SPACE-TEMPORAL EVALUATION OF THE EFFECTS OF DROUGHT USING REMOTE SENSING ON PAYTUNA LAKE WATER IN MONTE ALEGRE FLUVIO-LACUSTRY COMPLEX, PARÁ, BRAZIL: Is it possible to cultivate fish in this Amazonian environment? (Atena Editora)

Abstract

The production of fish from fisheries and aquaculture for global food security in the 21st century is of paramount importance. Considering that the world production of fish in 2020 was 178 million tons and fisheries contributed with 51% of this total, while aquaculture contributed with 49%. However, in the Amazon region, fishing has an even greater representation in fish production, especially in the context of riverside populations that use this activity to guarantee their food and livelihood. In recent years, extractive fishing activity has been strongly affected by extreme weather events, such as severe droughts, causing ecological impacts, harming aquatic biodiversity, and social impacts, with the reduction of protein sources for the Amazonian population. Thus, the study proposes to evaluate the variability of the physical-chemical and nutrient conditions of Lake Paytuna during the dry season, as well as to analyze the occurrence of a tendency to decrease the lake's flooded area over the years. For this, limnological data were collected in the months of October, November and December between the years 2019 and 2021. In addition, satellite images were acquired for the months of October, November and December between the years 2000 and 2020 to calculate the area of the lake in the dry period using the Normalized Water Difference Index (NDWI). The results showed that the limnological variables did not present significant differences between the sampling stations, except for dissolved oxygen, which presented a lower value in a specific point characterized as a lotic environment. There was a trend towards a significant decrease (S = -80; p-value = 0.0104) in the area of the lake and we pointed out a greater attention to the years 2005 and 2015 than the dry seasons of smaller registered areas. Overall, Lake Paytuna appears to be in an oligotrophic state, with low concentrations of total phosphorus and chlorophyll-a. These results are important for aquaculture, as they indicate that the lake has good water quality for fish farming. Fish farming has been considered an alternative to increase the supply of aquatic animal protein and meet the demand of the local population.