Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1033AAJ Buenos Aires, Argentina; Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (ESS-FBCB-UNL), 3000 Santa Fe, Argentina.
Ecotoxicol Environ Saf. 2013 Dec;98:142-51. doi: 10.1016/j.ecoenv.2013.09.010. Epub 2013 Sep 27.
Sediments are important elements of aquatic ecosystems and in general sediments accumulate diverse toxic substances. Amphibians potentially have a greater risk of exposure to contaminants in sediments, and the test of sediments provides first lines of evidences. Sediment outdoor microcosm experiments were conducted to analyze biological endpoints (survival, development, growth, and morphological and organ malformation), enzyme activity (butyrylcholinesterase, BChE; glutathione-S-transferase, GST; and catalase, CAT) and blood biomarkers in veined treefrog Trachycephalus typhonius tadpoles, a widespread neotropical species. Hatching (stage 23) of T. thyphonius was exposed until they reached metamorphosis (stage 46). Sediment tests were performed and four different treatments were used: three ponds (LTPA, ISP, and SSP) influenced by industrial and agricultural activities and a reference treatment from a forest (RFS). Physical and chemical variables and concentration of nutrients, pesticide residues, and metals were determined. One treatment was metal-rich (LPTA) and two were nutrient-rich (ISP and SSP). Sediment treatments had no significant effect on survival; in contrast they had significant sublethal effects on T. typhonius larval development and growth rates, and affected overall size and shape at stage 38. Principally, in LPTA animals were significantly larger than in RFS, exhibiting swollen bodies, tail muscles and tail fin. In addition, metamorphs from LPTA, ISP, and SSP were smaller and showed signs of emaciation by the end of the experiment. Statistical comparisons showed that the proportions of each type of morphological abnormalities (swollen bodies and diamond shape, gut uncoiling, diverted gut, stiff tails, polydactyly, and visceral and hindlimb hemorrhaging) were significantly greater in metal- and nutrient-rich sediment treatments. Moreover, activities of BChE, GST and CAT, as well as and presence of micronuclei, immature, mitotic, anucleated erythrocytes varied significantly among treatments. Our biological effects-based sediment study highlights the use of different biological endpoints and biomarkers on anuran larvae at sites where pond sediment is risky and sediment management should be considered. Finally, the information of those biological endpoints and biomarkers would be useful as a management tool to decide if there are sufficient exposures of tadpoles to suspected pollutants on sediment.
沉积物是水生生态系统的重要组成部分，通常会积累各种有毒物质。两栖动物接触沉积物中污染物的风险可能更大，而沉积物测试则提供了初步的证据。本研究采用室外沉积物微宇宙实验，分析了广泛分布于新热带地区的斑腿泛树蛙（Trachycephalus typhonius）蝌蚪的生物终点（存活率、发育、生长以及形态和器官畸形）、酶活性（丁酰胆碱酯酶、BChE；谷胱甘肽 S-转移酶、GST；和过氧化氢酶、CAT）和血液生物标志物。在孵化阶段（23 期），将斑腿泛树蛙暴露于实验中，直至变态发育阶段（46 期）。进行了沉积物测试，使用了四种不同的处理方法：三个受工业和农业活动影响的池塘（LTPA、ISP 和 SSP）和一个森林参考处理（RFS）。测定了物理化学变量以及营养物、农药残留和金属的浓度。其中一个处理富含金属（LPTA），两个富含营养物（ISP 和 SSP）。沉积物处理对存活率没有显著影响；但对斑腿泛树蛙幼虫的发育和生长速度有显著的亚致死影响，并在 38 期影响了整体体型和形状。主要是，LPTA 组的动物明显比 RFS 组的大，表现出身体肿胀、尾部肌肉和尾鳍肿胀。此外，到实验结束时，来自 LPTA、ISP 和 SSP 的变态动物体型较小，表现出消瘦的迹象。统计比较表明，在富含金属和营养物的沉积物处理中，畸形（肿胀的身体和菱形、肠道未卷曲、肠道移位、僵硬的尾巴、多指、内脏和后肢出血）的形态异常比例显著更高。此外，BChE、GST 和 CAT 的活性以及微核、未成熟、有丝分裂、无核红细胞的存在在处理之间存在显著差异。本基于生物效应的沉积物研究强调了在池塘沉积物存在风险的地点使用不同的生物终点和生物标志物来研究两栖动物幼体，应该考虑沉积物管理。最后，这些生物终点和生物标志物的信息将作为管理工具有用，以确定沉积物中疑似污染物对蝌蚪的暴露是否足够。
