This review is of the CAS library book Dynamic Aquaria: Building Living Ecosystems by Walter Adey and Karen Loveland. Copyright 1991.

First of all, let me tell you straight out this article reads quite negatively. This is not because I think that Dynamic Aquaria is a bad book. On the contrary, there are many aspects to the book I admire. But I am also very uncomfortable with other aspects of it. So uncomfortable, in fact, I feel I have to deal with them in detail, resulting in this highly critical (or at least critically sounding) article. But there is a lot of good solid work here too. It’s just harder to come up with a nice thing to say than it is to point out short-comings.

This book is (at least in aquarium circles) quite controversial. While living overseas I kept up with the controversy about this book on the Internet. I was intrigued by the ideas that were discussed on the web and very much wanted to read the book first hand to make my own mind up about it…but this is not a cheap book and it is not readily available. However, it is my belief that this is exactly the sort of book that the CAS library should have: a book that promises to advance the hobby but would be a significant investment for an individual club member to purchase. Therefore the book was on my first list of purchases when I became the new CAS librarian.

This book is about creating representative models of living ecosystems in a laboratory or home environment. As such, it is not really about the aquarium hobby as it is currently practiced. Adey and Loveland instead are promoting the use of artificial aquarium systems as research and educational tools in the study of natural ecosystems. They therefore advocate including as many of the real ecosystems’ organisms as possible in order to create a semi self-sustaining food web within the artificial environment. This, as a recreation of a "slice of nature", goes far beyond the "biotope" tanks as created by traditional hobbyists.

Because the book is about model ecosystems, it quite appropriately discusses in some detail the natural ecological systems that are to be modeled and the environmental conditions that are to recreated. These discussions may or may not be of interest to the aquarist, depending on how interested he is in the world around him, and how interested he is in creating something other than the traditional tropical fish display. For example, the discussion on the seasonal water turnover in temperate and tropical lakes is of little practical benefit to the angelfish breeder, but is certainly of interest to anyone studying freshwater ecology. And remember this is not another traditional aquarium book, it’s about quite another topic, and if that topic is of interest to you, then this book really shines.

The discussions of the interactions between the biosphere (living things), the hydrosphere (the water environment), the lithosphere (the rock substrate), and the atmosphere are thorough and fascinating. Strict scientific detachment is however not always maintained as the authors also discus, quite scornfully and with an obvious political bent, the interaction of our own species with the world around us. Also mentioned in several passages is the "Gaia hypothesis" of Lovelock (1987). This hypothesis postulates that the Earth’s biosphere is a "super-organism" in its own right. This hypothesis has been met with interest but appropriate skepticism from the scientific community.

However the book’s topics also concern the technological problem of recreating these ecosystems as model systems. The degree of interest this discussion would have to the home aquarist is easy to determine, because the techniques would have to be both practicable and successful to be worth reading about.

At the heart of the technique is the "algal turf scrubber". This is a wide shallow photosynthetic filter attached to the tank proper. The tray is provided with intense illumination for 12 to 18 hours a day, when the main tank's lights are off. A cover, or "turf", of filamentous algae is allowed to grow on a screen at the bottom of the scrubber tray. The growing algae crop removes nutrients, carbon dioxide, and metals from the water, and at the same time oxygenates it. The scrubber is the only form of filtration the model ecosystems receive. There are no mechanical, bacterial, or chemical filters employed, but detritus may be removed from the system by a bare-bottomed settling tank located upstream of the scrubber.

The basis of my concern about the book lies in the suggested design of the algal turf scrubber.

The tray is to be fed water through a dump bucket assembly to create wave agitation (rather than a smooth flow) through the tray. This is regarded as quite important by the authors as they site a 50% reduction in scrubber efficiency in a smooth-flow scrubber as compared to a wave agitated one. But reliable dump buckets (that always go to the "up" position again after a dump and do not splash water onto the floor) are very expensive and delicate pieces of equipment that are not readily available. They also require scrupulous cleaning to keep their Teflon bearings sliding smoothly (especially in marine aquaria). I do not believe that a dump bucket is a practical piece of equipment for a home aquarist, even if he could find one. Other forms of wave generators (such as a pneumatic piston and a tuned mechanical oscillator) are also illustrated and briefly mentioned, but these would only be available to the well equipped and clever handy man capable of working with electronically controlled motors, valves, or pistons. The cost of the requisite PC and controller cards quickly makes the creation of such a system a significant endeavor.

