Almir Manoel Cunico

Effects of abiotic variables on the distribution of fish assemblages in streams with different anthropogenic activities in southern Brazil

Studies on fish assemblages in streams point out, that understanding the relationship between species and their environment is crucial for conservation. The present study aimed at evaluating the effects of changes in abiotic variables on the composition and structure of fish assemblages in Neotropical urban streams from southern Brazil with different levels of urbanization. The composition and structure of fish assemblages showed significant differences along the urbanization gradient observed in the streams. Tolerant and non-native species were found in more urbanized sites. A matrix correlation revealed a relationship between abiotic variables and the spatial pattern of structure and composition of fish assemblages. Abiotic variables, such as total phosphorus, dissolved oxygen, and conductivity, determined the distribution of fish assemblages. Streams without urban influence exhibited intrinsically low species richness, suggesting that they are highly susceptible to species loss and diversity reduction. Thus, changes in water quality or hydrological conditions induced by urbanization may intensify these impacts.

Invasion risks by non-native freshwater fishes due to aquaculture activity in a Neotropical stream

This study investigated the potential of aquaculture to spread non-native species associated with a high risk of invasiveness. We identified the biogeographic origin of produced fish species in the micro-watershed of the São Camilo stream, Brazil, the occurrence of non-native species in the São Camilo stream and the potential risk of biological invasions. Fish farmers were interviewed to obtain information about the species produced, and samples with electrofishing equipment were taken in the stream to detect the occurrence of non-native species. The Fish Invasiveness Screening Kit (FISK) protocol was applied to classify non-native species according to their invasive potential. We identified 59 fish farms and 19 produced fish species, including 13 non-native species. The non-native species Oreochromis niloticus represented 93% of production and was the second most abundant species in the stream. Eleven species were classified with a high invasive potential and two with a medium potential. The results showed the prevalence of non-native species use in aquaculture, with species escapes with a high invasive potential. Thus, the non-native species produced in aquaculture represent an important vector of introductions and risk to biodiversity conservation. It is vital to establish biosafety norms, to enable aquaculture to develop in a sustainable way.

Comparison of fish and macroinvertebrates as bioindicators of Neotropical streams.

The biomonitoring of aquatic ecosystems in developing countries faces several limitations, especially related to gathering resources. The present study aimed at comparing the responses of fish and benthic macroinvertebrates to environmental change, to identify which group best indicates the differences between reference and impacted streams in southern Brazil. We determined reference and impacted sites based on physical and chemical variables of the water. For the analysis and comparison of biological responses, we calculated 22 metrics and submitted them to a discriminant analysis. We selected from this analysis only six metrics, which showed that the two studied assemblages respond differently to environmental change. A larger number of metrics were selected for macroinvertebrates than for fish in the separate analysis. The metrics selected for macroinvertebrates in the pooled analysis (i.e., fish and macroinvertebrates together) were different from those selected in the separate analysis for macroinvertebrates alone. However, the metrics selected for fish in the pooled analysis were the same selected in the separate analysis for fish alone. The macroinvertebrate assemblage was more effective for distinguishing reference from impacted sites. We suggest the use of macroinvertebrates as bioindicators of Neotropical streams, especially in situations in which time and money are short.

Non-native fish species are related to the loss of ecological integrity in Neotropical streams: a multimetric approach

The use of multimetric indices (MMIs) became a common practice for evaluating ecological integrity of aquatic ecosystems. However, most developed MMIs ignore non-native species as an impact source to establish reference conditions. We developed an MMI to identify if non-native fish species are associated with Neotropical stream integrity by considering the presence of non-native species as an impact source. We calculated and evaluated responsiveness to the presence of non-native species using fish metrics, which were selected with a bootstrap procedure. Streams for calibration and validation were also selected with a bootstrap procedure. From the candidate MMIs generated, we selected models with different combinations of fish metrics. The generated MMIs presented a satisfactory performance in distinguishing reference streams from those impacted by non-native species. The abundance of non-native species was highly correlated with urbanization and seems to be more important than urbanization to drive native abundance loss. Our study is one of the first attempts to develop MMIs in which non-native species are considered as impact sources and used to identify impacted and reference sites. The final MMI that we developed might be a useful tool for aquatic biodiversity conservation and the development and application of non-native species control actions.

