Lucileine de Assumpção

The use of morphometric analysis to predict the swimming efficiency of two Neotropical long-distance migratory species in fish passage

This study investigated the external body morphology (based on morphometric data) and the swimming efficiency in fish passages (based on the ascent time in a fish ladder) of two Neotropical long-distance migratory species. The fish were collected in the fish ladder of the Porto Primavera Hydroelectric Power Plant (known as Engenheiro Sergio Motta), upper Parana River, Brazil. The species differ in several morphometric ratios related to swimming performance. Prochilodus lineatus exhibited a higher muscle ratio and caudal fin length ratio. However, Leporinus elongatus showed higher values for the fineness ratio, a higher length from snout to pectoral fin base ratio, and a higher caudal peduncle depth factor. Although both species show good swimming performance, the characteristics listed above may enable L. elongatus to apply greater power and propulsion, allowing it to reach a high swimming speed and to exhibit greater efficiency than P. lineatus. Leporinus elongatus moves faster than P. lineatus and has a lower mean ascent time (1.39 hours) than P. lineatus (3.76 hours). Prochilodus lineatus would require a somewhat longer time to pass through the fish ladder.

Genetic Diversity of the Endangered Neotropical Cichlid Fish (Gymnogeophagus setequedas) in Brazil

Gymnogeophagus setequedas is a rare and rheophilic species of tribe Geophagini, considered endangered in Brazilian red lists. Its previously known geographical distribution range was the Paraná River basin, in Paraguay, and a tributary of the Itaipu Reservoir in Brazil. Since its description no specimens have been collected in the original known distribution area. However, recent records of G. setequedas in the lower Iguaçu River, in a region considered highly endemic for the ichthyofauna, extended the known geographical distribution and may represent one of the last remnants of the species. The aim of this study was to estimate the genetic diversity and population structure of G. setequedas, using microsatellite markers and mitochondrial haplotypes, in order to test the hypothesis of low genetic diversity in this restricted population. Muscular tissue samples of 86 specimens were obtained from nine locations in the Lower Iguaçu River basin, between upstream of the Iguaçu Falls and downstream of the Salto Caxias Reservoir. Seven microsatellites loci were examined and a total of 120 different alleles were obtained. The number of alleles per locus (NA) was 17.429, effective alleles (NE) 6.644, expected heterozygosity (HE) 0.675, observed (HO) heterozygosity 0.592, and inbreeding coefficient (FIS) 0.128. Twelve haplotypes in the D-Loop region were revealed, with values of h (0.7642) and π (0.00729), suggesting a large and stable population with a long evolutionary history. Thus, both molecular markers revealed high levels of genetic diversity and indicated the occurrence of a single G. setequedas population distributed along a stretch of approximately 200 km. The pattern of mismatch distribution was multimodal, which is usually ascribed to populations in demographic equilibrium. Nevertheless, the construction of a new hydroelectric power plant, already underway between the Salto Caxias Reservoir and Iguaçu Falls, could fragment this population, causing loss of genetic diversity and population decline, and for this reason it is necessary to maintain the Iguaçu River tributaries and downstream area from the Lower Iguaçu Reservoir free of additional dams, to guarantee the survival of this species.

Desenvolvimento embrionário, larval e juvenil de Hemisorubim platyrhynchos (Siluriformes, Pimelodidae) da bacia do rio Paraná

