1. Although 20% of Brazilian territory is covered by wetlands, wetland inventories are still incomplete. In 1993, Brazil signed the Ramsar Convention but a coherent national policy for the sustainable management and protection of wetlands has yet to be established. 2. Major gaps in the definition of a specific wetland policy are twofold: (1) the lack of standardized criteria by which wetlands are defined and delineated that reflects the specific ecological conditions of the country and (2) the lack of a national classification of wetlands that takes into account specific hydrological conditions and respective plant communities. 3. In recent years, efforts have been made at a regional level to improve public awareness of the ecology of Brazilian wetlands, their benefits to society, and the major threats endangering them. Studies have shown that wetlands play a crucial role in the regional hydrological cycle and provide multiple benefits for local populations. Furthermore, Brazilian wetlands contribute significantly to South American biodiversity. Therefore, wetland conservation and sustainable management should be given high legislative priority. 4. This article provides a synthesis of the current body of knowledge on the distribution, hydrology, and vegetation cover of Brazilian wetlands. Their definition, delineation, and classification at the national level are proposed in order to establish a scientific basis for discussions on a national wetland policy that mandates the sustainable management of Brazil’s extremely diverse and complex wetlands. This goal is particularly urgent in the face of the continuing and dramatic deterioration of wetlands resulting from large-scale agro-industrial expansion, and hydroelectric projects as well as the projected impact of global climate change on hydrological cycles

Questions: Two hypotheses were tested: (1) physical features, such as wetland surface area and habitat diversity, together with water chemistry, are important determinants of species richness and composition of macrophyte assemblages and (2) species richness and composition of macrophyte assemblages differ between wetlands of different types (i.e., palustrine versus lacustrine) and between wetlands of different hydrologies (i.e. permanent versus intermittent). Location: A subtropical coastal plain segment (2500 km2) of southern Brazil. Methods: Quarterly collections were carried out in 15 wetlands (2004–2005) in southern Brazil. Differences in richness over time were tested using repeated measures ANOVA. Stepwise multiple regression was performed to investigate relationships between total richness and environmental variables. Significance of differences between wetland types and hydroperiods on species composition was verified by MRPP (Multi‐Response Permutation Procedure). The influence of the environmental variables on species composition was assessed using CCA (Canonical Correspondence Analysis). Results: Macrophyte species richness changed with time, was not significantly different between wetland types, but was higher in permanent wetlands than in intermittent ones. Area, habitat diversity and soluble reactive phosphorus concentration explained 76% of the variation in species richness. Species composition was different between permanent and intermittent wetlands, although it was not significantly different between wetland types. Area, habitat diversity and water chemistry explained 50.1% of species composition. Conclusions: Species richness and composition of wetland macrophytes were mainly determined by area, habitat diversity and hydroperiod. These results can be used for the development of conservation and management programs in southern Brazil.

The main goal of this study was to determine how much variation in macrophyte richness and composition is explained by wetland area, altitude, water conductivity, and nitrate and total phosphorus concentrations in wetlands in southern Brazil, and to compare these variations in two wetland subsystems (palustrine and lacustrine). A total of 126 wetlands were sampled distributed in two subsystems: 87 palustrine and 39 lacustrine wetlands. A total of 153 species of aquatic macrophytes was found in wetlands of southern Brazil and the mean number of macrophyte species per site was 8.7 (range 1-23). From the variables tested, the altitude and area were the only predictor of macrophyte richness and explained 23.1% of variation in richness. The two first axes generated by CCA explained only 4.4% of the variation in the aquatic macrophytes distribution. The macrophyte richness was similar across lacustrine and palustrine subsystems. While altitude, area and conductivity explained 33.2% of variation in macrophyte richness in the palustrine subsystem, none of the variables were associated with macrophyte richness in the studied lacustrine wetlands.

Aim  We investigated the relative role of area, isolation, microhabitat diversity and number of individuals as explanatory factors defining the richness of waterbirds in wetland remnants.Location  Freshwater marshes along the Atlantic coastal zone of South Brazil. (30°56′–30°22′S; 50°58–50°22′W; Fig. 1).The study area (dashed line), in the Atlantic coastal zone of Brazil, is characterized by a high concentration of remnant wetlands used by resident and migratory waterbirds. Waterbirds were surveyed monthly along 2003 in 42 randomly selected wetland remnants.imageMethods  We surveyed waterbirds monthly for 1 year in 42 wetland remnants. We measured area, diversity of microhabitats, and isolation using aerial photographs and Landsat images. We compared the fit of the relationship between waterbird richness and wetland area across three models. We evaluated the ‘passive sampling effect’ comparing the observed species–area relationship with area‐based and individual‐based null models, performed with randomization without replacement. We used Path Analysis to measure the relative importance of direct and indirect effects of wetland area, isolation, microhabitat diversity and the total number of individuals on species richness.Results  Power functions showed that larger wetlands had proportionally fewer species, individuals and microhabitats as compared to smaller wetlands. Species richness was consistently lower than predicted by area‐based and individual‐based random placement null models. Path analysis showed significant direct effects of remnant area and microhabitat diversity on species richness, but no effect of isolation on species richness. When number of individuals was included in the model, it became the most important factor explaining species richness, followed by wetland area. The number of individuals was significantly influenced by area, isolation and microhabitat diversity.Main conclusions  We demonstrated that waterbird richness in fragmented landscapes is not a random placement phenomenon, but a biological one, significantly affected by the complex interplay of remnant area and isolation and diversity of microhabitats. We showed that the number of individuals plays a central role mediating the effect of these physical factors on species richness.

Effects of hydrological variation on the aquatic plant community in a fl oodplain palustrine wetland of southern Brazil Abstract This study analyzed macrophyte richness, biomass, and composition under fl ooding of brief duration (less than 3 days) and drawdown events over an annual cycle in a fl oodplain palustrine wetland in the south of Brazil. The study was carried out to test the hypothesis that fl oods of brief and very brief duration are not long enough to compromise the richness and the biomass of aquatic macrophytes and that the alternation between wet and drawdown phases may cause variations in the macrophyte richness and composition. A total of 26 aquatic macrophyte species were observed from April 2003 to May 2004: 13 species were observed during the wet phase, and 24 during the drawdown phase. The mean richness was higher during the drawdown phase than during the wet phase, however, the mean biomass was similar in both phases. Although macrophyte richness was not modifi ed after the three fl ooding events, mean biomass was modifi ed after two events. The number of macrophyte species of which the biomass was modifi ed after the fi rst fl ooding event increased with subsequent fl oods. These results illustrate the importance of the dynamics between brief fl oods and drawdown events to the aquatic plant community in fl oodplain wetlands in southern Brazil.