Coral Feeding

[wasp]

I'll read that reference and see if the manufacturer of the plankton products it's promoting has interpreted it very well.

Layton

What's to interpret? Seems pretty black and white to me. Proper scientific study too, rather than some of the opinion and hearsay we sometimes see .

I'm going to call it a night soon.

You go. Big day tommorrow!

More dodging work to spend all day posting, huh? :lol:

[lduncan]

Who's dodging work. I work for myself.

What's to interpret? Well first none of that text is taken directly from the reference, it is what a particular manufacturer of commercial phytoplankton suppliment has to say on the matter. Anyone can write something then stick a reference in there, sometimes it pays to read the references themselves and see what they actually say ;-)

I've just read the intro of one of those references. Very interesting:

Corals nevertheless are true heterotrophs, ingesting a wide range of food such as dissolved and particulate organic matter (Anthony, 1999; Anthony and Fabricius, 2000), sediment (Rosenfeld et al., 1999), bacteria (Farrant et al., 1987; Sorokin, 1991) and zooplankton (Lasker et al., 1983; Lewis, 1992; Ferrier-Pagès et al., 1998; Sebens et al., 1996).

So with all these methods available, why the huge focus on the one which is hardest to achieve? Zooplankton.

It goes on:

The relative importance of phototrophy vs. heterotrophy is still partially understood. In shallow waters and high-light-adapted corals, photosynthesis alone may meet all the nutritional needs (Falkowski et al., 1984) while in deep living corals or in some species depending mostly on predation, photosynthesis may only supply a small fraction of this energy demand (Szmant-Froelich and Pilson, 1984; for a review, see Barnes and Chalker, 1990). Corals living in turbid environments are also more dependent on heterotrophy than those living in clear waters (Anthony and Fabricius, 2000).

[wasp]

Well that certainly is interesting. Pretty much PROOF that feeding on particulate matter can be of benefit to corals!

[lduncan]

Um yeah. We've already establish that corals need food long ago.

[wasp]

Yes we have!

Now, next phase, to establish how good the bacteria are for the corals, and that bacteria live in sand beds.

[lduncan]

Wasp, you've missed the point.

Here's a summary:

The amount of food in your tank is virtually determined by what you put in it.

The crap which is produced by fish and corals is food for bacteria, and corals before it hits the sand.

The sand provides nothing. It can't possibly produce more food than what you put in to start with.

Bacteria don't require sand to grow and reproduce.

The sand harbours animals which are harder for corals to digest and require more energy to digest.

So, using sand to provide food food reefs is backwards, it can't possibly create more food, or more nutritious food than would otherwise exist without sand.

In short sand is never going to be better than having no sand in providing coral food.

Layton

[chimera]

perhaps you should read the entire article layton

http://www.dtplankton.com/phytoplankton ... dbeds.html

[lduncan]

I have. That's the one which Cookie posted earlier. The one which comes to a weird conclusion.

[Aquagold]

This discussion and it's opinions are interesting but we need to realise there is none amongst us who is a 'expert in nutrion and aquatic stimulus protocols in Corals. Talk has been on the fundamentals of parts but the are many things that create a response to eat from a given livestock.

Chemical/enzymes cues are now being heavily researched as per individual animal to find out what/how/why a given enzyme/chemical reacts to create a given feed response.

This is one of the arguments for live food over 'dead food.

This is reckonized for both 'juvenile developement, sub adult and adult developement, respective to their individual needs in their growth life stage.

If you come back to a plant you will see that the plant needs different 'growing conditions' to stimulate different stages in it's growth stage.......

Corals in part have this going on in the whole of it's existance; lunar sexual stages.....

Now we get back to what is easy for a given 'carer of aquatic stock' as to their 'skill' in husbandry of the stock.

Most of us like to be able to just throw in some food and see our animals grow abiet witha bit of maintenance.

It's the maintenance which we don't like and this is what facilitates to most peoples response to a feeding/maintenance protocol.

............

[cookie extreme]

The success of aquarists in Europe with stony and soft

corals in the 1970s and 1980s, without any feeding, would tend to

support this idea.

true, i have an old pic of my tank from '85. had great success with the hard corals available then. they must have feed on something as no one really had much a clue what they eat (goldfish flakes didn't work to well :oops: )

BUT skimmers didn't really exist much then (ok i did have one, air driven very small and total useless and expensive just to top it of)

and thats one of my arguments. how good is it to have a very powerful large skimmer? if its so efficient in removing "nutrients" then how much is left for corals? in BB tanks (which are cleaner no disagreement here) the skimmers works more efficient then in a sand bottom tank. so it removes more, true? which would result in adding more ($) food types to feed the corals (zeovit coral vital springs to mind as reef roids an others).

its also interesting to note that fish in sand bed tanks can be left alone without feeding for a long time (i have done it for over 4weeks) as the substrate recycles and produces new food sources on an on going basis. this of course could be due to the higher nutrients levels in the tank because of "poor" skimming.

[wasp]

I have. That's the one which Cookie posted earlier. The one which comes to a weird conclusion.

When I asked you exactly what it is that was weird, you quoted a bit of the article, and something from Eric, neither of which seemed weird to me.

