Question

Hi everyone,

I have another question. It's about phytoplankton this time. I need to know how to separate them into diatoms and so on for further analysis. I've been looking for protocols but to no avail. Can someone please help me out?

Thank you people.

Answer 1

Ooo that sounds like a task and a half, do you want to seperate "all" of what you find into families (Diatom is a family)? Or just seperate the diatoms out?

For things as little as phytoplankton your best source is going to be local books, though they do not necessarily exist. It may be a good idea to see if there are any experts at your local uni that would be able to help you.

This looks pretty good: oceandatacenter.ucsc.edu/PhytoGallery/
-Though I don't know much about phytoplankton

Answer 2

Oops, posted the wrong link, I meant this one (sorry for the long link):

http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CFEQFjAC&url=http%3A%2F%2Fgloballast.imo.org%2Fmonograph%25207%2520phytoplankton%2520catalogue.pdf&ei=DyIyUN-lLM2aiQeW_4GgCQ&usg=AFQjCNH3HOClq4eonLG8BmnQKgYwX1NFIw

Answer 3

Hi @TranceNova. Thanks for the link. It's really helpful. I actually need to separate a sample consisting of diatoms and the dinoflagellates. I need a technique to do that.If anyone knows about this could help me out or if you have any material on this particular topic. For the identification part, it's going to be okay but I want to separate them and that seems pretty impossible.

Answer 4

I don't know much about lab techniques (I'm still at a point in my studies where pretty much everything I've done has involved reading textbooks and watching lectures), but... a few things come to mind.

At least some species of diatom like to adhere to surfaces (e.g. slides) and move on it by gliding, whereas I THINK dinoflagellates are more likely to be free-swimming. When I looked at some slides that had been hanging in the water column during a marine bio course that I did last week, I saw far more diatoms than dinoflagellates, but I can't be certain that that wasn't just a coincidence -- I only looked at one slide.

Another thing that I remember from a protist course is that while diatoms are encased in silica, at least some species of dinoflagellates have cellulose plates. It might be possible to remove them from a sample with some sort of cellulase, though the plates in question are intracellular so I'm not sure if that would work.

Answer 5

Thanks @Calliope , I'll consider your observations and discuss about them with my project mates. By the way, do you have any link to understand the concept of biovolume?

Answer 6

I have no idea what biovolume is, I'm afraid.

Another idea that just came to mind is that you might be able to use light levels to partially separate phytoplankton. I guess most organisms in the top layer of water are probably going to be attracted to light to some extent, but I remember reading that phototrophs in particular tend to array themselves at a point where the light intensity is neither too low nor too high... and I wouldn't be surprised if that were different from species to species. It's just an idea, though. I have zero lab experience, so all I can do is dredge my mind for bits and pieces that I learned about in class.

Answer 7

Well, I must say that you're awesome. Actually, I don't have a knowledge of marine biology, and all of this is pretty new to me. What is of interest to me is the protein content of the latter. So, that's why I want to separate them.

Here's something on biovolume:
http://www.bgbm.org/bgbmpress/otherpubl/cediatom/cediatom123Lyakh.pdf

Answer 8

My knowledge of marine bio is pretty basic as well: I just got back from a week and a half long introductory course, but it covered a lot of different topics and there wasn't enough time to go into a lot of detail on most of them.

What sort of sample do you have, and do you know anything about what's in it? In the plankton samples that I looked at last week (really only a few, since it was just on one day of class), I remember seeing a lot of copepods, various arthropod larvae, snail larvae, plus a few radiolarians and forams. I guess some of the metazoans could probably be filtered out by size, but it might be difficult with the smaller ones as well as the heterotrophic protists.

Answer 9

Well, I'll start collecting my samples as from next week. And I'll be using a phytoplankton net of 5micron which means that I'll be having only diatoms and dinoflagellates in the samples.

Answer 10

Wait a second... if you're using a 5µm mesh size, won't that pick up a lot of things other than dinoflagellates and diatoms? I've never used a phytoplankton net (just a regular plankton net, and I only got to play with it once), but I would think it would catch anything that can't swim through it. With such a tight mesh, you'll get your phytoplankton, but you'll also get larger organisms... and probably smaller ones as well.

Answer 11

Hi @Calliope.. Well, you've got some points over here. Hmm.. what I know so far is that the smaller ones will pass through and to obtain only phytoplankton, I'll pass it through filtered sea water. I'm still working on the protocol. I'll confirm it once I'm settled. Thanks for voicing out your opinion..^^ It's really helpful.