Abstract
Abstract: The global biodiversity loss is a consensus. The biodiversity conservations shortfalls make conservation of biological diversity even more challenging. For many taxa, the knowledge about their distributions is deficient, and this is called the Wallacean shortfall. This situation is no different within algae biodiversity, especially in Brazil. There is still an enormous inequity of sample effort, as is the case of the Parnaíba River Basin (Northeast region), which had only 10 algal species in published (the lowest number of algal species reported among the main Brazilian basins). The present work had the objective of increasing the knowledge of algal flora in Brazil by conducting a taxonomic study of the stream macroalgal species of the Parnaíba River Basin. The sampling of macroalgae was carried out in 21 segments of streams from the Middle and Lower Parnaíba Basin, in the Piauí and Maranhão states. Macroalgae were manually removed and preserved in 4% formaldehyde. Environmental characteristics of each segment were measured in order to describe the sampling sites. The taxonomic survey of the macroalgal communities resulted in the identification of 38 taxa in total, of which 32 at a specific level; three vegetative groups; two sporophytic stages of red algae and one unidentified species. Among the 38 species recorded, 37 are new records for the Parnaíba River Basin. Following the same pattern, 23 species are new records for the Brazilian Northeast region, and Microcoleus lacustris represented the first report in Brazil. Despite the fact that it remains the Brazilian basin with the lowest number of algal species documented, this study contributed to the increase of almost five times the number of species sampled in the Parnaíba River Basin (from only 10 to 47 species). These data reinforce that the differences presented in algal diversity in the Brazilian regions are more related to the sampling effort than other factors (e.g. environmental characteristics, geographic distribution, biomes, among others). In addition, this survey illustrates not only the group's lack of information in the region but also shows the importance of this type of study as a tool for expanding the knowledge about biodiversity and its conservation.
Highlights
It is a consensus that global biodiversity is threatened and the species loss is taking place at an accelerated level (Whittaker et al 2005)
For stream macroalgae, the floristic surveys have focused basically only the Southeastern (Branco & Necchi Júnior 1996, Necchi Júnior et al 1997, Pereira & Branco 2010, Almeida et al 2011) and Southern regions of Brazil (Krupek et al 2008, Peres et al 2008, Branco et al 2008, 2009, 2011). These efforts have contributed profoundly to the knowledge of Brazilian flora, there is a huge gap in the knowledge of the distribution of organisms throughout the territory, clearly contributing to the Wallacean shortfall in the group
The sampling of macroalgae was carried out in 21 segments of streams belonging to Parnaíba River Basin, in the Piauí and Maranhão states (Figure 2, ICMBio License number 58717-3), during a period of drought and after a period of regular precipitation
Summary
It is a consensus that global biodiversity is threatened and the species loss is taking place at an accelerated level (Whittaker et al 2005). For stream macroalgae (sensu Sheath & Cole 1992), the floristic surveys have focused basically only the Southeastern (Branco & Necchi Júnior 1996, Necchi Júnior et al 1997, Pereira & Branco 2010, Almeida et al 2011) and Southern regions of Brazil (Krupek et al 2008, Peres et al 2008, Branco et al 2008, 2009, 2011) These efforts have contributed profoundly to the knowledge of Brazilian flora, there is a huge gap in the knowledge of the distribution of organisms throughout the territory, clearly contributing to the Wallacean shortfall in the group. This basin comprises a very interesting biogeographic region with the contact of three major Brazilian biomes (Cerrado, Caatinga, Amazônia, and its ecotones) and has a wide land use gradient. As this basin presents the lowest number of algal species recorded so far (among the main Brazilian basins), it is considered as of greater relevance and a valuable contribution to the reduction of the Wallacean shortfall
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