Loch Craiglin cannot be considered as merely an isolated basin of Loch Sween. Its shallowness, the great growth of vegetation round the shore and the fluctuations in salinity make it atypical. On the more complete isolation of the loch with the making of the dam, these conditions led to a lack of circulation, a consequent development of hydrogen sulphide in the deep water and very high pH values near the surface. One could not therefore expect the plankton to be very similar to that in the outside loch (see, however, Marshall, 1947). Unfortunately there are no records of seasonal variation before fertilization was begun. In spite of these drawbacks Loch Craiglin was a convenient and manageable area for small-scale experiments on fertilization.The experiments may be divided into two groups, those which were not followed up in detail and those in which the plankton and hydrographic results were followed from day to day. The former, made during the earlier stages of the work, are mainly described in the previous papers and led to the conclusion that the richness in phytoplankton of Loch Craiglin in 1943 was probably caused to a large extent by fertilization. Those of the second group, described above, were made to test special points and different fertilizers. Two experiments made during the summer of 1944 had apparently no effect on the phytoplankton but a third in which a very large excess of fertilizer (ten times the normal quantity) was added, gave a good increase after an initial lag. At that time the attached algae were abundant and their needs apparently had to be satisfied before any nutrients could be used by the phytoplankton.The remaining experiments, which were therefore made during the winter, showed that commercial ammonium sulphate, ammonium nitrate and monoammonium phosphate could replace the sodium nitrate and superphosphate used hitherto. Two further experiments in the following spring using ammonium chloride and urea did not, however, prove effective. All the salts used had been found in laboratory tests by Miss F. A. Stanbury to be suitable for diatom growth, and the reason for the failure of these two in the loch is unknown.The utilization of the nutrients was extremely rapid even in winter but it is probable that their disappearance is not entirely caused by the phytoplankton or bottom-living algae but partly by adsorption on the bottom mud or by suspended matter. On one occasion it may have been caused by a serious fall in loch level.The zooplankton which during the first year of fertilizations was richer in Loch Craiglin than in the outside loch diminished in the second year and remained poor thereafter in spite of, or perhaps because of, the intensive fertilizations. The dense phytoplankton and other vegetation raised the pH at times to levels dangerous to animal life.

中文翻译：

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海湖施肥的进一步实验（克雷格林湖）。不同植物营养素对浮游植物的影响

克雷格林湖不能仅仅被视为斯文湖的一个孤立盆地。它的浅浅、海岸周围植被的大量生长以及盐度的波动使其非典型。随着大坝的建造，湖泊更加完全隔离，这些条件导致缺乏循环，导致深水中硫化氢的发展和表面附近非常高的 pH 值。因此，人们不能指望浮游生物与外湖中的浮游生物非常相似（但是，请参见 Marshall，1947 年）。不幸的是，在受精开始之前没有季节性变化的记录。尽管有这些缺点，克雷格林湖还是一个方便且易于管理的小规模受精实验区域。实验可分为两组，那些没有详细跟踪的，以及那些每天都跟踪浮游生物和水文结果的。前者是在工作的早期阶段制作的，主要在以前的论文中有所描述，并得出结论，1943年克雷格林湖浮游植物的丰富性可能在很大程度上是受精造成的。如上所述，第二组的那些被用来测试特殊点和不同的肥料。1944 年夏天进行的两个实验显然对浮游植物没有影响，但在第三个实验中添加了大量过量的肥料（正常数量的十倍），在最初的滞后后得到了很好的增长。那时附着的藻类很丰富，显然必须满足它们的需求，浮游植物才能利用任何营养。因此在冬季进行的剩余实验表明，商业硫酸铵、硝酸铵和磷酸一铵可以代替迄今使用的硝酸钠和过磷酸钙。然而，在接下来的春天使用氯化铵和尿素进行的两次进一步的实验并没有证明是有效的。FA Stanbury 小姐在实验室测试中发现所有使用的盐都适合硅藻生长，而这两种盐在湖中失败的原因尚不清楚。即使在冬季，营养物质的利用也非常迅速，但它们的消失可能并不完全是由浮游植物或底栖藻类造成的，而是部分由底泥吸附或悬浮物质造成的。有一次，它可能是由于湖泊水位的严重下降造成的。在施肥的第一年，克雷格林湖中的浮游动物比外面的湖更丰富，但在第二年减少了，尽管如此，或者可能是此后仍然很穷因为，密集的施肥。密集的浮游植物和其他植被有时会将 pH 值提高到对动物生命危险的水平。在施肥的第一年，克雷格林湖中的浮游动物比外面的湖更丰富，但在第二年减少了，尽管或者可能是因为密集的施肥，但此后仍然很穷。密集的浮游植物和其他植被有时会将 pH 值提高到对动物生命危险的水平。在施肥的第一年，克雷格林湖中的浮游动物比外面的湖更丰富，但在第二年减少了，尽管或者可能是因为密集的施肥，但此后仍然很穷。密集的浮游植物和其他植被有时会将 pH 值提高到对动物生命危险的水平。