Valéria Flávia Batista-Silva

Relative abundance and reproductive tactics of a Loricariidae species at Saraiva Lagoon, Ilha Grande National Park, MS-PR, Brazil

This study aimed to evaluate population abundance patterns and the main events in the reproductive cycle of Loricariichthys platymetopon at Saraiva Lagoon, Ilha Grande National Park, MS-PR, Brazil. Monthly samplings were conducted from October 2004 to September 2005 in three sections of the lagoon: entrance, middle and end, which resulted in the capture of 175 individuals. Spatial and temporal variation in abundance was obtained through CPUE (number of captured individuals/1000 m2 of gillnets in 12 hours). The reproductive tactics considered were: duration, time and location of spawning, oocyte diameter and fecundity. The highest relative abundance was recorded in February, in the middle section of the lagoon, and the reproductive period lasted from September to February. The prevalence of females with spent ovaries and at rest in the following months indicated that reproductive activity ceased during autumn and winter. We observed that reproduction was high at the end section of the lagoon. The recorded mean oocyte diameter was 1.67 (SD ± 0.76) mm, mean absolute fecundity was 962.1 (SD ± 382.48) oocytes, and relative fecundity was 7.60 (SD ± 2.25) oocytes/g and 5.13 (SD ± 0.75) oocytes/cm. These tactics, probably are related to the settlement of L. platymetopom in Saraiva Lagoon, as well as in the different biotopes of the Upper Parana River floodplain.

Ichthyofauna from three streams of the lower Iguatemi River in the upper Paraná river basin, Brazil

The ichthyofauna from 3 streams (Água Boa, Perobão, and Santa Maria) to the lower Iguatemi River were inventoried, which is located in the upper Paraná river basin, in Mato Grosso do Sul state, Brazil. Sites in the upper, intermediate, and lower portions of each stream were quarterly electrofished from March to December 2008. All sampled fish (n = 6,816 individuals) represented 43 species of 5 orders, and 16 families. The most abundant species was Phalloceros harpagos (63.5%), followed by Astyanax aff. paranae (10.6%), Hypostomus ancistroides (5.9%), Gymnotus inaequilabiatus (3.4%), and Knodus moenkhausii (2.7%). Despite the high ichthyofauna richness in the lower portion of Iguatemi River, the need to implement and/or expand soil conservation practices and riparian forest restoration is of utmost importance to maintain these populations in the long term.

Assemblage of immature Odonata (Insecta, Anisoptera) in streams of the Mato Grosso do Sul State: spatial implications

This study investigated the assemblages attributes (composition, abundance, richness, diversity and evenness) and the most representative genera of Odonata, Anisoptera at Agua Boa and Perobao Streams, Iguatemi River basin, Brazil. Both are first order streams with similar length that are impacted by riparian forest removal and silting. Quarterly samplings were conducted from March to December 2008 in the upper, intermediate and lower stretch of each stream. The Mantel test was used to check the influence of spatial autocorrelation on the Odonata composition. Spatial variations in the composition were summarized by the Principal Coordinates Analysis (PCoA) using Mantel test residuals. The effects of spatial correlation on richness and abundance were investigated by the spatial correlogram of Moranʼs I coefficients. The most representative genera in each stream were identified by the Indicator Value Method. The spatial variations in the attributes of the assemblages were assessed using analysis of variance of null models. We collected 500 immature individuals of 23 genera and three families. Among the attributes analyzed only the composition and abundance showed significant spatial differences, with the highest mean abundance found in the Perobao Stream. Miathyria and Zenithoptera were the indicator genera of the Agua Boa Stream and Erythrodiplax, Libellula, Macrothemis, Progomphus and Tramea were the indicator genera of the Perobao Stream.