Bleaching anemone's: myth's, facts, discussion etc

[hypnoj]

I've read several hundred posts on RC where bleached anemone's are discussed and typically the OP is criticized for having a bleached anemone in his/her picture etc. It is probably the most "called out" thing that can happen to an anemone owner on this forum. So.. I want to open up a discussion on bleached anemone's, how to spot one, what causes bleaching, and discuss if it is even bad.
Most people might quickly say "ya, bleaching is bad". I think this happens because reefers are attempting to compare anemone's to hard corals; where bleaching is certifiably bad news. However, I think it is a poor comparison.

A little bit of history about myself. I currently have 3 saltwater tanks running for a little over 3 years with a total of 23 anemones (3 separate species). One tank is MH and T12's (one anemone), one tank has power compacts (two anemone's), and one tank has LED's (with currently 20 BTA's all of from different colors and family lines). I bring this up so that you understand that I have some experience.

In my LED driven anemone tank I have purchased many different transparencies when it comes to anemone's as well as watched many anemone's take on different transparencies and colors while attempting to adjust to my lighting (3 watt Cree's). I have a couple of anemone's that have been totally growing and thriving for several months while remaining fairly transparent and "bleached" as I'm sure most of you with an opinion would post.
So, back to the original quest... How do you spot a bleached anemone? What causes bleaching? And do you consider bleaching even bad and why (especially in a growing and thriving specimen)?

 

[BonsaiNut]

We just had a long discussion on anemone nutrition in another thread, and a discussion on anemone bleaching in a third. My typing fingers are getting sore But this is always a great topic.

Suffice it to say that clown anemones have symbiotic algae that provide nutritional benefit to the anemone not unlike the same benefit that is provided to many (but not all) corals. The algae is handed on from parent to offspring, and is even present in anemone eggs. There are different types of zooxanthellae (clades) that respond differently to different types of lighting, and anemones can have more than one type of zooxanthellae and can "juggle" populations based on environmental changes - increasing one kind, decreasing another, or evicting them outright.

Clown anemones rely on zooxanthellae for much of their energy needs. Clown anemones with zoonxanthellae grow much faster than those without - particularly in relatively nutrient-poor waters (like those on tropical coral reefs). However anemones do not require zooxanthellae to survive as long as supplemental feeding is available - just as most anemones species (particularly those in colder, nutrient-rich water) do not host zooxanthellae. Compare this to non-photosynthetic corals - they don't need the sun to survive, but they require much higher levels of supplemental food.

So you need to decide what kind of tank environment you are trying to create - a low light, high nutrient environment (like this month's Tank of the Month?)? Or a high light, low nutrient one? Clown anemones have evolved to thrive on shallow water tropical reefs. They are not found in deeper water, nor are they found outside of tropical (or in the case of two species - semi-tropical) water. When people respond to seeing a bleached anemone, it is typically the result of one of two broad causes - one, that the anemone bleached at some point during its collection and shipment and distribution to the owner's tank, or two, that the anemone bleached after arrival in the owner's tank. If the prior, the anemone will likely recover in a good tank environment. If the later, the anemone may be in trouble - because it speaks to likely problems in the reef tank environment.

Additionally bleaching can occur naturally even in the wild in good conditions. Anemones can bleach when they asexually reproduce. They can bleach when they move from one environment to another. But most of the time when anemones bleach in the wild it is due to a bad environmental situation.

 

[BonsaiNut]

To continue...

Zooxanthellae are actually dinoflagelletes - single-celled algae that appear brown to the human eye. They are opaque - not transparent - and an anemone with a healthy population of zooxanthellae is opaque - not transparent. The term "bleaching" comes from the fact that healthy clown anemones with healthy zooxanthellae populations ALL have a brownish coloration beneath their secondary pigmentation. Bleached anemones can often look like they were dropped in a bucket of bleach - the brown color is gone and the anemone will look whitish and transparent.

Clown anemones take a long time to recover from being totally bleached. For whatever reason, population doubling rates of zooxanthellae inside anemones is much longer than population doubling rates of the same zooxanthellae in vitro. One to three WEEKS is a fair estimate for zooxanthellae populations to double - so an anemone recovering from total bleaching can take months to recover a healthy population of zooxanthellae. During this time you have to treat the anemone as if it were a cold water anemone - i.e. with heavy supplemental feeding - or it will starve and die. Many anemones that come into LFS bleached have already begun to starve - hence the short tentacles, small compact wrinkled appearance, gaping mouths.

The best way for an anemone to recover from being bleached is to be placed in an environment as close as possible to the one in which it was collected. If you get an anemone from another reefer, you will want to try to match water chemistry, lighting, etc. If your anemone comes from the wild, you will want to introduce it to a pristine reef aquarium setting as gradually as is practical - being particularly careful to slowly introduce it to new lighting. During this time it is important to make sure that all the other needs of the anemone are being met; that is is protected from predators, that it has good flow of high oxygen water, and that it is not being overly disturbed - by the reefer or by aggressive clowns.

