551.48/M.N
Life in lakes and rivers
T. T. MACAN and
E. B. WORTHINGTON
Contents
<!--First Principles
The scope of this book. History of investigation on lakes and rivers. Some physical and chemical properties of water.
<!--A Typical Lake
Physical conditions: temperature layering in summer, mixing in winter: penetration of light. Chemical condition: the supply of nutrient salts. The role of the bottom deposits. Physical factors in shallow water: wave action, etc. differences between lakes and ponds.
<!--[if !supportLists]-->3 . A Pparatus for studuing lakes
Equipment for measuring temperature and penetration of light: water samples. Study of shore- and bottom-dwelling animals. Plankton nets, pumps and traps. Samplers for bottom deposits.
<!--Different Kinds Of Lakes
A tour of Britain, noting the main types of natural and artificial water-bodies. Their origin. The continental classification of lakes on oxygen content. The idea of an evolutionary series. History of windermere deduced from its mud.
<!--Rivers
Some of the schemes of classification. The rivers Duddon, Tees, avon, Itchen, and Lark, with particular reference to features which affect plants and animals. Rate of flow, chemical content, liability to flood, pollution, weed-cutting, dredging. The river as a mosaic of small habitats. Canals.
<!--Animals And Plants
Some elementary remarks on biological names and classification. The groups of plants and animals which occur in fresh water and the numbers in each. Aquatic organisms reclassified according to where they live: surface dwellers, stone- and weed-dwellers, plankton, swimmers, burrowers.
<!--The Organism In Its Environment
The fauna and flora of windermere; compared with other lakes; of some rivers; of pounds; of brackish water.
<!--A Closer Look At The Environment
Adaptable and adapted species. Dispersal. Geographical distribution. Varios factors which influence the ecology of closely related species. Competition. Chemical factors. Physical factors.
<!--Food-Chains And Productivity
Food-chains. Amount of living matter produced in different kinds of water. Some practical applications of the knowledge gained.
<!-- Life Around The Water
Swamps, marshes, fens, and bogs; their association of plants. Otter, water-vole, water-shrew, muskrat, and coypu. Newts, frogs, and toads. Water-birds related to their environment.
<!--[if !supportLists]-->11 . Animal Travels
Migration, emigration, and nomadism. The eel, and its life history. The salmon. Mosquitos. Flatworms. Dragonflies. Waterbugs. Dispersal or involuntary travel.
<!-- Stock And Crop
Mature fish of one species vary greatly in size. Cause of stunted populations. How to judge a stock of fish. Overfishing and underfishing. How excessive populations of perch and pike in windermere were reduced. Effect on other fish.
<!-- Fishponds And Manuring
More about the growth of fish. Temperature and food supply. Manuring: calcium, phosphorus, nitrogen, and potassium. Importance of the pond bottom. Sewage as a pond manure.
<!-- Impure Water
Sewage: how it causes pollution and its effects on plants and animals. Methods of sewage purification. Trade wastes. Pollution of rivers tees, trent and churnet. Lead in river Rheidol. Test for pollution. Enquiries, commissions, and legislation, but pollution continues.
<!-- Pure Water
Diseases crried by water. Sources of supply from underground and surface reservoirs, and rivers. Bacterium coli. Reservoirs and lakes compared. The prevention and cure of biological troubles in water supply. The biology of pipes.
ساحة النقاش