Skipping the nitrogen cycle?

[Cody Ray]

Abstract

Many ecological phenomena are characterized by context dependency, and the relationship between diversity and productivity is no exception. We examined the relationship between macroalgal diversity,and nutrient availability by evaluating the effects of reduced nutrients and their subsequent replacement via local-scale nutrient loading in tide pools. Macroalgae in Oregon coast high-intertidal pools have evolved in a nitrate-rich upwelling ecosystem, but instead of settling on low-intertidal reefs (where algae are often immersed in nutrient-rich nearshore waters) these individuals have colonized high-zone pools, where they are isolated from the ocean for extended periods of time and are subjected to extended periods, of nitrate depletion. In some pools, this nutrient stress was ameliorated by a positive interaction: the excretion of ammonium by invertebrates. We conducted experimental manipulations to quantify invertebrate-mediated ammonium loading and macroalgal ammonium uptake in high-intertidal pools. Variation in tide pool volume and invertebrate biomass created a gradient of local-scale nutrient inputs, allowing us to address the relationship between nitrogen loading and algal diversity. Slow-growing species tolerant of low nitrogen availability were joined by fast-growing species with higher nitrogen requirements in pools with higher ammonium loading rates. A fourfold increase in the ammonium loading rate was associated with a doubling in the number of macroalgal species, and macroalgal assemblages in more species-rich pools were characterized by higher rates of biomass-specific ammonium uptake. These patterns contrast with productivity-diversity relationships in terrestrial systems, where local-scale nutrient enrichments generally result in reduced producer diversity due to displacement of subordinate species by aggressive competitors. Our data suggest that the effect of enrichment on diversity is context-dependent. Each ecosystem has a critical level of nutrient availability, determined by the level of nutrients typically available in that system. Below this critical level, local-scale nutrient additions increase diversity, but above it, diversity declines with enrichment.

Original link

IMO our aquariums at home are very much like tidalpools. In short it seems that the macroalgae growing in these tidepools prefer ammonium/ammonia over nitrite and nitrate. I am starting a small system that will use only macro algae as filtration. Whether the macroalgae will use the ammonia and completely skip the nitrogen cycle or it in of itself house enough bacteria is to be seen.

10g display with 2 Hydor Koralia #1 pumps. This will be housing acropora, montipora, different zoanthus species, and a few fish. Right now I am thinking of using a 150watt metal halide for lighting.

10g sump where I will be housing several different species of macro including cheato, caulerpa, etc. There will be no skimmer and the only mechanical filtration will be a filter sock cleaned every few days. If the need arises I may install a calcium reactor if the corals grow well.

More to come.....

 

[Malenurse]

You didn't mention it, but I assume you'll also have live rock. In my experience, I've never had a tank started with well-cured live rock go through the ammonia to nitrite part of the nitrogen cycle.
Sounds like you have a very interesting project going. Keep ua all updated!

 

[gregg@AMS]

seems like a simpler way to test your hypothesis would be to add the macro algae to a sterilized tank, add NH3/4+ and see if the level of NH3/4+ drops w/o a correllating rise in NO2- or NO3-.

it seems like by adding corals and subsequently rock/substrate, you are inadvertently going to be populating the system with bacteria, and it could be difficult to measure what is really happening to the NH3/4+.

also, remeber that the limiting factor for growth in many algas is PO4+.

 

[greenbean36191]

Yes, macroalgae take up N as NH3/4+ and even do it preferentially to nitrate (which isn't what this article is saying BTW), but so do corals and anemones. The full nitrogen cycle still occurs though.

 

[gregg@AMS]

<a href=showthread.php?s=&postid=10473141#post10473141 target=_blank>Originally posted</a> by greenbean36191
Yes, macroalgae take up N as NH3/4+ and even do it preferentially to nitrate (which isn't what this article is saying BTW), but so do corals and anemones. The full nitrogen cycle still occurs though.

it would be interesting to compare different macroalgae growth rates between a system featuring full nitrogen cycling and a sterile envronment with the addition of NH3/4+. the trick would be to keep your test tank sterile and free of nitrosomonas/bacter.

you would also need to ensure that both systems were free of PO4+.

 

[MCsaxmaster]

While not well quantified in aquariums, it is likely that in a typical reef tank MOST of the ammonium excreted is taken up by algae and not by nitrifying bacteria (though both occur at significant rates, no doubt about that).

cj

 

[gregg@AMS]

<a href=showthread.php?s=&postid=10478793#post10478793 target=_blank>Originally posted</a> by MCsaxmaster
While not well quantified in aquariums, it is likely that in a typical reef tank MOST of the ammonium excreted is taken up by algae and not by nitrifying bacteria (though both occur at significant rates, no doubt about that).

cj

just noticed you were a spartan......







:thumbsup: :thumbsup: :thumbsup: :thumbsup: :beer:

'00 zoology grad, born with green blood.

 

[MCsaxmaster]

'06 grad here, working on my MS in marine biology down in NC now. Glad to see a fellow spartan around

I bleed green!

