Abstracts

Introduction

Floodplain environments support higher taxonomic and functional diversity (Welcomme 1985WELCOMME, R.L. 1985. River Fisheries. Food and Agriculture Organization Fisheries Technical Paper, v.262, p.1-330., Lowe-McConnell 1999LOWE-McCONNELL, R.H. 1999. Estudos Ecológicos de Comunidades de Peixes Tropicais. Edusp, São Paulo, 534p.), in response to the widely varying spatial and temporal dynamics of aquatic, terrestrial and ecotone habitats (Ward et al. 1999WARD, J.V., TOCKNER, K. & SCHIEMER, F. 1999. Biodiversity of floodplain river ecosystems: ecotones and connectivity. Regul. River. 15:125-139. http://dx.doi.org/10.1002/(SICI)1099-1646(199901/06)15:1/3%3C125::AID-RRR523%3E3.0.CO;2-E
http://dx.doi.org/10.1002/(SICI)1099-164... , Robinson et al. 2002ROBINSON, C.T., TOCKNER, K. & WARD, J.V. 2002. The fauna of dynamic riverine landscapes. Freshwater Biol. 47:661-677. http://dx.doi.org/10.1046/j.1365-2427.2002.00921.x
http://dx.doi.org/10.1046/j.1365-2427.20... ). Macrophyte beds are fundamentally important for the initial development of many fish species (Delariva et al. 1994DELARIVA, R.L., AGOSTINHO, A.A., NAKATANI, K. & BAUMGARTNER, G. 1994. Ichthyofauna associated to aquatic macrophytes in the upper Parana River floodplain. Rev. Unimar 3:41-60., Sánchez-Botero & Araújo-Lima 2001SÁNCHEZ-BOTERO, J.I. & ARAÚJO-LIMA, C.A.R.M. 2001. As macrófitas aquáticas como berçário para a ictiofauna da várzea do rio Amazonas. Acta Amazon. 31(3):437-447.), in addition to acting as feeding sites (Casatti et al. 2003CASATTI, L., MENDES, H.F. & FERREIRA, K.M. 2003. Aquatic macrophytes as feeding site for small fishes in the Rosana Reservoir, Paranapanema River, Southeastern Brazil. Braz. J. Biol. 63(2):213-222. http://dx.doi.org/10.1590/S1519-69842003000200006
http://dx.doi.org/10.1590/S1519-69842003... ) and a dispersal mechanism for small-sized species (Oliver & McKaye 1982OLIVER, M.K. & McKAYE, K.R. 1982. Floating islands – a means of fish dispersal in Lake Malawi, Africa. Copeia 1982:748-754. http://dx.doi.org/10.2307/1444082
http://dx.doi.org/10.2307/1444082... , Machado-Allison 1990MACHADO-ALLISON, A. 1990. Ecologia de los peces de las areas inundables de los llanos de Venezuela. Interciencia 15:411-423., Bulla et al. 2011BULLA, C.K., GOMES, L.C., MIRANDA, L.E. & AGOSTINHO, A.A. 2011. The ichthyofauna of drifting macrophyte mats in the Ivinhema River, upper Paraná River basin, Brazil. Neotrop. Ichthyol. 9(2):403-409. http://dx.doi.org/10.1590/S1679-62252011005000021
http://dx.doi.org/10.1590/S1679-62252011... ). The abundance and complexity of macrophyte beds are among the main determinants of fish communities in both lentic (Súarez et al. 2001SÚAREZ, Y.R., PETRERE-JÚNIOR, M. & CATELLA, A.C. 2001. Factors determining the structure of fish communities in Pantanal lagoons (MS, Brazil). Fisheries Manag. Ecol. 8(2):173-186. http://dx.doi.org/10.1046/j.1365-2400.2001.00236.x
http://dx.doi.org/10.1046/j.1365-2400.20... , 2004SÚAREZ, Y.R., PETRERE-JÚNIOR, M. & CATELLA, A.C. 2004. Factors regulating diversity and abundance of fish communities in Pantanal lagoons, Brazil. Fisheries Manag. Ecol. 11(1):45-50. http://dx.doi.org/10.1111/j.1365-2400.2004.00347.x
http://dx.doi.org/10.1111/j.1365-2400.20... , Petry et al. 2003PETRY, P., BAYLEY, P.B. & MARKLE, D.F. 2003. Relationships between fish assemblages, macrophytes and environmental gradients in the Amazon River Floodplain. J. Fish Biol. 63:547-579. http://dx.doi.org/10.1046/j.1095-8649.2003.00169.x
http://dx.doi.org/10.1046/j.1095-8649.20... , Pelicice et al. 2005PELICICE, F.M., AGOSTINHO, A.A. & THOMAZ, S.M. 2005. Fish assemblages associated with Egeria in a tropical reservoir: investigating the effects of plant biomass and diel period. Acta Oecol. 27:9-16. http://dx.doi.org/10.1016/j.actao.2004.08.004
http://dx.doi.org/10.1016/j.actao.2004.0... , Gomes et al. 2012GOMES, L.C., BULLA, C.K., AGOSTINHO, A.A., VASCONCELOS, L.P. & MIRANDA, L.E. 2012. Fish assemblage dynamics in a Neotropical floodplain relative to aquatic macrophytes and the homogenizing effect of a flood pulse. Hydrobiologia 685:97-107. http://dx.doi.org/10.1007/s10750-011-0870-6
http://dx.doi.org/10.1007/s10750-011-087... ) and lotic habitats (Bulla et al. 2011BULLA, C.K., GOMES, L.C., MIRANDA, L.E. & AGOSTINHO, A.A. 2011. The ichthyofauna of drifting macrophyte mats in the Ivinhema River, upper Paraná River basin, Brazil. Neotrop. Ichthyol. 9(2):403-409. http://dx.doi.org/10.1590/S1679-62252011005000021
http://dx.doi.org/10.1590/S1679-62252011... ).

