PAN-AMERICAN JOURNAL OF AQUATIC SCIENCES - PANAMJAS Executive Editor: Maria Cristina Oddone Scientific Editors: Gonzalo Velasco, Ana Cecília Giacometti Mai, Pablo Muniz, Ronaldo Angelini, Danilo Calliari, and Samantha Eslava G. Martins Honorary members: Jorge P. Castello, Omar Defeo, and Kirk Winemiller. Advisory committee: Júlio N. Araújo, André S. Barreto, Sylvia Bonilla S., Francisco S. C. Buchmann, Adriana Carvalho, Marta Coll M., César S. B. Costa, Karen Diele, Ruth Durán G., Gisela M. Figueiredo, Sergio R. Floeter, Alexandre M. Garcia, Ricardo M. Geraldi, Denis Hellebrandt, David J. Hoeinghaus, Simone Libralato, Luis O. Lucifora, Paul G. Kinas, Monica G. Mai, Rodrigo S. Martins, Manuel Mendoza C., Aldo Montecinos, Walter A. Norbis, Enir G. Reis, Getúlio Rincon Fo., Marcelo B. Tesser, João P. Vieira, and Michael M. Webster. PanamJAS is a non-profit Journal supported by researchers from several scientific institutions. PanamJAS is currently indexed in Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Aquatic Sciences and Fisheries Abstracts (ASFA) Directory of Open Access Journals Online Access to Research in the Environment IndexCopernicus International Thomson BiologyBrowser database Electronic Resources from Smithsonian Institution Libraries Divulgador Científico Ensenadense Sistema de Bibliotecas SISBI-UFU PAN-AMERICAN JOURNAL OF AQUATIC SCIENCES 2006, 1-2 2009, 4 (1) Quarterly Journal ISSN 1809-9009 (On Line Version) CDU 570 Cover photo of this issue: A juvenile of Atlantic Green Turtle Chelonia mydas (Reptilia, Testudines, Cheloniidae) photographed in situ in the Barra Grande beach, state of Piauí, Brazil. Picture taken by Ana C. G. Mai. Pan-American Journal of Aquatic Sciences Research articles Factors affecting the distribution and abundance of freshwater stingrays (Chondrichthyes: Potamotrygonidae) at Marajó Island, mouth of the Amazon River. ALMEIDA, M. P., BARTHEM, R. B., VIANA, A. S. & CHARVET-ALMEIDA, P. ....................................... 1 Natural food resources and niche breadth of Barilius bendelisis (Hamilton) (Pisces, Cyprinidae) in river Dikrong, an upland riverine ecosystem in India. SAHOO, P. K., SAIKIA, S. K. & DAS, D. N. ..........................................................................................12 Distribuição espacial e temporal da guaiúba Ocyurus chrysurus (Bloch, 1791) (Teleostei, Lutjanidae) capturada pela frota pesqueira artesanal na região nordeste do Brasil. DE NÓBREGA, M. F., KINAS, P. G., FERRANDIS, E. & LESSA, R. P. ....................................................17 First case of an infection of the metacercariae of Austrodiplostomum compactum (Lutz, 1928) (Digenea, Diplostomidae) in Hypostomus regani (Ihering, 1905) (Siluriformes: Loricariidae). ZICA, E. O. P., SANTOS, K. R., RAMOS, I. P., ZANATTA, A. S., CARVALHO, E. D. & SILVA, R. J. .......35 Feeding of Farfantepenaeus paulensis (Pérez-Farfante, 1967) (Crustacea: Penaeidae) inside and outside experimental pen-culture in southern Brazil. JORGENSEN, P., BEMVENUTI, C. E. & HEREU, C. M. ...........................................................................39 Remediation of eutrophied water using Spirodela polyrrhiza L. Shleid in controlled environment. ANSARI, A. A. & KHAN, F. A. ............................................................................................................52 Analysis of fluctuating asymmetries in marine shrimp Litopenaeus schmitti (Decapoda, Penaeidae). MAIA, S. C. A., MOLINA, W. F. & MAIA-LIMA, F. A. .........................................................................55 Size-related changes in diet of the slipper sole Trinectes paulistanus (Actinopterygii, Achiridae) juveniles in a subtropical Brazilian estuary. CONTENTE, R. C., STEFANONI, M. F. & SPACH, H. L. .........................................................................63 Morphological data, biological observations and occurrence of a rare skate, Leucoraja circularis (Chondrichthyes: Rajidae), off the northern coast of Tunisia (central Mediterranean). MNASRI, N., BOUMAÏZA, M. & CAPAPÉ, C. ........................................................................................70 Distribuição espacial e temporal da malacofauna no estuário do rio Ceará, Ceará, Brasil. BARROSO, C. X & MATTHEWS-CASCON, H. .......................................................................................79 Pan-American Journal of Aquatic Sciences (2009) 4 (1): 1-95 Population features of the spider crab Acanthonyx scutiformis (Dana 1851) (Crustacea, Majoidea, Epialtidae) associated with rocky-shore algae from southeastern Brazil. TEIXEIRA, G. M., FRANSOZO, V., COBO, V. J. & HIYODO, C. M. ........................................................87 Diffusion Material - Do not cite Original scientific photographs