Macrophytes in the upper Paraná river floodplain: checklist and comparison with other large South American wetlands Fernando Alves Ferreira1, Roger Paulo Mormul1, Sidinei Magela Thomaz2*, Arnildo Pott3 & Vali Joana Pott3 1. Postgraduate Program in Ecology of Continental Aquatic Environments, Universidade Estadual de Maringá- UEM, Av. Colombo 5790, bloco H-90, CEP 87020-900, Maringá, Paraná, Brazil; [email protected], [email protected] 2. Research Group in Limnology, Ichthyology and Aquaculture-Nupelia, Biological Science Department, Universidade Estadual de Maringá-UEM, Av. Colombo 5790, bloco H-90, CEP 87020-900, Maringá, Paraná, Brazil; [email protected] 3. Biological Science Department, Universidade Federal do Mato Grosso do Sul - UFMS CEP 79.070-900, Caixa - Postal 549, Campo Grande, MS, Brazil; [email protected], [email protected] * Corresponding author Received 04-VI-2010. Corrected 30-XI-2010. Accepted 07-I-2011. Abstract: Neotropical aquatic ecosystems have a rich aquatic flora. In this report, we have listed the aquatic flora of various habitats of the upper Paraná River floodplain by compiling data from literature and records of our own continuous collections conducted during the period 2007-2009. Our main purposes were to assess the macrophyte richness in the Paraná floodplain, to compare it with other South American wetlands and to assess whether the number of species recorded in South American inventories has already reached an asymptote. We recorded a total of 153 species of macrophytes in the Upper Paraná River floodplain, belonging to 100 genera and 47 families. In our comparative analysis, a clear floristic split from other South American wetlands was shown, except for the Pantanal, which is the closest wetland to the Paraná floodplain and, therefore, could be considered a floristic extension of the Pantanal. The species accumulation curve provides evidence that sam- pling efforts should be reinforced in order to compile a macrophyte flora census for South America. The high dissimilarity among South American wetlands, together with the lack of an asymptote in our species accumula- tion curve, indicates that the sampling effort needs to be increased to account for the actual species richness of macrophytes in this region. Rev. Biol. Trop. 59 (2): 541-556. Epub 2011 June 01. Key words: floristic survey, plant diversity, aquatic plants, Brazil. Wetlands are important sites for biological wetlands (Neiff 2001). Inventories of wetlands conservation because they support rich biodi- provide an indication of the sites with the versity and present high productivity (Mitsch & highest biological diversity and productiv- Gosselink 2000). The study of wetland plants ity (Taylor et al. 1995), and the information has been of interest to botanists for many years, collected through inventories is a necessary but the effort to identify and understand these prerequisite for conservation policies (Pressey plants has increased dramatically since the & Adam 1995). 1970s, when ecologists began to emphasize the Approximately 50% of the inventoried vital role that wetlands play in our landscapes wetlands in South America are located in Brazil (Cronk & Fennessy 2001). (Naranjo 1995). However, specific information One of the main ecological characteristics related to aquatic macrophytes is extremely of South America is the existence of large scarce. Diegues (1994) performed the first Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 59 (2): 541-556, June 2011 541 inventory of wetlands in Brazil, and his work other South American wetlands. Finally, using provided valuable data for evaluating eco- species accumulation curves, we examined logical and economic aspects of these regions. whether the number of species described in According to Neiff (1978, 1986), aquatic mac- South America is reaching an asymptote, or rophytes are important in shallow ecosystems, if more sampling efforts are still necessary to such as river-floodplain ecosystems, where accomplish a comprehensive inventory of the they colonize extensive areas and exhibit high rich aquatic flora of this area. rates of primary productivity. In addition, To accomplish these objectives, we adopt- macrophytes are a key component of river- ed the conceptualization of aquatic macro- floodplain ecosystems because they enhance phytes proposed by Cook (1996), in which the nutrient cycling, increase habitat heterogeneity author includes plants which photosyntheti- and provide food for a variety of organisms cally active organs are either permanently, or (Esteves 1998). for several months of the year, total or partially Floodplains are known as ecosystems with submersed in freshwater or floating in aquatic a high diversity of habitats and aquatic and