SPS polyp extension

[Twistedpro]

I was wondering if you could help, i have had SPS in my tank for around 2 months now and i used to have very good polyp extension however nitrates were very high without me knowing as the test kit was off.

I have improved the water quality considerably by the addition of a sump and a larger skimmer where nitrates are down to 5ppm and i have also increased the water flow from 2400lph to 4600lph.

Now i get very little if any polyp extension. IS this good bad or just an acclimitisation effect?

[clippo]

how long since the changes?

In my experience, some sps can take a while to 'relax' after disruption...

[SPS Hoover]

Could one of a few reasons

Salinity change from water changes, increased flow.

Were polyps out when the nitrates were high?

What is phosphate reading?

[Glenn@home]

This raises an interesting point about how to tell if corals are 'happy'.

Polyp extension is often cited although i am sure there are degrees ie between not extension and extended as far as physically possible for a given polyp.

What is not clear to me is what is normal for a given coral and how to tell when things are good or bad.

It has been suggested for example that polyp extension may be related to food avalability and when in short supply polyps become extended beyond a normla level.

Only throwing this into the ring since it seems to me that its possible to get focused on a single issue rather than the overall picture e.g. growth, colour, general condtion, behaviour etc.

JMHO

Glenn

[Twistedpro]

i use a refractometer for water changes, its always 1.026, and i always check the calibration before.

The nitrates were at around 40-50ppm and polyps were always out. Yes the flow has increased but its not fierce flow more diffuse but through the whole tank

[ahoy]

What other parameters do you check? The addition of a large skimmer (which model?) could lead to removal of many ions, as they are often complexed to proteins and smaller peptide chains.

I'd suggest you look at iodine, magnesium, calcium, KH & phosphate as well as the nitrate. Perhaps even look at strontium and molybdenum, although these are present in trace amounts and i'm not sure how sensitive the kits are (I don't measure these!)...

S.

[Martyn]

I talk here mostly about Acroporids as these are what I mostly keep.
Many Acropora in the wild do not have there polyps extended much during the day.
But extend there polyp's fully during the night and may feed on plankton as it rises up through the reef at night.


In the aquarium there are many factors different to on the reefs.
There is likely more food available (feeding fish and some keepers feed there corals and some do it during the day) in the aquarium during the day (lighted period) than on the reefs this is available for the polyps to expand during the day if they do not recieve enough light.
Also, closed systems are often high in nutrients which Also may give allow the polyps to expand and feed during the day if needed.


Lighting:
This may effect polyp extension if the acropora does not recieve enough light it may reoganise its zooanthellae to adapt too a different lighting parameter from what it was adapted to on the reef.
By taking in zooanthellae that is in the water ejected by the older existing corals that are in the system.
It may need more zooanthellae in less intence lighting and may need too change type of zooanthellae and may need to feed on whats in the water to suppliment for any less light it recieves to what it needs.
I wonder how much the zooanthellae has to play in the adaption of wild imported acropora's to less intence lighted aquariums.

The degree to which corals need to feed heterotrophically to supplement the carbon translocated from their symbionts depends on how actively the symbionts are photosynthesizing.

If photosynthesis by the zooxanthellae exceeds the respiration requirements of both the coral host and its zooxanthellae the coral is fully autotrophic and requires no supplementary feeding. When photosynthesis drops, the coral requires an additional food source.


Water movement:
May play a part in how food is carried to and through the Acropora branches as the coral grew and formed its structure and shape on the reef to the water movement and enviroment there.
Then has to be able too adapt too a closed system too a different water movement and light it recieves then.

Some other things I look for too judge the health of an Acropora is look at the tip growth if the tips are growing they are most often a different colour to the rest of the branches.
And the edge of the bases of a Acropora display growth like the tips.

If I get no polyp extention at night over a period of time I am worried something is not correct and if I have no tip growth this also may mean something is not correct.

So long as you have polyp extention at night and tip growth then most likely the Acropora is doing well.

Respiration
Polyp extension in SPS is primarily related to respiration needs by the coral.
Corals need to "breathe" at night and the polyp has the most surface area. Very little gas exchange occurs accross the tissue
Varying the degrees of polyp extension helps them regulate their metabolism better than constantly varying the amount of zoox in the tissue.

