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An ecological approach to the study of parasitism has, in recent years, been claiming the attention of increasing numbers of parasitologists. An excellent example of this approach, dealing with fishes and their parasites, is the work of Dogiel and his associates (1958; English translation 1961). In these studies emphasis is placed upon the total parasite fauna rather than upon individual species of parasites. We have used the term "parasite-mix" to refer to all the species of parasites in one host. An alternate term, coined by E. N. Pavlovski (1937), is "parasitocoenosis." In studying the dynamics of such populations of parasites, Dogiel et al. have stressed the fact that, "It is not merely the host but also the host's environment that forms the environment of the parasite. This is especially true for the ectoparasites of the aquatic animals, directly dependent on the temperature and hydrochemical features of the external environment. It must always be borne in mind that the environment of parasites is of dual character (Pavlovski, 1934). The name 'micro-environment' can be used for their direct habitat, the host, while the host's habitat, with which the parasites are linked by many indirect ties, can be called the 'macro-environment.'" During the past 4 years we have been making an intensive ecological study' of the parasite-mix of the estuarine fish, Gillichthys mirabilis. The fish have been collected regularly throughout the seasons of the years, and records of their size and sex, the numbers and kinds of parasites, as well as of water salinity, temperature, plankton, and other organisms, have been made. As Noble (1960) pointed out, "When a parasite is studied by itself, separated from its environment, only a part, and often a small part, of its total biology can be understood. The modern approach to parasitology envisages an ecological complex formed by the parasite, the vector, the host and various features of the host's environment." The gill parasites, being in direct contact with the external (and sometimes also with the internal) environment of the host, constitute a particularly interesting part of the parasite-mix for the ecologist. We have, therefore, avoided an intensive investigation of any one parasite. A group of parasites has been considered as part of |
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