habitats. More recently, Chambers et al. (2008) terrestrial species (Junk et al. 2000). Due to also included Charophytes within the defini- their high complexity and seasonal changes in tion of macrophytes. To avoid any confusion, physico-chemistry, these ecosystems are char- we did not use in any part of our text the term acterized by a variety of assemblages, which “vascular plants” but, instead, consistently used differ in richness and composition accord- the term “aquatic macrophytes”. ing to the water level. In the Upper Paraná River floodplain, for example, the vegeta- MATERIALS AND METHODS tion is highly conditioned by geomorphology (Souza-Filho 1993); trees dominate the more Study area: The floodplain of the Paraná elevated areas (levees), and shrubs colonize River is located downstream from the Porto less elevated areas that remain flood-free most Primavera Reservoir. This stretch has a length of the year, while aquatic macrophytes grow in of 160km and is the last region of the river permanently inundated areas of the wetlands. that remains not dammed in Brazilian territory. Despite the importance of these macro- Thus, it is of key importance to the conserva- phytes in the Upper Paraná River floodplain, a tion of the aquatic biodiversity of the Paraná stretch of this river that is key in maintaining Basin (Agostinho & Zalewiski 1995). the biodiversity of Brazilian inland waters, According to the Köppen system, the information about the aquatic vegetation in climate in this region is classified as tropical this region is scattered among several different and sub-tropical, with warm summers (mean papers and reports (Bini 1996, Kita & Souza annual temperature 22oC) and a mean annual 2003, Thomaz et al. 2004, Thomaz et al. 2009); rainfall of 1 500mm (Maack 2002). most of these studies emphasized that the flood The compiled list of taxa was based on pulse and changes in water physico-chemistry records of samplings conducted in the flood- are important factors controlling macrophyte plain since 1997. In addition, we utilized sev- populations and communities. eral other studies (published and unpublished) In the present study, we first addressed the that had been conducted in the floodplain. number of macrophyte species in the main hab- Macrophytes were collected in a variety of itats of the Upper Paraná River and its flood- habitats, such as the river main channel, lateral plain (herein only Paraná floodplain), using channels (anabranches), temporary and perma- records gathered since 1997 and intensive nent lakes, and in the aquatic-terrestrial transi- collections performed between 2007 and 2009. tion zone (ATTZ, sensu Junk et al. 1989). We Secondly, we used this dataset to compare the also analyzed and revised specimens depos- species richness and similarity of this area with ited in the Laboratory of Macrophytes and in 542 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 59 (2): 541-556, June 2011 Hoehne 1948, Cook 1996, Pott & Pott 2000, South America Amaral et al. 2008, Bove & Paz 2009). The list of taxa contains families and genera according to the “Angiosperm Phylogeny Group-APG II” (2003) for Magnoliophyta (Angiospermae), Colombia Willis (1973) for Pteridophyta, and Crandall- Ecuador Stotler (1980) for Hepatophyta. Plant life forms were chosen according to Brazil Pedralli (1990), and we followed Tur (1972) Peru for epiphytic forms. Plants growing in wet Bolivia soils (marshes locally known as “varjão” or “várzea”) were included in the category of amphibious (Irgang & Gastal 1996). In order to make comparisons among Sampling sites South American wetlands, we used the follow- ing lists of macrophytes obtained in long-term Argentina surveys (Table 1). All of the investigations and the lists of spe- 0 10 20 30 40 100 km cies that we used were carried out by specialists Scale and included several types of habitats (Fig. 1). Although there are several other papers describ- Fig. 1. Regions of South America included in the ing single habitats, we did not use these studies. sampling sites. It is difficult to guarantee that all studies follow the same methodology, but we believe that they are similar enough to at least contribute a first tentative of comparison of Neotropical wetlands to make inferences about the richness of macro- the Herbarium (HUEM) of the University of phytes in this region. Maringá. To complement the list of species To find similarity among these surveys, we recorded in previous investigations, we carried first converted all data into a large matrix con- out additional samplings between 2007 and taining species occurrence presence/absence. A 2009 in six habitats that are being monitored in matrix of similarity was built using the Bray- the Brazilian Long Term Ecological Research