According to this Spanish-language article, “Insects are the largest group of animals on the planet. An estimate of 5.5 million species has been made , 80% of which have not yet been found... Insects play every imaginable role in the ecosystem, including pollinating crops, controlling insects, and feeding other animals. The possible consequences of its fall are so dire that it is called a "pest catastrophe."
Over the past 20 years, there has been a “generalized decrease in insect numbers in all groups of aquatic insects studied, including mosquitoes, mayflies, and dragonflies.” At the same time, there has been an “increase in the number of invasive fish and a very unbalanced water chemistry, all environmental changes related to the construction of dams…dams block the flow of sediment and nutrients, alter the chemistry of the water, and make the water more transparent. Most aquatic insects are subject to camouflage in dark or dark water. The increased transparency of the water weakened their ability to hide and they were more vulnerable to being eaten by invasive fish.”