The rio Machado (also known as Ji-Paraná) is a tributary of the rio Madeira in the Amazon basin. Currently, the rio Madeira contains the greatest fish species richness of the world, with approximately 1,000 species. The present study presents the fish inventory from streams of the rio Machado basin. In total, 75 stream reaches, 80 meter-length, randomly selected, were sampled in 2011 (August to October) and 2012 (June to July). Overall, 22,875 fish in eight orders, 32 families, 89 genera, and 140 species were collected. Richness estimators indicate that almost 90% of the expected richness was registered. The great majority of specimens (52.2%) was represented by small sized piabas such as Serrapinnus aff. notomelas, Moenkhausia collettii, Serrapinnus microdon, and Hemigrammus melanochrous. Of the total richness, 25 species were restricted to 9°00’ S and 10°00’ S; among them, 14 were exclusive to the lower portion of the basin, which exhibits the larger proportion of native vegetation covering.
This work assessed freshwater fishes collected at 12 stations located along the Tarumã River, middle Machado River, Madeira River basin. The fieldwork took place in May and September 2015 during the high and low water seasons, respectively. We gathered 1,482 specimens representing seven orders, 30 families, 54 genera and 74 species using seine, gill, and hand nets. The family Characidae was the most representative, exhibiting the highest number of species captured. The species with the greatest abundance were Hemigrammus vorderwinkleri, Hyphessobrycon bentosi, Hemigrammus cf. bellottii, Bryconella pallidifrons, and Apistogramma resticulosa. Two species that remained unidentified are probably a new species. This study represents the third fish survey totally conducted at a Conservation Unit in the Rondônia State, and will certainly provide valuable information for future investigations on biodiversity conservation in the Machado River.
Keywords: Amazon, freshwater, conservation, ichthyofauna, inventory.
Peixes da Reserva Biológica do
Preliminary characterization of benthic invertebrates caught as by-catch in the shrimp fishery in the north of the Rio de Janeiro State, southeastern Brazil ABSTRACT. In order to characterize the biodiversity of the benthic invertebrate by-catch associated with the shrimp fishery at Farol de São Thomé harbour, northern Rio de Janeiro State, Brazil, in 2004, 11 monthly trawls were conducted using bottom trawl nets between 22°00'S and 22°20'S and from 3 to 5 nm from the shoreline. The analyzed data for each taxon and/or species include frequency of occurrence, numeric frequency, biomass, Index of Relative Importance, and abundance. In total, 27 benthic invertebrate species were recorded, including Porifera, Cnidaria, Mollusca, Annelida, Crustacea, Echinodermata, and Bryozoa. The most representative group was Crustacea, both in number of specimens (Petrochirus diogenes, Hepatus pudibundus, Callinectes ornatus) and in biomass (P. diogenes, H. pudibundus). In terms of the frequency of occurrence in the samples, 11 species (40.7%) were constant, 6 species (22.2%) were accessories, and 10 species (37.0%) were by-catch.
The subterranean fish Phreatobius sanguijuela, originally described from Bolivia, was captured in different wells near São Francisco do Guaporé, Rondônia State, Brazil. Thirty wells were investigated in April and July 2012, and September 2013. These surveys resulted in the capture of 58 individuals from eight wells and comprised three to 14 individuals per well. The capture of the individuals allowed a detailed evaluation of their colours in life, behaviour in the field and in captivity, aspects of their biology, confirmation of the species identification and provided new diagnostic characteristics to distinguish between P. sanguijuela and Phreatobius dracunculus. Cannibalism, territorialism, agonistic interactions and phototaxis behaviour were not observed. Phreatobius sanguijuela exhibited cryptobiotic habits and two behaviours under stressful conditions. The analysis of stomach contents reveals that this species apparently feeds on invertebrates, almost exclusively on earthworms. The sex ratio was 1:1. The absence of opercular movement during the resting period associated with intense blood irrigation of the skin indicates a possible cutaneous respiration as an alternative form of gas exchange. Local people often mistake P. sanguijuela for helminths and have the habit of releasing non-native fishes into the wells or to use chemicals to eliminate them. The consequence of this habit for the conservation of the species requires further evaluation.
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