APPENDIX IV 



NOTE ON KELP 



The variety of kelp {Macrocystis pyrifera) found upon the coast of South Georgia 

 seems to have one very marked feature, a feature noticed at Undine in the north-west, 

 at Larsen in the south-east, and at every intermediate point so far examined both in 

 sheltered and exposed situations. This is that in no case has it been found rooted at a 

 greater depth than 14 fathoms low water (chart datum). In this respect it seems to differ 

 from that found in Patagonia by H.M.S. 'Beagle', of which Darwin writes. 



In South Georgia, owing to the steepness of the bottom, it was often found that 

 although 20 or even 30 fathoms were obtained at the tips of the plant's fronds, the roots 

 were invariably in 14 fathom or less. It appears that the kelp grows in as little as 

 I fathom or less, but never very close to a shelving beach, owing no doubt to the con- 

 tinual wash of the surf. For the same reason the tops of breaking rocks have invariably 

 been found to be quite bare, although often surrounded by kelp in somewhat greater 

 depths where the water does not break. This is particularly so in more open water, where 

 the waves break with greater violence. 



The kelp only grows on a rocky or stony bottom and never on sand, mud, or even 

 shingle, unless the latter is of large stones ; this is of course quite understandable since 

 it requires only a firm anchorage. 



In fjords which contain a glacier, kelp is never found within a considerable distance of 

 the glacier — often a mile or more. This is caused mainly by the ice which is constantly 

 floating away from the glacier, but may be partly due to the freshness of the water. 



It is reported, but not personally verified, that the kelp shows a considerable shrinkage 

 in some of the harbours of South Georgia and also to some extent along the coasts, and 

 I have formed the opinion that this is due almost entirely to the movements of vessels. 

 The rate of growth of kelp during the close season cannot be sufficient to make up for 

 the destruction caused during the remainder of the year, especially as it is not com- 

 pletely undisturbed even then. The rate of growth must nevertheless be considerable, 

 as it was seen that some of the channels, such as those at Husvik and in Merton passage 

 (Barff Point), had appreciably narrowed between May and September 1929. 



King Edward Cove (Chart I), having a maximum depth of 1 1 fathoms with a gravel 

 bottom, was apparently completely covered by kelp when first visited, but has now only 

 a small fringe near the entrance. This disappearance must be due primarily to move- 

 ments of vessels and has been helped latterly by the fouling of the water and the bottom 

 by effluents from the whaling station. Although the depth was here not too great, the 

 gravel bottom in the centre would be unsuitable and the kelp must have grown out from 

 the sides. At Stromness Harbour kelp is reported to have extended over a considerable 

 part of the harbour, though only a narrow strip round the shore is shoal enough for it to 

 grow. We have evidence that the fronds grow to a great length, and though none were 

 actually measured, some that we saw must have exceeded 100 ft. Ice undoubtedly 

 destroys a great deal of kelp, but this cannot account for the shrinkage which has 

 occurred during the past twenty-five years. 



