Satellite imagery is used to determine the best location to release stranded sea turtles. Click image for larger view.

Satellites in Use

Sea Surface Temperature

Sea surface imagery is being used in many innovative ways. For example, it helps wildlife rehabilitators to determine where to release stranded sea turtles. Two important aspects in this process are that (1) turtles require temperatures above 68 degrees F (20 degrees C) to survive, and (2) they must be released to a current that will not carry them back toward shallow coastal waters where they are susceptible to predators. Using a satellite image to plot the distance of the main portion of the Gulf Stream from Hatteras Inlet, where a ship would leave port, the best location to release turtles can be determined. In this case, the turtles would have the greatest chance of survival if they were released at the end of the white line (cruise track; image at right). In this spot the waters are warm enough, and there is a much lower chance of them getting caught in a trough that would carry them back to shore. If the release area was determined solely by measuring the sea surface temperature from aboard the ship, the scientists would have little knowledge of the eddies existence. If the turtles were released into the eddy, they would most likely perish as they were swept shoreward.

Satellites are used to determine areas where water temperatures are above normal. Click image for larger view.

Another example of how scientists are using satellite imagery is in determining areas of potential coral bleaching in the Caribbean that may be related to the 1998 El Niño event. Bleaching occurs when corals become stressed. Under such conditions, they expel the colorful algae (called zooxanthellae) that normally live inside them. While corals can survive for a period without the algae, they cannot last indefinitely, and severely bleached corals often die. Bleaching occurs for a variety of reasons, but one of the more common catalysts is unusually warm water in the summer months. Satellite data can be effective in monitoring for these anomalously “hot spots”. This image shows a hot-spot map for the summer of 1998 at the end of an El Niño event. Warm colors (yellow to red) reveal areas where corals are at risk of bleaching because the temperature is 1 or more degrees Celsius warmer than the warmest normal water temperature.

Hurricane Floyd stirred up sediment along North Carolina's coast (aqua color) and swept swampy plant material into the estuary (dark color near coast). Click image for larger view.

Imagery and Color

This image shows the North Carolina coast just after Hurricane Floyd passed through in September 1999. The strong winds stirred up offshore sediments, causing the water to turn a bright aqua color. Then, heavy rains from Floyd, and the previous hurricane caused severe flooding. The flood water passed through low swampy areas, bringing dark tannins (plant substances) into the estuary. Satellite and aircraft imagery are being used to document the impact of this rare flood on the Pamlico Sound estuary.

New methods are being developed to detect harmful algal blooms and monitor the impacts of excessive nutrients (eutrophication) in coastal waters. Episodes of nutrient enrichment often manifest in excessive increases (blooms) in algae. These images show the high chlorophyll concentrations along Florida's Gulf Coast in October 2000, and the location of a harmful algal bloom detected there. This bloom actually moved in from offshore waters

An algal bloom was monitored along Florida's Gulf Coast with the use of satellite imagery. Click image for larger view.