debor042

Greetings from the confines of my office!  I have not posted in over a month but lucky for you, the other bloggers have kept you entertained with Alligator vomit , post-quals stress disorder and the joys of working with carcinogens, flammable materials and high-voltage equipment .  If those don't make you want to be a graduate student and/or scientist, then I don't know what will! So what have I been doing?  A whole lot of non-exciting blogging material like processing DIDSON videos , analyzing data, and preparing for conferences.  The good news is now I have some results to share!   One of the most interesting and surprising things I've found in my DIDSON videos is schools of small prey fish (< 12 cm).  Not just one or two on occasion, but nearly every time I go out, in all three of the canals I work in, there are schools.    Some are small (you may need to make the video full screen to even see them): Others are quite large: Some are hi...

For those of you who read Using "Sound" to See Underwater  and Everglades at Night ,  you've learned a bit about the DIDSON (an imaging sonar) and have gathered that some of my work occurs at night in the glades.  Below, I'll explain how I'm using the DIDSON to understand the role of predatory fish in canals of the Everglades. Canals were dredged  in the early 20th century to drain the wetlands and have now become a permanent fixture in the Everglades landscape.  I could write a whole separate article on the harm canals have done, but for now I encourage you to read  The Effects of Canals and Levees on Everglades Ecosystems  for a review on their history and role in the landscape.  Their relevance to my study is that the canals harbor large, piscivorous fish (fish that eat other fish), which is great for recreational fishermen but bad news for the little fish who have to fight for survival in these canals.  Small fish play...

When I first tell people I don't need my eyes or a video camera or even light to see under water, you can imagine the look on their faces and the numerous questions that immediately follow.  Instead, I "look" at fish using a sonar - a Dual Frequency Identification Sonar (DIDSON) to be exact. Dual Frequency Identification Sonar The black cord connects the underwater DIDSON (above) to a computer  on the boat.  This allows me to watch and record everything the DIDSON "sees." Without getting into all the technical details of the DIDSON (visit  the company's webpage  for that), the sonar emits sound-waves that "bounce" off of objects (such as fish) and then return to the unit with information on how far the wave traveled and the "intensity" of the object it hit.  The DIDSON then uses that information to create an image.  Now it's worth noting that the image it creates does not capture information on the color of the fish it hit and it may ...