It's not that they are programmed to open at night, it's that they are programmed to close when the coral has had enough light. They tend to be open early in the morning, closed during the day, and open again late in the afternoon and through the night.

During light periods, zoox are metabolizing and producing oxygen. Corals will close because they can get too much, or can't excrete the wastes fast enough.
Remember they have to maintain a "average" of zoox. Enough for early morning, late afternoon, cloudy days too. It's easier for them to close than shed and regrow.

We're talking typical SPS here - Acroporids, Pocilloporids, Porites mainly,
So we cant look at the corals polyp as just a food capturing device, it has alot of functions beyond that of capturing food.

Food availability and predation by coral-eating fish may be of minor issue,

Then you move on to feeding corals a lot of controversial views here lol.

SPS corals are mostly a thin skin adhering to a dead internal skeleton.
There's not a lot of meat on a SPS coral to support = not a lot of food needed.
SPS aren't that good at capturing prey.

You have to distingish between coral types to what its food requirements are,

An Acropora has evolved to have a highly developed ability to make its own food with the use of its zoox.

Closed systems are high in nutrients and for the most part are perfectly capable of supporting them without direct feeding.

when does the actual growth of the coral take place ?

The majority of the coral's extension growth occurs at night.

http://www.aims.gov.au/pages/laser2.html

Checking the effects of light, temperature, water movement and human impact on the growth of coral will not only allow researchers to better understand factors effecting coral health and growth in nature, but will also potentially make maintaining and culturing corals in laboratories and aquariums easier.


Martyn.

[wayne in norway]

Martyn, in the wild acropora is as tough as old boots, surving lighting, salinity changes, temperature changes (to a point) which sem incredible to anyone who keeps them in an aquaria.

What do you think an aquarium is missing? Is it feeding. Are our acros so starved they are jsut hanging on, and the slightest disruption finishes them off?

[Martyn]

Martyn, in the wild acropora is as tough as old boots, surving lighting, salinity changes, temperature changes (to a point) which sem incredible to anyone who keeps them in an aquaria.

What do you think an aquarium is missing? Is it feeding. Are our acros so starved they are jsut hanging on, and the slightest disruption finishes them off?

It will take some time for me to reply to you Wayne as it is a very good question and there is no simple answer or straightforward reply to this. :eek:

Martyn :D

[kim]

Oh oh, we're in for a long one !

:)

(Just a joke, Martyn, I'm looking forward to it.)

Nice to see you popping in ! Hope things are on the mend,

kim

[Martyn]

I think I will do this in stages i don't have the time to write much in one go and I take ages to get what I think down in writing I will try to keep it simple and basic .

I guess I should start from here.

Yes to a degree SPS corals on the reefs are hardy and handle swings in water parameters.

As to why they seem too be harder to keep in a closed system then we have to look at a few things starting from collection of SPS/Acropora on the reefs.

First the stresses that SPS corals can go through from removal and after they have been collected from the reefs to adapting to the hobbyist tank.

(1) Collection holding tanks = stress
(2) Transporting = stress
(3) destination wholesale holding tanks = stress
(4) transporting to retail outlet = stress
(5) retail holding tanks = stress
(6) transporting to hobbyist tank = Stress
(7) adapting to hobbyist tank = Stress.


Costs of providing correct lighting and water movements and time holding and care for adaption to artificial environment is likely not cost effective for the wholesaler and retail outlet shops and in some situations not the skilled staff with a good knowledge of the care for Acropora.


The coral size in many species from the amount of growth it developed on the reef is not right for the new environment in the aquarium and can not change what it has already grown on the reef to be right for the aquarium environment.
How its new growth forms once in the aquarium is good but what was already grown on the reef may cause problems in the Aquarium unless you help it by pruning so it may re grow its lower down near the base reef grown branches to better suit the water movement and light in the aquarium.
How often has anyone seen the base of a Acropora slowly over time die.
The above treatment is just one of many ways of trying to sort out base die back.
Often a base with tightly packed branches coming of it then thining out if you see the first signs of a problem is often helpful.

The smaller the coral the less time it has had in its growth patterns on the reef and this is less likely to cause problems it may find its smaller amount of growth it had formed on the reef is ok in its new environment.

