PROTOZOOPLANKTON DYNAMICS, URBANIZATION, AND AGRICULTURE: A GEOENVIRONMENTAL APPROACH TO WATER QUALITY IN AQUACULTURE PONDS

Abstract

The aim of the study was to document the composition, abundance, and density of free-living protozoa in aquaculture pond water, the impact of urbanization and agriculture, as well as to assess the potential use of these organisms as bioindicators of water quality. The study was conducted in 20 aquaculture farms, with sample collections taken during both hydrological seasons: the rainy season (from September 2021 to April 2022) and the dry season (from May to August 2022). For qualitative sample composition, horizontal and vertical drags were performed at the water surface of the ponds, while each quantitative sample was obtained using a plankton net (50 μm mesh). The abundance and density of protozoa were presented as (Ind mL^-1). Free-living protozoa were found in the water of 55% (11/20) of the aquaculture farms. Eight species of protozoa, all from the phylum Ciliophora, were identified: Paraenchelys terricola, Apospathidium terricola, Spirostomum teres, Linostomella vorticella, Halteria grandinella, Sphaerophrya magna, Paramecium bursaria, and P. caudata. The most abundant species were P. terricola (106.26 Ind mL^-1 in the rainy season and 105.09 Ind mL^-1 in the dry season) and A. terricola (82.15 Ind mL^-1 in the rainy season and 85.63 Ind mL^-1 in the dry season). This study represents a preliminary survey of protozooplankton in aquaculture ponds, contributing significantly to the understanding of the diversity and distribution of free-living protozoa. Although the results did not show substantial differences in abundance among sampling points, free-living protozoa are valuable tools for analyzing environments impacted by varying degrees of pollution. Further studies on the dynamics and distribution of aquatic microorganism communities will continue to expand knowledge of the taxonomic diversity and ecology of these species, particularly in impacted environments.