There is also a problem with the justification of the algal turf scrubbing as the sole filter. The algal turf scrubber is compared in the text to the standard aquarium bacterial filter, and the shortcomings of bacterial filters are discussed in detail. I have no problem with this comparison, but the assertion that photosynthesis in algal turfs is the primary "filter" of all natural marine ecosystems is suspect. As proof of this assertion, a natural algal turf on a coral reef is shown in color plate 10, and it is implied the picture illustrates a typical reef scene. However I have dived extensively on coral reefs in Hawaii and Australia, as well as temperate reefs in British Columbia and Tasmania, and I can state quite certainly that a healthy reef looks nothing like the picture in color plate 10. On a healthy reef such a patch of lower algae would be quickly grazed out and replaced by larger macroalgaes, coralline algae, and encrusting invertebrates. I can not refute or confirm the assertion that algal turfs process most of the nutrients on a coral reef, but if they in fact do, they somehow manage to do it without occupying a significant fraction of the reef surface. The picture's misrepresentation of a coral reef is most troubling because Adey (according to his publication list) has studied reef ecology and so should know what one looks like.

Furthermore, Adey and Loveland state quite clearly that they do not recommend the use of standard impeller-driven centrifugal pumps, because they kill planktonic organisms that pass through them. Various alternatives are mentioned, such as an Archimedes screw, a vacuum pump, and a diaphragm pump. But none of these plankton-friendly pumps are available commercially. A high-capacity airlift would move water without killing plankton, but practical home airlifts can lift water no more than a few centimeters, so the algal filter would have to be at the same height as the tank. This is often impractical, and the dump bucket the authors describe as "extremely important" could not be used. It would consequently be nearly impossible for Adey and Loveland’s techniques to be precisely followed by even the most ardent and advanced home aquarist.

But if one could set up such a system, how well would Adey and Loveland’s ecosystem approach work?

The book leaves you with the clear impression that the system works very well, as proven by their successful implementation of it in practical, thriving displays located through the world. But not all of these displays have proven to be unqualified successes.

This book is most controversial among reef aquarists, who have developed their own sophisticated and highly successful techniques for the keeping and raising of stony corals and other reef invertebrates. J. Charles Delbeek and Julian Sprung discuss these techniques in The Reef Aquarium, a book that is also in the CAS library. Recent articles in magazines such as Fresh Water and Marine Aquarium (where Sprung has a monthly column) and Aquarium Fish Magazine (where Delbeek has a monthly column) also discuss these ideas in depth. Proponents of these techniques feel that the authors of Dynamic Aquaria misrepresent them by both presenting inaccuracies in their details and by understating the results they can achieve.

On page 229 a schematic view of the plumbing and machinery used in a "modern reef aquarium" is illustrated, along with text that discusses the shortcomings of such a system. This is probably the source of the assertion that this book misrepresents alternative methods of aquarium keeping, as the system described is quite out of date. Mention is made of "trays of carbonate gravel often used", while gravel trays were obsolete well before the book’s 1991 publication date. A wet/dry trickle filter is also shown, a device that Delbeek and Sprung no longer recommend. Delbeek and Sprung instead advocate the use of copious quantities of porous "live rock" and "live sand". The presented comparison of an ecosystem aquarium with a "modern" reef aquarium is therefore really a comparison with an obsolete reef aquarium.

So the question becomes whether corals and other reef invertebrates can be kept healthy more easily in an ecosystem aquarium as described by Adey and Loveland than in a reef aquarium as described by Delbeek and Sprung. Although Delbeek and Sprung have refrained from directly criticizing the Adey and Loveland aquarium, people on the Internet have been less polite. Claims are made that the systems Adey and Loveland cite as examples, such as the Smithsonian reef exhibit in Washington DC and the Great Barrier Reef Aquarium in Townsville Queensland, have fared poorly, with stony corals dying within a year. This is usually blamed on the algal cells in the scrubber leaking dissolved organic carbon back into the aquarium water. The Smithsonian reef exhibit is now closed, but a picture of the then-operating exhibit appears on page 153 of The Reef Aquarium. This picture clearly shows that its algae-scrubbed water has an unacceptable green-yellow color indicative of a high concentration of algal exudates and poor water quality.

An archive of this debate is maintained on the Internet by Eric Olson in The Krib, at http://www.thekrib.com/Filters/scrubber.html. Included at this site is a history by Jamie Oliver of the problems at the Adey-designed Great Barrier Reef Aquarium in Townsville (http://www.thekrib.com/Filters/scrubber.html#3). It is reported that the Great Barrier Reef Aquarium has abandoned the Adey and Loveland system and have gone to a reef system incorporating protein skimmers, carbon filtration, and calcium supplementation, etc. as recommended by Delbeek and Sprung.

