THE JOURNAL OF THE LINNEAN SOCIETY, (B0 T ANY.) The Algte of the Yan Yean Rrser+oir, Victoria : LL Biological and CEcological Study. By G. S. WEST,M.A., D.Sc., F.L.S., Lecturer on Botany in the University of' Birminghain. (PLATES1-6 and 10 Text-figures.) [Read 18th June, 1908.1 Page Introduction .................................................. 1 I. The Phytoplankton ........................................ G General Notice .......................................... 6 AIonthly Stateinelit of Plankton froni Feb. 190.5 to Feb. 1906 . 11 Tahle of Phytoplmkton .................................. 14 Dominant Forms nud their Periodicity ..................... 18 11. The Littoral Alga-flora (or Microphytic Benthos). ............... 22 General Notice .......................................... 22 Monthly Statement of the Jlicrophytic Benthos from Feb. 1905 to Jan.1906 .......................................... 23 Table of Littoral Alga-flora ................................ 26 Dominant Forms and their Periodicity ...................... 33 111. The Algae of the Yan Pean Drainage Area.. .................... 35 IV. The Relations between the Plankton, Benthos, and Ales of the Drainage Area. ........................................... 40 V. Systematic Account of the niore Noteworthy Species ............ 43 VI. The Peculiarities of the Australasian Alga-flora ................ 82 VII. General Summary ....... ................................... 84 INTRODUCTION. ABOUTthe middle of October, 1'304,T received from Mr. A. D. Hardy, F.L.S., of the Lands Department, Melbourne, two slides of Alge from the Yan Yenn Reservoir, and their inspection revealed such a number of interesting species LIZ". J0URN.-BOTANY, VOL. XXSIX. R 2 DR. a. s. WEST ON THE ALGB OF that I asked permission to examine more of the material. The sample had been obtained in February, 1904, about two hrindred yards from the shore, and froin the nature of the species observed I felt certain that the A1g-i~of the Yan Yean Reservoir would be well worth investigation. Shortly afterwards, in response to my suggestion, Mr. Hardy very kindly consented to obtain for me periodical collections from this large sheet of water, and I have to tender him my best thanks for one of the most interesting and instructive series of collections I Lave yet examined. Mr. Hardy forwarded me, according to detailed instruction, samples of the plankton taken by boat at regular monthly intervals for thirteen months, in addition to samples from the weedy margin of the reservoir taken with tho same regularity, and others from various parts of the drainage area. The value of these collections is greatly enhanced hy records of the temperature, both of air and water, by remarks upon the meteorological conditions prevailing at thc time of collecting and between the dates of collection, as well as by sundry information which has :t bearing upon the distribution of AlgE in this district of Victoria. The Yan Yean Reservoir +,which has a superficial area of about 1460 acres, furnishes part of tlie water-supply for the city of Melbourne, distant about 25 miles. Some of the water comes by an open aqueduct from the Toorourong Heservoir, a smaller body of water of 36 acres, supplied by srnall streams which, witli their tribntarics, drain a large portion of both the soutiicrn and northern slopes of the range of mountains dividing Victoria into a northern drier and a sonthern well-watered territory t. The formation of the reservoir began in 1853 by the construction of an embankment, five- eighths of a mile in length and SO feet in height, to join the ends of Iow hills which form the south-westerly extrcrnity of the catchment basin-an area of 4500 acres. The rescrioir was completed in 1857, but only since 1883 has the main water-supply been along the aqueduct from the Toorourong Reservoir. The intake by this aqueduct is roughly about six times the amount received from the rainfall in the catchment Fasin $. Mucli of the Toorourong siipplp is similarly obtained along an open channel, * It may be of interest to know that the name ‘( Yan Yean” is recorded as having been that of an Rustidinn aboriginal chief, who signed the Batman Treaty (June 11, 1835), and means dc boyish ” or a (‘ bachelor.” .t A chart coinpiled by Mr. Hardy from data furnished by Mr. P. Baracchi, the Govern- ment Astronom‘er,clearly shows a wide diflerence in the rkirifall of the nortliern as contrasted with the southern district. Prof‘. J. W. Gregory, however, does not recognize the dividing range, and from geological evidence states that, “ in spite of geographers and biologists,” the Gretit ilividing Range is a misleading geographical myth. f The intake by aqueduct in 1903 was 5,984,000,000 gallons, and by rainfall in catchment basin wa9 1,021,953,000 gallons. In 1901 the figures were respectively 7,417,949,000 gallons and 1,125,326,000 gallons. THE YAN YEAN REBERVOIR, VICTORIA. 