The Mangrove Mystique: Beyond the cool looks.

As you know by now, we are huge fans of mangroves.

And, I see a lot more interest in them in recent years; it's particularly noticeable on social media. Like so many hobby areas that are new to hobbyists, there is a mixture of good, bad, and outright awful information propagating out there about mangroves and mangrove care.

Now, I'm not anything close to an "expert" on mangroves in the aquairum. However, I have studied them in the wild, and have kept them in all sorts of aquariums for the better part of 20 years. In that time, I've learned a few things that have led me to be quite successful with them.

Yeah, when we are talking about brackish water aquariums, we'd be completely remiss if we didn't mention the "stars" of this habitat, the Mangrove trees! In our practice , we'll focus on the readily available, reasonably hardy "Red Mangrove", Rhizophora mangle. 

Hardly what you'd call an "aquarium plant"- I mean it's a tree.

Yeah, a fucking tree.

Remind yourself about that, okay? 

That being said, the Mangrove is an amazing tree that certainly has applications for aquariums- specifically, brackish aquariums. Now, without going into a long, long, recap of what mangroves are and how they function (You can Google this stuff and get hundreds of hits with more information than you could ever want- and you can reference one of the many blogs/podcasts we've done on mangroves here over the years), let's just say that mangroves are a group of trees and shrubs which live in the coastal intertidal zone, in areas of warm, muddy, and salty conditions that would simply kill most plants.

Mangroves possess specialized organs within their branches, roots, and leaves which allow them to filter out sodium, absorb atmospheric air through their bark, and generally dominate their habitats because of these and other remarkable adaptations.

There are about 100-plus different species of mangroves, all of which are found between tropical and subtropical  latitudes near the equator, as they are intolerant of cold temperatures.

Mangroves put down extensive "prop roots" into the mud and silt in which they grow, giving them the appearance of "walking on water." These root tangles help them withstand the daily rising/falling tides, and slow the movement of the water, allowing sediments to settle out and build up the bottom contours of the local ecosystem.

Oh, and before you start going off on me about their unsuitability for aquariums or some ethical implications for their "removal" from the wild, let's talk for a second about how we acquire them and how they grow. First off, removing a growing mangrove tree or seedling from the natural environment is damaging, unethical, illegal in most areas, and essentially idiotic.

NO ONE should even consider doing that. Period. Full stop. Propagules are readily, legally available, easy to sprout, and should be utilized by any hobbyist who is contemplating playing with these trees.

I'm sure that you know this already, but it's worth mentioning again.

Interestingly, their roots, which are arguably the most attractive part of the tree to us as aquarium geeks, are perhaps the part of the tree where there is the most confusion in the aquarium hobby about how to take advantage of their growth and structure.

I see literally dozens and dozens of social media posts, pics, and videos in which the aquarist takes the (perhaps partially sprouted) propagule and just shoves it into the substrate (which is usually, just dead, fine aragonite sand). Maybe it continues to grow for a while. Maybe it doesn't. You rarely see follow up videos. I do hear from plenty of hobbyists who take this "approach" (if you can dignify it by calling it that) and complain that the propagule either rots, or simply doesn't grow.

That doesn't surprise me, because that practice of shoving them into the sand sort of glosses over the way mangrove propagules root and sprout into seedlings in Nature.

The propagule ("seed pod") actually germinates while still on the tree, and they are ready to take root as soon as they drop off. This process takes about 2-3 years! Yeah, the "seed pod" is a couple of years old before it even drops off the tree! If you take away one thing about mangroves from this piece, it's that they do everything slowly! If you're expecting to have a beautiful miniature tree in your tank a few months, you're in the wrong place if you're playing with mangroves!

When the propagules fall off in Nature, they can float around in the water for many weeks before washing up on shore or finding some other terrestrial niche to sprout in. Some of these propagules go right to shore and take root quickly, while others may float around in the ocean for many months, or even a year or more, before finding a comfy spot in which to take root. In the comparative buoyancy of seawater, a propagule often lies horizontally and floats significant distances. When a propagule finds its way into fresher, brackish water the seedling turns into a vertical orientation, and its roots point downward.

Tip: The bottom of the propagule is a brownish color, and will orient itself towards the bottom as the propagule waterlogs and sinks vertically to the bottom. After lodging in the substrate, the propagule sends additional roots into the substrate, and begins to sprout leaves.

In my opinion, the key to success with mangroves is NOT to shove your propagules right into the substrate. It's better to let them float in an aquairum, bowl, or jar, and put down roots naturally.

Alternatively, you could anchor them in an aquarium, securing them to some object well above the substrate, and allow them to "find the bottom" by themselves.

Or, you could get "fancy", as I did in my recent brackish water mangrove aquarium, and anchor them to some dried mangrove roots.They eventually put down their own roots and touched down into the deep, rich substrate that I created for them.

Oh, substrates. That's something we need to talk about!

Mangroves come from habitats which ecologists call "mangals." These habitats are characterized by a very rich mud-like substrate.  

And of course, such rich substrates are, in my humble opinion, the best medium in which to grow mangroves in the aquarium.

When I first started playing with mangroves in brackish water aquariums, one of my "must haves" was the inclusion of "biosediment"/mud in the substrate mix. Now, I knew, since I wasn't initially planting the substrate with rooted, brackish-tolerant aquatics (like Cryptocoryne ciliata), and how I sprout my propagules, that the substrate would serve little purpose initially (until the prop roots of my mangrove propagules "touched down" into it months after the tank was established), other than to "enrich" the overall ecosystem of the tank. 