I've seen some weird conclusions, but not in that article

[lduncan]

I quoted more than a little part of the article. I followed Dr Ron's own writings. And there was nothing in there from Eric. I've already spelt out the weird part. Here it is again:

Ok here's what I find wierd. First he says that bacteria are better than pods for providing nutrients. Bigger bang for your buck.

Then he says that detritus is a good food source for this bacteria to colonise.

He then goes on to say that sand dwelling creature are a big competitor to corals for this nutrients:

But then goes on to promote the use of sand as a food source:

To me that's just a weird conclusion. Using something which actually eats one of the most nutritious forms of food for corals (bacteria), and converts much of it into a form which is harder for corals to digest, and provide less nutrition.

Seems kind of backwards to me. Surely you want the food which is in you tank to be easy for corals to digest and nutritious? The habitat sand provides does the opposite, by Ron's own writing.

Layton

And again without the quotes:

First he says that bacteria are better than pods for providing nutrients. Bigger bang for your buck. Then he says that detritus is a good food source for this bacteria to colonise, and they do so quickly, and goes on to say that sand dwelling creatures (critters) are a big competitor to corals for this nutrients. But then goes on to promote the use of sand as a great way to provide food for corals.

To me that's just a weird conclusion. Using something which actually eats one of the most nutritious forms of food for corals (bacteria), and converts much of it into a form which is harder for corals to digest, while providing less nutrition.

Instead of trying to come up with cock'n'ball stories of how sand beds are great for this and that, they're little copies of natural systems etc etc. Why don't people just say I use sand 'cause I like the look of it? Instead of going to all the effort of pretending it does something amazingly useful for corals?

Layton

[Feelers]

Well some points I think have been looked over,

1st - what do the critters eat? - Bacteria and detrius. Arent they pretty much big shopping bags full of whatever they have been eating? This is similar to nutrient enriching brine shrimp with phytoplankton.

They may have less nitrogen weight for weight than bacteria -but a coral wont really be too worried about the density of nutrients in a food source, especially ones that are comparable in nutrition counts.

If I eat a hamburger, its pretty much the same as eating a hamburger and a jug of water. Maybe a tiny difference, but nothing major.

Granted that chitin will be hard to diest, but phytoplankton also have tough cell walls, and cellulose is harder to digest than Chitin I believe, but is still considered an excellent food source for coral (I think).

Perhaps small critters only function as concentrated bacterial delivery systems.

[wasp]

Yes, got to say Layton I still don't find it "weird" at all, even with your own particular "twist", or "spin", on it.

You seem to be still hung up on the idea that critters are "worse" food than bacteria. While bacteria are excellent food, many critters are excellent also. You tried to say that "critters" would be worse because they have a shell content to them. You forgot that so do bacteria.

When I set up my new tank a few months ago it went through a time of high nutrients, which resulted in a pod population explosion. The 6 line wrasse LOVED it, spent all day picking over the rocks for them, big fat belly on him. He certainly looked in peak health and was not complaining about the shell content of the pods.

To be straight up, if you want to talk "weird", there are way better examples on this site than that .

[Feelers]

Wasp are you gonna have a siphon into the tank to keep all the pods alive or is this not possible in your setup?

[cracker]

When you eat sardines and salmon out of a tin, you eat the bones and all, (Well I do anyway). It gets digested.

The polyp will do the same!

[wasp]

Wasp are you gonna have a siphon into the tank to keep all the pods alive or is this not possible in your setup?

Not totally sure yet but I'm thinking something higher than the tank, with an overflow into the tank. I'm also going to make an effort to actually feed the critters. Substrate, I'm thinking a DSB, with some coral rubble on top to provide good environement for them. I will be cleaning it out periodically to prevent buildup of nasties, but only one section at a time so it can get re-seeded from the other bit. I've still got higher nutrient levels in the tank than desireable so that's the first priority but they are slowly coming down, once that's achieved I'll feed whatever possible provided nutrient levels stay under target levels.

When you eat sardines and salmon out of a tin, you eat the bones and all, (Well I do anyway). It gets digested.

The polyp will do the same!

Exactly right. The way I see it, what could be better for them than what they eat in nature.

[lduncan]

Well some points I think have been looked over,

1st - what do the critters eat? - Bacteria and detrius. Arent they pretty much big shopping bags full of whatever they have been eating? This is similar to nutrient enriching brine shrimp with phytoplankton.

They may have less nitrogen weight for weight than bacteria -but a coral wont really be too worried about the density of nutrients in a food source, especially ones that are comparable in nutrition counts.

First, only some soft corals have the ability to gain nutrients from phytoplankton. And of those that can, it only supplies a small part of their nutrition. Most corals can't digest phytoplankton at all.

Second yes, these animals could be what you call "gut loaded" however the energy the coral has to expend to get this nutrients, is much more than if it had never been consumed by these animals. Chitin is not simple to digest. Think eating a crayfish with shell.

As for corals not worrying about density of nutrients, your right, as long as it provides them with more energy than they previously had. But talking efficiencies here, you have a certain amount of food in the system, doesn't it make sense to maximise the nutritional value of this food? Encasing it in a thick chitin shell at the expense of easy to digest bacterial flock is not maximising nutritional value.

