POTASH FROM KELP. 39 
prietors of seaside resorts complain that the kelp set adrift by har- 
vesters litters the beaches, temporarily ruining them for bathing. 
Great quantities of buoyant kelp are often set adrift by harvesters 
and come in on the beaches, whereas, if not cut, most of it would 
eventually sink. However, this littering of the beaches is periodic— 
less than the usual amount of sloughing occurring between cuts—and 
the perishable harvest drift is not so persistent as litter as the large 
plants which often are torn loose and washed up on the beaches; fur- 
thermore, this objection can be overcome by properly timing the cut- 
ting of beds adjacent to beach resorts. 
It is not at all unlikely that clearing away the mat of kelp from 
the surface repeatedly would disturb the fish that hide in the shad- 
ows of it, and might drive away some. Doubtless the kelp indirectly 
furnishes some food to useful fish, as well as to some forms which 
are not useful. But harvesting does not destroy fish or fish spawn. 
Inspection of nearly 1,000 tons of kelp in process of being harvested 
and of hundreds of tons aboard the harvesters failed to reveal a total 
of 10 pounds of sea food, even including kelp crabs. Nor has careful 
examination, from rowboats, of hundreds of acres of kelp revealed 
a single fish egg. 
Instead of its killing the des harvesting is apparently beneficial 
to Macrocystis in many cases. It might thin out elk kelp (Pelagophy- 
cus) which grows and fruits at the top and which can not come up 
again from the base if cut off, but in the case of Macrocystis, which, 
normally is continuously renewing itself from the base, harvesting 
is comparable to pruning trees or cutting hay. Just as trees with 
very heavy foliage are sometimes upr ooted in violent storms, so kelp 
plants with an excess of floating material are driven ashore in storms. 
Harvesting this floating material whenever a considerable quantity 
accumulates tends to reduce destruction of the beds by storms. 
As for exposing the shores, the heavy “ground swell” seems able 
to get through any kelp bed, no matter how heavy, violent storms 
tearing out any plants that may oppose. In addition to maintain- 
ing a proper balance between holdfast and floating fronds, har- 
vesting removes old fronds fouled with animal and vegetable 
growths, which obstruct the passage of light and are of little or no 
service to the plant. Usually in a heavy kelp mat there are uprooted 
plants drifting and decaying on the surface of the water along with 
rubbish of all kinds. Such refuse obstructs the passage of light, 
hinders circulation, and furnishes a breeding ground for disease. 
Harvesting clears this refuse away and floods with light the actively 
growing parts at the bases of the plants, stimulating the production 
of an abundant healthy new growth, and probably increasing the 
production of spores and the growth of new plants. On the other 
hand, most of the floating kelp usually consists of growing or 
recently matured fronds, which are absolutely necessary to the plants 
in elaborating their food materials; therefore, harvesting does in- 
jury in removing such fronds. Successive cutting, must, accord- 
ingly, be separated by sufficiently long intervals to allow the plants 
to renew their food supply. Furthermore, careless operation of a 
harvester, or the employment of improper methods, may result in 
the destruction of many plants, and should be guarded against. 
