Comparison of biometric factors of the invasive species Plagioscion squamosissimus (Heckel, 1840) in four reservoirs of the Paranapanema River, upper Paraná, Brazil

Abstract: The Paranapanema River is an important, extensively explored tributary of the Upper Paraná River basin. The fish fauna of the Paranapanema River has been investigated since the 1990s; however, no study has characterized the richness of fish species throughout the basin, including the main channel of the river, marginal lagoons, its tributaries, and sub-tributaries. Thus, we performed a review with 90 independent studies conducted at the upper, middle, and lower sections of the basin. We recorded 225 species, of which 165 were native, and 60 were non-native. We found that 77% of the species within the basin are composed by Siluriformes and Characiformes. Cichliformes had a significant number of non-native species established in impoundment sections of the basin. Incidence-Based Estimators (Bootstrap and Chao 2) demonstrated that the richness of native species is still underestimated. Some native (e.g., Hypostomus ancistroides) and non-native species (e.g., Plagioscion squamosissimus) are widely distributed in the basin, while others had a more restricted distribution. Among the registered species, the family Bryconidae had the highest number of representatives with threatened conservation status. In addition, we observed that the Capivara Reservoir and its tributaries were the most sampled regions, with the majority of studies performed in the Lower Paranapanema basin. The species richness recorded in large tributaries, such as Tibagi, Cinzas, Congonhas, and Pirapó rivers is critical for maintaining the fish fauna in the Paranapanema River. Our contribution may be used to support management actions and conservation strategies, as well as to indicate regions in the basin that need to be better inventoried.

The objective of our study was to evaluate the efficacy of DNA barcoding as a tool to identify non-native fish in their early stages of life. Specimens were collected from 14 sites in the lower and middle regions of the Paranapanema River—the main tributary of the Upper Parana River basin in southern Brazil. Over three reproductive periods from 2012 and 2015, 75 eggs and 170 larvae from 13 non-native fish species were identified. The most abundant species were Plagioscion squamosissimus (75 specimens) and Serrasalmus marginatus (68 specimens). The highest abundance was found near the Rosana hydroelectric plant reservoir. The removal of the natural physical barrier is the main reason that fish are introduced into the Paranapanema River basin with higher occurrence in the Rosana reservoir. P. squamosissimus was found in all reservoirs. DNA barcoding is a useful tool for identifying non-native fish during their reproductive phase. Furthermore, recording the presence of potentially invasive species in their early development stages may provide information useful for the rapid and effective control.

Fish diversity loss is threatened by the construction of dams as they prevent the regular natural dispersal among populations. Thus, conservation of key riverine habitats for fish reproduction may be essential for the recruitment of new native species of fish. The present study aimed to identify key habitats for fish spawning and early development in the Paranapanema River basin, as well as to determine the taxonomic composition, reproductive and life-history strategy, and to report spatial distribution of eggs, larvae and juveniles. The importance of lagoons, tributaries, and sub-tributaries was evaluated in the Paranapanema River basin between October 2012 and March 2013. Eggs and larvae samples were collected at dawn and dusk with conical plankton nets (0.5 mm mesh size), whereas juveniles were captured during the day with seine and sieve (0.5 cm mesh size). A total of 547 eggs, 904 larvae and 1 228 juveniles were captured. We observed that 2 larvae and 288 juveniles of non-migratory species, parental care, and equilibrium life-history strategy, predominated in lagoons and tributaries. On the other hand, 13 larvae and 60 juveniles of short migratory distance, no parental care, and periodic life-history strategy predominated in sub-tributaries. The highest densities of eggs were recorded in tributaries and sub-tributaries (Tukey’s test, P = 0.001 and P = 0.03, respectively), and the highest densities of larvae were recorded for lagoons and tributaries (P = 0.005 and P = 0.0001, respectively). Captures of eggs and larvae were higher at night; while the highest catches per unit effort of juveniles were recorded for tributaries and sub-tributaries. Fish species that adopt different life-history strategies can use diverse types of habitats during the early stages. Lagoons, tributaries and sub-tributaries of the Paranapanema River play different roles in the reproductive success of fish fauna in a heavily modified basin. The preservation of spawning and nursery areas trapped between reservoirs is necessary for Neotropical fish species recruitment and survival. Rev. Biol. Trop. 66(2): 605-621. Epub 2018 June 01.

