CHAPTER 3 The Fouling Community The term "fouling" is commonly employed to gation buoys of the Elbe (4). Hentschel listed distinguish the assemblages of animals and plants about 50 species from ships docking at Hamburg which grow on artificial structures from those oc- (3). Seventy-seven kinds of animals and plants curring on rocks, stones, and other natural objects. are listed from ships examined in United States Frequently its use is limited to situations in which waters by Visscher (11). the results of the growth may be considered harm- In order to make available the information on fuL. The concept of fouling is thus based on the the composition of fouling, a comprehensive list practical considerations which have indeed given has been prepared of species recorded from the the subject its importance rather than on any valid principal types of structure affected. This list is biological distinctions. Fouling is, however, a bio- presented in Chapter 10. It includes records from logical phenomenon. If it is to be dealt with ef- structures on which fouling gives rise to problems fectively from an engineering point of view, it is of some technical interest, i.e., ships, buoys, water important that the biological principles which de- conduits and pipe systems, wrecks, telegraph termine its development be understood. cables, rafts, floats, pontoons, and test panels. The. animals and plants which take part in Records from wharf piles, piers, quays, jetties, fouling are primarily the attached, or sessile, bridge abutments, and similar structures have forms which occur naturally in the shallower water been omitted. along the coast. Each of these is adapted to live The following general conclusions are based on successfully under some restricted set of environ- the analysis of this list. mental conditions which limit the particular Nearly 2,000 species of animals and plants have places, both on a geographical and local scale, been reported from fouling. The number of species where it may be found. The development of an representing each of the major groups of organ- assemblage of fouling organisms on any structure isms, listed in Table 1, includes 615 kinds of immersed in the sea depends on the ability of cer- plants and 1,361 varieties of animals. The list in- tain members of the natural population locally cludes 13 of the 17 commonly accepted phyla of present to live successfully in the new situations animals and all the major groups of marine Thalo- created by man. From the biological point of view, phytes. The four missing phyla of animals are the fouling is thus an accident, and of very recent Ctenophora, Chaetognatha, Nematoda, and Phor- ongin. onidea. The two former are pelagic organisms not The development of permanent and massive likely to occur in fouling. The Nematoda are com- growths depends on the ability of sessile forms to mon free living members of fouling communities, adhere firmly enough to avoid being washed away. but have escaped record because they are diffcult Many free living animals are found among such to identify. The Phoronidea contain very few sessile organisms. They are an integral part of the species, but may be recorded ultimately since fouling ,community and cannot be separated from they are sessile forms, partial to crevices in rocks. it on any reasonable grounds. Separation on the Although the number of species reported from basis of freedom of movement or firmness of at- fouling is large and is widely distributed among the tachment is diffcult, since some sessile forms like existing groups of organisms, it actually includes the mussel are able to cast off their anchorage and a very small proportion of the known marine move from place to place, while some motile species. The proportional representation among forms such as the chiton can cling to smooth sur- the different groups is also very unequal. These faces with a tenacity which resists the most violent facts are brought out by Table 2 in which the water movements. total numbers of known marine species are com- The organisms occurring in fouling have been pared with the numbers reported from fouling. It recorded frequently. A few attempts have been is only among five groups that the species known made to prepare lists of the species but these to foul make up more than 2 or 3 per cent of the have been limited to those found on particular recognized species. These are the Barnacles, structures. Kirchenpauer compiled a list of 84 spe- Tunicates, Hydroids, Marine Plants, and Bryozoa cies, ,the majority of them plants, from the navi- -all groups which are predominantly sessile and 37 38 MARINE FOULING AND ITS PREVENTION which contribute heavily to fouling. Certain other tered in fouling. Those reported most frequently sessile groups, such as the sponges and corals, from all types of structures are listed in Table 3. are recorded relatively infrequently from fouling. The frequency with which various species were . found on the ships examined by Hentschel (3) TABLE 1. Number of Species of the Various Groups and Visscher (11) is recorded in Table 4. Whidi are Reported from Fouling Total Plants 614 There is litte doubt that some differences exist Total Animals 1,344 Total List 1,958 TABLE 2. Comparison of the Total Number of Marine Species Plants Totals Assigned to Various Groups and the Number of Each Group B~~ria. 37 Reported from Fouling. Estimated Totals for Animals from Fungi.......................................... 