Okay, "enrich" is one of those deliberately vague "buzz words" I love to play with...I mean, WTF does it really mean? Well, I like to think that it means that it will impart minerals and organics to the water which would foster the growth of bacteria, beneficial microorganisms, and potentially, some small crustaceans which would help establish a little "food web" in my tank.

And, in my botanical-style brackish water aquariums, it did just that! I've seen an interesting explosion of small life forms. And the addition of mangrove leaf litter has no doubt assisted in fostering this. The small life forms in the substrate region are busy breaking down the leaves and other matter into a rich "compost" of sorts. Although there isn't very much of this visible in the tank, it's there- and the Olive Nerites snails which I like to populate my brackish tanks with have certainly seemed to appreciate this "diversity", and spend much time grazing on the substrate! 

The other "wild card", if you will, was the inclusion of mangrove root and branches into the hardscape. Both of these materials impart organic materials into the water. Quite frankly, even though I love the stuff, I personally believe that mangrove root wood is really "dirty"- and you'll see a release of "stuff" locked up in the wood tissues over time that is different than that I've experienced with other types of woods we use in aquariums.

Let's talk about what to expect when you use mud in your mangrove systems.

Of course, with all of the "functional" benefits of these kinds of materials, you'll also experience some stuff which perhaps challenges your long-held aesthetic beliefs about what a "successful" aquarium looks like! The water may not always be crystal clear (tinted or otherwise). In the same manner in which leaves and botanicals get covered in biofilms and break down, "dirty" wood and rich, muddy substrates can do their own "editing" to your tank's aesthetic!

I focused on the substrate in this situation as the source of this cloudiness.

I use a mix of several materials in my substrates- a mix you'd definitely be interested in if you're growing mangroves- but a substrate which, if disturbed, is almost certainly a recipe for some cloudy water! 

And that's exactly what I experienced in my "mudded" tanks.

I realized that my inclusion of external electronic Vortech MP10 pumps to create "intelligent" water movement at every level of the tank would possibly disturb the substrate a bit. Combined with the activities of some bottom-dwelling fishes like Bumblebee Gobies and the slow "excavating" on the surface of the substrate done by the snails, it was a certain recipe for...some turbidity- cloudiness, if you will.

It's something I kind of knew would be an issue going in these setups. I mean, not completely positive, but pretty certain. And quite frankly, I wasn't 100% certain how long it would last, or if it would ever go away. I mean, when you play with mangroves, you need a fairly deep substrate in some parts...so that's a big "supply" of sediments that could potentially cloud the water!

As a long-time reefer, I always thought about "crystal clarity" of water as being a sort of "measure" of overall water quality...which, of course, isn't really a complete story. You can have turbidity and high water quality, right?

Depends what's causing it.

When I began playing with mud in my mangrove tanks, I needed to see what it was that was causing the cloudiness, and what impact on water quality it was having.

So, what did I do? How did I cope with this question?

Well, it was pretty straightforward to me: First,  I needed to ascertain exactly what was going on. I did the "sniff test" to see if one of those obvious and classic "bad news" scenarios of bacterial blooms or other pollution was immediately apparent.

Nope. No smell!

Now, I've been in the game long enough to know that smell isn't the whole game, so a full "suite" of basic water testing (pH, nitrite/ammonia/nitrate/phosphates) was undertaken...The results were no nitrite and ammonia, and virtually undetectable nitrate and phosphate. The latter two are generally agreed to be a good "biological yardstick" of aquarium water quality, so it kind of made sense.

And I kind of figured that was the case.

I felt that it was a direct result of the decision to include very fine sediments/mud in my substrate mix.  Now, you could look at the potential "negatives" of this turbidity (umm, mainly that it looks kind of...well, shitty to many!) and think that this is a huge problem. Or, you could embrace it- much like we do in our blackwater/botanical-style aquariums with their "look"- as part of the "functional aesthetics" of a rich, active substrate in a dynamically-evolving aquarium. These episodes seem to wax and wane over time, too.

If you look at some of the surface level and underwater photos of mangrove habitats in Nature, you'll see this similar "haziness" as well. Now, not all of these environments feature this haze, although most do- and an aquarium is a closed system without the benefit of miillions of liters of water for dissolution- but the analog is, ahem- clear to me!

And curiously, I've noticed these kinds of phenomenon before in my aquariums which utilized mud-based substrates. And often, the cloudiness dissipates over time. It could be sediments...it could also be a bloom of microorganisms which are flourishing in in the water as a result of the organic materials from this sediment. Obviously, a micro-assay or other more focused study would be far more conclusive.

However, I think that the critical part of this equation is how we think about this stuff and accept it into the "big picture" of the management and "lifetime" of our aquarium systems- and how we react!

This lead to- you guessed it-another mental shift in my aquarium work

In my situation, the options I had were pretty straightforward: I could flat-out dismantle the aquarium and re-set it without mud. Totally unacceptable to me. Or, I could keep the system running and continue to do regular water exchanges, utilize micron filter socks, and chemical filtration media.

Essentially, dong "nothing different" to address the issue. Consistency. Patience. Acceptance.

And that's what I did. I kept doing what I was doing. And interestingly, the cloudiness subsided substantially after about a week. Kind of like I thought it might.

It always has worked out like that in every mangrove tank I've played with.

Go figure.

 

Our representation of them in the aquarium, while certainly more limited than Nature in terms of function, can still provide a very interesting, productive  habitat for a variety of fishes and other organisms, with unique benefits seldom embraced in the hobby.

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