Great questions-I'm happy to see you are thinking a lot about the different parts of your project. Your hypothesis looks good:
"My independent variable is the different concentrations of gold nanoparticles.
Also my hypothesis is that the mortality rate will increase while the dosage is going up as well."
What research have you done on Daphnia? How long do they live? What do they eat? What do they look like under the microscope?
Here are some suggestions to your questions:
As Heather suggested, read: http://www.sciencebuddies.org/science-f ... background1. Should I start culturing them first before experimenting?
--Yes, you will need to have all your materials ready for use. So you should have your Daphnia already and your gold particles/solutions made.2. Will it be better to have a sample size of 30-50 daphnia than just having 5-10 for each concentration? If so, then how will the serial dilution start off with? Can I start it off with 10 ml of gold nanoparticles with 90 ml of water? or is that concentration too small to start with 30-50 daphnia magna?
--A) The bigger the sample size, the better reliability your results will be. It will be up to you how many you want to start with, but keep in mind that some may die before your experiment is over (at no fault of your own), so having a larger sample size will allow for this variable. Personally, for each concentration, I would have around 20 organisms.
--B) Based on your research from environmental studies, Daphnia natural environments, other research on similar projects to this one, what is a recommended concentration of heavy metal to water? I don't have the answer to that, so you will need to research that.
Please read these resources, also here is where you can get cultures of Daphnia:http://www.carolina.com/daphnia/daphnia ... it+daphniahttp://www.carolina.com/teacher-resourc ... tr10492.tr
--C) 10mL solute (gold) seems like an awful lot to me, but again, it depends on what you found in your research. I would start with a concentration within uL (microliters: 10x-6 L), a really tiny amount. For making serial dilutions see my post below and the link to it. Also:http://www.wikihow.com/Do-Serial-Dilutions3. Should I be feeding the invertebrates while doing the experiment? Since this experiment is based on the survival rate, I'm not sure if this is a good idea or not.
--Based on your research, what is the average life span? You should keep all conditions the same except your independent variable (gold concentration), so that means you need to keep food, temperature, amount of water in dishes, number of Daphnia in dishes, etc. the same between all your samples. This means you will have to measure out the food, water, with a pipette or other measuring device.4. Will having an incubator be a good idea for a controlled environment? If so, do you know any places or websites where the pricing is not too high? Are there any alternatives to make a controlled environment? If the pricing may be too high, then I might just have to make my own incubator.
--What is the normal temperature for Daphnia? Since they are water creatures that live in cool water rivers, etc. I don't think they need incubation, but don't quote me on that. Refer to your research.
Hope that helps. Let me know if you are confused by any of it. Happy New Year!