The term ‘aquatic macrophytes’ refers to a diverse group of aquatic photosynthetic organisms, all large enough to see with the naked eye, being represented by seven plant divisions: Cyanobacteria, Chlorophyta, Rhodophyta, Xanthophyta, Bryophyta, Pteridophyta and Spermatophyta, consisting of at least 41 orders and 103 families (Chambers et al., 2008CHAMBERS PA., LACOUL, P., MURPHY, KJ. and THOMAZ, SM., 2008. Global diversity of aquatic macrophytes in freshwater. Netherlands: Springer. p. 9-26. Developments in Hydrobiology, vol. 198.). This group colonizes many different types of aquatic ecosystems and this variety of environments results from a set of adaptive strategies achieved over evolutionary time (Thomaz and Cunha, 2010Thomaz, SM. and Cunha, ER., 2010. The role of macrophytes in habitat structuring in aquatic ecosystems: methods of measurement, causes and consequences on animal assemblages’ composition and biodiversity. Acta Limnologica Brasiliensia, vol. 22, no. 2, p. 218-236. http://dx.doi.org/10.4322/actalb.02202011.
http://dx.doi.org/10.4322/actalb.0220201...
).
The aquatic macrophyte assemblage is usually composed of species with different life forms and this has been considered very important for maintaining the integrity of aquatic ecosystems (Boschilia et al., 2008Boschilia, SM., Oliveira, EF. and Thomaz, SM., 2008. Do aquatic macrophytes co-occur randomly? An analysis of null models in a tropical floodplain. Oecologia, vol. 156, no. 1, p. 203-214. http://dx.doi.org/10.1007/s00442-008-0983-4. PMid:18274779.
http://dx.doi.org/10.1007/s00442-008-098...
). This community is highly productive in floodplains and their structure shows response closely linked to the flood pulse flood disturbance in these environments (Junk and Piedade, 1993Junk, WJ. and Piedade, MTF., 1993. Biomass and primary production of herbaceous plant communities in the Amazon floodplain. Hydrobiologia, vol. 263, no. 3, p. 155-162. http://dx.doi.org/10.1007/BF00006266.
http://dx.doi.org/10.1007/BF00006266...
).
The process of pulses occurring in Amazonian rivers reaches its greatest amplitude in the floodplain ecosystems (Tundisi, 2007TUNDISI, JG. 2007. Exploração do potencial hidrelétrico da Amazônia. Estudos avançados, vol. 21, no. 59, p. 109-117.). The variability generated by constant hydrological disturbance promotes new processes of ecological interactions (Junk et al., 1989Junk, WJ., Bayley, PB. and Sparks, RE., 1989. The flood pulse concept in river-floodplain systems. Canadian Special Publication of Fisheries and Aquatic Sciences, vol. 106, p. 110-127.), generating environmental fluctuations in space and time and providing conditions for the existence of a high diversity of species. These features are observed in the lower stretch of the Xingu River, where large uneven rapids, a series of anastomosing channels, and high amount of tributaries generate specific hydrological conditions and a broad regional limnological heterogeneity. Thus, this scientific note aims to list the species of macrophytes recorded in the Xingu River and tributaries that make up the middle section of the basin of the Xingu River along with 2 full hydrological cycles. This note is related to the large scale limnological survey that is carried out by International Institute of Ecology and Environmental Management in influence area of Belo Monte hydroelectric dam.
Between the years 2012 and 2013, 39 sampling stations were monitored quarterly in different types of environments in the riverine landscape, such as the main course of the Xingu River (XR), different lagoons (La), and affluents (Af) of the Xingu River (Figure 1). In these stations 106 species of aquatic macrophytes were registered, belonging to 33 families and 1 sub-family (Mimosaceae) (Table 1). The families with the highest species (spp.) richness were: Cyperaceae (35 spp.), Poaceae (17 ssp.), Podostemaceae (6 spp.), Pontederiaceae (5 spp.), Fabaceae (4 spp.) and Onagraceae (4spp.). In contrast, 17 families were represented only by one single species (Figure 1 and Table 1).
