| effects of water ph and calcium concentration on ion balance in fish of the rio negro, amazon. | we examined the effects of acute low-ph exposure on ion balance (na+, cl-, k+) in several species of fish captured from the rio negro, a dilute, acidic tributary of the amazon. at ph 5.5 (untreated rio negro water), the four rio negro species tested (piranha preta, serrasalmus rhombeus; piranha branca, serrasalmus cf. holandi; aracu, leporinus fasciatus; and pacu, myleus sp.) were at or near ion balance; upon exposure to ph 3.5, while na+ and cl- loss rates became significant, they were relative ... | 1998 | 9472808 |
| parasitic fauna of eight species of ornamental freshwater fish species from the middle negro river in the brazilian amazon region. | twenty-seven specimens of cardinal tetra paracheirodon axelrodi, 33 rosy tetra hyphessobrycon copelandi (characidae), 28 marbled hatchetfish carnegiella strigata, 26 blackwing hatchetfish carnegiella martae (gasteropelecidae), 27 bodó ancistrus hoplogenys (loricariidae), 31 brown pencilfish nannostomus eques, 38 oneline pencilfish nannostomus unifasciatus (lebiasinidae) and 13 angelfish pterophyllum scalare (cichlidae) were collected from the middle negro river, state of amazonas, brazil, for pa ... | 2010 | 20624347 |
| evidence of mercury biomagnification in the food chain of the cardinal tetra paracheirodon axelrodi (osteichthyes: characidae) in the rio negro, central amazon, brazil. | in this study, nitrogen stable isotope (δ(15) n) and total mercury (thg) analyses were conducted on algae, submersed and emergent macrophytes, shrubs and trees, macrobrachium sp. and paracheirodon axelrodi collected in three streams that drain a large interfluvial region in the middle rio negro, amazonas state, brazil. samples were collected during different hydrological periods over 12 months in lower stream reaches and their headwaters; the latter being characterized by shallow, open-canopy sw ... | 2016 | 27028984 |