EFFECT OF WATER SALINITY AND FOOD SALT CONTENT ON GROWTH AND SODIUM-EFFLUX OF HATCHLING DIAMONDBACK TERRAPINS (MALACLEMYS)
EFFECT OF WATER SALINITY AND FOOD SALT CONTENT ON GROWTH AND SODIUM-EFFLUX OF HATCHLING DIAMONDBACK TERRAPINS (MALACLEMYS)
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DOI：
10.1086/physzool.58.6.30156077
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发表时间：
1985-11-01
期刊：
影响因子：
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通讯作者：
DUNSON, WA
中科院分区：
文献类型：
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作者：
DUNSON, WA
在孵化时和之后的许多个月内（直到它们达到约 50 克），小菜斑龟无法在盐度高于约三分之二的海水中生长。然而，盐分和每两周喝一次淡水只能实现有限的生长。与淡水或 50% 海水中的动物相比，在 28℃ 25% 海水中，孵化水龟的生长受到刺激。在渗透压与 25% 海水相似的 0.25 摩尔甘油溶液中生长的幼体，其生长速度与淡水中相同。注射了氯化钠的幼龟的钠流出率升高（约65μmol/100g湿质量.cntdot.h），表明泪腺盐腺具有功能。孵化时，体内含水量（77.0%）远高于成虫（64.5%），体内钠浓度（μ.ol/g干重）略高。然而，以μol/g湿质量为单位的钠浓度仅为成人水平的71%。当开始喂养时，体内钠浓度（以μmol/g湿重计）上升至成人水平。海水盐度进一步增加至 50%。在 100% 海水中，身体大小与水流出量之间存在反比关系，这种差异似乎是较小水龟对盐水耐受性较差的原因之一。相比之下，幼体的钠流入量仅略有增加。喂食水龟的钠流出率与喂食率直接相关。然而，高盐度下钠吸收的主要来源似乎是摄入食物期间偶然吞咽的水，而不是食物本身的盐含量。
At hatching and for many months afterward (until they reach about 50 g), diamondback terrapins cannot grow in salinities above about two-thirds seawater. Yet salinities and offered one drink of fresh water every 2 wk can achieve limited growth. In 25% seawater at 28 C, growth of hatching terrapins is stimulated in comparison with animals is fresh water or 50% seawater. Hatchlings grown in 0.25 Molal glycerol solutions, osmotically similar to 25% seawater, have the same growth rates as those in fresh water. Hatchling terrapins injected with NaCl have an elevated rate of sodium efflux (about 65 .mu.mol/100 g wet mass .cntdot. h), indicating that the lachrymal salt glands are functional. At hatching, body water content (77.0%) is much higher than that of adults (64.5%), and body sodium concentration (.mu.ol/g dry mass) is slightly higher. However, sodium concentration in units of .mu.ol/g wet mass is only 71% of adult levels. When feeding commences, body sodium concentration (as .mu.mol/g wet mass) rises to adult levels. Further increases occur in salinities up to 50% seawater. There is an inverse relation between body size and water efflux in 100% seawater, and this difference appears to be one cause of the lesser tolerance of smaller terrapins to saline water. In contrast, sodium influx in hatchlings is only slightly elevated. The rate of sodium efflux in fed terrapins is directly correlated with feeding rate. However, the main source of sodium uptake at higher salinities appears to be incidental swallowing of water during ingestion of food-not the salt content of the food itself.