**6. Relationships between the external medium and an animal's body**

In assessing organisational levels, it is necessary to analyse those relationships beyond the physical dimension of the animal's body and that provoke the defined interactions. Among these relationships are the connections between the various components of a community, i.e., trophic webs. According to the environment, the trophic web may be more simple or complex, e.g., with more connections and interactions between components or with greater or lesser possibility of prey choice by top members.

In these communities, whether they are subjected to fumigation or the biocides that enter the physical environment with runoff caused by rain, there will be species that are more sensitive than others, and these pollutants can make these species disappear or decrease their numbers extensively. This alteration will also be reflected in species that use this directly affected species as food, leading to increased competition among predators for fewer prey species. In this way, a decrease in diversity and a simplification of the system occurs.

In addition, all community members are in contact with the biocide, which may accumulate in organisms. When predators eat contaminated prey the toxic conditions of the biocides from the lower elements of the food chain are transferred to the other trophic levels of the chain, magnifying their effects.

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Thus, the direction of flow of energy and matter through the food web can be affected, changing both direction and intensity, affecting the ability of each species and population to persist.

The movement of populations occurs and can be induced by abiotic, biotic and human factors. In the last case, this movement can be induced after rainfall, when biocides accompany rainwater. The xenobiotics in sediment, suspended in colloids or dissolved in rainwater are trapped. These biocides can cause changes in abiotic conditions (pH, conductivity, nutrients) and water and sediment qualities. The different factors make it difficult to identify a cause and/or cause-effect relationship, but these factors increase stress and impair various species' activities under various conditions. According to the timing of a rainfall event, the population may or may not be in its most vulnerable condition, based on its endogenous cycles (e.g., moult, reproduction).