Abstract: This work is the most comprehensive survey of the Laranjinha River´s fishes, a tributary of the Cinzas River, Paranapanema River basin. Throughout its course, there is only a low-height dam, including a transposition system located 98 km from its mouth. The sampling was carried out in nine locations, from the source to the mouth, with six field incursions in each location, using different fishing gear. A total of 11,924 fish were collected, distributed in seven orders, 27 families, and 100 species. The most representative order in the number of species was Siluriformes, followed by Characiformes. As for the families, Loricariidae comprised 21% and Characidae 14% of species richness. Phalloceros harpagos was the species with the highest absolute abundance, representing 11.3% of the total, followed by Hypostomus ancistroides with 9.8%. However, considering the average abundance and frequency of occurrence, Hypostomus ancistroides was the most abundant species, followed by Hypostomus cf. paulinus, Psalidodon aff. paranae and Phalloceros harpagos. Among the collected species, the Apteronotus acidops, Brycon orbygnianus, Brycon nattereri, Crenicichla jupiaensis, and Rhinelepis aspera were classified as endangered on the most recent IUCN Red List. Also, from the total sampled fish, 9.8% are considered non-native species. Among the native species recorded, 10 species are large migratory species, which indicates that the Laranjinha River is a route for spawning and maintenance of species diversity in the middle Paranapanema River. Therefore, the Laranjinha River is a heritage of fish diversity and deserves special attention in its preservation.

Cytogenetic and morphometric analyses were carried out in Hoplias aff. malabaricus specimens from six distinct populations from the lower Paranapanema River basin, located between the states of Paraná and São Paulo, Brazil. Measurements were also taken from a specimen collected in Surinam. In a population from a fish farm station at Universidade do Norte do Parana (EPUNOPAR), two sympatric cytotypes (2n = 40 and 2n = 42 chromosomes) are found. A population from a fish farm station at Universidade Estadual de Londrina (EPUEL) shows 2n = 42 meta-submetacentric chromosomes for males and females with a simple sex chromosome system of XX/XY type. Populations from the Vermelho and Rancho Alegre Rivers, Três Bocas Stream and Paranapanema River have 2n = 39 chromosomes in males and 2n = 40 chromosomes in females, showing a multiple sex chromosome system of X(1)X(1)X(2)X(2)/X(1)X(2)Y type. Twenty morphological variables were studied. These measurements were used for an analysis of the canonical variables and standard analysis of proportional measurements. The most variable measurements among the specimens are the maxilla length (MXL) and the pre-dorsal distance (PDD). Analysis of canonical variables indicates three distinct groups in the first canonical axis formed by: (1) Três Bocas Stream, (2) Rancho Alegre + Vermelho River + EPUNOPAR and (3) EPUEL + Paranapanema River. This axis retained 79.4% of information from the original matrix. Analysis of morphometrics reveals differences among populations from the Paranapanema River basin and between these and the specimen from Surinam. The morphometric and cytogenetic differences among the studied populations suggest a species complex.

The influence of cage aquaculture on the attraction and aggregation of wild fish was evaluated with an experimental tilapia farming structure. The structure was installed in the Corvo River, Rosana Reservoir, Paranapanema River basin, for 140 days. Samples were taken before and after farming began. Gillnets on the surface and near the bottom at different distances from the cages (0, 100 and 400 m) were used for fish sampling. The effects of the food supply at two protein levels were also analysed: Phase 1 = 32% PB and Phase 2 = 28% PB. Changes in species richness and abundance were observed, with the number of individuals and the fish biomass increasing significantly just after the farming began. Some species, such as Iheringichthys labrosus, presented increased abundance near the cages, while others, such as Plagioscion squamosissimus, were more abundant far from the cages. Auchenipterus osteomystax was the most abundant species during the experiment, especially when the protein content of the pellets was higher. It was demonstrated that farming tilapia in cages profoundly altered the abundance and composition of the wild ichthyofauna, suggesting the need to propose effective regulations for such activities, including fisheries restrictions in farmed areas or even the prohibition of cage farming.

