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This programme illustrates some methods of studying the primary productivity of lakes and how the growth of planktonic algae is affected by physical and chemical factors.
Metadata describing this Open University video programme
Module code and title: S323, Ecology
Item code: S323; 02
First transmission date: 26-02-1974
Published: 1974
Rights Statement:
Restrictions on use:
Duration: 00:24:35
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Producer: Neil Cleminson
Contributors: Jack Talling; Peggy Varley; John W. G. Lund
Publisher: BBC Open University
Keyword(s): Chemical factors; Experimental investigation; Hydrosere; Lake District; Microflora; Monitoring; Physical factors; Phytoplankton; Planktonic algae; Silica
Footage description: Aerial shots of Lake Windermere. Commentary by Peggy Varley introduces the programme. She describes the lake as an eco-system. Shots of the Freshwater Biological Assn. Headquarters at Ferrybridge, Windermere. Shots of several lakes, in the area and their surrounding vegetation. Commentary by Peggy Varley describes Pearsall's work early this century in the Lake District - his concept of giant succession. Peggy Varley introduces a sequence on ways to determine the reasons for variations of plant productivity in the various lakes. Shots of J.F. Talling in a rowboat. He is shown taking water samples from Esthwaite. Shots of Talling analysing samples in the lab. Talling explains why he chose Esthwaite for his studies of planktonic algae production in lakes. Shots of the lake and the laboratory accompany the discussion. Talling shows a pen graph which illustrates seasonal changes in algae density. His commentary explains the graph. Shots of Talling and assistant in a rowboat. Commentary by Peggy Varley discusses the effect of solar energy on lake temperatures. Shots of Talling and assistant taking readings of light intensity, oxygen level, and temperature at various depths in Esthwaite. Shots of graphs showing data gathered above. Isotherms and oxygen content are plotted. Commentary by Talling explains how the graphs are constructed. Peggy Varley analyses the graphical data. Aerial shots of Windermere and graphs. Talling continues his commentary and also analyses the data. Further shots of Talling and assistant in a boat. Shots of inflow stream to Blelham tarn. Commentary by Peggy Varley lists the two inputs of chemical nutrient to the lake. 1. Lake floor sediment. 2. In-flow stream. John Lund explains why Blelham tarn is particularly suitable for his experiments on the effects of chemical nutrients on algal growth. Shots of research workers on a boat taking water samples from several depths for monitoring of nutrient and planktonic levels. Peggy Varley examines the reasons for the increase of chemical nutrients in Blelham tarn since 1952. Shots of Outgate village and surrounding farms. Commentary by Lund also discusses reasons for increase of chemical nutrients in the tarn (Increased sewage from the village and increased use of fertilisers on farms). Lund discusses some of the reasons for choosing a particular design, the Blelham tubes, for his experiment which tested the effect of chemical nutrient inflow on phytoplankton productivity in the tarn. Design and installation of the Blelham tube experiment shown. Film shots and diagrams are used, Commentary explains. Shots of the experiment in progress. Temperature, oxygen, nutrient and phytoplankton readings are taken in the tubes and from elsewhere in the tarn. Commentary by Varley and Lund. Samples of water from the tarn and the tubes are taken and fixed for examination. Shots of water/algae samples being examined in the laboratory. Shots of microscopist identifying and counting the various species in the sample. Further shots of samples being examined in the laboratory. Commentary by Varley discusses the correlation between silicon dioxide content in the water and diatom population. Further shots of samples being taken in the tarn. Lund sums up the programme with a discussion on the difficulty of studying a natural system. Shots of Blelham tarn.
Master spool number: 6HT/71290
Production number: 00525_1133
Videofinder number: 1025
Available to public: no