ODA, F. H., FELISMINO, M. F., LOPES, L. P. C. & ODA, T. M. ...............................................................I Pan-American Journal of Aquatic Sciences (2009) 4 (1): 1-95 Factors affecting the distribution and abundance of freshwater stingrays (Chondrichthyes: Potamotrygonidae) at Marajó Island, mouth of the Amazon River 1 2 MAURICIO PINTO DE ALMEIDA , RONALDO BORGES BARTHEM , ANDERSON 3 4 DA SILVA VIANA & PATRICIA CHARVET-ALMEIDA 1 Post-Graduate Program in Zoology, Federal University of Pará (UFPA) and Emílio Goeldi Museum, Pará (MPEG). Av. Perimetral, 1901 - Terra Firme. CEP: 66077- 830 - Belém - PA - Brazil. E-mail: [email protected] 2 Emílio Goeldi Museum, Pará (MPEG). Zoology Dept. / Ichthyology. P.O. Box: 399. CEP 66017- 970. Belém-Pa. E-mail: [email protected] 3 Federal University of Para (UFPA/ICEN). Av. Augusto Correa, 1. CEP: 66075-110. Belém - PA - Brazil. E-mail: [email protected] 4 Collaborating Researcher, Emílio Goeldi Museum, Pará (MPEG). Av. Perimetral, 1901 - Terra Firme. CEP: 66077- 830 - Belém - PA - Brazil. E-mail: [email protected] Abstract. Experimental fisheries were carried out at Marajó Island in regions with different environmental characteristics and using various fishing gears. A total of 344 specimens belonging to five described species (Plesiotrygon iwamae, Paratrygon aiereba, Potamotrygon motoro, Potamotrygon orbignyi and Potamotrygon scobina) and to two undescribed species were captured. The specific abundance and biomass were related with the environmental characteristics of the sampling points. Number of specimens captured, catch per unit effort (CPUE) and total weight values indicated that Potamotrygon motoro is the predominant species in this region, especially in the center of the island. Larger specimens of Potamotrygon motoro were registered in Arari Lake, while smaller ones were present on the island’s bordering areas. As other elasmobranchs, it is suggested that potamotrygonids present habitat occupation and use preferences related to environmental conditions. Key words: species composition, experimental fishery, potamotrygonids, Amazon estuary. Resumo: Fatores que afetam a distribuição e abundância de raias de água doce (Chondrichthyes: Potamotrygonidae) na ilha de Marajó, foz do rio Amazonas. Pescarias experimentais foram efetuadas na ilha de Marajó em regiões com características ambientais distintas e utilizando vários apetrechos de pesca. Um total de 344 espécimes, pertencentes a cinco espécies descritas (Plesiotrygon iwamae, Paratrygon aiereba, Potamotrygon motoro, Potamotrygon orbignyi e Potamotrygon scobina) e a duas não descritas foram capturados. A abundância e a biomassa por espécie foram relacionadas com as características ambientais dos pontos amostrais. O número de exemplares capturados, as capturas por unidade de esforço e peso total indicaram Potamotrygon motoro como sendo a espécie predominante nesta região, especialmente no centro da ilha. Exemplares maiores de Potamotrygon motoro foram registrados no lago Arari, enquanto que os menores estavam presentes nas bordas da ilha. Assim como observado em outros elasmobrânquios, é sugerido que as raias de água doce apresentam preferências quanto à ocupação e uso de habitat associados às condições ambientais. Palavras-chave: composição de espécies, pesca experimental, potamotrigonídeos, estuário Amazônico. Introduction Freshwater stingrays belong to the nomenclature of group remains unsolved but there Potamotrygonidae family, a monophyletic group of are approximately 20 described species for the elasmobranchs restricted to most river basins of the Neotropical region (Rosa 1985, Mould 1997, Neotropical region (Rosa, 1985). The taxonomy and Carvalho et al. 2003, Rosa & Carvalho 2007). Pan-American Journal of Aquatic Sciences (2009) 4(1): 1-11 2 M. P. DE ALMEIDA ET AL. Some Potamotrygonidae species previously al. 1967, Mabesoone 1970, Goulding et al. 2003, considered stenohalines (Brooks et al. 1981, Barthem & Goulding 2007). The present study seeks Thorson et al. 1983), have been observed in brackish to understand the relationship between the waters of the Amazon River mouth region (Charvet- freshwater stingray species composition and Almeida 2001, Almeida 2003). abundance and characteristics of the different Like other elasmobranchs, they have distinct habitats in the Amazon River mouth. environment occupation and habitat use patterns that include vertical and horizontal movements that may Materials and Methods lead to spatial and sexual segregation processes The Amazon River mouth is formed by the (Carrier et al. 2004). Johnson (1980) recognized that confluence of the Amazon and Tocantins River with habitat selection is a hierarchical process, with the Atlantic coast. The seasonal discharges