Environmental characterization of an Amazonian lake for Isoëtes cangae translocation

The Amazon endemic quillwort Isoëtes cangae is a critically endangered submerged plant found exclusively at the Lake Amendoim, at iron rock fields in Serra dos Carajás, Eastern Brazilian Amazon. Lake Amendoim is an oligotrophic lake with high iron content and rocky to organic-clay sediment. Another aquatic ecosystem in the vicinity, Lake Três Irmãs-3, was evaluated for its limnological characteristics and the ecophysiological markers to assess whether this ecosystem is suitable for the translocation and conservation of I. cangae . Over the course of 2 years, underwater light spectra and water physicochemical characteristics were determined at both sites during dry and rainy periods. In addition, the chlorophyll a fluorescence of I. cangae was measured using Pulse-Amplitude Modulated fluorometry. Our findings reveal that the limnological dynamics of both lakes are very similar, and differences in limnological conditions between time periods were restricted to a few variables associated with climatic regime shifts (such as temperature, turbidity and total solids). We also identified that I. cangae can maintain its photosynthetic performance and reproduced in the Lake Três Irmãs-3. Our findings suggest that Lake Três Irmãs-3 is a suitable candidate ecosystem for I. cangae conservation due to the high limnological similarity between the studied lakes and the ecophysiological results.