Paulo Vanderlei Sanches

Morphological description of the developmental stages of Parauchenipterus galeatus (Linnaeus, 1766) (Siluriformes, Auchenipteridae) on the floodplain of the upper Paraná River

We provide morphological and morphometric descriptions of the developmental stages of Parauchenipterus galeatus, from the floodplain of the Upper Parana River. Specimens were obtained by induced spawning. The species has large adhesive eggs with a double membrane. The incubation period is long, 65 hours at 27°C. The larvae are well developed at hatching, with relatively rapid larval development. Analysis of the morphometric data showed that the body parts of P. galeatus grow proportionately.

Ontogenetic shifts in digestive tract morphology and diet of fish larvae of the Itaipu Reservoir, Brazil

We analyzed the ontogenetic shifts in digestive tract morphology and diets of the young of Iheringichthys labrosus, Hypophthalmus edentatus and Plagioscion squamosissimus, sampled in the Itaipu Reservoir, Brazil-Paraguay. We described the dental structures, the gill rakers and the digestive tract, and analyzed the diet of the young fish. We observed teeth in the jaws and pharynx in young of the three species. In H. edentatus, the gill rakers developed more rapidly, and were longer and more numerous on the first arch, related to their planktivorous feeding habit. I. labrosus and P. squamosissimus had long gill rakers only on the first arch, they were short and thick on the rest. The stomach was defined only in P. squamosissimus, with pyloric caeca. Their diets were mainly zooplankton. I. labrosus fed particularly on cladocerans and rotifers; H. edentatus consumed essentially cladocerans; and P. squamosissimus fed basically on copepods. We observed greater similarity in diet between the young of I. labrosus and H. edentatus, especially for the first length classes. The diet of I. labrosus became more diversified at the end of the larval period, indicating a transition in the feeding habit and habitat for this species. P. squamosissimus showed a very different diet from the others species. The differences in oral anatomy, allied to the morphology of the digestive tract, visual acuity, swimming hability, way of foraging, and especially mouth position, form and size, were determining factors in the diets of these species.

Spatial and temporal distribution of larvae and juveniles of Hoplias aff. malabaricus (Characiformes, Erythrinidae) in the Upper Paraná River floodplain, Brazil

Spatial and temporal distribution of larvae and juveniles of trahira, Hoplias aff. malabaricus (Erythrinidae), and their relationship with environmental parameters in the Upper Paraná River floodplain were analyzed. Sampling of larvae and juveniles of H. aff. malabaricus has been conducted during the period from November 1991 through February 1995, with 42 sampling stations distributed in four sub-areas: Ivinhema I, Ivinhema II, Baía, and Paraná. During the same period, data were obtained for water temperature, dissolved oxygen, pH, electrical conductivity, river level, precipitation index, and photoperiod. The largest catches of larvae were in the Ivinhema I sub-area (47.06%), and of juveniles in the Paraná sub-area (54.55%). Larvae and juveniles were caught from October to February. Larvae were mainly collected at night and in all types of environments sampled (lotic, semi-lotic, and lentic). Principal Component Analysis of the environmental parameters and larval density showed that the largest catches were obtained in dry season months, with low values for temperature, electrical conductivity, river level, and photoperiod, and with high concentrations of dissolved oxygen and pH. This reproductive strategy may minimizes predation and maximizes food utilization, as it enables the fish to reach advanced developmental stages, while most other species are spawning.

Caracterização morfológica e distribuição temporal de larvas e juvenis de Apareiodon affinis (Steindachner) (Osteichthyes, Parodontidae) no alto rio Paraná, Paraná

With the purpose of characterizing morphologicaly the larvae and juveniles of Apareiodon affinis (Steindachner, 1879) and to verify their temporal distribution monthly samples were taken at Leopoldos Inlet, upper Parana River. The specimens were captured with a conic-cylindrical plankton net of mesh size 0,5mm from March 1991 to February 1992. Soon after identification, the specimens were separeted according to their development (prefle-xion, flexion, posflexion and juvenile) and then the moiphometric analyses were performed. The results showed that the larvae were captured from August 1991 to February 1992, with greatest densities in November 1991. The specimens occured in every timetable, however, larvae in pretlexion and flexion were captured during day time and, posflexion and juvenile, at night. According to series of morphological development, high body proportions variation were verifyed mainly in the head lenght, eye diameter and in height body. Moreover, the individuais showed little pigmentation and myomeres number changing between 39 to 42. The majority of morphometric characteristics have negative allometry with the cxception of head lenght with regard to standart lenght that have positive allometry.

Spatial and temporal distribution patterns of ichthyoplankton in a region affected by water regulation by dams

The aim of this work was to study the occurrence of ichthyoplankton in a region affected by water regulation by dams. The study area was located in the region of Ilha Grande National Park, upper Parana River floodplain. Specifically, we examined the temporal and spatial distribution of Ichthyoplankton, identified spawning areas and established the relationships between the abundances of fish eggs and larvae and some limnological and hydrological variables. Samples were taken monthly between October and March from 2001 to 2005 at 24 sampling sites. For analytical purposes, the sampling sites were grouped into upper, middle and lower areas. The upper area of the National Park had the highest egg density and should be considered the primary spawning area. The middle area should be considered a drift area, and the lower area likely functions as a growth and feeding habitat. Statistical analyses showed that the spawning was influenced by water temperature, pH, fluviometric level and rainfall, and that larval density was influenced by pH, conductivity, dissolved oxygen and rainfall. The results also revealed that the tributaries apparently are used as migratory routes by fish, and and this shows the need to protect these sites.

Temporal distribution and composition of the ichthyoplankton from Leopoldo's Inlet on the Upper Paraná River floodplain (Brazil)

Univ Estadual Maringa, Dept Biol, Posgrad Ecol Ambientes Aquat Continentais, BR-87020900 Maringa, Parana, Brazil