CHAPTER 10 Species Rècorded from Fouling A list of species recorded from fouling is given groups varies from phyla to subordinal categories; as an Appendix to this chapter. A classified bibli- in general, groups have been selected on the basis ography and an index showing the items dealing of probable convenience for the average worker. with different types of structures are included. Where there are several records for the same Analyses of the composition and the natural origin species on a given type of structure, the arrange- of fouling communities, based on this list, have ment is chronologicaL. been given in Chapter 3. The present chapter de- scribes the technicalities of the list's preparation, TABLE 1. Summary of the Types of Structures and the and presents some further analyses of its content. Number of Reports on Which the List of Recorded Fouling Organisms is Based These matters are of interest primarily to biologists No. concerned with the details of the composition of Type of Strictiire Reports fouling. SHIPS Including yachts, skiffs, barges, lighters, and 73 vessels of all descriptions except lightships and Preparation of the List wrecks. TEST SURFACES Including small objects exposed 51 to study the accumulation of organisms. Differen- TYPES OF RECORDS INCLUDED tiation by composition of units impossible with most Records of fouling on ten kinds of structures published data. BUOYS 48 have been used. Each entry in the list gives the SUBMARINE CABLES 17 type of structure from which the record came. FLOATS Including rafts, pontoons, livecars, land- 15 The ten types include all occurrences which may ing stages, etc. PIPES Including sea water circuits in ships, indus- 15 be construed as prima facie fouling for general trial installations on tide water, and tide-mil ma- naval and maritime purposes. Table 1 identifies chinery. the structures, and summarizes the number of WRECKS 14 LIGHTSHIPS Tabulated separately from ships be- 6 reports providing information about each. The cause moored in open waters or other unusualloca- total of 153 sources probably does not exhaust the tions. literature of fouling, but all the known major pub- ROPES 4 lished studies are included, together with impor- DOCK GATES 1 tant unpublished reports and data in the files of the Navy Department and the Woods Hole EXCLUDED INFORMATION Oceanographic lnstitution. The latter include a Records of species from wharf-piles, bulkhead- large volume of unpublished data from collections ing, beacons, quays, jetties, abutments, and other of fouling from navigation buoys along the coasts special harbor facilities have been excluded. Often of the United States, which have not as yet been these are regarded as fouling, and the study of completely analyzed. populations in such places has contributed im- In general, all scientifically designated genera, measurably to the understanding of growths on species, and varieties have been listed. Forms iden- ships, etc. The wharf-pile literature in particular, tified to the genus only (i.e. Ulva sp. as opposed to however, is extensive, and inclusion of even a Ulva lactuca, etc.) have been entered separately representative selection from it would multiply the and counted in the tabulations, as have also the size of the list several times. Such a mass of data records for varietÍes.The names used are those would divert attention from records more directly employed in the source reports, no changes having related to practical problems, and this considera- been made beyond adoption of uniform spellngs tion, rather than any biological distinction, has and elimination of subgenera. Some probable guided the selection. synonyms among the more important genera are Restriction of the list to scientifically desig- noted in the comments on the records of the major nated genera and species also has ruled out much groups, but correction of the list itself for errors of valuable information. Among sources not covered this sort has not been attempted. by the list for this reason are the U. S. Navy dock- The species in the list ar,e alphabetized under ing reports, test surface analyses to major groups the various major groups, which are arranged only, and all the wartime experience with mines roughly in phylogenetic order. The rank of the and nets. Exact data comprise only a small frac- 165 166 MARINE FOULING AND ITS PREVENTION tion of the total general knowledge about the com- ever, is one of the most diffcult problems, for at position of fouling. least in part the unequal distribution of investiga- Organisms of interest primarily as borers, such tion must be supposed to reflect the concern of the as the teredos and related forms, have also been maritime world. To that extent, the list is a fair omitted in compiling the list. Some boring species review of fouling as met in past practice. such as the clam, Saxicava arctica, contribute to Because the list appears long, its -actual brevity fouling and are included. Exact knowledge of the is not immediately appreciated. In point of fact, habits and importance of all such species has not only a relatively small amount of precise work has been readily obtainable, and doubtless some mis- been done on fouling, and this results in the most takes have been made in rejecting or accepting important of all limitations inherent in the data. particular species as members of fouling com- All biological generalizations based on our present munities, but these errors are probably of minor knowledge of fouling are liable to considerable consequence. errors because the inadequacy of the available in- formation can not be assessed. Comparisons of the LIMITATIONS AND BIASES INHERENT IN THE DATA numbers .of species recorded from fouling with the Certain limitations or biases inherent in the data total numbers of known marine forms, such as reduce the value of the list as a basis for biological given in Table 2 of Chapter 3, are misleading in generalizations. In regard to the composition of that they are affected much more by the relative fouling, occasional authors state that they ignored intensities of the study of fouling and natural some groups, notably the free-living and the populations than by the biological characteristics microscopic forms. Other reports cited deal spe- which permit species to take part in fouling. Com- cifically with only one group, or with relatively parison of the fouling list with a list of natural few groups, as in the case of the Woods Hole records prepared from a like number of sources Oceanographic Institution data for buoy fouling. having limitations and biases similar to those of the There appears to be no investigation of fouling, fouling bibliography would afford in some ways a in fact, in which a truly complete study of all the much better insight into the nature of fouling. forms present has been made. The list, therefore, falls short of a full description even of the com- Comments on Records of Major Groups munities which have been examined. Two tables have been prepared summarizing the Inequalities exist in the amount of attention contents of the list by major groups and by types devoted to various types of structures. More test- of structures. Table 2 shows the number of forms surface units have been inspected, undoubtedly, in each group reported from the various types of than any other kind of structure, although it is structures. Table 3 shows the total numbers of diffcult to estimate the number. Navigation buoys records in the same way. These tables suggest and ships appear to be second and third in this many differences in the relative importance of respect, with perhaps 1,000 buoys and 500 ships various groups, and many distinctions in the char- as the approximate numbers of unit-inspections acter of fouling of different structures. Because of providing useful records. To a degree, the variety the limitations and biases in the data, however, it of species reported from each type of structure wil is very diffcult to evaluate these features of the depend on the intensity of its investigation. list. An attempt to point out some of the more reli- The intensity of investigation has been very un- able distinctions in the occurrence of different equal in different parts of the world. North tem- groups, and to distinguish them from apparent perate coasts have received the greatest attention, distinctions which have no real significance, is although stil far from what is to be desired. De- presented in the following comments. These notes tailed knowledge about tropical fouling is quite are based largely on Tables 2 and 3, supple- inadequate, while data from the southern hem- mented by additional tabulations which sum- isphere are almost wholly lacking. Ship fouling is marize the occurrence on different structures of the somewhat better known, geographically, than chief genera of the groups of greatest interest. other types, but even so there are many regions Several groups of minor significance are not dis- for which documentation rests on only one or two cussed. vessels. Certain apparent features of fouling prob- ably depend on these geographical inequalities, for BACTERIA example, the relatively small participation of Although bacterial slimes apparently form on all corals. The evaluation of geographical biases, how- submerged surfaces, and bacteria of other sorts SPECIES RECORDED FROM FOULING 167 TABLE 2. Number of Species in Each Group Reported from Various Structures Total No. Light- Dock Test of Species Ships ships Wrecks Bu.oys Floats Cables Ropes Pipes Gates