In the Pantanal, few and spatially poorly distributed analyses of fish communities have been published. Some studies have been carried out in the northern Pantanal (Baginski et al. 2007BAGINSKI, L.J., FLORENTINO, A.C., FERNANDES, I.M., PENHA, J.M.F & MATEUS, L.A.F. 2007. A dimensão espacial e temporal da diversidade de peixes da zona litoral vegetada de lagoas marginais da planície de inundação do rio Cuiabá, Pantanal, Brasil. Biota Neotrop. 7(3): http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn04007032007 (último acesso em 27/08/2012).
http://www.biotaneotropica.org.br/v7n3/p... , Pacheco & Silva 2009PACHECO, E.B. & SILVA, C.J. 2009. Fish associated with aquatic macrophytes in the Chacororé-Sinhá Mariana lake system and Mutum River, Pantanal of Mato Grosso, Brazil. Braz. J. Biol. 69(1):101-108. http://dx.doi.org/10.1590/S1519-69842009000100012
http://dx.doi.org/10.1590/S1519-69842009... , Fernandes et al. 2010FERNANDES, I.M., MACHADO, F.A. & PENHA, J.M.F. 2010. Spatial pattern of a fish assemblage in a seasonal tropical wetland: effects of habitat, herbaceous plant biomass, water depth, and distance from species sources. Neotrop. Ichthyol. 8(2):289-298. http://dx.doi.org/10.1590/S1679-62252010000200007
http://dx.doi.org/10.1590/S1679-62252010... , Milani et al. 2010MILANI, V., MACHADO, F.A. & SILVA, V.C.F. 2010. Assembléias de peixes associados às macrófitas aquáticas em ambientes alagáveis do Pantanal de Poconé, MT, Brasil. Biota Neotrop. 10(2): http://www.biotaneotropica.org.br/v10n2/en/abstract?article+bn02310022010 (último acesso em 28/08/2012).
http://www.biotaneotropica.org.br/v10n2/... , Silva et al. 2010SILVA, H.P., PETRY, A.C. & SILVA, C.J. 2010. Fish communities of the Pantanal wetland in Brazil: evaluating the effects of the upper Paraguay River flood pulse on baía Caiçara fish fauna. Aquat. Ecol. 44:275-288. http://dx.doi.org/10.1007/s10452-009-9289-9
http://dx.doi.org/10.1007/s10452-009-928... , Lourenço et al. 2012LOURENÇO, L.S., FERNANDES, I.M., PENHA, J.M.F. & MATEUS, L.A.F. 2012. Persistence and stability of cichlid assemblages in neotropical floodplain lagoons. Environ. Biol. Fish. 93:427-437. http://dx.doi.org/10.1007/s10641-011-9933-9
http://dx.doi.org/10.1007/s10641-011-993... ) and the central region (Súarez et al. 2001SÚAREZ, Y.R., PETRERE-JÚNIOR, M. & CATELLA, A.C. 2001. Factors determining the structure of fish communities in Pantanal lagoons (MS, Brazil). Fisheries Manag. Ecol. 8(2):173-186. http://dx.doi.org/10.1046/j.1365-2400.2001.00236.x
http://dx.doi.org/10.1046/j.1365-2400.20... , 2004SÚAREZ, Y.R., PETRERE-JÚNIOR, M. & CATELLA, A.C. 2004. Factors regulating diversity and abundance of fish communities in Pantanal lagoons, Brazil. Fisheries Manag. Ecol. 11(1):45-50. http://dx.doi.org/10.1111/j.1365-2400.2004.00347.x
http://dx.doi.org/10.1111/j.1365-2400.20... ); however few data are available from the southern Pantanal. This study aimed to characterize the composition of fish species associated with aquatic macrophytes in Porto Murtinho Pantanal, near the limit of the Upper Paraguay River.

