Copepoda of the genus Cyclops, and the Harpacticidae are only found in this region. Water-mites, nearly all the Rotifers, Gastrotricha, Tardigrada and Molluscs are found here, and Rhizopods are abundant. A large number of the littoral species in Loch Ness extends down to a de th of about 300 ft. The abyssal) region, in Scottish lochs, lies, as a rule, deeper than 300 ft., and in this deep region awell-marked association of animals appears in the muds on the bottom, but none of them are peculiar to it: they all extend into the littoral zone, from which they were originally derived. In Loch Ness the following sparse population was recorded:-
I Molluscz
Pisidium puslllmn (Gmel).
3 Crustacea:
Cyclops viridis, ]urine
Candona candida (Miill).
Cypria ophthalmiea, jurine.
3 W0rms: Slylodrllus gabreleae, Vejd. Oligochaete, not determined.
Automolos morgiensis (Du Plessis). 1 Insect: Chironomus (larva).
lnfusoria: Several, ectoparasites on Pisidlum and Cyclops, not determined.
In addition, the following were found casually at great depths in Loch Ness: Hydra, Llmnaea peregra, Proales daphnlcola and Lynceux ajinis.
The pelagic region of the Scottish lakes is occupied by numerous microscopic organisms, belonging to the Zooplankton and Phytoplankton. Of the former group 30 species belonging to the Crustacea, Rotifera and Protozoa were recorded in Loch Ness. Belonging to the second group 150 species were recorded, of which 120 were Desmids. Some of these species of plankton organisms are almost universal in the Scottish lochs, while others are quite local. Some of the species occur all the year through, while others have only been recorded in summer or in winter. The great development of Algae in the surface waters, called “ flowering of the water ” (Wasserblillhe), was observed in August in Loch Lomond; a distinct “ flowering, ” due to Chlorophyceae, has been observed in shallow lochs as early as July It is most common in August and September, but has also been observed in winter.
The plankton animals which are dominant or common, both over Scotland and the rest of Europe, are:- Diaptomus gracilis.
Daphnia hyalina.
Diaphanosoma brachyurum.
Leplodora kindlli
Conochilus unicorn ls.
Asplanchna priodonta.
Polyarlhra plalyptera
Anuraea cochlearlm
Nolholca longlsplna
Ceratium hirundinella.
Aslerionella.
All of these, according to Dr Lund, belong to the general plankton association of the European plain, or are even cosmopolitan. The Scottish plankton on the whole differs from the plankton of the central European plateau, and from the cosmopolitan freshwater plankton, in the extraordinary richness of the Phytoplankton in species of Desmids, in the conspicuous arctic element among the Crustacea, in the absence or comparative rarity of the species commonest in the general European plankton. Another peculiarity is the local distribution of some of the Crustacea and many of the Desmids.
The derivation of the whole lacustrine population of the Scottish lochs does not seem to present any difficulty. The abyssal forms have been traced to the littoral zone without any perceptible modifications. The plankton organisms are a mingling of European and arctic species. The cosmopolitan species may enter the lochs by ordinary migration. It is probable that if the whole plankton could be annihilated, it would be replaced by ordinary migration within a few years. The eggs and spores of many species can be dried up without injury, and may be carried through the air as dust from one lake to another; others, which would not bear desiccation, might be carried in mud adhering to the feet of aquatic birds and in various other ways. The arctic species may be survivors from a period when arctic conditions prevailed over a great part of Europe. What are known as “ relicts " of a marine fauna have not been found in the Scottish fresh-water lochs.