If I eat a hamburger, its pretty much the same as eating a hamburger and a jug of water. Maybe a tiny difference, but nothing major.

No the mass in that example is not constant. It's more like eating a hamburger vs. eating a certain mass of that hamburger, with the remaining mass substituted for water. There's a significant difference there.

Granted that chitin will be hard to diest, but phytoplankton also have tough cell walls, and cellulose is harder to digest than Chitin I believe, but is still considered an excellent food source for coral (I think).

Absolutly chitin is hard to digest, as is the cellulose of algae cells. But few corals digest phytoplankton. This is the kicker, this stuff takes more energy to digest, than the bacterial food that these critters eat to begin with. They're spending more energy to get the same nutrition, so the net gain is less with these chitin encased nutrient than with bacterial detritus.

Perhaps small critters only function as concentrated bacterial delivery systems.

Bacteria don't need this delivery system. Water flow in the aquarium can deliver them in a more nutrient packed and easy to digest form than critters ever could.

Layton

[lduncan]

Yes, got to say Layton I still don't find it "weird" at all, even with your own particular "twist", or "spin", on it.

The quotes are directly from Dr Ron himself. The bulk of his writing points to one thing, then in the conclusion he promotes the opposite. It's weird.

You seem to be still hung up on the idea that critters are "worse" food than bacteria.

Exactly. Because they are MUCH better. It's the reason why it took so long for researches to prove that corals actually ate bacteria. They are digested so quickly, that by the time that they collected them and got them to labs, the bacteria were beyond recognition, while the zooplankton was all that they could identify from gut analysis.

While bacteria are excellent food, many critters are excellent also. You tried to say that "critters" would be worse because they have a shell content to them. You forgot that so do bacteria.

Are you saying that bacteria and critters have the same nutritional value? Can you quantify "excellent"? Bacteria usually have prokaryotic cell walls. (Some have other substances during dormant cyst stages, few can produce chitin). But the fact remains that they are easier to digest, and provide far more nutrition for the coral energy expended. So critters with their chitin casings ARE worse. There is no denying it.

When I set up my new tank a few months ago it went through a time of high nutrients, which resulted in a pod population explosion. The 6 line wrasse LOVED it, spent all day picking over the rocks for them, big fat belly on him. He certainly looked in peak health and was not complaining about the shell content of the pods.

Are you comparing fish to a coral polyp? Different animals have developed different methods of dealing with digestion of different things. For example teeth. Animals use them mechanically break these compounds so that the gut has easier access to the useful stuff. Coral polyps are not all the same, different species have different abilities to process different stuff.

You seem to be implying that all food has the same nutritional value. It doesn't.

To be straight up, if you want to talk "weird", there are way better examples on this site than that .

Care to elaborate?

[lduncan]

When you eat sardines and salmon out of a tin, you eat the bones and all, (Well I do anyway). It gets digested.

The polyp will do the same!

The polyp may ingest it. It doesn't necessarily have the ability to assimilate it. That's the whole point of excrement, to remove indigestible stuff. Not all food has the same nutritional value.

Just because the coral grabs it doesn't mean it uses it, it could just get crapped out again.

As a final anecdote: back in the early '80s when I was doing nightly dives trying to pin-point coral spawning, I kept seeing the corals bulge their oral disks and then spit out stuff just at dusk as they expanded their polyps. The first few times I got all excited thinking it was the beginning of spawning. But syringe samples I collected, when observed under the microscope, showed the stuff to be made of : sponge spicules, zooplankton carapace parts, lots of marine snow like material that was totally unrecognizable, zooxs, foram tests etc etc. In other words, anything they could get their little tentacles on but couldn't digest.

Regards,

Alina Szmant

*******************************************************************

Dr. Alina M. Szmant

Coral Reef Research Group

UNCW-Center for Marine Science

5600 Marvin K. Moss Ln

Wilmington NC 28409

Tel: (910)962-2362 & Fax: (910)962-2410

Cell: (910)200-3913

email: [email protected]

Web Page: http://people.uncw.edu/szmanta

******************************************************************

[wasp]

Absolutly chitin is hard to digest, as is the cellulose of algae cells. But few corals digest phytoplankton. This is the kicker, this stuff takes more energy to digest, than the bacterial food that these critters eat to begin with. They're spending more energy to get the same nutrition, so the net gain is less with these chitin encased nutrient than with bacterial detritus.

Layton

That's the kicker .

A sandbed does not generate phytoplankton, that happens in the water column.

A sandbed will generate the high nutrient bacterial detritus you refer to, plus critters.

[lduncan]

Oh God. This is going to be long! I really don't think you understand enough of this wasp.

So where do phytoplankton get the nutrients from?

[wasp]

Oh God. This is going to be long! I really don't think you understand enough of this wasp.

Oops! When cornered get abusive.

Temper Temper!!

[lduncan]

It's not temper. It's the truth. If you did understand more, you wouldn't have asked that question. But i'll persist...

[lduncan]

Made that statement I mean. Not asked that question.