Brazil naturalizes non-native species

Brazils national policies are putting the countrys megadiversity at risk ([ 1 ][1]–[ 3 ][2]). After passing a 2016 law that will put constraints on biodiversity research ([ 3 ][2]), the Ministry of Agriculture, Livestock, and Supply has taken another controversial action: A new ordinance

Occurrence of non-native fish species in a Neotropical river under the influence of aquaculture activities

A introducao de especies nao nativas e uma das grandes mudancas globais e uma das principais ameacas a ictiofauna continental. Dessa forma, esse trabalho teve por objetivo avaliar a composicao e estrutura da ictiofauna do rio Azul, um tributario da margem esquerda da bacia do rio Piquiri, a fim de determinar a ocorrencia, abundância e distribuicao de especies de peixes nao nativas. Para isso, quatro amostragens foram realizadas de fevereiro a novembro de 2014 em tres locais ao longo do rio, por meio do uso de equipamento de pesca eletrica. Durante o periodo amostral, 32 especies de peixes foram registradas, as quais pertenceram a 20 generos, 11 familias e cinco ordens. Houve o registro de oito especies de peixes nao nativas, dentre elas Gymnotus inaequilabiatus e Oreochromis niloticus estiveram presentes entre as cinco mais abundantes no rio Azul. Desse modo, a ictiofauna do rio Azul seguiu o padrao de distribuicao esperado para a regiao Neotropical, com predominância de Characiformes e Siluriformes. Por outro lado, o aumento de ocorrencia de especies de peixes nao nativas, observado da cabeceira para a foz do rio, indica possivel processo de homogeneizacao biotica, potencialmente intensificado pelo escape de peixes nao nativos advindos de pisciculturas.The introduction of non-native species is one of the greatest global changes and is a substantial threat to continental fish fauna. This study aimed to evaluate the composition and structure of the fish assemblage of the Azul River, a tributary along the left margin of the Piquiri River basin, to determine the occurrence, abundance and spatial distribution of non-native fish species. Sampling was carried out from February to November 2014 at three sites along the river using of electric fishing equipment. Thirty-two fish species belonging to 20 genera, 11 families and five orders were collected. Eight non-native fish species were recorded, and Gymnotus inaequilabiatus and Oreochromis niloticus were listed among the five most abundant species in the Azul River. The fish fauna followed a distribution pattern expected for the Neotropical region, with a predominance of Characiformes and Siluriformes. However, the high representativeness of the abundance of the non-native species of the Gymnotiformes and Perciformes orders highlights the potential negative impacts on the structure of the fish assemblages of the Azul River due to species introductions.

The same old mistakes in aquaculture: the newly-available striped catfish Pangasianodon hypophthalmus is on its way to putting Brazilian freshwater ecosystems at risk

In the state of São Paulo in southeastern Brazil, a dangerous decree allows the culture of hybrids and non-native extralimital fish species in the Paraná and East Atlantic River basins. We recorded the illegal importation and sale of the non-native striped catfish Pangasianodon hypophthalmus in northeastern, central-western, southeastern, and southern areas of the country. This species is already consumed across Brazil and is cultivated for ornamental purposes. Besides escapes from fish farms and ‘fish and pays’, P. hypophthalmus can reach natural environments through aquarium dumping and ornamental ponds, motivated by its large size that reach after being sold at small size. The species has been introduced in many countries, and if established in Brazil, could put native Brazilian biodiversity and ecosystems at risk. Although importing specimens of P. hypophthalmus is prohibited by law, Decree 62.243/2016 in the state of São Paulo creates a new opportunity for invasion. In fact, once a novel fish species is moved to a new continent, it is irrational to supposed that it will stay static just in the area for which it was intended. In general, the fish disperse in the novel area on their own, by escapes from captivity or deliberate and illicit releases by persons or associations. The unwise attitude of Brazilian decision-makers and lay people in their attempt to develop aquaculture with non-native species goes against the objectives of responsible aquaculture based in native species.

Effects of land use on sediment composition in low-order tropical streams

The objective of this study was to evaluate the relative effects of watershed land-use on streambed substrate composition in eight low-order tropical streams. Data were collected at 24 sampling sites for eight wadeable streams in the Pirapó River Basin, southern Brazil. According to the percentage of impervious surfaces in the watershed, we defined the streams as either urban or rural. We estimate the percentages of the different streambed substrates, hydrological variables, and the rainfall intensity. The results showed that silt, sand and coarse particulate organic matter (CPOM) contributed to significant differences in streambed substrate composition between urban and rural streams. Silt, sand and CPOM were found in a higher mean proportion in the rural streams. Probably the urban streams have a greater bed load, promoted by precipitation and discharge, than rural streams, especially fine sediment. Rural streams have soft hydrographs, with stream flow slowly increasing during a rainstorm and subsequently decreasing over a long period after the rain event is over. These characteristics can provide the lixiviation of fine sediments into the stream channels due to land-surface clearance for agricultural activities and their accumulation in the streambed due to the moderate discharge regime.