Drift Net In Action (at least practicing)
Posted 31 January 2009 - 05:37 PM
The net bag is made of organza silk, with a very fine mesh, held by an edging of denim. This all slides over a rectangular PVC pipe frame that's 12 x 18 inches. A denim sleeve on each short side is designed for a stake or peg that can be driven into the substrate to hold the net. I lost my good metal stakes in our building move, so today I tried cut bamboo poles. The whole point of using a net like this is to sample whatever is entrained in a stream, such as insects or ichthyoplankton; set up the net in a likely place for an hour or two, and then check what you've netted. Below are some pictures of the net in use. We quickly found that the bamboo poles couldn't be driven far enough into the substrate to withstand the strong current, so I convinced Brittany and Taito to hold the net in place for about 15 minutes as a test.
Here are Brittany and Taito holding the net, in just over a foot of water. I positioned the net so that the top bar was just out of the water. I wanted to be sure that water is flowing through the bag, and that little turbulence is at the entrance to the bag.
Here's a closer view of the bag in action. It trapped some air bubbles but that didn't seem to disrupt it. We quickly had a few insects in the bag, and a growing collection of twigs and leaves. It's amazing how much stuff is bouncing along the bottom even in very clear water. After 15 minutes we also had a surprising amount of sand in the bag, also being swept in the current. No ichthyoplankton, though, it's still a little early.
So, the net seems to work as planned. I have to acquire stouter metal pegs with a pointed end, and that can withstand being driven with a hammer. But I like the net, and I'm lucky that my wife is a fabric artist who was able to sew the bag together.
Posted 31 January 2009 - 08:48 PM
Reply to this topic
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users