If you decide to supplementally feed your anemone, make sure you start slowly with small bits of food. Clown anemones are opportunistic feeders that normally accept a broad range of foods - they will swallow first and ask questions second. This is not to say that they can digest everything - they often have preferences based on where they were collected and what they are used to eating - and one anemone may accept food that another will reject. Try different foods and try a varied diet and see which foods the anemone digests fully versus foods that it digests partially - or doesn't digest at all. Above all, make sure to feed FRESH food; there is anecdotal evidence that you can kill anemones via food poison by feeding bad seafood (particularly bad shrimp and bad silversides).

Slow and steady is the key. Anemones are simple creatures that have limited capacity to adapt quickly to change. Provide a stable, healthy environment, and give them plenty of quiet time to adjust, and they can become quite robust creatures that are extremely long-lived.

 

[hypnoj]

What is your take on a tank full of BTA's where one BTA is considered "bleached" directly beside another BTA that isn't (assuming that both BTA's have been this way for several months)?
Also, what does the color of the anemone (a loss of which is called "bleaching") have to do with zooxanthellae? I've heard that zooxanthellae are brownish.

 

[BonsaiNut]

What is your take on a tank full of BTA's where one BTA is considered "bleached" directly beside another BTA that isn't (assuming that both BTA's have been this way for several months)?
Also, what does the color of the anemone (a loss of which is called "bleaching") have to do with zooxanthellae? I've heard that zooxanthellae are brownish.

You can have anemones in the wild that exhibit this. Often it is the case of asexual reproduction, but not always. Sometimes it is environmental - one anemone clone is in slightly shallower water and is exposed at low tide, while its neighbor is able to sit in a shallow pool of water. In cases where light is barely adequate, a deeper anemone can bleach (or be lighter) than a shallower one.

Anemone pigmentation has nothing to do with zooxanthellae. All clown anemones with healthy zooxanthellae populations have a brownish color INSIDE due to the color of the zooxanthellae. Anemone pigmentation is usually on the OUTSIDE of an anemone, and its function is not fully understood. In some cases the pigmentation blocks UV radiation, and its presence is directly related to the presence of UVR - the more UVR the more pigmentation (up to a point). But some pigmentation does not block UVR and does not appear to have any direct functional role. Hence you can have "bleached" anemones with no zooxanthellae that still have pigmentation even in the total absence of sunlight. In these cases, the bleached anemone often takes on a different color once it regains zooxanthellae - for example a BTA with pink pigmentation might appear red or orange with zooxanthellae - or a S. gigantea with yellow pigmentation might appear greenish.

Additionally, some anemones can have more than one type of pigmentation. Some can have UVR blocking pigmentation and "normal" pigmentation. Some can have stripes, or blocks of different colors (particularly S. haddoni, S. mertensii, or C. adhaesivum). Tentacles on some anemones can have different colors over their length, or different colors on their tips. These are all pigmentation and have nothing to do with zooxanthellae. Some of this pigmentation will get darker or lighter depending on presence of different wavelengths of light - but not always.

The jury is still out on how this pigmentation develops and what triggers different color morphs (in sexually reproduced anemones). In one case involving sexual reproduction of S. gigantea, only adults with bright color morphs were used, and yet half of all offspring were "brown" i.e. showed only zooxanthellae coloration. All the other gigantea babies were green. Over time (several years) about half of the "brown" ones turned blue. Was this due to the environment? Or do blue giganteas take longer to develop their pigmentation? Who knows?

 

[hypnoj]

Thank you for the good explanation BN. I think this lends well to the discussion and can help clarify some common misconceptions about anemone's and coloration.

 

[LeLutinBanni]

Thank for sharing Bonsai

 

[bues0022]

Very well put summary!

 

[KeLusth]

The best way for an anemone to recover from being bleached is to be placed in an environment as close as possible to the one in which it was collected. If you get an anemone from another reefer, you will want to try to match water chemistry, lighting, etc. .

If you buy a slightly bleached to bleached anemone. Do you put it in high light like its natural environment right away or do you put it in the same lighting that you purchased it from? If it was purchased from low lighting do you put it in low lighting to begin with and then hope that it moves safely to higher lighting when it wants to or hope that you can move it to higher lighting later?

 

[hypnoj]

i recommend putting anemone's at the bottom of tanks and letting them climb to the top if they need it.

 

[ct_vol]

I have mine at the bottom and will move it upward as it colors up.

 

[canadianeh]

What your takes on this one? It is sold as gold tip BTA. It is much yellow/gold/orange in person.