Breaking the misconception of a dry and lifeless semiarid region: the diversity and distribution of aquatic flora in wetlands of the Brazilian Northeast

Abstract

The semiarid region of northeastern Brazil possesses a set of wetlands characterized by hydrographic basins with deficient drainage networks, a few large and permanent lotic systems and several permanent and temporary lagoons. Aquatic plants are widely distributed in these wetlands and the present study aims to determine if those of Ceará state have similar species compositions and differences in species richness. We hypothesized that lentic ecosystems would have more species and different growth forms of aquatic angiosperms than lotic ecosystems. A total of 1619 records of aquatic angiosperms in 43 wetland areas were analysed. The most representative families were Cyperaceae, Poaceae, Fabaceae, Alismataceae, Malvaceae, Nymphaeaceae and Pontederiaceae. Most of the species are helophytes and bottom-rooted emergent hydrophytes. Permanent lentic ecosystems had the highest number of exclusive species (27.85 %), followed by temporary lentic ecosystems (20.54 %). Contrary to our hypothesis, the different aquatic ecosystems were found to possess distinct species compositions and different proportions of growth forms, and all wetland types contributed to the macrophyte richness of the study area, although they differ in species richness. Therefore, conservation plans for the native aquatic macrophyte biota should include all wetland ecosystems in the semiarid state of Ceará.