Material and Methods

1. Study area

Porto Murtinho is an extreme southern portion of the Pantanal, defining the southern limit of the Upper Paraguay River Basin and comprising approximately 2.8% of the total Pantanal area (Silva & Abdon 1998SILVA, J.S.V. & ABDON, M.M. 1998. Delimitação do Pantanal brasileiro e suas sub-regiões. Pesqui. Agropecu. Bras. 33:1703-1711.). The predominant vegetation is savanna steppe (Chaco). The river reaches its highest level in June and July, and its lowest level from November through January.

2. Sampling

Samples were collected monthly from February 2009 through January 2011, in beds of aquatic macrophytes along the banks of the Paraguay and Amonguijá rivers and in the floodplain lakes Criminosa and Flores (Figure 1). Fish were sampled using a sieve (0.8 × 1.2 m), drag nets (1.5 × 5.0 m) with 2 mm mesh, and seines (1.5 × 10 m) with 15, 20 and 30 mm between adjacent knots. A total of 109 sample units were obtained, with non-standardized sampling effort. The scientific samples were authorized by the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA/SISBIO # 13458-1).

Fishes were fixed in 10% formalin and preserved in 70% ethanol for identification and counts. In the laboratory, identification was carried out with the help of the identification key to the Fishes of the Pantanal (Britski et al. 2007BRITSKI, H.A., SILIMON, K.Z. & LOPES, B.S. 2007. Peixes do Pantanal: Manual de Identificação. 2. ed. Embrapa, Brasília, 227p.). Voucher specimens were catalogued in the collection of fishes of the Department of Zoology, Universidade Federal do Rio Grande do Sul, Porto Alegre, and in the Coleção de Peixes do Nupelia, Universidade Estadual de Maringá, Maringá, Brazil.

The richness per order in each locality was compared using a chi-square test to verify any differences in the general pattern of taxonomic composition among localities.

Results

A total of 46,327 specimens were collected, belonging to 144 species in nine orders. The Characiformes showed the highest richness, with 73 species (50.7%), followed by Siluriformes with 39 (27.1%), Perciformes with 16 (11.1%), Gymnotiformes with 10 (6.9%) and Cyprinodontiformes with 2 (1.4%). Other orders (Lepidosireniformes, Rajiformes, Synbranchiformes and Beloniformes) had one species each (Table 1). The chi-square test showed that no significant variation (chi-square=5.85; df=12; p=0.92) in richness per order existed among the localities (Figure 2).

The most abundant species were O. pequira (10,259 individuals/22.14%), followed by O. paraguayensis (8,617 individuals/18.60%) and B. exodon (4,275 individuals/9.23%). In contrast, 22 species were each represented by only one individual. Thus, the three most abundant species comprised approximately 50% of the total sampled individuals, while 123 species represented individually less than 1%, and together comprised 14.14% of the total sample. Despite the predominance of small species, many of the fishes collected are important for fisheries, including P. corruscans (Pintado), Z. zungaru (Jaú), S. brasiliensis (Dourado), and S. lima (Jurupensen), among others.

Among the species collected, the tucunaré Cichla piquiti, an introduction from the Amazon basin, was found in the Paraguay River. Another, Cynopotamus sp., was recorded for the first time in the Upper Paraguay River, and its taxonomic status is unknown. Pimelodus mysteriosus, a species of the Paraná basin, was recorded for the first time in the Upper Paraguay River.

