Impacts of Climate Change and Local Disturbance on Stream Fish Assemblages in the Amazon

Freshwater environments are among the most threatened by anthropogenic impacts in the world. Among these environments, streams are especially vulnerable to structural changes, water pollution, alterations in food chains, and loss of biodiversity, resulting from deforestation, agricultural land use, as well as small dams and road construction. Changes in rainfall patterns and increased temperature resulting from climate change may boost the negative effects of local habitat disturbances and disrupt physiological, biological and behavioral responses of the aquatic biota, including the instability of seasonal predictability. Here, we evaluate the current knowledge regarding the effects of local anthropogenic disturbances and those from ongoing planetary climate changes on the aquatic environment and fish fauna of small streams worldwide, with a special focus on Amazonian forest streams. To do so, we conducted a (non-exhaustive) literature review searching for information regarding direct and indirect impacts of climate change on the structure and hydrological dynamics of headwater streams around the world. Then, we present information on the effects of such environmental changes in species distributions, on the taxonomic and functional structure and composition of stream fish assemblages in the Amazon and in other biomes. Despite the scarcity of published references dealing with combined/synergic effects of climate change and local anthropogenic impacts on the biology and ecology of stream fishes worldwide, we bring some insights about these emerging environmental problems affecting Amazon stream fishes.