzschioides GRUNOW, Thalassiosira decipiens (GauNo\v) JORO~NS~N, Triceratium al- ternans BAILEY, Triceratium favus Fc,HRENBERG. Protozoa. Rhizopoda: Amoeba sp., Pelomyxa sp., Thecamoeba sp., Sp. div. F 1a g e 11 a t a : Bodo sp., Distephanus speculum EHe,~N~ER¢, Monas sp., Pteridomona sp., Salpingoeca urceolata K~NT, Sp. div. Ciliata: Acineta tuberosa ErtRENt~e,O, Actinotricha saItans COt~N, Aspidisca fusca KAHL, Aspidisca polypoda (DuJARDIN), Aspidisca steini (v. BUI)D~N~ROCK),Aspidisca sp., Carchesium sp., Chilodonella heIgo- landica KAHL, Condylostomum rugosum KAHL, Cothurnia maritima E~REN~rl<O, Corynophrya lyngbyei (EHR~N~RO), Cyclidium sp., Dysteria ovalis (GouRRrT-RoE- SrR), Dysteria sp., Euplotes elegans KAI-IL forma littoralis, Euplotes graciIis KAi-IL, Eu- plotes mutabilis TUrVRAtr, Euplotes vannus MULLER var. balticus, Euplotes sp., FoIli- culina gigantea DoNs, Holosticha diademata (RErs), Holosticba milnei KaI~L, Holo- sticha sp., Keronopsis rubra (EHREN~RO), Keronopsis rubra (E~R~N~RO) var. tiara, Keronopsis sp., Lembus longivelatus KAHL, Litonotus sp., Placus socialis F~BR~-Do- MER¢Ur, Stichotricha marina S~E~N, StrobiIidium minimum (GRu~R), TracheIocerca phoenicopterus COliN, Trochilia salina ENTz, Trochilia sigmoides DUJARDIN, TrochiIia sulcata (CLAVARED~-LAcI~MANN),TrochiIioides recta KArtL, Uronema marinum DU- JARDIN, Vorticella marina GREZFV, Vorticella nebulifera MULLER, Vorticella perlata KARL, Vorticella sp., Zoothamnion commune KA~tL, Sp. div. Coelenterata. H y d ro z o a: Laomedea exigua SARS, Tubularia larynx ELLIS-So- LANDER, A 11 t h o z o a.. Immature forms. Bryozoa. Bowerbankia gracilis L~I)y, Farrella repens (FARR~), Merr~branipora pilosa L~NN~. Mollusca. L a m e 11 i b r a n c h i a : Mytilus edulis L~N~r. 448 G. P~RSOONE Vermes. Nem at o d a : Metaparoncholairnus campylocercus (DE MAN), Monhy- stera disjuncta BASTIAN, Monhystera parva (BASTIAN), Prochrornadorella germanica (BuTSCHLI), Theristus acer BASTIAN. P o i y c h a e t a : Fabricia sabelIa (EHI~ENB~RG), Nereis kerguelensis (MclNTosH), Polydora ciliata (JoHNsToN). R o t i f era: Colurella colurus (E~REN~ERG), Encentrum rnarinurn (DuJARDIN), Proales reinhardti (EHR~N- BERG. Crustacea. A m p h i p o d a : Corophium insidiosum CRAWFORD. C i r r i p e d i a : Balanus improvisus DARWIN', Elminius modestus DARWIN. Co pep o d a : Euterpina acuti]rons (DANA), Mesochra pygmaea (CLAus), Nitocra typica BoEc~:, Tisbe furcata (BAIRD). Dec a p o d a: Carcinus rnaenas (LINNE) (juvenile forms). The quantity and diversity of the species present sufficiently illustrate the com- plexity of the settling of organisms on submerged surfaces. Diatoms and ciliates were by far the most abundant of the groups present, at least as regards the number of spe- cies, consisting of up to 70 °/0 of the total number