Perception of Amazonian fishers regarding environmental changes as causes of drastic events of fish mortality

Abstract

Events of catastrophic fish mortality in the lakes of the Amazonian floodplains are not uncommon. They are generally associated with thermal inversion of the water column, which is provoked by cold air masses that originate from the south of the continent. These events occur in the period of high water when the lakes are stratified. This paper reports an event of fish mortality that occurred during the low water season in a large floodplain system on the right-hand margin of the Amazon River. Information from seasoned fishers, who live in the same area where the event happened, and hydrological and satellite image analysis was used to identify the potential cause of fish mortality events. The amplitude of the flood pulse and the duration of extreme ebb showed to be the key factors responsible for the occurrence of events of fish mortality. These factors determine connectivity patterns between the floodplain lakes and the river channel, which are essential for maintaining water quality and the biota in the systems.

Indications that fishers perceive socio-environmental problems related to hydroelectric plants in the Tocantins river, Brazil

“…The changes in the flood pulse observed in Tocantins river must be associated with dams because, in the downstream region, dams tend to decrease the variability of the pulse, by reducing the extent of the floodable area and the volume of water released (Nilsson and Berggren, 2000;Poff and Hart, 2002), while upstream, there is a higher chance of unexpected flooding (Prado Jr. et al, 2016). Changes in pulse amplitude and flooding and duration of droughts are associated with fish mortality events (Pinheiro et al, 2022).…”