It is somewhat remarkable that none of the organisms living in fresh-water lochs has been observed to exhibit the phenomenon of phosphorescence, although similar organisms in the salt-water lochs a few miles distant exhibit brilliant phosphorescence. At similar depths in the sea-lochs there is usually a great abundance of life when compared with that found in fresh-water lochs. Length, Deplh, Area and Volume of Lakes.-In the following table will be found the length, depth, area and volume of some of the principal lakes of the world? Sir John Murray estimates Divergenee between certain of these figures and those quoted elsewhere in this work may be accounted for by the slightly different results arrived at by various authorities. the volume of water in the 560 Scottish lochs recently surveyed at 7 cub. rn., and the approximate volume of water in all the lakes of the world at about 2000 cub. m., so that this last number is but a small fraction of the volume of the ocean, which he previously estimated at 324 million cub. m. It may be recalled that the total rainfall on the land of the globe is estimated at 29,350 cub. m., and the total discharge from the rivers of the globe at 6524 cub. m.
BRITISH Laxas
Length Depth Area Volume in
in in in million
Miles. Feet. sq. m. cub. ft.
I. England- Max. Mean.
Windermere 10-50 219 78-5 5-69 12,250 Ullswater 7-35 205 83 3-44 7,870 Wastwater 3-00 258 134-5 1-12 4,128 Coniston Water 5-41 184 79 1 -89 4,000 Crummock
Water 2-50 144 87-5 0-97 2,343 Ennerdale
Water 2-40 148 62 1-12 1,978
Bassenthwaite
Water 3 83 70 18 2-06 1,023
Derwentwater 2-87 72 18 2-06 1,010 Haweswater 2-33 103 39-5 0-54 589 Buttermere 1-26 94 54-5 0-36 537 ll. Wales-
Llyn Cawlyd 1-62 222 109-1 0'I8 941 Llyn Cwellyn 1-20 122 74-1 0-35 713 Llyn Padarn 2-00 94 52-4 0-43 632 Llyn Llydaw 1-11 190 77-4 0-19 409 Llyn Peris 1-10 1 14 63-9 0- 19 344 Llyn Dulyn 0-31 189 104-2 0-05 156 III. Scolland-Ness
24-23 754 433 02 21-78 263,162
Lomond 22-64 623 121 29 27-45 92,805 Morar 11-68 1017 284 00 10-30 81,482 Tay 14-55 508 199-08 10-19 56,550 Awe - 25-47 307 104 95 14°85 43,451 Maree 13-46 367 125 30 11-03 38,539 Lochy 9-78 531 228 Q5 5-91 37,726 Rannoch 9-70 440 167 46 7-37 34,387 Shiel 17-40 420 132-73 7-56 27,986 Arkaig 12-00 359 152~71 6-24 26,573 Earn 6-46 287 137-83 3-91 14,421 Treig 5-10 436 207 37 2-41 13,907 Shin 17-22 162 51 O4 8-70 12,380 Fannich 6-92 282 108 76 3-60 10,920 Assynt 6-36 282 101 IO 3-10 8,731 Quoieh 6-95 281 104 60 2-86 8,345 Glass 4-03 365 159-07 1-86 ' 8,265 Fionn (Carnmore)
5-76 144 57 79 3-52 5,667
Laggan 7-04 174 67 68 2-97 5,601 Loyal 4-46 217 65 21 2-55 4,628 IV. Ireland-Neagh
17 102 40 153 161,000
Erne (Lower) 24 226 43 43 62,000 E1-ne (Upper) 13 89 IO 15 5,000 Corrib 27 152 30 68 59,000
Mask 10 191 52 35 55,000
Derg 24 119 30 49 47,000
EUROPEAN CONUNENTAL LAKEs
Length Depth Area Volume in
in in in million
Miles. Feet. sq. m. cub. ft.
Max. Mean.
Ladoga 12 5 732 300 7000 43,200,000 Omega 145 740 200 3800 2 1,000,000 Vener 93 292 IOS 2149 6,357,000 Geneva 45 1015 506 225 3,175,000 Vetter 68 413 128 733 2,543,000 Mjosen 57 1483 139 2,882,000
Garda 38 1 124 446 143 1,766,000 Constance 42 827 295 208 1,71 1,000 Ochrida 19 942 479 105 1,391,000 Maggiore 42 1220 574 82 I,310,0001 Como 30 1345 513 56 794,000
Hornafvan 7 1391 253 93, 777,000
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