| A | B |
|---|
| keystone species | one that is necessary for the health of ecosystem |
| ex. keystone species | beaver and alligator |
| cavities | holes in dead trees (used by woodpeckers or flickers) |
| dead trees | snags |
| oligotrophic lakes | early stages of a lake; have little plant life or algae, clear water, good light penetration, low nutrient levels, high dissolved oxygen, deep waters, steep slopes, limited fish pop. |
| eutrophic lakes | latter stages: shallower water, lot of sediment, high nutrient levels, low dissolved oxygen, murky waters, poor light penetration, many plants and animals |
| mesotrophic lakes | in between early and latter lakes |
| profundal zone | deepest zone in a lake; no light penetrates this zone |
| detritus | disintegrated material or debris; loose fragments washed away from rocks |
| thermal stratification | temperature layering of temperate lakes (related to depths which light penetrates & temp. change with depth) |
| thermocline | boundary between warm water and colder water |
| epilimnion | upper layer, has higher oxygen content due to plants and algae's photosynthesis; rich animal life |
| hypolimnion | colder, denser layer; rich in nutrients, low in oxygen because decomposition takes place here |
| metalimnion | middle lake layer |
| the thermocline is within this lake layer | metalimnion |
| overturn (or turnover) | a mixing of the waters caused by temperature changes |
| fall turnover | O2-rich surface waters cool, become denser and sink; the warmer lower layers rise to surface carrying nutrients up |
| bog | a wetland formed in a formerglacial depression by the accumulation of organic matter, known as peat, and which supports mosses tolerant of acidic conditions |
| temperature at which water is most dense | 4 degrees Celsius |
