By plankton net, and specific mesh size can segregate zoo ------and phytoplankton

Dear Nabonita Pal,

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The value of paleobotany. Extinct plants to some extent used for correlating geologic layers, but their main value lies in the fact that they shed light on the evolution of the earth's flora. The fossil record shows that some groups living plants are very old, and the others emerged relatively recently. You can also get an idea of the general aspect of the vegetation landscape of the Earth in the past era. As a detailed knowledge of the recent history of humanity, it is important for the understanding of contemporary social processes, information on plant development are an indispensable aid in the study of many of the problems of modern botany.

Regards, Shafagat

After site election, at each site, 2 L of seawater is collected to estimate phytoplankton biomass. Using the pump, the phytoplankton sample obtained immediately after and at the same depths. The bottles were stored in a dark icebox until return to the laboratory.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.2.9068&rep=rep1&type=pdf

Most phytoplankton are too small to be individually seen with the unaided eye. However, when present in high enough numbers, some varieties may be noticeable as colored patches on the water surface due to the presence of chlorophyll within their cells and accessory pigments (such as phycobiliproteins or xanthophylls) in some species.

https://en.wikipedia.org/wiki/Phytoplankton

20 micron is best for phytoplankton collection

for qualitative analysis you can use a plankton net, for quantitative analysis like biovolume you need to know your sample volume so use a sampler, a tube, a pump. For selection of sampling depth or the depth of sampled water column, it is necessary to know whether your water body is stratified.

The most common method is to pull a fine mesh net through the water, either vertically or horizontally. for easy use There are statistical methods to identify the number of samples required to accurately characterize the plankton at a particular time in a lake.

Hi Nabonita, what is it that you want to know? since the early 60s, when I was young and energetic, it was well known that algae smaller than 20-30 micrometers dominated most phytoplankton assemblages (I would risk: all phytoplankton assemblages, but then I did not look at all of them, did I?), which is why in those times phytoplankton was quantified with the Utermohl technique or some other technique which basically consisted in concentrating a known volume of water on a slide.

For larger phytoplankters, a net is appropriate, and the mesh size will depend on several factor, but yes, as you say, 20 microns is probably appropriate,

If on the other hand you are interested only on larger species, you might want to consider a 30-50 microns mesh (small zooplankton, such as rotifers, copepod nauplii etc, and of course larger phytoplankton), 100-120 microns (mesozooplankton). Nets with 300 and 500 microns mesh witll take care of the rest.

there are several manuals on the subject. In my times (actually, a few years later) the ultimate word could be found in the UNESCO series (Monographs on oceanographic methodology), but I am sure that the many followers of this question will have some additional and better suggestion.

luck

As Domencio says, it depends a lot on the size but also the environment you want to study phytoplankton. My main area is on picoplankton and nanoplankton, including phytos, and I use filtration system to analyze them; using for DNA/RNA extraction and microscope analysis with DAPI. The amount of water suggested above (2L) will actually vary on the environment you are extracting phytoplankton from. Eutrophic zone such during blooms or in highly producing coastal areas should be fine with 2-3L. However, oligotrophic waters, such I survey in the Arctic, would require more approximately 6-7L to have better resolutions of your data, especially when analyzing DNA/RNA. 

Also, if you aim for the smaller size fraction of phytos, prior to filtration on small size filters (0,45/3um/10um) you may removed >20/50um size cells using mesh at the input of the filtration system. 

The advantageous of filtration from colleced water using rosettes is that you can select exactly the depth vs nets which you are more limited in the accuracy of depth. Therefore using Niskin bottles to collect seawater would be much more efficient to analyze depth distribution. I invite you to have a look at Connie Lovejoy's work where our techniques are desbribed.

We typically collect whole water samples and fix with Lugol's iodine solution (~1% or so sample resembles weak tea). A known volume is settled in an Utermohl chamber and allowed to settle overnight before counting all protozoans (we are interested in the 20-200 um size range). For zooplankton, we stream a 153 um mesh net (0.5 m diam, 1:4 mouth:length ratio) equipped with a flowmeter beside the boat at a relatively low speed for 2 minutes. The sample is poured through a 2000 um mesh into a bottle w/ formalin so that the final concentration is 5%.  We then concentrate the sample to a known volume and remove an aliquot of the sample for counting purposes. If you are only interested in a certain size fraction, you can pass the sample through a number of sieves (330 um, 500 um, etc.) to isolate the size fraction that you are interested in.  Good luck!

Hi !

First of all You have to decide what kind of plankton would You like to collect and if the collected sample should be only qualitative or both qualitative and quantitative. Simple qualitative sample You can take by plankton net. Mesh size of plankton net up to what kind of plankton You sampled. In my opinion mesh size 25 µm is pretty enough for zooplankton. My colleague for phytoplankton use plankton net with mesh size 10 µm.

Methodology for zooplankton and for phytoplankton is different (also methodology for freshwater and seawater is different). We take samples in freshwater ecosystems.

Qualitative and quantitative samples for zooplankton should be taken by special samplers (bucket). I use Patalas sampler (1 L or 5 L). Water is filtered through a plankton net; mesh size 25 µm. The methodology we describe more precisely in our articles. There are also a base references.

Best wishes

Hi !

First of all You have to decide what kind of plankton would You like to collect and if the collected sample should be only qualitative or both qualitative and quantitative. Simple qualitative sample You can take by plankton net. Mesh size of plankton net up to what kind of plankton You sampled. In my opinion mesh size 25 µm is pretty enough for zooplankton. My colleague for phytoplankton use plankton net with mesh size 10 µm.

Methodology for zooplankton and for phytoplankton is different (also methodology for freshwater and seawater is different). We take samples in freshwater ecosystems.

Qualitative and quantitative samples for zooplankton should be taken by special samplers (bucket). I use Patalas sampler (1 L or 5 L). Water is filtered through a plankton net; mesh size 25 µm. The methodology we describe more precisely in our articles. There are also a base references.

Best wishes

Hello,

Sampling zooplankton would use plankton net and NIskin sampler. Segregation or sorting may use stereomicroscope or zooscan and other imaging instruments.

Goodluck

EMetillo

Dear Nabonita,

You can collect the planktonic biomass from any aquatic body by using any standard bolting silk  plankton net but if you prefer to use it for Freshwater then 60um is good and for brackish or marine 100um will give you good sample catch. Later on segregation can be done using a series of different meshed conical funnels arranged in order from highest mesh to lowest mesh size (order of mesh is best determined by  you according to the species interested). Good luck.

Dear Nabonita,

for phytoplankton enough good results are obtained by using Utermohl settling method, and Lugol's solution. But if you are acting with some groups of flagellates, especially soft, better to calculate them at life. If no possibility, can use Shaudinn or Nissenbaum fixation. You can find a lot of variants in the Internet, but should know that different methods can guide you to a different results, so you should select one to have compareble results.

Andrey