14 Pratt (8), for Plants from ZoBell (12) Algae..Diatoms ......................... 111 563 Total Marine Species %in Blue green 32 Group Species in Fouling Fouling Green 127 Goose barnacles 200 50 25.0 Brown 88 Acorn barnacles 300 60 20.0 Tunicates 700 116 16.6 R~ 2~ Hydroids 3,000 260 8.7 Animals Marine Plants 8,000 614 7.7 Protozoa. Bryozoa 3,000 139 4.6 Mastigophora 5 99 N udibranchs 1,000 32 3.2 Foraminifera 43 Polychaetes 3,500 99 2.8 N emerteans 500 11 2.2 Other Sarcodina 3 Amphipods 3,000 60 2.0 Ciliata 39 Pycnogonids 400 8 2.0 Suctoria 9 . Pelecypods 9,000 115 Porifera. 33 1.3 Coelenterata.. .. Anemones 1,000 12 1.2 Hydrozoa (Hydroids) 260 286 Sponges 3,000 33 1.1 Hydrocorallnae 1 Decapods 8,000 76 1.0 A1cgonaria 5 Isopods 3,000 24 0.8 Actinaria (Anemones) 12 Gastropods (other than 4,900 58 0.8 Madreporaria (True Corals) 8 Nudibranchs) Echinoderms 4,800 19 0.4 Platyhelminthes... 12 Corals 2,500 8 Nemertea.. ....................................... 11 0.3 Trochelminthes (Rotifers) . ~ 5 Bryozoa... 139 TABLE 3. Nineteen Forms Cited More Than 12 Times From Brachiopoda. 1 Annelida. 108 Fouling, in Order of Frequency of Citation. Archiannelids 1 (Data from Fouling List, Chapter 10) Polychaeta Errantia 44 Number OJ Polychaeta Sedentaria (Tubeworm:s) 55 Form Group Citations Oligochaeta 4 M ytilus edulis Pelecypod Molluscs 34 Hirudinea (Leeches) 4 Bugiila neritina Bryozoa 24 Arthropoda. 292 Copepoda 7 Balanus eburneus Acorn barnacles 23 Ostracoda 5 Balanus crenatus Acorn barnacles 22 Lepadomorpha (Goose Bamacles) 50 Balanus improvisi/.s Acorn Barnacles 21 Balanomorpha (Acorn Barnacles) 60 Lepas anatifera Goose barnacles 20 Amphipoda 60 Balanus tintinnabulitm Acorn barnacles 18 Isopoda 24 Balanus balanoides Acorn barnacles 16 Decapoda 76 H ydroides norvegica Tubeworms 15 Pycnogonida 8 Balanus amphitrite Acorn barnacles 15 Insecta 2 C onchoderma aitrititm Goose barnacles 15 Conchodernia viigatum Goose barnacles 14 Mollusca. 212 Amphineura 3 Enteromorplia sp. Green algae 14 Nudibranchiata 32 Cladophora sp. Green algae 14 Pteropoda 4 Schizoporella unicornis Bryozoa 14 Other Gastropoda 59 Tubu;laria larynx Hydroids 14 Pelecypoda 121 Ciona intestinalis Tunicates 13 Tubulai'ia crocea Hydroids 12 Echinodermata.. 19 Crinoidea 3 Ectocarpits sp. Brown algae 11 OphiuroideaAsteroidea 73 HolothuroideaEchinoidea 51 between the assemblages of organisms likely to be Chordata... 127 found on different types of structure. It is diff- Tunicata 116 cult, however, to state very definitely what these Pisces 11 differences are, or to justify such statements with quantitative data. The amount of information Few species of Pelecypods are recorded although available from examinations of different struc- some such as the oysters and mussels are among tures is very unequal, so that statistical compari- the most important foulers. sons are impossible. The differences also depend Only 50 to 100 species are commonly encoun- not so much on the character of the structures as THE FOULING COMMUNITY 39 on the circumstances under which they are ex- TABLE 5. Numbers of Species of Fouling Organisms posed and the degree of fouling which is permitted on Buoys and Ships to develop before examination. Navigation buoys, Number of Species per Unit which foul heavily before servicing, support a Units Range Average 4 Buoys, Plymouth Sound 31-37 34.0 6 Buoys, Estuary 5-19 14.3 TABLE 4. Frequency of Various Forms in Ship Fouling All 10 Buoys-Milne (6) 5-37 22.4 The numbers indicate the number of ships on which each 83 Ships-Visscher (11) 1-13 4.18 species was reported by Hentschel (3) and Visscher 48 Ships-Hentschel (3) 1-12 4.39 (11). The total number of ships examined was 131. after a month's exposure may give a very inac- ACORN BARNACLES BRYOZOA (conL) curate picture of the fouling organisms available, Balanus improvisus 44 Bitgula tiirbinata 1 since only the rapidly developing forms are re- Balanus eburneus 34 Watersipora citciillata 1 Balanus amphitrite 27 Callopora lineata 1 corded. Balanus tintinnabiilum 25 Callopora sp. 1 Balanus sp. 2S Alcyoiiidimii sp. 1 Some quantitative differences between the char- Balanus crenatus 7 M embranipora savartii 1 acter of the fouling assemblages on ships and Balanus psittacits 3 Electra pilosa 1 Clielonibia patula 2 Scliizoporella unicornis 1 buoys are brought out in Tables 5 and 6.