| light and electron microscopic study of a myxosporean, tetrauronema desaequalis n. sp. (fam. tetrauronematidae), from an amazonian fish. | tetrauronema desaequalis n. sp. described from the bases of the ventral fins of the teleost hoplias malabaricus boch, 1794, was collected in an estuarine region of the amazon river near belem, brazil. this myxosporean produces large cysts (1-2 mm in diameter) that represent plasmodia containing all life cycle stages, including spores. spores averaged 22.5 microns in total length and possess 2 pairs of posterolateral unequal projections extending from beside the sutural ridges near the terminus o ... | 1996 | 8604098 |
| mercury and selenium concentrations in fish samples from cachoeira do piriámunicipality, parástate, brazil. | mercury is a major public health concern because of its widespread occurrence in the environment and its toxic effects on humans, mainly through fish ingestion. on the other hand, selenium is known by its antioxidant effect. for this reason, the knowledge of the correlation between mercury and selenium concentrations in fish samples can bring important information allowing a better understanding of mercury equilibrium in the inhabitants of the amazon region. in this paper, total mercury and sele ... | 2005 | 15589232 |
| mutagenic effects of mercury pollution as revealed by micronucleus test on three amazonian fish species. | genotoxic effect of mercury pollution over amazonian fish species was evaluated by using the micronucleus test (mnt). distinct mean frequencies of micronuclei (mn) were observed in three trophically distinct characin fish species collected in two riverine environments in the amazon basin: the madeira (polluted area) and the solimões (unpolluted area) rivers. mean frequencies of mn observed in prochilodus nigricans (detritivore), mylossoma duriventris (omnivore), and hoplias malabaricus (piscivor ... | 2005 | 15589237 |
| fish mercury bioaccumulation as a function of feeding behavior and hydrological cycles of the rio negro, amazon. | the acidic black waters of the rio negro are unimpacted by anthropogenic sources and yet, are characterized by fish containing relatively high hg concentrations. regular annual flooding alters the aquatic environment, thereby affecting fish feeding strategies. we studied the impact of annual flooding on fish-hg bioaccumulation. tucunarés (cychla spp, carnivorous), peixe-cachorro (hydrolycus scomberoides, carnivorous), traíra (hoplias malabaricus, carnivorous), piranha-branca (serrasalmus aff. ei ... | 2006 | 16443397 |
| factors controlling hg levels in two predatory fish species in the negro river basin, brazilian amazon. | a number of environmental factors have been shown to influence the dynamics of hg in aquatic ecosystems. here we investigate the influence of fish size, ph, dissolved organic carbon (doc), and the availability of potential methylation sites (floodplain forests and hydromorphic soils) on the concentration of total hg in two carnivorous fishes: cichla spp. and hoplias malabaricus in the negro river, brazil. fish and water samples for chemical analysis were collected from 33 sites in the negro basi ... | 2006 | 16690103 |
| influence of ecological factors and of land use on mercury levels in fish in the tapajós river basin, amazon. | mercury (hg) contamination of riparian communities and of environmental compartments of the amazon can be directly related to the occupation of the territory. the objective of this study was to identify the characteristics of aquatic environments that are associated with high levels of hg in ichthyofauna. our research aimed at determining the influence of variables related to fish ecology, types of aquatic environment, fishing activities by local riparian populations, and watershed use on the le ... | 2009 | 19356749 |
| seasonal pattern in parasite infracommunities of hoplerythrinus unitaeniatus and hoplias malabaricus (actinopterygii: erythrinidae) from the brazilian amazon. | the present study investigated the effects of seasonal variation in parasites infracommunities of hoplerythrinus unitaeniatus and hoplias malabaricus from a tributary of amazon river. for h. unitaeniatus and h. malabaricus, 11 parasite species were similar, and greatest parasite richness occurred during the rainy season. ichthyophthirius multifiliis was the dominant parasite species for both hosts. in h. unitaeniatus, infection by whittingtonocotyle caetei, whittingtonocotyle jeju, urocleidoides ... | 2016 | 26751882 |
| structure of the parasites communities in two erythrinidae fish from amazon river system (brazil). | this study compared the parasite communities of hoplias malabaricus and hoplerythrinus unitaeniatus from amazon river system. hoplias malabaricus were infected by ichthyophthirius multifiliis, piscinoodinium pillulare, tetrahymena sp., urocleidoides eremitus, braga patagonica, metacercariae of clinostomum marginatum, procamallanus (spirocamallanus) inopinatus, larvae of contracaecum sp. and larvae of nomimoscolex matogrossensis. hoplerythrinus unitaeniatus were also infected by these same specie ... | 2015 | 26083690 |