© 1974 by The Society for Integrative and Comparative Biology
Interspecific Aggression and its Relevance to the Concept of Territoriality in Reef Fishes
Rosentiel School of Marine and Atmospheric Science University of Miami, Miami, Florida 33124
Territorial behavior is a conspicuous determinant of social organization in many reef fishes. Field observations have indicated that an accurate description of a given organization must consider not only conspecific encounters but also those involving members of the other species which make up the behavioral community. Data, relevant to the above consideration, were gathered on the reef for the three-spot damselfish, Eupomacentrus planifrons, at intervals throughout the year.
Experiments determined (i) the greatest distance from its residence ("maximum distance of attack") that a territorial male would initiate attacks on given individuals of various species, and (ii) number of nips that such a male directed at "intruders" when the latter were placed adjacent to its residence.
The "maximum distance of attack" was found to be characteristic for each "intruding" species: conspecifics—farthest from, congenerics—slightly closer to, and the remaining species—closest to the residence. Territorial males appeared to ignore any given fish until it had reached its respective boundary. Over a broad range, size within a given species appeared unimportant. The number of attacks directed at "intruders" adjacent to the residence was, however, less clearly species-specific. Both parameters varied seasonally in a parallel fashion, this seasonality reflecting closely the annual reproductive cycle of E. planifrons. General observations on populations of E. planifrons and other damselfishes were carried out by SCUBA and the use of underwater television.
Results demonstrated that territorial males of E. planifrons not only recognize different species of reef fishes, but also that they possess serial territories whose areas of defense vary depending on the particular species of intruder present at the time. Random observations on other species of reef fishes indicate that this important feature of interspecific aggression is not unique to the single species tested here.