Discussion

The fish species associated with aquatic macrophytes in Porto Murtinho Pantanal comprised 53.5% of the total species richness known for the Pantanal (Britski et al. 2007BRITSKI, H.A., SILIMON, K.Z. & LOPES, B.S. 2007. Peixes do Pantanal: Manual de Identificação. 2. ed. Embrapa, Brasília, 227p.). This shows both the homogeneity in fish species distribution across the Pantanal floodplain, and the importance of aquatic macrophytes for maintenance of fish diversity. Moreover, the predominance of Characiformes and Siluriformes observed follows the Neotropical biogeographic pattern and other studies in the Pantanal (Willink et al. 2000WILLINK, P.W., FROEHLICH, O., MACHADO-ALISSON, A.M., MENEZES, N.A., OYAKAWA, O.T., CATELLA, A.C., CHEMOFF, B., LIMA, F.C.T., TOLEDO-PIZA, M., ORTEGA, H., ZANATA, A.M. & BARRIGA, R. 2000. Fishes of the rios Negro, Negrinho, Taboco, Aquidauana, Taquari, and Miranda, Pantanal, Brasil: Diversity, distribution, critical habitats and value. In Biological Assessment of the Aquatic Ecosystems of the Pantanal, Mato Grosso do Sul, Brasil (P.W. Willink, B. Chemoff, L.E. Alonso, J.R. Montambault & R.A. Lourival). Conservation International, Washington, p.63-81. RAP Bulletin of Biological Assessment. n.18., Súarez et al. 2001SÚAREZ, Y.R., PETRERE-JÚNIOR, M. & CATELLA, A.C. 2001. Factors determining the structure of fish communities in Pantanal lagoons (MS, Brazil). Fisheries Manag. Ecol. 8(2):173-186. http://dx.doi.org/10.1046/j.1365-2400.2001.00236.x
http://dx.doi.org/10.1046/j.1365-2400.20... , Baginski et al. 2007BAGINSKI, L.J., FLORENTINO, A.C., FERNANDES, I.M., PENHA, J.M.F & MATEUS, L.A.F. 2007. A dimensão espacial e temporal da diversidade de peixes da zona litoral vegetada de lagoas marginais da planície de inundação do rio Cuiabá, Pantanal, Brasil. Biota Neotrop. 7(3): http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn04007032007 (último acesso em 27/08/2012).
http://www.biotaneotropica.org.br/v7n3/p... , Pacheco & Silva 2009PACHECO, E.B. & SILVA, C.J. 2009. Fish associated with aquatic macrophytes in the Chacororé-Sinhá Mariana lake system and Mutum River, Pantanal of Mato Grosso, Brazil. Braz. J. Biol. 69(1):101-108. http://dx.doi.org/10.1590/S1519-69842009000100012
http://dx.doi.org/10.1590/S1519-69842009... , Milani et al. 2010MILANI, V., MACHADO, F.A. & SILVA, V.C.F. 2010. Assembléias de peixes associados às macrófitas aquáticas em ambientes alagáveis do Pantanal de Poconé, MT, Brasil. Biota Neotrop. 10(2): http://www.biotaneotropica.org.br/v10n2/en/abstract?article+bn02310022010 (último acesso em 28/08/2012).
http://www.biotaneotropica.org.br/v10n2/... ).