O objetivo deste estudo foi descrever o desenvolvimento embrionario, larval e juvenil da jurupoca, Hemisorubim platyrhynchos (Valenciennes, 1840), bem como as mudancas nos padroes de crescimento alometrico durante a ontogenia inicial da especie. Um total de 90 ovos, 210 larvas e 24 juvenis provenientes de reproducao induzida foram analisados quanto a variaveis morfometricas e meristicas, alem do coeficiente de crescimento alometrico em relacao a cabeca, tronco e cauda durante o periodo larval e juvenil inicial. Os ovos apresentaram diâmetro medio de 1,74 mm, espaco perivitelino amplo (21,29%), com media de 0,37 mm, e diâmetro medio do vitelo de 1,08 mm. O comprimento padrao (CP) das larvas variou de 3,47 a 11,85 mm, com a maioria das medidas apresentando aumento proporcional ao longo do desenvolvimento. O numero total de miomeros variou de 40 a 46 (pre-anal=15-17 e pos-anal=24-30). As larvas iniciais de H. platyrhynchos apresentam pigmentacao na cabeca e na regiao ântero-ventral do corpo (anterior e posterior do saco vitelino). No estagio de pos-flexao, a pigmentacao se intensifica, distribuindo-se na regiao dorsal da cabeca, formando uma faixa longitudinal que se estende do focinho ao operculo, assim como uma faixa transversal, de um flanco a outro, passando pela regiao anterior da nadadeira dorsal, com maculas distribuidas ao longo do corpo nos juvenis (CP=19,5-49,09 mm). Nos primeiros estagios de desenvolvimento larval, a cabeca e a cauda crescem muito mais rapidamente do que o tronco, o que indica prioridades relacionadas a alimentacao e natacao, as quais posteriormente tendem a isometria, com um crescimento rapido do tronco nos juvenis iniciais.

Mudanças morfológicas no trato digestório e composição da dieta de larvas e juvenis do linguado catathyridium jenynsii no reservatório de Itaipu, rio Paraná, Brasil

The objective of this study was to characterize the diet and digestive tract morphology of flounder, catathyridium jenynsii (gunther, 1862) (achiridae), in its early stages of life. for analysis of the digestive tract, we used a specimen of each larval stage, pre-flexion to post-flexion, and juvenile. a total of 256 larvae and 16 juveniles, belonging to five classes of standard length was analyzed for diet. data were collected in the itaipu reservoir, parana river, brazil, from september, 2001 to march, 2002, and from september, 2002 to february, 2003. the occurrence and numerical methods were applied for determining the occurrence frequency and numerical frequency of each food item in different standard length (sl) classes. the anterior digestive tract of c. jenynsii began to differentiate into the stomach at 4.70 mm sl (not presented pyloric caeca). since the stage of pre-flexion, there are three intestinal folds and a lot of grooves in the digestive tract. the dietary analysis showed that the smaller larvae (class 1) had a distinct diet, with dominance of cladocerans (mainly bosmina hagmanni and bosminopsis deitersi). for class 2, the copepod notodiaptomus sp. was important both in number and occurrence, however b. hagmanni also had significant importance in the diet. already the largest larvae (classes 3 and 4) and juveniles (class 5) showed a similar diet, consuming mainly copepods (notodiaptomus sp.). therefore, in this study, larvae of c. jenynsii can be considered zooplanktivore, since in all stages of development, copedods and cladocerans dominated the diet. changes in diet followed the morphological changes of the early stages of c. jenynsii.

DISTRIBUIÇÃO ESPACIAL E TEMPORAL DE OVOS E LARVAS DE PEIXES NO RIO AGUAPEÍ SP, ALTO RIO PARANÁ

Este estudo teve como o objetivo avaliar a ocorrencia e distribuicao espacial e temporal de ovos e larvas de peixes, bem como, verificar a composicao e estrategias reprodutivas das especies ao longo do rio Aguapei - SP. As coletas foram realizadas mensalmente de outubro/2009 a marco/2010, atraves de arrastos horizontais na superficie da agua durante 10 minutos ao anoitecer utilizando rede de plâncton conico-cilindrica de 0,5mm de malha. Diferencas significativas na densidade media do ictioplâncton entre os locais e meses foram averiguadas atraves da Analise de Variância Unifatorial (ANOVA one-way). Um total de 1.626 ovos e 1.547 larvas foram coletados. A ANOVA aplicada nao demonstrou diferencas significativas nas densidades do ictioplâncton em relacao aos pontos amostrados. Com relacao a distribuicao temporal diferencas significativas p<0,05 foram constatadas para a densidade de ovos e larvas ,com pico na densidade media de ambos em novembro. Trinta e tres taxons de larvas foram identificados, com ocorrencia de especies com diferentes estrategias reprodutivas. As larvas da familia Anostomidae foram as mais abundantes, porem, destacaram-se a ocorrencia de quatro especies migradoras de longa distância ( Prochilodus lineatus, Hemisorubim platyrhynchos/Pseudoplatystoma corruscans, Pimelodus maculatus e Sorubim lima ). Os resultados obtidos neste trabalho demonstram a importância do rio Aguapei como area de desova de varias especies de peixes, sendo importante a preservacao destas areas de desova a fim de manter as populacoes de peixes do rio Parana.

