sps... feeding?

[Snappy]

There was a thread a while ago regarding sps and the question, to feed or not to feed? Do they only need light & calcium? Etc.

Here is a quote from a recent article by Chris Jury I was reading about some common aquarist hobbiest beliefs and perpetuated myths.

Thought this might create some further discussion on the subject.
For the whole article, as this is but one small part here is the link.
http://reefkeeping.com/issues/2006-03/cj/index.php


Myth
SPS Corals (order Scleractinia): This is an acronym for small-polyped stony/scleractinian corals, i.e., stony corals with relatively smaller, less fleshy polyps than LPS. They need very clean, nutrient-poor water. They need super-bright light and very strong, chaotic water flow. They don't need any food, just light. They're very sensitive and difficult to keep. They don't take stress well. When they're happy, they turn beautiful colors, but only if the tank is nutrient-poor. If they aren't colorful, nutrients in the aquarium are making them turn brown.

Reality
As far as food goes, corals with small polyps eat, and there is no question about that. To reach the conclusion that feeding these corals is not important requires a reversion to the time before C.M. Yonge's studies in the 1930's on the Great Barrier Reef (or earlier), as well as complete ignorance of the past 75 years' worth of research. While it is true that some of these corals eat more than others, the species that are least reliant on food are not those that hobbyists believe are. In particular, study after study after study has found that corals such as Acropora are highly efficient predators, and that they eat large amounts of prey including a lot of zooplankton and particulate material every night in nature (Anthony, 1999; Anthony, 2000; Bongiorni et al., 2003; Bythell, 1988). Corals such as Porites cylindrica tend not to eat quite as much food as most corals, but they are the exception and not the rule (Anthony and Fabricius, 2000). They have merely circumvented the need for large amounts of food and can subsist on very little. Just to put some numbers on things, as aquarists tend to resist tooth and nail the idea that these corals eat things and need to be fed, Bythell (1988) found that Acropora palmata (the ultimate "SPS" coral) gets 70% of the nitrogen it needs for health, growth and reproduction from eating things such as zooplankton and particulates. These corals have to eat to be healthy! A recent study by Ferrier-Pages, et al. (2003) that was later confirmed by further testing found that corals that are fed grow their skeleton 30-75% faster, grow tissue 2-8 times faster, have more protein, have more chlorophyll and are in every way healthier and doing the things we want them to do faster than those that are not fed. Conversely, corals that are not fed suffer a precipitous drop in the amount of protein in their tissue and in their chlorophyll a concentration (Shick et al., 2005). A study by Sebens, et al. (1996) examined the differences in prey capture between two corals (Montastraea cavernosa and Madracis mirabilis). The Montastraea (relatively larger polyps) is known to catch a lot of food and to be very heterotrophic. The surprise is that the same sized colony of the Madracis (relatively smaller polyps) in a flume caught and ate 36 times as much food in the same span of time! Hmmm, seems to me like they need to be fed. Please do not take this information to mean that corals with small polyps need more food than corals with large polyps (let's not overcompensate now!), or you'll be missing the whole point. My intention is to illustrate that different species of corals show different food preferences, and that these preferences are not based on polyp size but rather on differences in each species' niches. It must also be noted, however, that a single species of coral can and will adapt to higher rates of heterotrophy or autotrophy depending on the conditions in which it grows (Anthony, 2000; Anthony and Fabricius, 2000). Corals often thought of as requiring bright light and little food can, and do, adapt in nature to conditions of low light with high food availability all the time.

[StirCrazy]

Greg, what most of us were saying is that with all the crap in our tanks from feeding fish, there is no need to go buy some "miracle food" for your SPS.

That article was off studies done over the years like any other article and it has been real generalized.. the study was done with one specific type of acropora which is known to eat and inferences are taken from there. This is why I hate articles from the on line mags as reference material as it is one persons interpretation of the data and for the most part they are really loosely interpreted.

If I had to money to pay for access to the articles they use as research for making there new articles I could easily come up with a report that says they don't eat and it would be just as valid. so without the original studies and the time to interpret them most of these on line articles remain just one opinion.

Steve

[Johnny Reefer]

Originally Posted by StirCrazy

.... This is why I hate articles from the on line mags as reference material as it is one persons interpretation of the data and for the most part they are really loosely interpreted. ....

Further to that, what gets me is whether or not what is written, and what one is reading, is accurate and valid.

Case in point....the following I copied and pasted from the above article excerpt.

Quote:
....study after study after study has found that corals such as Acropora
are highly efficient predators.....

Predator? Correct me if I am wrong, but I don't think so. I'm still quite new to alot of reefkeeping aspects and I have not kept SPS yet, but I find it hard to believe that Acropora actually prey on their food. For starters, they're sessile. I don't know..... Maybe I don't understand the definition of predator, but I have thought up to now that predation kind of involves some sort of movement and stalking.

As I said...makes me wonder how much of what one reads is accurate.

Just a thought.

Cheers,

[Aquattro]

Predators prey on food, "prey" defined as such...To hunt, catch, or eat as prey.

so yes, SPS do catch food and therefore are predators.

[GMGQ]

I agree. Food sticks to the polyps because cells on the polyps contract or whatever to make them sticky, then they retract into the skeleton to 'eat' it.

So in the mildest definition of "prey" I would agree that they do.

Originally Posted by reef_raf

Predators prey on food, "prey" defined as such...To hunt, catch, or eat as prey.

so yes, SPS do catch food and therefore are predators.

[Snappy]

If sps polyp extention, especially at night, is for purposes other than eating I would be interested to know what those actually are. Since I have a mixed reef I need to feed my Gorgonians, LPS and Clams etc. anyway, so if the sps want eat it's they can. I feel it's sort of like chicken soup for a cold, may not help but it won't hurt.