Amyloodinium ocellatum life cycle

[ThRoewer]

I've been looking to find detailed data on the Amyloodinium ocellatum lifecycle, but have so far come up empty with actual research papers on that matter.

What I found is
- feeding stage (on fish): 3 days to a week
- reproductive stage (cyst): ~5 days to a week, can lay dormant for months due to low temperature
- infective stage (free swimming): a week to a month depending on strain

I also found that the temperature has (unlike Cryptocaryon) a significant influence on the development speed in each stage.

Has anyone links to research articles that go into more details, similar to what can be found for Cryptocaryon?

[ReefTeacher]

ThRoewer,

this is very interesting. What do you think this means for QT? I have read the rumors that TTM is not effective for Amyloodinium but I have never seen a scientific reference that substantiates this "encystation on the fish" idea. I think it is hokum!

When I do TTM I transfer every 2 days instead of every 3. I have also heard that given high temps Amyloodinium can have a very rapid life cycle. It also helps to keep water cleaner when I transfer more often. I will do some research and see if I can find any articles on this. One time I asked a guy who worked in a fishery why there was so little literature on Amyloodinium. He claimed that it kills so fast is it hard to do research. He also said it was not as common an infection as Cryptocaryon in food fish culture.

Thoughts?

[microlady]

I'm interested in how fish can act as carriers, especially if they are exposed to levels of copper. How does copper exposure actually mask the infection for several weeks?

[snorvich]

Originally Posted by ThRoewer

I've been looking to find detailed data on the Amyloodinium ocellatum lifecycle, but have so far come up empty with actual research papers on that matter.

What I found is
- feeding stage (on fish): 3 days to a week
- reproductive stage (cyst): ~5 days to a week, can lay dormant for months due to low temperature
- infective stage (free swimming): a week to a month depending on strain

I also found that the temperature has (unlike Cryptocaryon) a significant influence on the development speed in each stage.

Has anyone links to research articles that go into more details, similar to what can be found for Cryptocaryon?

When I was reading the literature, a synopsis f what I could find:

The Life Cycle of Amyloodinium ocellatum

• Free-swimming cells called dinospores are released from a mature cyst and go in search of a host fish. Typically these cells can survive seven to eight days without a host, but at temperatures around 75-80 degrees, some strains may last up to 30 days or more. Raising the temperature will speed up the lifecycle but it also reduces dissolved oxygen in your tank water. For fish with this parasite in their gills, this treatment can be dangerous.

• Once a host is found, typically heading for the soft tissue inside the gills first, the dinospores lose their swimming capabilities and become non-motile parasitic trophozoites. At this stage they turn parasitic, as each attaches to the host fish by sending out a filament for feeding.

• After feeding for 3 days to a week, the trophozoites become mature and either drop off into the substrate, remain hidden in the mucous membrane, or sometimes remain deeply embedded in the tissue of a host fish. At this point, each forms a hard shell covering.

• Inside each encrusted cyst, the cells, now called tomonts, reproduce internally by non-sexual division. Upon reaching maturity in about five days, each cyst ruptures and releases hundreds of new free-swimming dinospores to start the cycle all over again, but in much large numbers.

[snorvich]

Originally Posted by microlady

I'm interested in how fish can act as carriers, especially if they are exposed to levels of copper. How does copper exposure actually mask the infection for several weeks?

I do not know why a non-therapeutic level of copper masks velvet and other parasites. I do know, from a large number of anecdotal experiences of my own and from folks here, that it does. It seems that many LFS also figured that out to keep their fish from perishing.

[jason2459]

Thought this was pretty cool.

[ThRoewer]

Originally Posted by microlady

I'm interested in how fish can act as carriers, especially if they are exposed to levels of copper. How does copper exposure actually mask the infection for several weeks?

My theory is that the copper kills or impairs enough of the parasites to prevent the "avalanche-effect" of a "normal" infection, but not enough to clear the fish or the system.
This may also give the fish the time to build up some partial immunity against these parasites, which may account for the delay after the copper is no longer present.

Originally Posted by snorvich

When I was reading the literature, a synopsis f what I could find:

The Life Cycle of Amyloodinium ocellatum

• Free-swimming cells called dinospores are released from a mature cyst and go in search of a host fish. Typically these cells can survive seven to eight days without a host, but at temperatures around 75-80 degrees, some strains may last up to 30 days or more. Raising the temperature will speed up the lifecycle but it also reduces dissolved oxygen in your tank water. For fish with this parasite in their gills, this treatment can be dangerous.

• Once a host is found, typically heading for the soft tissue inside the gills first, the dinospores lose their swimming capabilities and become non-motile parasitic trophozoites. At this stage they turn parasitic, as each attaches to the host fish by sending out a filament for feeding.

• After feeding for 3 days to a week, the trophozoites become mature and either drop off into the substrate, remain hidden in the mucous membrane, or sometimes remain deeply embedded in the tissue of a host fish. At this point, each forms a hard shell covering.

• Inside each encrusted cyst, the cells, now called tomonts, reproduce internally by non-sexual division. Upon reaching maturity in about five days, each cyst ruptures and releases hundreds of new free-swimming dinospores to start the cycle all over again, but in much large numbers.

I actually read in one research paper that the dinospore stays motile for up to 24h after attachment. This allows it to find a new host in case the current host dies or if it gets dislodged by other means. After feeding for more than 24h it is capable of dividing (less often though) should the host die.

The most scary - and the reason why TTM is not a reliable method here - is the fact that it can actually encyst on the fish.

