Dissolved Oxygen Oxygen gas (O 2 ) incorporated evenly as a solution (dissolved) with water. http://i.huffpost.com/gen/12 41617/thumbs/o-FRESH- WATER-facebook.jpg
El Ni ño Changes in weather patterns, prevailing tropical trade winds blowing east to west weaken to reverse direction. http://www.ncdc.noaa.gov/t eleconnections/enso/images /winds_over_ocean.gif
Endangered Species Wild species with so few individual survivors that the species could soon become extinct in all or most of its natural range. http://images.nationalgeographic.c om/wpf/media- live/photos/000/004/cache/black- rhino_468_600x450.jpg
Old-Growth Forests Virgin and old, second-growth forests containing trees that are often hundreds-- sometimes thousands--of years old. (Virgin forest- a forest in its natural state, before it has been explored or exploited by man) (Second-growth= natural regrowth of a forest after fire, cutting, or some other disturbance) Białoweiża Forest is on the border separating Belarus and Poland. It is part of the original forest of the European Plains, and is one of the largest remaining pieces.
Oligotrophic (lake) Characterized by a low accumulation of dissolved nutrientsalts, supporting but a sparse growth of algae and other organisms,and having a high oxygen content owing to the low organic content. http://plants.ifas.ufl.edu/educatio n/images/oliogotrophic%20lake.jp g
Pasture(s) Managed grassland or enclosed meadow that usually is planted with domesticated grasses or other forage to be grazed by livestock. http://www.lautnerfarms.co m/wp- content/uploads/Bertolla- 130321-great-pasture- shot.jpg
Threatened Species Wild species that's still abundant in its natural range, but is likely to become endangered because of a decline in numbers. The beluga whale, a near threatened species. http://images.nationalgeographic.com/wpf/media- live/photos/000/004/cache/belug a-whale_458_600x450.jpg
Transition Zone Middle zone of the 3 zones of the downhill flow of water, between the source zone and floodplain zone, where headwater streams merge to form wider, deeper, and warmer streams that flow down gentler slopes with fewer obstacles. http://mastermanapes.pbwo rks.com/f/1295130812/stream zones.jpg
Turbidity CLOUDINESS IN A VOLUME OF WATER. A MEASURE OF CLARITY OF WATER IN LAKES, STREAMS, AND OTHER BODIES OF WATER.