Chris

 

[wooden_reefer]

<a href=showthread.php?s=&postid=10470917#post10470917 target=_blank>Originally posted</a> by Malenurse
You didn't mention it, but I assume you'll also have live rock. In my experience, I've never had a tank started with well-cured live rock go through the ammonia to nitrite part of the nitrogen cycle.
Sounds like you have a very interesting project going. Keep ua all updated!

Only if cured means cycled. If the LR is really cured, meaning has been sitting in the LFS for weeks, then the cycling is already done.

 

[wooden_reefer]

<a href=showthread.php?s=&postid=10478793#post10478793 target=_blank>Originally posted</a> by MCsaxmaster
While not well quantified in aquariums, it is likely that in a typical reef tank MOST of the ammonium excreted is taken up by algae and not by nitrifying bacteria (though both occur at significant rates, no doubt about that).

cj

Some will be, but most is hard to say.

The closer one is commited to keeping very few fish and active invertebrates, the closer you are right.

 

[stony_corals]

I think that's the big question if he's going to have live rock in it or not. But I supposed everything that's alive, corals, algae, etc will have bacteria cultures on them and thus be a source of bacteria.

Wouldn't it make sense to limit the variables? Skip the live corals, but the macro in and start dosing an inorganic source of ammonia?

 

[wooden_reefer]

<a href=showthread.php?s=&postid=10643426#post10643426 target=_blank>Originally posted</a> by stony_corals
I think that's the big question if he's going to have live rock in it or not. But I supposed everything that's alive, corals, algae, etc will have bacteria cultures on them and thus be a source of bacteria.

Wouldn't it make sense to limit the variables? Skip the live corals, but the macro in and start dosing an inorganic source of ammonia?

Eventually, but before then many livestock would have already died.

The whole notion of cycling centers on the fact that nitrification bacteria are slow to grow. Before theoretical equlibrium, many of the livestock will be dead.

 

[stony_corals]

They're not that slow to develop.... I've set up a couple of systems that had no live rock/sand, but put in some sps and things were fine.... Especially if you are using macro, there would also be bacteria that are living on them. This is where I disagree with Adey, even in an ATS, there still is bacteria in the system and hence are nitrifying/denitrifying, they aren't mutually exclusive.... an aquarium without bacteria is impossible. Without a source of bacteria, it'll take time to develop, but they will. Adding livestock, adds bacteria, many of the corals that produce mucus are typically farming bacteria for heterotrophic feeding. This is why I'm saying to only add macro and add ammonia, and test NH3, NO2, NO3. If you add live rock, corals etc, you will be adding a source of bacteria and will have a culture in no time.

 

[wooden_reefer]

<a href=showthread.php?s=&postid=10644648#post10644648 target=_blank>Originally posted</a> by stony_corals
They're not that slow to develop.... I've set up a couple of systems that had no live rock/sand, but put in some sps and things were fine.... Especially if you are using macro, there would also be bacteria that are living on them. This is where I disagree with Adey, even in an ATS, there still is bacteria in the system and hence are nitrifying/denitrifying, they aren't mutually exclusive.... an aquarium without bacteria is impossible. Without a source of bacteria, it'll take time to develop, but they will. Adding livestock, adds bacteria, many of the corals that produce mucus are typically farming bacteria for heterotrophic feeding. This is why I'm saying to only add macro and add ammonia, and test NH3, NO2, NO3. If you add live rock, corals etc, you will be adding a source of bacteria and will have a culture in no time.

I think this ties in with the concept of mini-cycling. You add a small amount of livestock and the accompanying bacteria, and the total population will adjust.

I would agree that the degree to which many invertebrates can tolerate ammonia varies, and this mini-cycling (not really in no time) may work more often than not. Nitrification bacteria ARE slow to grow, this is a given. Your argument against the significance of this slowness of grow may be also valid. However, I consider thorough cycling an insurance policy even if mini-cycling works most of the time.

Besides, not everyone is interested in slowly adding a few invertebrates.

I routinely stock numerous fish at once, some large ones, after very thorough cycling. After robust cycling, the nitrification capacity is extremely high, so I can stock quickly. I don't recommend that newbies do so because of their lack of skills in disease control, but the need to add livestock slowly and accept mini-cycle is completely illogical. For me, mini-cycling with large fish is a joke.

How can one mini-cycle with an 8-inch angel fish in a newly cycled tank? In this case, one must proactively make sure that the nitrification capacity is high enough before introduction. I won't hesitate to put one or two 8 inch fish in my newly cycled tank, as it is always robustly cycled.

An aquarium is not a tidepool. Many livestock keep are never found in a tidepool. Has one ever found a queen angel in a tidepool?

 

[stony_corals]

I didn't experience any spikes in NH3, nor NO2 so I wouldn't say there was any cycling happen, or if it did, it wasn't enough to cause any spikes.

I agree, I hope my comments were not advocating this as an approach to setup of a new system. My comments were simply around the experiment design. If the hypothesis is something like " Macroalgae are able to absorb ammonia/ammonium such that nitrofication will be eliminated", then limiting variables such as adding livestock which would be a source of bacteria will skew the results of this experiment. That's all...