Hi,
I am an undergraduate student at Bowling Green State University in Ohio. I have been given the oppurtunity to work on an independent research project here. I am deciding to use Native Fish for the research project. The fish I already have collected for the project are Variegate Darters, Iowa Darters, and Blackside Darters. I was looking for some ideas for what I could do with the fish. I have a 45 gallon tank to use for the project. So far, I think I might be doing a habitat analysis project in which I put all those fish together (4 of each) and watch them (video tape) and see how space and competition drive which fish to which parts of the aquarium. I will then compare that to literature available on the fish. I will have the tank portioned off into three different habitats...1.) Rocky with a powerhead set up to maximize flow 2.) Woody debris to create breaks in the flow 3.) Planted area with lots of thick vegetation. What do you guys think? Can you think of any ways to improve the design?

-Nate

Habitat partitioning is well documented especially recently in diverse communities of darters. I could rattle off a half dozen plus that are just cited in my thesis within the last 10 years.

I think the biggest problem with the design is the size of the tank and the fact is one tank. Regardless of how many times you repeat the trial you will have a sample size of 1 because you are really doing a repeated measures design. The tank is awfully small to be setting up such starkly different habitats with twelve darters in it. Behavior will be driving much of your partitioning rather than competition for resources (food). That is an awfully high density for a community of darter species too, you'd have some mighty big inter and intraspecific interactions going on. Also, the Iowa darters aren't collected from the same areas correct? You'd be collecting them most likely out of natural lakes, while the variegates are from swift riffles, so of course they'd be going to different ends of the tank.

Here is my suggestion while keeping along the same lines. Use only one species at a time in the tank (remove interaction). Alter habitat variables such as substrate size, heterogeneity, % vegetation, % cover, flow, you could even manipulate depth by height of substrate (Now you have replication, not repeated measures and the dreaded N=1). Since you're using a video camera make habitat observations at specific time intervals. You then will have a wealth of data on occupancy times, such as under or on top of rocks, habitat use in a closed environment, and you could even do behavioral such as position into flow, active, feeding, resting, pelagic, benthic, etc. Since you have multiple species you can do it with multiple species if you'd like.

Are you saying to remove other species and do one species at a time and then alter one habitat component at a time to measure the affect each component has on behavior?

Yes and no. One species, but alter the habitat multiple (or one) at a time just measure what you change it to prior to reintroducing the fish to the system. Say start off with 100% pea gravel with no cover and 1 powerhead and run your trial. Remove the fish then change it to 75% pea gravel 25% some sort of larger gravel, and 25% cover with 1 powerhead and reintroduce the fish and run it again. And on, and on, and on.....

sounds good. I submitted it to the IACUC board to get it approved and one thing they mentioned upon the return of the proposal was they wanted me to control for interspecies competition. This will help. I could just do one at a time.