action, nature of effect on the population of dependent species or 

 intensity. The diagram (Fig. 6) shows the 16 most important connections 

 within this system. 



The dominant species of the biocenosis is the hydroid. The second 

 species, in terms of abundance, is the Balanus . They usually settle in 

 May and develop simultaneously. Under favorable conditions, with a 

 favorable quantity of plankton food, the hydroid forms a thick cover on 

 the substrate within a month. Its branching stolons cover the Balanus 

 and hinder their access to the water and food--paired, indirect, topical 

 and tophic connection 1 develops, reducing the growth rate and, later, 

 the population of Balanus . Soon, Vorticella develop on the stolons of 

 the hydroid (direct topical connection 2) and the suppression of the 

 Balanus is increased (connection 3). The population of the Vorticella 

 on the stolons of the hydroids is regulated during this period by its 

 intraspecific indirect topical connection (4). In June, the Tenellia 

 appear in the community. They live on the stolons of the hydroids and 

 feed on the hydroids and Vorticella (direct topical and trophic 

 connection 5 and direct trophic connection 6). With a low population of 

 Tenellia, its food demands are met almost entirely by eating the 

 Vorticel^la , thus protecting the hydroids from being eaten by the 

 Tenel 1 ia~ ri ndi rect trophic connection 8). If the population of Tenellia 

 is high, it not only eats out the Vorticella , but also suppresses the 

 development of hydrants to the extent that some portions of the colony 

 having none of them die and separate from the substrate. This improves 

 the conditions of nutrition of the Balanus , creating an indirect trophic 

 connection between the Tenellia and Balanus (7). The suppression of the 

 hydroids decreases the area of the substrate and the quantity of food 

 for new generations of Tenellia . The Tenellia population is regulated 

 by paired indirect connection 9, as a result of which, some of its 

 individuals are expelled from the hydroid colony and carried away from 

 the community by the flow of the water. In late June, the bryozoan 

 Boverbankia appears in the community, overgrowing the stolons of the 

 hydroids (direct topical connection 10), partially expelling the 

 Vorticella (indirect topical connection 11). In July, crab larvae begin 

 to settle. The young crabs grow rapidly, and are quite voracious. They 

 eat the Vorticella and Bryozoa (connections 13 and 14), and the 

 Calanipeda which they find among the hydroids, mysids hiding among the 

 stolons of the hydroids, their own juveniles (connection 16) and quite 

 eagerly eat the Tenellia and its clutches of eggs (connection 15). 

 After the crab appears, the population of Tenellia decreases rapidly, 

 and, therefore, the damage done by the Tenellia to the hydroids also 

 decreases. Since the predator has disappeared, the hydroid once again 

 begins to grow and, during the autumn development of zooplankton, the 

 colonies grow and multiply. 



In order to even approach a quantitative evaluation of some of the 

 connections in this system, we utilized the method of mathematical 

 planning of experiments, which allowed us to vary the number of species 

 of animals interacting in the experiment. The experiment was undertaken 

 with four species--the hydroid, Balanus , Vorticella and Tenellia . We 

 studied the strength of the connections relating to two complexes: 

 suppression of the Balanus by hydroids (complex I) and the interaction 

 of the hydroid with the Tenellia (complex II). The experiments were 



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