This study presents the first record of the sardine Platanichthys platana (Regan, 1917) in the Paranapanema River basin and provides insights into the species' ecological traits. A total of 164 juveniles and adults were sampled in 2019 and 2020 in the Lower Paranapanema River. Morphological analyses confirmed species identification, while reproductive analyses revealed different age classes among individuals, with higher sex ratio of females and mature gonads. Additionally, stomach analyses indicated a diet primarily composed of insects, followed by microcrustaceans. This species has been dispersing rapidly in the Upper Paraná River, where its reproductive characteristics may help its establishment, especially in reservoirs. Also, its feeding ecology favors its survival. However, interactions with large-sized invasive predators and influx of heavy metals in the food chain can occur, in addition to competition with small-sized native species.

A new species of Phenacorhamdia is described from Paranapanema River, Upper Paraná River basin, southeastern Brazil. The new species is distinguished from congeners by the combination of following characters 45-46 vertebrae; an entirely dark-brown body; nine pleural ribs; eight branched rays in upper lobe of caudal fin; seven branched rays in pectoral fin; 13 anal-fin rays with 9-10 branched; first basal radial inserted at the 13th vertebrae and eight branchiostegal rays.

Here we provide an ichthyofaunistic inventory of the Cerqueira César municipality, in the middle Paranapanema River drainage, upper Paraná River basin, São Paulo State, southeastern Brazil. Collections were carried out in 10 streams and in the Novo River, an important watercourse in the Paranapanema River basin. We caught a total of 808 individuals comprising 49 fish species. Among our main findings-in addition to the high species richness in the sampled region-was the capture of a probably undescribed species of Cambeva and the non-native poeciliid Poecilia reticulata. Some individuals were not identified accurately at the species level, requiring future evaluations. Our study fills an important gap on the ichthyofauna of the municipality of Cerqueira César and may, in the future, assist in new studies on impacts on waterbodies in the studied region.

Fish introductions are common practices due to intentionally or unintentionally translocations of species between watersheds. Herein we report the spread of the non-native cichlid Laetacara araguaiae Ottoni & Costa 2009 in the Paranapanema River basin, southern Brazil. Native from the Araguaia River (Central Brazil), this species was probably introduced by releases made by aquarists. Its new area of occurrence is characterized as natural nursery and important for the life cycle of native fish. Due to its biological characteristics, the species has the ability to cause a negative impact on the aquatic biota through possible interactions, such as predation of eggs, larvae and juveniles of native fish, and spread of parasites.Keywords: biological invasion, Cichlinae, fish, exotic species, Upper Paraná River basin.

O trabalho apresenta os resultados do inventário e da distribuição das diatomáceas da classe Bacillariophyceae de sedimentos superficiais de cinco reservatórios em cascata do rio Paranapanema. Amostras foram coletadas com draga em três locais (montante, região intermediária e lacustre) dos reservatórios. Foram identificados 44 táxons infragenéricos, sendo 23 (52,3%) novas citações para a bacia do rio Paranapanema, quatro (9,1%) para o Estado de São Paulo e duas (4,5%) para o Estado do Paraná. São disponibilizados dados morfométricos, comentários relevantes, distribuição espacial e local de ocorrência das espécies para os Estados de São Paulo e Paraná. A riqueza de espécie foi nitidamente mais elevada no primeiro reservatório da série (Jurumirim) e na estação com influência do rio Tibagi. Este trabalho traz contribuição pioneira para o país no que se refere à biodiversidade e distribuição espacial das diatomáceas em reservatórios em cascata, podendo subsidiar futuros estudos sobre conservação e monitoramento na bacia hidrográfica do rio Paranapanema.

