Helpful Method for Identifying Dinoflagellates

sonnus

Premium Sponsor
Premium sponsor
Joined
May 7, 2009
Messages
562
Likes
9
Points
18
Location
La Canada, CA
#1
There have been dozens (probably hundreds) of posts from people trying to identify dinoflagellates in their aquarium. I have posted this in other threads but figured it might be helpful to start a thread explaining this method.

Dinoflagellates are single-celled organisms that aggregate to form visible colonies on surfaces in our aquariums. They are typically described as a brown slime algae.

Correct identification of dinoflagellates is important since different algal blooms have specific treatments that are most effective depending on which type of bloom you're dealing with. Many posters have suggested that microscopic identification is necessary but this is obviously not reasonable for most of us.

I accidentally stumbled on this phenomenon many years ago while siphoning dinos from my tank through a filter sock into a bucket. The water was essentially clear in the bucket but after sitting in the bucket outside I noticed brown slime algae "growing" in the bucket. After stirring the bucket water vigorously the algae disappeared completely only to reappear a little while later.

To identify dinoflagellates you'll need to siphon some algae into a container preferably with a lid or cap. After filling up the container shake the water up vigorously to break up the algae. Then filter the water through a paper towel or filter sock, the water should be rather clear. Leave the water exposed to ambient light in this container for 30-120 minutes. In my experience dinoflagellate algae will be the only type that aggregates back together quickly in the container.


Here's the sample water after filtering through a paper towel



And here's the same water after sitting in ambient light for about an hour
 

Tangwich

2
2020 Philanthropist
Joined
May 20, 2009
Messages
11,949
Likes
1,090
Points
63
Location
Pasadena
#3
Fish tank snot is how I refer to it, but your description is a bit more eloquent. Lol
 

sonnus

Premium Sponsor
Premium sponsor
Joined
May 7, 2009
Messages
562
Likes
9
Points
18
Location
La Canada, CA
#7
In my experience, this is also a good way to distinguish between the different types of brown algae.

Dinoflagellates will disperse in the container completely after being shaken and will pass through the filter almost completely with only detritus remaining in the filter. Once the filtered water has been left sitting in ambient light for about an hour they will organize back together into their typical slimy appearance. Dinos seem to be the most neutrally buoyant of the three.

Cyanobacteria will typically stay matted together even after shaking the capped container vigorously with lots of small bits resembling torn paper. Most of the algae will be caught in the filter with the detritus but the filtered water will still be discolored. The algae will not organize back into colonies after an hour. The water tends to stay brown but sometimes the cyano settles on the bottom of the container. Cyano seems to be close to neutrally buoyant most of the time.

Diatoms will disperse much more than cyano when shaken vigorously into a brownish tint but sometimes tiny bits stay together like the cyano. Much more of the diatoms will pass the filter compared to the cyano. The diatoms will not reorganize after the filter and they tend to be more negatively buoyant than the cyano or dinos so they settle on the bottom of the container faster.

I think all of these algae can change their buoyancy so this might vary but the diatoms are constantly less buoyant than the others.
 

s2k

Member
Joined
Jun 29, 2007
Messages
1,141
Likes
84
Points
38
Location
91801
#8
Aaron the Algae Expert!!! When are you at your shop? I need to stop by one of these days.
 

Latest posts

Top