Transactions
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TRANSACTIONS Vol. I. Part 1. 1931 Editor - F. C. GARRETT, D.Sc. CONTENTS An Apparatus for studying the growth of Epiphytic Algae with 1 special reference to the River Tees. By R. W. Butcher, B.Sc., Ph.D., F.L.S. The Late-Glacial and Post-Glacial periods in the North 16 Pennines. By A. Raistrick, Ph.D., F.G.S., and K. B. Blackburn, D.Sc., F.L.S. Terrestrial Acari of the Tyne Province: IV Tyroglyphidae , By 37 Rev. J. E. Hull, MA. The Rotifers of the Northumberland Plankton. By B. Millard 45 Griffiths, D.Sc., and F. E. Cocks The Northumberland and Durham Primulas of the section 48 Vernales. By J. W. Heslop Harrison, D .Sc., F.R.S. Price: Four Shillings. Post Free. PRINTED BY ANDREW REID & COMPANY, LIMITED, NEWCASTLE-UPON- TYNE. NORTHERN NATURALISTS' UNION. OFFICERS, 1931. President: REV. J. E. HULL, M.A. Vice-Presidents: MISS K. B. BLACKBURN, D.SC. RANDLE B. COOKE. B. MILLARD GRIFFITHS, D.Sc. J. W. HESLOP HARRISON, D.Sc., F.RS. T. ASHTON LOFTHOUSE. JOHN E. NOWERS. HON. TREASURER: J. E. RUXTON, ELMFIELD, BIACKHIII, CO. DURHAM. HON. SECRETARY: F. O. GARRETT, D.Sc., SOUTH VIEW HOUSE, ALNMOUTH, NORTHUMBERLAND. COUNCIL : MISS L. E. BARNETT, B.Sc., A. W. BARTLETT, M.A., M.SO. W: HALL. J. J. HILL. J. E. PATTERSON. R H. SARGENT. M. LAWSON THOMPSON. R WALTON. Members of the Union pay an annual subscription of seven shillings and sixpence, and receive the Transactions and The Vasculum (quarterly) free of charge. 1 AN APPARATUS FOR STUDYING THE GROWTH OF EPIPHYTIC ALGAE WITH SPECIAL REFERENCE TO THE RIVER TEES. R. W. BUTCHER, B.Sc., Ph.D., F.L.S. (Assistant Naturalist, Ministry of Agriculture and Fisheries.) INTRODUCTION. In all shallow rivers so far investigated it has been found that large growths of algae occur on the river-bed, on the embankments, on the Phanerogams and on any other submerged objects. These growths are of immense importance in the biology of a stream because (1) they provide the chief source of food for a large number of animals, (2) they are important agents in aerating the water, and (3) they are the source of most of the algae in the plankton (that is, the collection of organisms found floating in the water). A method was evolved therefore by which it was possible to estimate the nature and extent of these attached growths, and a note of this method was published in 1927 (Butcher, Pentelow & Woodley (1)). As the study of these organisms has been very much neglected, probably because there are many difficulties in collecting them, the method is here described and discussed in greater detail, not merely for its use in rivers but also for its possible application to the study of algae and similar organisms in pond, and lakes. DISCUSSION OF METHOD. Several workers on the Continent (Hentschel (6), Hurter (7), Geitler (:3) ) have exposed in the water various artificial substrata for the purpose of obtaining growths of micro-organisms, and among these, pieces of glass obviously suggest themselves as a convenient medium on which to examine growths of algal, protozoa and bacteria under a microscope without undue disturbance. Most of the other substrata tried were of an opaque nature and were soon abandoned in favour of glass. The apparatus employed by each investigator in which to fix the glass slips varied according to the nature of the situation. In the course of my researches on rivers for the Ministry 2 of Agriculture and Fisheriea I have found a rigid metal photograph ie printing-frame, as supplied by Messrs. Houghton-Butcher Ltd., to be a quite satisfactory device. Postcard size frames were chosen, as these held five slides, each 31/2 in. by 1 in. This frame holds the slides quite firmly if a piece of thin rubber sheet is put between the glass slides and the back of the frame. Even in the River Tees with its rapid currents and it extreme conditions of varyino flood and low water, this apparatus has proved successful if it was anchored by means of chain and links to iron stakes driven into the river-bed, fixed as shown in Fig. I. The precautions to be taken in fixing this apparatus are that the stakes must be driven flush into the river bed so that the frame lie fiat on its back, and the tops of the stakes, especially the up-river one, should be allowed to protrude as little as possible so that no debris catches upon them. The chains also should be as tight as possible or the currents will swing the frame backwards and forwards and the glass slides will be broken. The large plants should be cleared away so that these do not rub over the surface of the glass slides and prevent the organisms settling. This apparatus has been used since 1926 on rivers of varied character and the most important results are now summarised. RIVERS INVESTIGATED. I.