Characterization of the early development of Pseudoplatystoma reticulatum Eigenmann & Eigenmann, 1889 (Siluriformes: Pimelodidae) from the Paraguay River Basin

This study described the initial development of Pseudoplatystoma reticulatum, as well as changes in growth patterns. Morphometric and meristic variables were analyzed during embryonic, larval and juvenile periods, even as allometric growth coefficients for larvae and juveniles. Eggs showed an average diameter of 1.79 mm and broad perivitelline space (23.41%). The total length (TL) of the larvae ranged from 3.05 to 25.72 mm, and the total number of myomeres ranged from 45 to 50 (preanal = 13-16 and postanal = 30-35). Initial pigmentation is poor, concentrated at the extremities of the yolk sac. In the flexion stage, the pigmentation intensifies and forms a longitudinal stripe extending from the snout to the operculum and two longitudinal stripes on the body, one dorsal and the other ventral, that unite at the caudal peduncle. At first, there is a differential growth of the head and tail, and then there is the growth of the body, which shows changes in the ontogenetic priorities of feeding, swimming, and breathing capacities. Our results are very important for ecology, systematics, and hatchering, especially in terms of ontogenetic variation in morphology, growth, feeding, behavior, and mortality of P. reticulatum.

Morphological differentiation among migratory fish species from the Paraná River basin

Este estudo caracterizou as diferencas morfologicas entre especies de peixes migradores da bacia do rio Parana. Um total de 117 peixes adultos das especies Leporinus elongatus, Leporinus macrocephalus, Prochilodus lineatus, Salminus brasiliensis, Pimelodus maculatus, Pinirampus pirinampu, Pseudoplatystoma corruscans, Pterodoras granulosus e Rhaphiodon vulpinus foram capturados no Canal da Piracema, um sistema de transposicao para peixes na barragem de Itaipu, rio Parana. As especies migradoras foram analisadas atraves de 22 medidas morfometricas e razao fineza para identificar padroes morfologicos relacionados a capacidade natatoria. Quatro grupos de especies foram evidenciados pela Analise de Cluster: I) R. vulpinus; II) P. corruscans; III) L. macrocephalus, L. elongatus, P. lineatus, P. maculatus e S. brasiliensis, medidas de altura de cabeca e comprimento da nadadeira anal formaram este grupo; e IV) P. granulosus e P. pirinampu - medidas de largura maxima do corpo e largura do pedunculo caudal contribuiram para a formacao deste grupo. As variaveis morfometricas que mais contribuiram para distincao dos grupos I e II foram comprimento da cabeca e largura da boca. As especies R. vulpinus e P. granulosus diferiram das demais, apresentando razao de fineza de 9,4 e 3,7, respectivamente. Leporinus elongatus, L. macrocephalus, P. lineatus, P. maculatus, S. brasiliensis diferiram significativamente das demais especies com valores de razao fineza que variaram entre 4,57 a 5,19, indicando que estas especies podem apresentar melhor desempenho natatorio. As especies migradoras de longa distância que utilizam o Canal da Piracema para ascender areas a montante diferiram morfologicamente, caracteristicas morfologicas como pedunculo caudal estreito e largura maxima do corpo, bem como os valores de razao de fineza foram determinantes na diferenciacao das especies aqui analisadas.