Dorea Jose G, Barbosa Antonio C, Silva Gilmar S
Faculdade de Ciências da Saúde, Universidade de Brasília, Brasília, Brazil.
IBAMA (Brazilian Environmental Agency), Brasília, Brazil.
Comp Biochem Physiol C Toxicol Pharmacol. 2006 Mar-Apr;142(3-4):275-283. doi: 10.1016/j.cbpc.2005.10.014. Epub 2006 Jan 27.
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. eigenamanni, carnivorous), Piranha-preta (Serrasalmus rhombeus, carnivorous), Acará (Acarichthys heckellii, omnivorous), Aracú (Leporinus friderici, omnivorous), Orana-preta (Hemiodus unimaculatus, omnivorous), Sardinha (Triportheus elongatus, omnivorous), Branquinha (Potamorhina latior, detritivorous), Jaraqui-escama-fina (Semaprochilodus taeniurus, detritivorous), and Pacú-branco (Myleus torquatus, herbivorous) were studied during high (July) and low waters (February) and categorized by body mass. Regardless of hydrological period, ranges of total-Hg concentrations were higher for carnivorous than for omnivorous, detritivorous and herbivorous species. Some species (Traíra, Sardinha, Peixe-cachorro, Piranha branca, Piranha preta) showed changes in feeding patterns as indicated by an inverse trend of Hg bioaccumulation with season. Species with similar trends of Hg bioaccumulation showed higher Hg concentrations during the flooded season (Aracú, Pacú branco and Orana preta) and some had lower Hg (Acará, Branquinha and Tucunarés). Fish Hg concentration is species specific and reflects changes in feeding-behavior dominance brought by annual inundation.
内格罗河酸性黑水未受人为污染源影响，但其中鱼类的汞浓度相对较高。每年定期的洪水会改变水生环境，进而影响鱼类的觅食策略。我们研究了年度洪水对鱼类汞生物累积的影响。在高水位期（7月）和低水位期（2月）对图库纳雷鱼（Cychla属，肉食性）、狗鱼（Hydrolycus scomberoides，肉食性）、虎鱼（Hoplias malabaricus，肉食性）、白食人鱼（Serrasalmus aff. eigenamanni，肉食性）、黑食人鱼（Serrasalmus rhombeus，肉食性）、阿卡拉鱼（Acarichthys heckellii，杂食性）、阿拉库鱼（Leporinus friderici，杂食性）、黑斑半线脂鲤（Hemiodus unimaculatus，杂食性）、细长锯脂鲤（Triportheus elongatus，杂食性）、宽体半鲇（Potamorhina latior，食碎屑性）、细纹半鲇（Semaprochilodus taeniurus，食碎屑性）和白腹脂鲤（Myleus torquatus，草食性）进行了研究，并按体重进行了分类。无论水文时期如何，肉食性鱼类的总汞浓度范围均高于杂食性、食碎屑性和草食性鱼类。一些物种（虎鱼、细长锯脂鲤、狗鱼、白食人鱼、黑食人鱼）表现出觅食模式的变化，汞生物累积与季节呈反向趋势。汞生物累积趋势相似的物种在洪水季节汞浓度较高（阿拉库鱼、白腹脂鲤和黑斑半线脂鲤），有些则较低（阿卡拉鱼、宽体半鲇和图库纳雷鱼）。鱼类汞浓度具有物种特异性，反映了年度洪水带来的觅食行为优势变化。
