Rich in minerals and bases. The term is usually used of nutrient-rich lakes and ponds but it may be applied in other contexts, e.g. to fen peats that contain relatively high proportions of minerals and bases. Eutrophic lakes and ponds support a prolific growth of aquatic plants. When these plants die they accumulate as a thick layer on the lake bottom. The organisms decomposing this material diminish the dissolved oxygen in the water so fish are scarce or absent. Eutrophication may unwittingly be accelerated by man when, for example, sewage effluents enter a lake, or water rich in dissolved fertilizers seeps in from surrounding fields. In such instances the amount of oxygen used to decompose the plant remains may be so great that the fish die from oxygen dep. rivation. Compare oligotrophic. |