The dominance of two small species of Cheirodontinae (O. pequira e O. paraguayensis) follows a habitat pattern, since other studies on fishes associated with aquatic macrophytes have yield the same general results (Súarez et al. 2001SÚAREZ, Y.R., PETRERE-JÚNIOR, M. & CATELLA, A.C. 2001. Factors determining the structure of fish communities in Pantanal lagoons (MS, Brazil). Fisheries Manag. Ecol. 8(2):173-186. http://dx.doi.org/10.1046/j.1365-2400.2001.00236.x
http://dx.doi.org/10.1046/j.1365-2400.20... , Baginski et al. 2007BAGINSKI, L.J., FLORENTINO, A.C., FERNANDES, I.M., PENHA, J.M.F & MATEUS, L.A.F. 2007. A dimensão espacial e temporal da diversidade de peixes da zona litoral vegetada de lagoas marginais da planície de inundação do rio Cuiabá, Pantanal, Brasil. Biota Neotrop. 7(3): http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn04007032007 (último acesso em 27/08/2012).
http://www.biotaneotropica.org.br/v7n3/p... , Pacheco & Silva 2009PACHECO, E.B. & SILVA, C.J. 2009. Fish associated with aquatic macrophytes in the Chacororé-Sinhá Mariana lake system and Mutum River, Pantanal of Mato Grosso, Brazil. Braz. J. Biol. 69(1):101-108. http://dx.doi.org/10.1590/S1519-69842009000100012
http://dx.doi.org/10.1590/S1519-69842009... , Silva et al. 2010SILVA, H.P., PETRY, A.C. & SILVA, C.J. 2010. Fish communities of the Pantanal wetland in Brazil: evaluating the effects of the upper Paraguay River flood pulse on baía Caiçara fish fauna. Aquat. Ecol. 44:275-288. http://dx.doi.org/10.1007/s10452-009-9289-9
http://dx.doi.org/10.1007/s10452-009-928... ). This suggests that the macrophyte habitat is favorable for these species, probably because of the good availability of food and protection from predators. Moreover, the greater dominance of a few species is common in tropical communities. Magurran & Henderson (2003)MAGURRAN, A.E. & HENDERSON, P.A. 2003. Explaining the excess of rare species in natural species abundance distributions. Nature 422:714-716. http://dx.doi.org/10.1038/nature01547
http://dx.doi.org/10.1038/nature01547... suggested that abundant/common species are those residing in this habitat, while other species are occasional visitors. This hypothesis can be used to explain our data, in response to the close association between the species found and macrophyte beds. The smaller fish species are possibly more abundant because they are resident in the macrophyte beds.

Also, the occurrence of some commercially important species occurred as juveniles, suggesting that macrophyte beds are also an important habitat for the initial development of larger species, as demonstrated by Delariva et al. (1994)DELARIVA, R.L., AGOSTINHO, A.A., NAKATANI, K. & BAUMGARTNER, G. 1994. Ichthyofauna associated to aquatic macrophytes in the upper Parana River floodplain. Rev. Unimar 3:41-60. for the Upper Paraná River.

In relation to introduced specie tucunaré Cichla piquiti, Resende et al. (2008)RESENDE, E.K., MARQUES, D.K. & FERREIRA, L.K.S.G. 2008. A successful case of biological invasion: the fish Cichla piquiti, an Amazonian species introduced into the Pantanal, Brazil. Braz. J. Biol. 68(4):799-805. http://dx.doi.org/10.1590/S1519-69842008000400014
http://dx.doi.org/10.1590/S1519-69842008... defines as a well-established species in the Pantanal, and reported its occurrence from the Piquiri River (northern Pantanal) to the region of Corumbá (central Pantanal). Our data revealed that it occurs approximately 400 km southward, at the limit of the Pantanal (Upper Paraguay River). Therefore, along the main river (the Paraguay), the tucunaré occupies approximately 70% of the north-south axis of the Pantanal, although its occurrence in tributaries of the Paraguay River has not been evaluated, nor has its influence on aquatic communities.

The specimens of Cynopotamus sp. collected are of unknown taxonomic status; they differ from others reported from the Pantanal, although they may have been recorded in the Middle Paraguay River. Only after careful analysis can we can determine if this record is a geographical expansion of distribution, or an undescribed species. Complementarily, P. mysteriosus is a species described from the Paraná basin, and is here first recorded in the Pantanal.

In conclusion, the fish diversity associated with aquatic macrophytes in Porto Murtinho Pantanal is composed by small-sized species, with some juveniles and adults of larger species occurring in different frequencies. Some species were recorded for the first time in the Pantanal (Cynopotamus sp. and P. mysteriosus), or the record represents an expansion of the known distribution (e.g., C. piquiti). Finally, the great fish diversity, typical of the Pantanal, suggests the fundamental importance of macrophyte beds for fish and fisheries ecology.

Acknowledgments

The authors gratefully acknowledge the Centro de Pesquisa do Pantanal (CPP/MCT), Fundect, UEMS for their financial, personnel, and logistical support. We are indebted to Ediléia A. Silva, Maiane J. Pereira, Mariane I. Santos, Marcelo M. Souza, Marlon C. Pereira, Gabriela S. V. Duarte, Patricia L. Rondon and William F. Antonialli Júnior for help in the field work. Y. R. Súarez is supported by productivity grants from CNPq.

References

Publication Dates

History