Talk About It!

What are "transects"? What is "ground truthing"?

Asked by Dan from Honolulu on Sep 15, 2002.
While reading about your progress on the Ship Logs and enjoying the wonderful photographs, I noticed that there are a few terms that may not be familiar to readers. What is "ground truthing"? And what are "transects"? What does it mean to "put in a permanent transect"?

Answered by the NOW-RAMP Crew on Sep 16, 2002.
A transect is a given length, I think they are using 25 Meters, along the sea bottom that the scientists count critters along. Usually they lay down a tape in a given direction, then follow the tape and count the critters - either coral, other invertebrates, fish, or algae (limu). The scientists usually do 3 transects in a given area and record a GPS (satellite latitude/longitude coordinate for the area. This type of sampling method allows the scientists to figure out what is there. As permanent transect is when the scientists actually place stainless steel bars in the reef, or substrate so that when they return they will follow the EXACT same path they sampled the last time instead of a general path for the area. This type of transect is most important for corals since it allows more accurate growth measurements over time, and in repeat visits.

Ground truthing is a visual inspection of areas that have been mapped via sattelite maps to see how accurate the remote sesing maps are. Remote sensing specialists have methods to analyze satellite images and from these images, and the frequency of light different areas reflect determine what type of bottom cover is there - coral, rubble, sand, pavement, etc. Ground truthing is a way to visit these areas and see if what the remote sensing habitat type maps actually match up with what is recorded there from a visual inspection. It is a kind of error checking, and correcting.

Educators in the NWHI

Asked by Allen from DOE on Jan 25, 2005.
Wishful thinking question: Is there a possibility that an expedition to NWHI will someday include a few educators who currently teach the NWHI curriculum to youngsters? Were this to occur, the possibilities would seem endless. Thank you!

Answered by Dan from U. Hawaii on Jul 10, 2005.
At the time you asked your question, we didn't know of such an opportunity, but now we know: yes, there will be an expedidition for educators. I'm sorry that the application deadline has passed. See http://www.hnlc.org/home/index.php?story=372