RESUMO Com o declínio evidente de populações de anfíbios causadas pela alteração do hábitat, muitas áreas que estão inseridas em hotspots do Brasil ainda precisam ser estudadas, a fim de aumentar o conhecimento sobre a anurofauna e fornecer melhores perspectivas de conservação. Um dos ecossistemas criticamente ameaçados é a Floresta Estacional Semidecidual (FES), cuja extensão foi reduzida a aproximadamente 7% da cobertura original, dispersos em pequenos fragmentos. O objetivo deste estudo foi descrever a anurofauna de uma localidade inserida em paisagem de FES na região da Bacia Hidrográfica do Rio Paranapanema, considerada uma lacuna geográfica no conhecimento de anfíbios. Além disso, foi avaliada a eficiência de métodos de amostragem de anuros e verificada a similaridade com taxocenoses inseridas em FES e/ou Cerrado de diferentes regiões da mesma bacia hidrográfica. O estudo foi conduzido nas margens do Rio Paranapanema, divisa dos estados de São Paulo e Paraná. Foram realizadas nove fases de campo trimestrais, entre novembro de 2005 a novembro de 2007 que resultou em um esforço de 45 dias de amostragem. Foram registradas 25 espécies de anfíbios anuros distribuídas em seis famílias. Pelo método de amostragem em sítio de reprodução obteve-se o maior registro de espécies (88,5%). O método de armadilhas de interceptação e queda também foi eficiente, proporcionando o registro de cerca de 45% das espécies, além de possibilitar o registro exclusivo de Physalaemus nattereri (Steindachner, 1863) eRhinella ornata (Spix, 1824). Além disso, 90% das espécies terrícolas registradas, que são tipicamente categorizadas como espécies de área aberta, foram registradas no interior dos remanescentes florestais por este método. Através da comparação com as outras taxocenoses, verificou-se uma alta dissimilaridade de espécies mesmo em áreas mais próximas e que a composição de espécies entre as localidades não está sendo determinada pela distância geográfica. Características distintas entre as espécies registradas, como modo reprodutivo e associação a diferentes hábitats, em conjunto com grau de diversidade encontrada entre as taxocenoses, deixa clara a importância da preservação desta região para a conservação de anfíbios.

Factors affecting arsenic and mercury accumulation in fish from the Colombian Caribbean: A multifactorial approach using machine learning.

The development of cage fish farms has been associated with an increase in parasitic diseases. Organic matter resulting from feed waste and faeces attracts animals such as birds and invertebrates that can act as hosts for parasites. The aim of this study was to evaluate the influence of cage farming on Austrodiplostomum compactum metacercariae infections of Plagioscion squamosissimus collected close to a cage farm in the Chavantes reservoir (Paranapanema River). Thirty-seven fish were collected in an area close to cages (CF), and 28 in an area not influenced by cages (CT). All specimens were weighed, measured and the eyes removed for morphological analyses of metacercariae. The prevalence, mean intensity of infection, mean abundance and condition factor were calculated. The prevalence (CF = 86.4%, CT = 57.1%), mean infection intensity (CF = 20.31 ± 1.13, CT = 4.29 ± 7.14) and mean abundance (CF = 17.70 ± 6.27, CT = 2.35 ± 0.77) were higher in the CF (P< 0.05) group. There were no significant correlations (P> 0.05) between the mean abundance and standard length or the total weight and condition factor in either group (P> 0.05). Fish farms may interfere with the life cycle of A. compactum, leading to more infections with P. squamosissimus. This could be due to an increase in the number of host animals that are attracted by the availability of food resources derived from fish farms.

This study reports the occurrence of Austrodiplostomum compactum metacercariae in the freshwater fish Schizodon intermedius (ximborê/piava) from a Neotropical reservoir in the Paranapanema River, state of São Paulo, Brazil. From a total of 75 fish collected, we found 38 infected with A. compactum metacercariae (prevalence = 50.67%) in the eyes. The mean intensity of infection and mean abundance were 9.05 ± 4.26 (1-155) and 4.59 ± 2.20 (0-155), respectively. Poulin's Discrepancy Index was 0.87 and four specimens presented more than 10 metacercariae in their eyes. No correlation was observed between parasite abundance and standard length, total weight and condition factor (p>0.05). These metacercariae are reported for the first time in S. intermedius.