-The River Lark.-This small, slow-flowing stream in Suffolk, a tributary of the Great Ouse, was the first river on which the frames were used. Only one place was selected on this river for the work and that was at Lackford, where the water was about two feet deep, 3 GROWTH OF EPIPHYTIC ALGAE the bottom stony and the current moderate (about 1,000 yds. an hour). There was not a very great deposit of silt nor any big increase in depth due to flood-water, and as the normal variation was only eighteen inches, it was always possible to obtain the frame simply by wading. This is an important point because if dragged out without due care, the water weeds wipe off some of the growth from the slides or, if just dropped into the water one cannot be certain which side up the frame will come to rest. The large growth of water-plants in this stream was rather a drawback as these had to be continually removed so as to prevent- them wiping the surface of the glass. The Lark frames were only fixed by a single piece of picture wire to a peg on the bank and, because of the lack of current, there was no strain upon this, and the frame remained where it was placed . As the development of organisms was very rapid throughout the spring and summer, fourteen days was chosen as the period during which the slides remained in the water, and by that time they were covered with a growth of between 5,000 and 1,000,000 organisms a sq. cm. When the slides were collected they were put into 4 in. x It in. collecting tubes containing formalised distilled water and were kept in the laboratory until required. The chief objects of the Lark investigations were to discover the nature of the algal growths that had been noticed on the river bed, to estimate their quantity and to outline the seasonal variation. The full results are published in the paper by Butcher, Pentelow & Woodley (2) and only a summary is given here. The quantitative method here employed to estimate these growths was to dry four slides at 1000 C. and calculate the dry weight by difference. The deposit was then incinerated and the final result given as total organic matter in the deposit on a sq. cm. of glass surface, which was considered to be a more accurate index of growth in the river than dry-weight of the deposit, which includes a considerable proportion of silt. On the remaining slide a percentage count was made. 2.-The River Tees.-More detailed investigations have been made continuously since 1929 on the river Tees. This familiar northern river forms the boundary between the North Riding of Yorkshire and the county of Durham, and it is well known for the beauty of its upper valley, for the unique features of its flora, and as a very good fishing stream. An important character of the river 4 is the swiftness of its currents and the rapidity of the rise and fall of the water. It is no unusual event during time of moderate rainfall to see the river rise in a single hour by two or three feet in its upper, or by six to eight feet in its lower portion. The average rate of flow is about 21/2 miles an hour. From the source to Croft the river-bed is being continually scoured away and the boulders moved by floods, but below this point there is a tendency for it to remain stable. Observations have been made monthly in at least fifteen places, but in this paper particular attention is given to the results from three stations, which amply illustrate the general distribution and variation of the algae in this river. A place was chosen within four miles of the source to be clear of any pollution, and this is at the junction of the main stream and a small stream called Trout-beck situated at an elevation of 1,700 feet. The river is about twenty feet wide, normally two feet deep and with a current of about 1,000 yards an hour. Being so near the source, the rise of water due to heavy rainfall is never very great-twenty-four inches being the highest recorded, though doubtless in exceptional cases it is greater. Another station was chosen at Barnard Castle to iIIustrate what happens in the upper river, Here the river is about sixty yards wide, two to three feet deep, with a stony bed, and a current of about 2,000 yards an hour.