Better to buy small wild imported corals.


Consider how many hobbyists don’t allow the home aquarium to mature and add SPS coral.
I am not just talking about the nitrogen cycle here but the algae cycles and how the water in a new setup can go through many changes over the first year or so this can make a very unstable system.
Systems are much more stable and develop greater stability over time.

I would say at lest a year for a mature aquarium but if starting to learn from your first reef aquarium longer.
I would say that SPS corals are not really for the hobbyists who are first starting into a reef aquarium.
There is a lot to learn and for someone first starting out in reef keeping mistakes are likely going to be made.
Plus there aquariums are not very mature from ageing.

For those that have had some experience and mature systems they have likely started with soft and LPS corals and once they have got the hang of these and there system and all seems to being doing well they often want to try SPS coral.

To have the correct lighting and water movement for such a selection and keep everything happy is not easy to do.
Then you also have the chances of problems with chemical warfare going on between the 3 different types of corals.


Knowing the corals you keep.
How many read and study and ask question about the corals they want before they buy them.
How many look at the corals in there local shop and can not resist buying this and that with out having any idea of what there needs are?

We all are learning to understand what is happening in our systems.
We are learning the limitations and the additional requirements that may be necessary.
What all the life in the aquarium will feed on and what and how much uptake and decomposition and recycling there will be relative to any food inputs.
Increasing the biodiversity as much as we can and learning to make this as close to the wild as possible.
Making sure our circulation/turbulence and oxygen is high enough to get through the nights with high bio loads and that all the corals receive the correct amount of water movements as they grow.

Remember that a Stressed Acropora is at risk of going RTN which is highly contagious to other Acropora and many SPS corals.

Sorry I am struggling and rambling and likely going of track lol but there is so much to say to why SPS corals can be fragile in a closed system.
I have found they can be hardy and fragile.
I will continue when I have more time and if anyone is really interested in what I have to say and if I am making any sence hehe.

Later
Martyn

[kim]

Keep going !

:)

I remember tuan saying that (well, I'm not sure exactly of the context, but this is the drift) he was concerned at having too much flow when starting off his SPS tank. Not something many people would worry about.

But his argument was this would encourage the corals to develop their "high flow" forms. Then as they grow, this form would be inappropriate to the reduced flow conditions (flow is blocked, both by the coral itself and by its neighbours), leading to problems.

Probably in nature the much more random, more powerful (it has a lot of weight behind it), "coming at all angles" nature of the flow means this is less of an issue (plus dying corals aren't so obvious, of course).

Sort of along the same lines as some of your comments above. It stuck in my head at the time.

kim

[Twistedpro]

thanks for that it was a very interesting read, looking at peices in the LFS you can see the branch development due to the conditions they have been exposed to.

I look forward to reading more

[Martyn]

Yes Kim
An interesting idea of Tuans.
The way that pumps are set up to create turbulence and chaotic water movements too and through the coral on a long term bases allowing for future growth in an aquarium has always been an important factor to me.
Tuans idea is tricky to put into practice if you have lower flow rates to start with when you introduce your say Acropora then trying to keep a similar flow rate as everything grows the flow to and through the coral is going to change a lot if you just increase the flow rates as every thing gets larger you are still going to get major changes in flows through and around the coral.

I try to have the same type and strength of water movement to and through the corals as they get larger.
My way of doing this is to create a downwards movement moving water to the corals from above and at different angles from above.
If this is fairly constant and is not restricted by other corals in the way which does not come into play so much as the water flows are coming from above.
This should allow the coral to form its branch growth to allow the same type of constant flows to reach its base.
Where a few water flows hit each other above the corals sends water downwards and at different angles.

This is an interesting abstract below on Branching Patterns of Acropora you may have already read this if not well worth a read.


http://people.hws.edu/mitchell/oz/papers/markzon.html (http://people.hws.edu/mitchell/oz/papers/markzon.html)

And thanks twist.


Martyn

[Twistedpro]

its an interesting read, its amazing how corals with the same genetic background have such a diverse morphalogical form. Water flow is an amazing factor in sps development

[kim]

Ahhhh...that makes sense.