So a modern reef aquarium would seem to be more successful than the technique suggested in Dynamic Aquaria. But it should be remembered that modern reef techniques were refined after the publication of Dynamic Aquaria, and the modern reef aquarium does incorporate many aspects of the Adey and Loveland ecosystem approach. Delbeek and Sprung do, in fact, cite Dynamic Aquaria as a primary reference for their book, The Reef Aquarium. Clearly, the use of porous live rock and live sand advocated by Delbeek and Sprung is an attempt to increase in the tank’s ecological complexity and thus stability, as advocated by Adey and Loveland. Delbeek and Sprung also discuss "refugia", which are auxiliary tanks attached to their aquaria that provide a place for invertebrates to thrive, protected from the predators in the tank proper. This is also an Adey and Loveland ecosystem technique. The "algal turf scrubber" of Adey and Loveland also has a counterpart in Delbeek and Sprung’s refugia and their "reverse photosynthesis". Reverse photosynthesis is a technique where the lights over the refugium are on when the main tank’s lights are off. This provides continuous photosynthetic activity and hence a counterpart to the "algal scrubbing" of Adey and Loveland.

So...what’s the difference between Adey and Loveland’s aquarium and a modern reef aquarium? The modern reefkeeper would use protein skimming and carbon filtration to maintain water clarity and purity. Calcium and other ionic supplements would be added. Economically feasible impeller-driven water pumps would be used rather than diaphragm or screw pumps. The modern reefkeeper would also promote the growth of coralline algae and vascular plants and discourage the growth of filamentous green algae in the photosynthetic filter (or refugium). And their systems are unlikely to incorporate the dump buckets that Adey and Loveland advocate.

These may seem like small differences in practice, but they are significant differences in ideology. The modern reefkeeper’s promotion of one kind of algae over another, and the removal of plankton through impeller pumps and skimmers, does, in Adey and Loveland’s view, convert a representative of an ecosystem into a display garden, something they obviously consider much less interesting than the model ecosystems they wish to create. However, it is the pragmatic view of most reefkeepers that this level of artificial management is required in a practical real-world reef aquarium. The history of the Adey-designed reef system in Townsville would argue that this view is correct.

Although almost all the controversy and discussion concerning this book is in regards to reef aquaria, the book advocates the ecosystem approach in all kinds of aquaria; fresh and marine, temperate and tropical. No one seems to have a problem accepting the fact that applying the principles discussed in Dynamic Aquaria to non-reef aquaria will result in healthy tanks, only whether or not it is practical to do so.

Clearly, if one is only interested in maintaining thriving freshwater fish and plants, the dump bucket and plankton-friendly pumps can be safely dispensed with. Advanced techniques discussed in such CAS library books as The Optimum Aquarium (Horst and Kipper, 1986) don’t include a dump bucket and use conventional pumps. But then the Optimum variety of aquarium has never been promoted as a "model ecosystem". It is instead an artificially maintained display of aquatic plants and fishes; of much less scientific interest than any ecosystem. The Dynamic Aquaria therefore appeal to my scientific curiosity much more than an Optimum display would, but then again the aesthetic appeal of Horst and Kipper’s tanks is difficult to disregard.

Practical matters, however, would make the choice easy. Although the techniques of both The Optimum Aquarium and Dynamic Aquaria are technically complex, The Optimum Aquarium, with its CO₂ injection and undergravel heating, is at least feasible. And inexpensive alternatives to Horst and Kipper’s wallet-busting German equipment are also available. But the dump bucket and plankton-friendly pumps of Dynamic Aquaria have no commercial availability, and they would be quite difficult for all but the most advanced DIYer to build.

I am left with very ambiguous feelings about Dynamic Aquaria. The discussions on ecology are informative and interesting, as are the ideas it presents about aquarium management, but the concerns I discuss above make me wary.

I do not regret purchasing the book for the CAS library, as it contains valuable discussions and great food for thought. So by all means would I recommend that all inquisitive people read it. But I am also happy that I had the opportunity to borrow the book from the CAS library, and did not have to pay for it myself.

Adey, W. H. and Loveland, K. 1991 Dynamic Aquaria: Building Living Ecosystems, Academic Press, Incorporated

Delbeek, W. C. and Sprung, J. 1994 The Reef Aquarium, Ricordea Publishing

Horst, K. and Kipper, H. 1986 The Optimum Aquarium. Aqua Documenta, Germany

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