Taxa and biological forms of macrophytes recorded in riverine landscapes of the Xingu River during two years of sampling.
Five biologic forms of macrophytes were recorded in riverine landscape, and those that had a greater number of species were amphibians (41 species), emergent (37 species) and floating (free: 10; prostrate: 6). Rheophyte and submerged, the others 2 forms registered, had 5 and 6 species, respectively.
In terms of environments analyzed, the Xingu River showed the highest richness in riverine landscape with 67 species identified. In lagoons and affluents 59 and 55 species were recorded, respectively (Table 1). Twenty species had high distribution, being registered in all environments analyzed (e.g Salviniaauriculata). On the other hand, 54 taxa occurred only in one type of enviromment (e.g Thaliageniculata L.) (Figure 1 and Table 1).
In the sampled stations on the Xingu River was possible to identify two different regions concerning the distribution of macrophytes, one located in the upstream, with rocky stretches and rapids, where predominated the species belonging to the Podostemaceae family, and another located downstream, with milder hydrological conditions and more backwaters, colonized by species such as Montrichardia linifera and Echinochloa polystachya. Among the species registered in the first region (upstream), it is worth mentioning the occurrence of Mourera fluviatilis, which appears in the list of endangered species of flora (Brasil, 2008Brasil. Ministério do Meio Ambiente – MMA, 2008. Instrução normativa no 06, de 23 de setembro de 2008. Diário Oficial da República Federativa do Brasil, Brasília. 55 p.).
Acknowledgements
The authors wish to express their thanks to Norte Energia S. A. forsupport and funding of the project. Also, Jorge Luiz Rodrigues-Filho would like to acknowledge Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP/Process nº 2013/19602-0) for Post-doctoral fellowship at International Institute of Ecology and Environmental Management.
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(With 1 figure)
- Boschilia, SM., Oliveira, EF. and Thomaz, SM., 2008. Do aquatic macrophytes co-occur randomly? An analysis of null models in a tropical floodplain. Oecologia, vol. 156, no. 1, p. 203-214. http://dx.doi.org/10.1007/s00442-008-0983-4 PMid:18274779.
» http://dx.doi.org/10.1007/s00442-008-0983-4 - Brasil. Ministério do Meio Ambiente – MMA, 2008. Instrução normativa no 06, de 23 de setembro de 2008. Diário Oficial da República Federativa do Brasil, Brasília. 55 p.
- CHAMBERS PA., LACOUL, P., MURPHY, KJ. and THOMAZ, SM., 2008. Global diversity of aquatic macrophytes in freshwater. Netherlands: Springer. p. 9-26. Developments in Hydrobiology, vol. 198.
- Junk, WJ. and Piedade, MTF., 1993. Biomass and primary production of herbaceous plant communities in the Amazon floodplain. Hydrobiologia, vol. 263, no. 3, p. 155-162. http://dx.doi.org/10.1007/BF00006266
» http://dx.doi.org/10.1007/BF00006266 - Junk, WJ., Bayley, PB. and Sparks, RE., 1989. The flood pulse concept in river-floodplain systems. Canadian Special Publication of Fisheries and Aquatic Sciences, vol. 106, p. 110-127.
- Thomaz, SM. and Cunha, ER., 2010. The role of macrophytes in habitat structuring in aquatic ecosystems: methods of measurement, causes and consequences on animal assemblages’ composition and biodiversity. Acta Limnologica Brasiliensia, vol. 22, no. 2, p. 218-236. http://dx.doi.org/10.4322/actalb.02202011
» http://dx.doi.org/10.4322/actalb.02202011 - TUNDISI, JG. 2007. Exploração do potencial hidrelétrico da Amazônia. Estudos avançados, vol. 21, no. 59, p. 109-117.
Publication Dates
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Publication in this collection
Aug 2015
History
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Received
06 Feb 2014 -
Accepted
19 Feb 2014
