In today’s post, we’ll take a look at how to pick the right aquarium lighting system for the beautiful corals in your reef tank.
However, this isn’t your typical article with technical aspects to consider but rather looking at it from a different perspective; by letting your aquarium inhabitants decide!
This post is specially written by, Jason Russell, an aquarium & fisheries professional with over 2 decades of experience in the aquariums industry.
We’ll let Jason take it away from here..
What Do Corals Say About Reef Aquarium Lighting?
Nautilus Aquatics provides a wide variety of aquariums for a wide variety of people all over the state and the country, but one thing almost all our aquarium customers have in common is the request for help on choosing the right lighting for their set-ups.
Choosing The Right Lighting For Reef Aquariums
This is understandable, as choosing the right lighting in reef aquarium applications can be a daunting task. Choices range from metal halide, to T5 bulbs, to compact flourescent, and now to LED. There are more manufacturers of lighting systems than you can shake a stick at, and more recommendations and advice on internet groups and forums that it has become a heavily debated topic.
There are so many types, brands and styles to choose from that it is really no wonder why hobbyists and laypeople alike find aquarium lighting choices to be, at times, overwhelming; and with the variations in pricing, and with the expense involved in some lighting systems it is no wonder that this topic has become so heated. It’s also easy, as a hobbyist, to feel lost in a sea of too many lighting choices.
A Change In Perspective
Our customers often turn to articles written on aquarium lighting systems for advice, but many of these articles only focus on the technical aspects of those systems. In this article, however, I’d like to look at things from a perspective that includes more natural history and aquarium ecology In other words, let’s see what happens when we let the creatures we love and keep in our aquariums inform us about their needs in terms of lighting.
Saltwater corals are carnivorous marine organisms exhibiting stinging cells and tentacles, and are related to jellyfish and sea anemones. The reason they are called corals is more of an ode to their skeletons (Which basically serve as a refuge).
These skeletons can be soft, or hard (being composed of a higher concentration of minerals).
A fossil reef that is well studied on Manitoulin Island, Ontario Canada consists of a long ancient shoreline where many different corals grew at a very shallow depth below the low tide line. Some of these were turned over or damaged which shows evidence of repeated storm fronts. During this time (Silurian Period) this locale was in the tropics just passing through the equator. Most of the surrounding area was covered by a warm, shallow sea (this area later would become North America). These corals which formed on the Manitoulin Island reef are now extinct.
Today more than 2300 species of corals exist, with all of the present day corals popping up in the Middle Triassic Period (around 240 million years ago). Most of the modern coral reefs today were formed on top of these old prehistoric reefs. Coral reefs in short are prolific exporters of biological diversity and play an important role in other oceanic environments.
Modern Day Corals
So now let’s shift our focus to modern day corals and the dynamic balance between light and nutrition involved in their study. There are corals that exhibit the ability to shift the balance of their nutritional uptake between particles, dissolved molecules and photosynthesis when it is required for them to do so.
Naturally deeper water specimens receive less light, and bleached corals have to find other means, such as Montipora capitata which actually increases it’s plankton uptake after bleaching to increase metabolic requirements. This increase in plankton uptake in theory could enable them to reproduce annually in spite of bleaching effects. According to observations and the historical record, species which increase feeding when things go into a natural recession are more likely to remain the survivors.
Nutritional Effects On Corals
Nutritional effects on corals are profound with essential process such as photosynthesis and the buildup of it’s organic composure. So as a result plankton supplementation plays an important role. To some people feeding and photosynthesis are different things, I would like to point out that instead of this train of thought let’s come to an understanding that they are actually interlinked.
More feeding stimulates zooxanthellae growth. In terms of high intensity of lighting it is become acknowledged that corals actually grow much less than expected. This is particularly evident if a coral is growing close to the lighting system in aquaria.
This problem is most likely due to the lack of essential building blocks, such as the fact that under higher lighting conditions in natural summers zooplankton is more readily available.
French scientists have discovered that this can be alleviated by providing extra nutrition, obviously by dosing zooplankton in extra amounts. When these corals received a less intense form of lighting, or shade it led to fleshier corals. So a decline in growth rate can be countered with additional zooplankton feeding.
Corals acquire 75% of inorganic carbon from metabolism, with the remaining amount being derived from the water column. This leads to a higher production of bicarbonates. Which in turn provides more building blocks in the formation of the coral skeleton.
As with other organisms in nature more nutrition equals more energy; so by feeding corals it does provide an increase in tissue production.
While more light showed a decrease in fat content. Is this a contradiction? Not if the corals in question placed more of their fatty acids into zooxanthelle production.
This could be an adaption to higher light levels. Never-the-less, tissue doubled with zooplankton feeding under high intensity lighting and low intensity lighting. With fatty acids and chlorophyll increasing their concentrations it leads to the conclusion that symbiotic algae and the corals themselves profit from planktonic feeding.
It needs to be established that aquarists prefer vibrant coloration, and this is due to coral pigmentation. A duller brown zooxanthellate enriched with chlorophyll is thought to be unattractive.
However these corals are housing the energy for extra growth that is not found in the more brightly colored pigmentation of corals thought to be more attractive. This comes with the expense of slower growth, and most likely a decrease in lifespan as it is tougher on the corals.
(pix source: Flickr)
In aquariums strong lighting has always been thought to be the cure all for coral growth, but additional feeding is most likely the best way to approach the matter. It may not be visible that corals soak up protozoa, amino acids and detritus….they in fact do.
So, to sum it up: fed corals are happy corals, and the debates over high intensity lighting can rage on, but with this knowledge perhaps you can put priorities first and think of the animals you are keeping, and what is best for them.
And now, the million dollar question: what lighting system do I prefer?
Well Kessil is the brand I prefer because I have found them to be durable, long lived, and I like the design which enables me to focus lighting in certain areas of the tank and a little more subdued in others.
There are many times when a coral does not do well under high intensity lighting because it was in fact collected in deeper waters.
Ultimately the decision is yours, and I hope that this article helps to make your decision of lighting scheme to be much easier. Whatever you choose, make sure and remember the old saying….you get what you pay for.
So choose wisely. Happy Reefing!