The effect of salinity on the acute toxicity of cadmium to the tropical, estuarine, hermaphroditic fish, Rivulus marmoratus: A comparison of Cd, Cu, and Zn tolerance with Fundulus heteroclitus
The effect of salinity on the acute toxicity of cadmium to the tropical, estuarine, hermaphroditic fish, Rivulus marmoratus: A comparison of Cd, Cu, and Zn tolerance with Fundulus heteroclitus
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盐度对热带河口雌雄同体鱼类Rivulus marmoratus镉急性毒性的影响：与Fundulushetroclitus的Cd、Cu和Zn耐受性比较
DOI：
10.1007/bf00230709
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发表时间：
1993
影响因子：
4
通讯作者：
W. Dunson
中科院分区：
文献类型：
--
作者：
H. Lin;W. Dunson
红树林中的鱼，Rivulus marmoratus，是唯一的脊椎动物，是一个同步的，内部自我繁殖的雌雄同体。这种独特的繁殖模式产生的后代几乎没有遗传变异，这为该物种在生物测定中的使用提供了显着的优势。在淡水（低[Ca+Mg]、低[Na+K]）、含Cl盐的14 ppt模拟海水（高[Ca + Mg]、高[Na + K]）和两种人工条件（高[Ca + Mg]、低[Na +K]和低[Ca+ Mg]、高[Na+K]）下，进行了Cd急性（96 h）LC 50试验。对于四种处理中的每一种，在不同时间进行两次重复，结果具有很好的重现性。结果表明，Cd对土壤的平均LC_（50）（mg/L）分别为2.96（淡水）、21.12（高[Ca+Mg]、高[Na+K]）、17.86（高[Ca+Mg]、低[Na+K]）和12.67（低[Ca+Mg]、高[Na+K]）。在14 ppt海水（由Instant Ocean™盐制成）中进行的另一项测试产生了24.48 mg Cd/L的96 h LC 50，因此与高[Ca+Mg]-高[Na+K]处理相似，尽管阴离子和阳离子浓度存在一些差异。[Ca+Mg]、[Na+K]和[Cl]相互作用决定Cd毒性的程度尚不清楚，尽管[Cl]的作用可能等于或大于[Ca+Mg]。当所有的溶质是高的，它是可能的，与Cl（248 mM）的Cd络合物的形成导致所观察到的减少镉毒性与硬淡水相比，而不是增加的二价[Ca+Mg]水平。需要进一步的试验中，各种阳离子和阴离子的变化，尽可能独立，以确定它们的作用，在影响游离[镉]，或与鳃相互作用，以减少Cd toxicity.Interstrain镉毒性的变化是显着的，四个菌株的R。在高[Ca+Mg]、高[Na+K]条件下，测定了不同浓度Cd对大理石鲈的LC_（25）、LC_（50）和LC_（75）。应变DS始终是最敏感的，而应变NA始终是最耐镉在三个镉暴露水平。因此，我们建议使用一个单一的菌株进行毒性试验，或菌株随机化处理。两个重复的96小时LC 50的三种重金属，镉，铜和锌，为条纹细溪的每一个被发现的值forFundulus heteroclitus，一个标准的河口生物测定鱼。Cd、Cu和Zn在14 ppt时对Rivulus的平均LC_（50）分别为21.1、1.4和147.9mg/L，对Fundulus的平均LC_（50）分别为18.2、1.7和129.5mg/L。这种相似性的毒理学反应由两个物种从不同的地理区域（热带与温带）可能是由于类似的生理和生化适应的非生物压力河口。
The mangrove-dwelling fish,Rivulus marmoratus, is the only vertebrate that is a synchronous, internally self-fertilizing hermaphrodite. This unique reproductive mode yields offspring with little genetic variation, which offers significant advantages for the use of this species in bioassays. We conducted acute (96 h) LC50tests of Cd toxicity under four different water chemistry conditions, representing fresh water (low [Ca+Mg] and low [Na+K]), 14 ppt sea water simulated with Cl salts (high [Ca+Mg] and high [Na+K]) and two artificial conditions (high [Ca+Mg], low [Na+K] and low [Ca+Mg], high [Na+K]). Two replicates were conducted at different times for each of the four treatments and the results were very reproducible. The mean LC50's as mg total Cd/L were 2.96 (fresh water), 21.12 (high [Ca+Mg], high [Na+K]), 17.86 (high [Ca+Mg], low [Na+K]) and 12.67 (low [Ca+Mg], high [Na+K]). An additional test in 14 ppt sea water (made up from Instant Ocean™salts) yielded a 96h LC50of 24.48 mg Cd/L, and was thus similar to the high [Ca+Mg]-high [Na+K] treatment, despite some differences in anion and cation concentrations. The degree to which [Ca+Mg], [Na+K] and [Cl] interact to determine Cd toxicity is still unclear, although the role of [Cl] is likely to be equal to or greater than that of [Ca+Mg]. When all solutes are high, it is likely that the formation of a Cd complex with Cl (248 mM) leads to the observed reduction in Cd toxicity in comparison with hard fresh water, not the increased divalent [Ca+Mg] levels. Further tests are needed in which the various cations and anions are varied as independently as possible in order to determine their roles in affecting free [Cd], or interacting with the gills to reduce Cd toxicity.Interstrain variation in Cd toxicity was marked; four strains ofR. marmoratuswere exposed to three levels of Cd (LC25, LC50and LC75estimated from tests of high-[Ca+Mg], high-[Na+K] conditions). Strain DS was consistently the most sensitive, whereas strain NA was consistently the most resistant to Cd across the three Cd exposure levels. Thus we recommend use of a single strain to conduct toxicity tests, or randomization of strains across treatments.Two replicate 96h LC50tests of each of the three heavy metals, Cd, Cu and Zn, forRivulus marmoratuswere found to be similar to values forFundulus heteroclitus, a standard estuarine bioassay fish. The mean LC50's of Cd, Cu and Zn at 14 ppt forRivuluswere 21.1, 1.4 and 147.9 mg/L, respectively, whereas those forFunduluswere 18.2, 1.7 and 129.5 mg/L. This similarity in toxicological response by two species from different biogeographic regions (tropical vs temperate) may be due to similar physiological and biochemical adaptations to the abiotically stressful estuary.