Macroinvertebrados e influência da época do ano na ocorrência de insetos bioindicadores em trechos do Rio Piranhas-Açu/RN

Abstract

Environmental assessment of river water quality can be done through the use of bioindicator insects. This methodology represents the presence of insects in water in the different forms according to the stage of development of these animals. The presence of some types of insects are indicative of good water quality and consequently of a healthy environment, while the presence of other types of insects can be used as indicative of environments that have undergone some type of environmental degradation and pollution. The use of indicator insects can be used alone or in conjunction with other water quality assessment methodologies, such as the physicochemical water analysis technique. As an advantage, the use of bioindicator insects shows the richness of aquatic life present at a particular point in a river, stream, lagoon or similar and the application of this technique is relatively simple, from water collection to insect analysis, identification and counting in laboratory. After that, it is common to use scales to know how much that collection point is environmentally healthy or not. This research aimed to verify the structure of the macroinvertebrates that occur in four collection points / right margin and left bank of the Piranhas-Açu River, located in the municipalities of Açu, Ipanguaçu, Pendências and Alto do Rodrigues during the dry periods (December of 2016) and of rain (July of 2017) that exists of fauna. Of the total of 4,881 aquatic organisms found, 53,90% (2,631 individuals) were related to the rainy season and 46.10% to the dry period (2,179 aquatic organisms). In relation to the rainy season, Chironomidae, Thiaridae, Bivalve and Planorbidae, corresponding respectively to 51.69%, 35.04%, 3.88% and 3.31% of the total organisms identified in the period. In relation to the dry season, Thiaridae, Nematodae, Chironomidae and Planorbidae each represented 41.38% 32.00%, 12.49% and 10.58% of the total of the identified species in the period. Considering both periods, the highest concentration of Thiaridae (37.97%), Chironomidae (33.62%), Nematodae (15.06%) and Planorbidae (6.66%) stands out.