Variação das comunidades Ficoperifíticas em tanques de piscicultura experimentais com sistema de Aquaponia no Oeste do Pará

Abstract

Periphyton is defined as a complex community of organisms that adhere to substrates. Periphytic communities are essential to the balance and metabolism of aquatic environments, they are the base of the food chain and primary producers responsible for releasing oxygen to the environment. The aim of this study was to determine the variation of phycoperiphytic communities in experimental fish farming ponds, comparing ponds with and without aquaponics. The study took place at the Universidade Federal do Oeste do Pará, in the city of Oriximiná-Pará, for four months. There are four experimental fish farming tanks with aquaponics system and water recirculation, two Treatment tanks (TA and TB) containing aquaponics with Acmella oleracea (L.) R. K. Jansen (jambu) and two Control tanks (CA and CB) without aquaponics. Abiotic parameters were sampled weekly using portable devices. For phycoperiphyton sampling, artificial substrates measuring 10 x 5 cm were used. In each tank, a set of three substrates was inserted consecutively, which remained for a period of 30 days each for colonization. After this period, the periphytic material was scraped off, fixed with 1% Lugol, and stored with approximately 100 ml of distilled water. Phycoperiphyton quantification was performed using sedimentation chambers under an inverted microscope. The phycoperiphytic community was classified in terms of genera, orders and taxonomic classes, density calculations, ANOVA analysis of variance and Tukey's test were applied, as well as diversity indices; Shannon, wealth, equity and dominance. The results showed that the total density values increased temporally, with the exception of a Control tank, the analysis of variance showed no significant difference in the total density values between the Treatment and Control tanks. The highest density values presented were from the Chlorophyceae class in the Treatment tanks. Analysis of variance showed that the density data of phycoperiphytic groups did not differ significantly between the Treatment and Control tanks. For Shannon's diversity, richness, dominance and evenness indices, the Control tanks showed the best values. For the abiotic data, the results showed that there was no significant difference between the Treatment and Control tanks for most of the analyzed parameters, with the exception of water transparency and nitrite. The excess of ammonia in the experimental tanks was a determining factor for the increase in algae density, low diversity and richness, in addition to the predominance of the Chlorophyceae class. Finally, aquaponics with Acmella oleracea caused a reduction in nitrite values and differences in transparency values between the tanks, however, it did not cause a reduction in ammonia values in the medium and did not result in significant differences in phycoperiphytic density.