Red tide - please explain something to me?

[pwnell]

I tried to isolate the organism responsible for the red coloration in the red tide we had recently. However I seem to be struggling a lot. The only organism I could find that has a red tint to it is shown below. They consist of very small blobs (about 6 times the width of a red blood cell) that swim very fast - they swim almost like some ciliates. I can clearly see flagella, or bristles, that they use to swim with. However, as soon as I place a drop on the slide to photograph, they expire within 10 seconds. They would swim quickly, then stop, then the next moment they explode - the bristles drift away and their body changes into small cells that fluoresces. Each and every single of these organisms did the same - even in a slide with a depression so that cover slip pressure could be ruled out - that is why I could never get closer than with my 40x. Also, these images are very heavily cropped.

Please can someone ID this organism and tell my why their behaviour is so odd?

Shot within 10 seconds of placing on the slide:

20140713-DSLR_IMG_0024-Edit.jpg by pwnell, on Flickr
Red tide @ Coal Harbour, 40x/0.6*1.25, DIC, HF B

Shot within 10 seconds of the previous shot:

20140713-DSLR_IMG_0035.jpg by pwnell, on Flickr
Red tide @ Coal Harbour, 40x/0.6*1.25, FLUO-C4

Shot within 10 seconds of the previous shot - it "exploded" between this and the previous shot:

20140713-DSLR_IMG_0036.jpg by pwnell, on Flickr
Red tide @ Coal Harbour, 40x/0.6*1.25, FLUO-C6

Shot within 10 seconds of the previous shot:

20140713-DSLR_IMG_0041-Edit.jpg by pwnell, on Flickr
Red tide @ Coal Harbour, 40x/0.6*1.25, FLUO-C6, HF C

Three more... This one swam about and stopped in a weird position:


Then it exploded:

[rjlittlefield]

Waldo, I am not familiar with these beasts but I wonder if perhaps they are very sensitive to light rather than any other condition of being on a slide. Have you checked to see if they will survive on a slide with the illumination turned off?

--Rik

Edit: relevant link? http://siobiolum.ucsd.edu/dino_intro.html

[pwnell]

Waldo, I am not familiar with these beasts but I wonder if perhaps they are very sensitive to light rather than any other condition of being on a slide. Have you checked to see if they will survive on a slide with the illumination turned off?

That sounds plausible but there are two things that concern me: If they were so light sensitive, why do they proliferate in the ocean causing Red Tide only when the temperatures are very high and the sun is shining very brightly? And lastly, how would I verify they do not die if I do not shine a light on them? Only way I can think of testing that is to put them on the slide in darkness, wait say 2 minutes then turn back on the light? Unfortunately the red tide has disappeared overnight and I have no more samples.

[Greg Gavelis]

Hi Waldo,
From the speed of it and the plastids, it seems like it could be Myrionecta--a kleptoplastic ciliate.

[rjlittlefield]

Only way I can think of testing that is to put them on the slide in darkness, wait say 2 minutes then turn back on the light?

Right, that's what I was thinking. But if they're gone, that won't work.

As for the light brightness, i haven't run the numbers or taken the measurement, but I would not be surprised if the light intensity in the condenser focus of a scope was substantially higher than full but unfocused sunlight, even at the surface of the water column.

--Rik

[rjlittlefield]

it seems like it could be Myrionecta--a kleptoplastic ciliate.

Many thanks for this reference. After a short search, I found http://skepticwonder.fieldofscience.com ... necta.html, which is a delightfully complicated tale!

--Rik

[pwnell]

it seems like it could be Myrionecta--a kleptoplastic ciliate.

Many thanks for this reference. After a short search, I found http://skepticwonder.fieldofscience.com ... necta.html, which is a delightfully complicated tale!

--Rik

I was reading the exact same article. Very interesting!

[René]

I agree, it is Myrionecta. They are very susceptible to stress and fall apart easily. In sedimentation chambers for use on inverted scopes they will keep a bit longer, and sometimes you can be lucky to find them still for a few seconds before they fly off again. Chasing them in such a chamber is a good sport...

I couldn't make anything of the first set of images from the red water, but now it is clear. From my memory, the chloroplasts are cryptophytes, which explains the yellow autofluorescence with some of the filter cubes.

Best wishes, René

[billporter1456]

I love threads like this which start with a mystery and end with a solution!