Simple brown film on front glass – Wild ecosystem!

[Wampatom]

I have been trying to identify algae growing in my tanks. It is way more complicated and less stable than I expected.

I placed a microscope slide against the front glass of my 75 gal reef tank and left it there for 1 week. It is a low flow area that gets a light brown film every week. I took the slide out, cleaned the bottom, and placed a cover slip on top.

Here is a low magnification view (4x objective)

Below is a link to a movie of the same scene. It is best to look at it with a 1080p screen to see the detail.


Next is a 40x objective view in a slightly different location:

It is a thick slide so all of the organisms can’t be focused at the same distance. Working from high to low. (A) shows a ciliate, (B) I believe is Amphidinium (Small Cell) with mysterious red object. (C) is a common (to my tank) green algae. (D) is a type of green hair algae. One end is attached to the glass. At the lowest level is a brown algae (E) that attaches to the glass. It is the most common algae in my tank, maybe Symbiodinium-like Chrysophyte? Taricha help please! It is in focus toward the end of the video link below.

Here is a link to a movie of the same scene. In the second half of the movie I change the focus. First high (away from the glass) and then slowly focus down toward the glass.

 

[vetteguy53081]

A combination of inorganics and algae. Light is the main food source for this film you see which easily cleans up but a pain. I have to remove every 2 days on my drop off tank.
If your tank is at or near a window, it becomes more frequent

 

[Wampatom]

At this early stage it is all live organisms. I remember the response to a question here of R2R asking how often people scrape their glass. Most people have to scrape and do it about 1-2 times a week.

I am interested in this layer. It appears to me there is a distinct organization of algae rather than a mono-culture.

 

[taricha]

At the lowest level is a brown algae (E) that attaches to the glass. It is the most common algae in my tank, maybe Symbiodinium-like Chrysophyte? Taricha help please! It is in focus toward the end of the video link below.

@Dan_P will be a fan of your biofilm community explorations here.

Oh, boy. I love when I have no idea.

Here you can see a number of the same cells that are mostly empty. Maybe this represents concentration of cell contents into a few small compartments for storage - perhaps a cysts stage. Or some of the totally empty ones may mean these are cell coverings that have been shed like dinoflagellates do.

bottom right and top left you can see these same cells in an edge-on view, showing that they are flat bottom ovals and not uniformly round. Clearly these are attaching to things with the flat side, and they seem totally immobile and without flagella. (but lots of flagellates lose flagella for some phases of their life)

here's one in edge-on that is growing as an epiphyte on the green filamentous algae, as the others grew on the glass.

General observations and presumptions.
Probably too golden brown to be a green algae / chlorophyte, though a few can make a bunch of carotenoids and look golden under extreme conditions. But probably has to be something with a different pigment set: Chlorophyll C like diatom, dinoflagellate, cryptophyte, yellow-green, or Phycobilins like a cyano.
The cells are almost all asymmetric. Light spot near one edge surrounded by darker chloroplast everywhere else. That kind of asymmetry in the majority of cells doesn't really show up in diatoms or cyano much at all.
The cryptophytes are much more mobile and predatory and pretty much always have flagella flapping. So I'm talking myself into a resting phase of a dinoflagellate as the most likely, I think.
Or it's something entirely off my radar and a good bit weirder.

 

[Dan_P]

@Dan_P will be a fan of your biofilm community explorations here.

Oh, boy. I love when I have no idea.

Here you can see a number of the same cells that are mostly empty. Maybe this represents concentration of cell contents into a few small compartments for storage - perhaps a cysts stage. Or some of the totally empty ones may mean these are cell coverings that have been shed like dinoflagellates do.

bottom right and top left you can see these same cells in an edge-on view, showing that they are flat bottom ovals and not uniformly round. Clearly these are attaching to things with the flat side, and they seem totally immobile and without flagella. (but lots of flagellates lose flagella for some phases of their life)

here's one in edge-on that is growing as an epiphyte on the green filamentous algae, as the others grew on the glass.

General observations and presumptions.
Probably too golden brown to be a green algae / chlorophyte, though a few can make a bunch of carotenoids and look golden under extreme conditions. But probably has to be something with a different pigment set: Chlorophyll C like diatom, dinoflagellate, cryptophyte, yellow-green, or Phycobilins like a cyano.
The cells are almost all asymmetric. Light spot near one edge surrounded by darker chloroplast everywhere else. That kind of asymmetry in the majority of cells doesn't really show up in diatoms or cyano much at all.
The cryptophytes are much more mobile and predatory and pretty much always have flagella flapping. So I'm talking myself into a resting phase of a dinoflagellate as the most likely, I think.
Or it's something entirely off my radar and a good bit weirder.

Thanks for the heads up on this post. Nice piece of work. I like the glimpses of these little ecosystems. Whenever I see them, I try to imagine why those organisms are there, what nutrients are enabling them to be there and what unseen biofilm of bacteria is enabling it to exist. It would great fun but technically challenging to feed this slide with more phosphate or more nitrate to see what that does.

By the way, were there cyanobacteria filaments present?

Relative to studying “grunge” in the substrate, it would be amazing to study aragonite surfaces like a slide surface. Would I “glue” some clean substrate on a glass slide and sink it and then retrieve it in a week?

Dan

 

[taricha]

By the way, were there cyanobacteria filaments present?

Yes, you can see the pink filaments OP labeled (F) in the pic.

Next is a 40x objective view in a slightly different location:

It is a thick slide so all of the organisms can’t be focused at the same distance. Working from high to low. (A) shows a ciliate, (B) I believe is Amphidinium (Small Cell) with mysterious red object. (C) is a common (to my tank) green algae. (D) is a type of green hair algae. One end is attached to the glass. At the lowest level is a brown algae (E) that attaches to the glass.