Seasonal variation of physical and chemical conditions of the goiana and megaó estuary, northeast brazil

Abstract

Estuaries are coastal ecosystems of transition between continental and marine waters, among their characteristics, there is the salinity variation due to tidal cycles, being necessary environmental monitoring actions for the identification of possible anthropic influences. The aim was to characterize seasonally the physical and chemical variables of water in the estuary of the rivers Goiana and Megaó. The study area comprises the estuary of the Goiana and Megaó rivers, located in the Northeast of Brazil, and is a protected area of sustainable use for the development of artisanal fisheries. A total of 20 points along the estuary were sampled during the months of May, July, September and November 2021, January and March 2022, collecting temperature (ºC), pH, salinity, dissolved oxygen (mg/L)  and transparency (cm). Temperature, salinity and transparency varied significantly between the dry and rainy seasons. The dissolved oxygen registered was lower than that described in the Brazilian legislation, causing a state of hypoxia in the estuary. Mitigation measures are needed to improve the quality of the estuarine water, ensuring the maintenance of local biodiversity.