Protection gaps in Amazon floodplains will increase with climate change: Insight from the world's largest scaled freshwater fish

TL;DR

This study models the current and future distribution of the Amazonian fish Arapaima sp., revealing significant protection gaps in floodplain areas that are threatened by climate change and dam constructions, emphasizing the need for expanded protected areas.

Contribution

It introduces a novel modeling approach that incorporates climate, habitat, hydroperiod, and dam presence to assess protection gaps for Amazon floodplain fish species.

Findings

Climate change will reduce suitable habitats for Arapaima sp. by around 17-19%.

Approximately 70% of suitable habitats are currently unprotected, increasing with climate change.

Dam constructions may hinder fish dispersal across the basin.

Abstract

The Amazon floodplains represent important surfaces of highly valuable ecosystems, yet they remain neglected from protected areas. While the efficiency of the protected area network of the Amazon basin may be jeopardised by climate change, floodplains are exposed to important consequences of climate change but are omitted from species distribution models and protection gap analyses. We modelled the current and future (2070) distribution of the giant bony-tongue fish Arapaima sp. accounting for climate and habitat requirements, with consideration of dam presence (already existing and planned constructions) and hydroperiod (high- and low-water stages). We further quantified the amount of suitable environment which falls inside and outside the current network of protected areas to identify spatial conservation gaps. We predict climate change to cause the decline of environmental suitability by 16.6% during the high-water stage, and by 19.4% during the low-water stage. We found that about 70% of the suitable environments of Arapaima sp. remain currently unprotected, which is likely to increase by 5% with future climate change effects. Both current and projected dam constructions may hamper population flows between the central and the Bolivian and Peruvian parts of the basin. We highlight protection gaps mostly in the southwestern part of the basin and recommend the extension of the current network of protected areas in the floodplains of the upper Ucayali, Juru\`a and Purus Rivers and their tributaries. This study showed the importance of taking into account hydroperiods and dispersal barriers in forecasting the distribution of freshwater fish species, and stresses the urgent need to integrate floodplains to the protected area networks.