Many thanks for the link...I know how many links anyone tries before finding something useful, which is then gold dust.

kim

[Martyn]

I was searching for some of my notes I have written over the years about things I have observed and tried on my coral propagation farm.
And I came across this writing which is not something I wrote and have tried to find the link I got it from so I could add the link but had no luck in finding where I got this info from or who wrote it.
I will copy and paste it here it is an interesting read and useful info I feel.

Martyn

Unknown Author

Corals in captivity are already reported to produce a skeleton that is lighter and more fragile than those in the wild. Limited access to nutrients and/or light in nature allows the corals to regulate its use of energy, directing it toward various metabolic functions. It is obivous that corals producing a fast-growing skeleton are allotting a large percentage of of their energy budget to growth. This may contrary to normal metabolic processes.
Growth may be favored, but other systems, including defense, immune and reproductive systems, could be compromised.
In fact, growth and reproductive viability are often a direct trade-off (Ward, 1995a, 1995b, et al.).
While trying to emulate natural growth rates is certainly worthwhile, the proliferation of gadgets, additives, and other growth enhancers seem to imply that some sort of race exists, that we can somehow do it "better than Mother Nature." If captive corals are not growing by leaps and bounds, aquarists often feel they are failing, somehow. This worry is usually unfounded.
For example, lighting and ambient nutrient levels vary from tank to tank. There are systemic calcification gradients that exist in branching corals that do not exist in massive ones. This is illustrated in studiesof skeletal densities: massive and bushy corals are the most porous, foliaceous corals are the most dense, and some branching corals have porous, fast-growing ends but dense that are barely growing at all. There are noticeable differences in growth rates between, and even within, species-and even between colonies of the same species in similar enviorments.
Massive corals can calcify as quickly as branching ones, although they do so in a different manner, which may not be as obvious. Water flow rate, latitude, temperature, CO2 availabilty, and countless other factors significantly affect calcification. Calcification mechanisms in corals are different from day to night, and there is even speculation of a possible third mechanism in aquariums using Kalkwasser. Branch density may be favored over linear growth, even though calcification rates remain the same. Some corals have a genetically predetermined maximum size that may or may not be environmentally affected.
The most rapidly extending corals ever mesured are Acropora cervicornis and A. formosa, with branch-length growth ratesof 14.5 and 18.5 cm (5.7 and 7.3in.) per year, respectively. Yet these same species have also been reportedin healthy wild reefs with linear extension rates of just 0.40 and 0.37 cm (0.16 and 0.15 in.) per year, respectively, with no indications of relative degrees of colonial "success," health, or viability.
In other words, growth rate is varied, even in the wild, and related to many factors. Trying to achieve some "standard" of growth in the aquarium is not valid, nor should it be sought. There is even a model, called Leslie's matrix, that predicts that in organisms exhibiting developmental plasticity, there is no consistent correlation between size and age (Hughes, 1984). A fascinating example of this can be seen in old collections of bonsai trees, with oak trees that are alive, growing and beautiful, morer than 100 years of age but no more than 60 cm (24 in.) tall. Provided that corals polyps are expanding and healthy, no comparisonof growth rates achieved by different aquarists is likely to have much meaning. More properly, the success of a well-planned reef community as a whole should be the aquarist's goal.

[xxmattyxx]

What a star, thankyou Martyn. In plain English too.


Matt

[Martyn]

I have not written any more just thinking of where to go from here.
Was looking at some pics of my Acropora's and thought this pic a good example of tip growth and polyp extension however the polyps where out more as the lights had only been turned on half an hour or so before the pic was taken.
Also this was a young coral that had been grown on from a frag in the earlier stages and at this stage of a young Acropora they seem to mostly have more polyp extention under lighting than the older more mature Acropora's.

http://www.ultimatereef.net/uploads/Mh024%20crop%20sec.jpg

This pic below also gives an idea of good growing tips of frags growing into small coral colonys.

http://www.ultimatereef.net/uploads/Dscn0572.jpg

Forgot to mention that different speices of Acropora have different amounts of polyp extension during lighting periods some have none other have a little and some have a lot and as mentioned above I have found frags and younger colonys can have more than older mature colonys.

Regards
Martyn

PS Arg can a mod resize this pic for me to prevent it taking up so much room please I am useless when it comes to high tech stuff :D