[an error occurred while processing this directive]

Zoom In

Water Pressure

<< Back to Feature Page

View exclusive photographs and get the facts behind the frame.

Zoom In Thumbnail 1
Click to ZOOM IN >>

Zoom In Thumbnail 2
Click to ZOOM IN >>

Zoom In Thumbnail 3
Click to ZOOM IN >>

Zoom In Thumbnail 4
Click to ZOOM IN >>

Zoom In Thumbnail 5
Click to ZOOM IN >>

Water Zoom In 3

For Many Species It’s Sink or Swim
Photograph by Peter Essick

A southern sand darter hovers in Alabama’s unbridled Cahaba River, which boasts remarkable freshwater biodiversity with more fish species per mile than any other river in North America. But the introduction of dams and other diversions alters much of the world’s river habitat. Some species can adapt, but for others the results can be devastating: Modifications of natural river flows are part of the reason that during the past decade 20 percent of all freshwater fish species have become threatened or endangered—or extinct.

Photo Fast Facts

Camera: Canon EOS 1N
Film Type: Fujichrome Velvia 50
Lens: 17-35mm
Speed and F-Stop: 1/250 @ f/5.6
Weather Conditions: Sunny
Time of Day: Near sunset
Lighting Techniques: I used a polarizer and gyro.

© 2002 National Geographic Society. All rights reserved. Privacy Policy       Advertising Opportunities       Masthead

National Geographic Magazine Home Contact Us Forums Shop Subscribe