Originally Posted by jason2459

Thought this was pretty cool.

Well, this is the info you find everywhere, but it does not contain the details or time periods of each stage which is the info I'm looking for.

Especially of interest is the duration and properties of the reproductive stage. Also does Amyloodinium form attached cysts like Cryptocaryon or is the reproductive stage rather loose in the substrate? If it attaches, can it attach to inverts, corals,...?

I want to know for how long inverts and corals can possibly carry a "cysts".
After the dinospores have hatched it should be possible to wash free stages away with a series of tank transfers or full water changes. Therefore the maximum "cyst" stage length is what's of most interest.

Raising the temperature may or may not be a possibility with corals and inverts, but it would be good to have time tables how long the fallow period would need to be at which temperature.

The issue with the free infective stage is that it can linger for quite some time as it can generate energy via photosynthesis.
After all, Amyloodinium is not a true protozoan, but rather something in-between plant and animal.

This is the parasite that gives me sleepless nights - not Cryptocaryon.

[jason2459]

The information is common but the images are not which is what I found interesting. This is the first life cycle chart I've seen using actual pictures of the different stages. Normally they are drawn images.

[jason2459]

Potentially A. ocellatum has different varieties or species being classified as the same. I wouldn't be surprised if they are both phototrophs and heterotrophs but not all dinoflagelets are.

This study incubated from trophont and made notes of the tomont and dino spore stages. They varied quite a bit.


Scanning electron microscope study of dinospores of Amyloodinium cf. …
https://www.google.com/url?sa=i&sour...93070349&rct=j

That should open a pdf

[curtcherry]

Good video with actual microscope shots. More about ich, but discusses other parasites, etc.

https://www.youtube.com/watch?v=946_XDuKR2Y

[jason2459]

Originally Posted by jason2459

Potentially A. ocellatum has different varieties or species being classified as the same. I wouldn't be surprised if they are both phototrophs and heterotrophs but not all dinoflagelets are.

This study incubated from trophont and made notes of the tomont and dino spore stages. They varied quite a bit.


Scanning electron microscope study of dinospores of Amyloodinium cf. …
https://www.google.com/url?sa=i&sour...93070349&rct=j

That should open a pdf

Direct link to the PDF
http://www.int-res.com/articles/dao/20/d020p023.pdf

[ThRoewer]

On my search I came across an interesting research paper that found that Amyloodinium is part of the food chain:

Ecological and morphological features of Amyloodinium ocellatum occurrences in cultivated gilthead seabream Sparus aurata L.; a case study

"Abstract
Understanding the patterns of occurrence of the ectoparasite Amyloodinium ocellatum and the conditions that result in its maintenance at non-dangerous levels for gilthead seabream Sparus aurata could be very useful, since outbreaks of heavy infestation by this parasitic dinoflagellate can cause severe mortality in temperate aquaculture. We have evaluated the interactions between A. ocellatum and related environmental variables for the first time. Biotic and abiotic parameters of water quality in production ponds from a temperate aquaculture (Sado Estuary, Portugal) were monitored and subsequently analysed. Dissolved oxygen, water temperature, pH, phytoplankton biomass and salinity were closely related to A. ocellatum occurrences; dissolved oxygen, water temperature, pH and phytoplankton biomass had significant negative relationships with A. ocellatum trophonts, while salinity had a significant positive relationship with A. ocellatum trophonts in fish gills. Phytoplankton biomass was significantly correlated with increases of dissolved oxygen in production ponds. An increasing of rate of water renewal increased salinity, due to persistence of low water levels in production ponds during the water renewal procedure. Salinity negatively affected phytoplankton biomass and consequently the level of dissolved oxygen, raising the probability of A. ocellatum occurrences. Fish biomass in production ponds was correlated with the average and the maximum number of trophonts found in fish gills, highlighting the importance of defining stocking levels and production values in ponds. The present results help to improve understanding of the interactions between biotic and abiotic variables, fish farm management practices and parasite incidence in temperate terrestrial pond aquaculture. A morphological feature of the A. ocellatum tomonts cells in division phase, collected from the most infected fish gills, is discussed. We also give a description and illustration of the phases of the A. ocellatum life cycle.

Keywords: Amyloodinium ocellatum, environmental variables, life cycle, aquaculture"


"...
Phytoplankton is important in the ecology of complex estuarine food webs. Amyloodinium ocellatum is one of the many organisms that compose estuarine food webs and its population dynamics should be controlled by the roles of predator-prey or consumer-resource relationships. Increased phytoplankton would cause the zooplankton to increase. Those microorganisms and bacteria could feed on A. ocellatum at some stage of its life history and thus lessen chances of increase in its numbers (Brown, 1934).
..."

So adding rotifers like Brachionus which feed on Phytoplankton to a fallow tank or an invert QT system is likely to decrease the free, infective stages of Amyloodinium quickly.

This may be a way to decrease the chances of an infective stage hanging out longer than expected. It's not an alternative to a fallow period or to cut it short. And for sure it's not a treatment option for sick fish.

The article also shows the risks involved with overstocking a tank with too many fish.

It also highlights how beneficial a diverse micro fauna can be in preventing outbreaks should a pathogen ever slip through the quarantine.

[microlady]

Dinoflagellates are a part of phytoplankton, so that does make sense. What interests me is that they can have different life stages which include both photoautotrophic and chemoheterotrophic forms. As nasty as it is, it is clearly a marvel of adaptive evolution.

[microlady]

Thanks for sharing the links. SEM photos always make everything look more menacing!