3 about 8 miles in length, partly natural and partly paved, which comes from the Wallaby Creek Weir, a dam at almost a thousand feet greater altitude. The water of the Wallaby Creek weir is in a like manner partly brought along an open paved channel from a still higher dam, the Silver Creek Weir, distant about 5 miles. A constant supply of water along the aqueduct to the Yan Yean Reservoir is assured by the dams at Toorourong, Wallaby Creek, and Silver Creek. The catchment area for the two upper dams is 11,500 acres, and the outflow streams find their way into King Parrot Creek. The catchment area of the Toorourong Reservoir is 10,500 acres, the water-supply from which is addi- tional to that along the open channel from the upper dam$, and the outflow of the reservoir is the east branch of the Plenty River. The following records of the rainfall, although incomplete, indicate a great increase in the amount registered corresponding to a relatively small increase in altitude :- I Yan Yeam. 1 Toorouroihg. j Wa2lab.y &eel 1 SiGver Creek. I Altit. 400 ft. Altit. 736 ft. Altit. 1717 ft. Altit. 1740 ft. Catchment area Oatchment arm Catchment area ll,macres. 4500 acres. 10,500 acres. ( 1903. 2903 ins. 3685 ins. 51.7 ins. Registered 1904. 26.67 ,, 33-75 ,, 66.39 ,, No records. rainfall 1905. 29-63 ,, - - As the chief part of the water-supply of the Yan Yean Reservoir (some six-sevenths of the total volume) comes along the aqueduct from the Toorourong Reservoir, which is in turn largely supplied from the Wallaby Creek dam, it is therefore derived from a large area in which the rainfall is considerably greater than that which actually obtains in the Yan Yean catchment basin itself. The full capacity of the reservoir is 6,400,000,000 gallons, and its average depth is a little over 24 feet. The geological formations of the entire drainage area are Silurian and Granitic. The more distant supplies come from the granite of Mt. Disap- pointment (2630 feet), about 8 miles to the north, and the rest of the drainage is on outcrops of Silurian. Some of the banks of the Pan Yean Reservoir are natural, others are stone-faced from below the low-level to above the high-water mark, and an embankment forms an nrtificial boundary at the south-west corner. The shores when gently sloping are weedy, but away from the margin the lake is fairly free from evident vegetation. B2 4 DR. Q. 8. WEST ON THE ALQX OF Mr. Hardy has furnished me with much information concerning the spermatophytic and pteridophytic flora of the district. He records Prunella vulgaris, Bulbine bulbosa, Burchardia uinbellata, Arthropodium strictum, Cras- pedia richea, Leptorhynchus tenuqolius, Drosera Menziesii, D. Wldtakeri, Stackhousia Zinariifolia, Glycene clandestina, Eryngium uesiculosum, Stylidiuni Fig. 1. The Yan Yean Reservoir, ehowing the aqueduct from the Toorourong Reservoir, and the lower, swampy parts of the two creeks (Rana Creek and Ottelia Creek) in the catch- ment baain. The line of plankton collection is also indicated. graminiijolium, Aster sp., Helichrysum sp., Ranunculus lappaceus, €2. aquutilis, Diu& aulphurea, D. maculata, etc., as growing on the grassy slopes draining into the reservoir and sheltered by the pine plantation which almost surrounds it. On the remoter parts of these slopes a few native Australian shrubs and trees occur> such as Exoearpus cupressiformis, Banksia marginata, Casuarina THE PAN YEAN RESERVOIR, VICTOBIA. 5 quadrivalvis, Acacia melano,aylon, Eucalyptus globulus, E. citriodora, Hakea laurina, etc. Mr. Hardy states that the few recent (Post-Pliocene) deposits of the catchment area of the Yan Yean carry only stunted growths, and that the low-lying part of the Silurian country to the north is sparsely timbered with several kinds of Eucalyptus, but that the timber improves with increasing altitude, growing taller and straighter, while the undergrowth becomes denser. The gullies are rich in shrubs, and the creeks afford moisture for numerous ferns. Of the large tree-ferns, Dicksonia Bi~lardier~and Alsophila australis are common, the brown trunks often being draped with Hymeno- phgllum. The shade-loving Pteris incisa and P. tremula are conspicuous, but Pteris aquilina is everywhere, while along the aqueduct between Wallaby and Silver Creeks Gleichenia eircinata and species of Lomaria are abundant. At the weedy margins of the Yan Yean the marsh plants are chiefly the rush-like Heleocharis sphaeelata (the flowering shoots of which attain in places a length of eight feet), Arundo Phragmites (only in the N.W. corner), Triglochin striata, rWyriophyllum viriifoliuin, Limnanthemum exaltatum, and Potamogeton natans, the two latter almost monopolising small areas. Further out are Potanzogeton obtusus, Triglochin procera, Myriophyllum elatinoides, Vallisneria spiralis, and a species of Nitella (about two feet in length). Flourishing among these larger plants there is an abundant littoral Alga- flora which will be considered in its relation to the phytoplankton. Mr. Hardy’s enthusiasm, combined with a sound knowledge of the require- ments of the work he was so kindly undertaking €or me, caused him to visit, at considerable trouble and inconvenience to himself, the different parts of the entire drainage area.