Steve Tyree

Reef Building Stony Corals - The Natural Physical Environment

November 1, 1998 on #reefs

Introduction

In the early 1990's I acquired my first living Acropora colony. At that time there were only a handful of aquarist attempting to maintain these corals in the US and there was no hobbyist orientated literature concerning their captive maintenance. During the early and mid-1990's, I became successful maintaining these corals in semi-closed systems and was eventually asked to author a book concerning their captive maintenance. As I began writing the microcosms captive maintenance book, I realized that while I knew a lot about the corals in captive systems, I knew very little about their natural physical environment. It became clear to me that any guidelines for captive maintenance needed to be supported with information describing what the corals actually experienced in nature. So I proceeded to research the scientific reports and papers that documented the corals natural environment. I soon realized that a summary or review of this information could be very beneficial to those of us attempting to mimic the natural environment. This led me to self publish the research in a book containing six main areas: The Ocean Environment; The Reef Environment; Coral Distribution; The Natural Light Environment; The Water Motion Environment and Natural Propagation. Due to space limitations this presentation will cover The Reef Environment, Coral Distribution and The Natural Light Environment. Perhaps we can do a followup later covering The Ocean Environment, The Water Motion Environment and Natural Propagation.

The Reef Environment

Reef Building Stony Corals, (SPS corals), have the ability to become the primary framework for massive underwater reef structures in warm tropical waters. In the semi-tropical areas and in tropical areas not suited for reef development, reef building stony corals can still proliferate but do not form reefs. The colder marginal habitats contain much less diversity or speciation. Located in-between reefs are inter-reef habitats where sediment levels tend to be higher. Scientists refer to reefs and their inter-reef areas as reef complexes.

Aquarist may be surprised to discover that the same algal succession that occurs in new captive systems also occurs in the natural world ! The Start Phase is when a new surface becomes populated with diatoms and algae. The Preparation Phase follows where algae eating organisms control the algal growths as non-coral organisms settle into the area. That phase is followed by the Coral Colonization Phase where corals begin to inhabit the area. The early reef building corals in nature are called pioneer corals. In the Indo- Pacific the pioneer species are Stylophora pistillata, Pocillopora damicornis, P. verrucosa and Porites species.

A young and growing coral reef does not contain a lot of sedimentary deposits. These young patch reefs can eventually develop into lagoonal reefs when sedimentary deposits and coral growth create reef flats near the waters surface. As maturing reefs slow their growth and erode, sediments accumulate on the reef structure. Entire islands can be created on these flats from the collection of sediments derived from animal and plant material. This is the ultimate form of ecomorphology where land masses are created entirely from the structure and deposits of lifeforms. Some of these islands are completely composed of coral shingle (coral gravel). The areas of a coral reef can be defined into distinct and separate zones that experience unique environmental conditions. The lower section of the reef on its seaward side is called the fore reef slope, outer slope or deep fore reef. It generally occurs below a depth of 18 meters or 60 feet. On Caribbean fore reef slopes, the common corals are Montastrea, Porites and Siderastrea. On deep Pacific fore reef slopes, there are zones of Leptoseris and Echinophyllia. The upper area of the seaward reef slope is called the upper fore reef or terrace. Spur and grooves are often found in this area with strong turbulent currents. Coral growth is usually rich with forms that are affected by the strong current. In the Caribbean there can be Acropora palmata zones in this area of the reef. In the Indian Ocean Millepora sp. zones occur, while in the Western Pacific their are Acropora cuneata zones. The lower zones of the upper fore reef can contain a greater diversity of corals.

The seaward upper edge or ridge of a reef is a very high energy environment. On strong current Indo-Pacific reefs this ridge can be composed of coralline algae and is called the Algal Ridge. On some reefs this area is called a boulder zone. A Solomons Island high energy reef has tabular Acropora inhabiting this incredibly high energy zone. Acropora humulis is also found in the area. On Caribbean reefs the Algal Ridge is replaced by a Millepora Zone. The reef flat area is located inside the outer fore reef and outer ridge. Coral growth can be sparse on these shallow water flats with depths up to 1 m (3.2 feet). Deeper flats contain more extensive coral growth and can contain Echinopora, Porites lutea, Heliopora coerulea and Acropora palifera zones. Located inland from the reef flat there is typically a lagoon or back reef. Upper Lagoon Reef Slopes extend to a depth of 3 m (9.8 feet) and can contain prolific growths of foliaceous and branching corals. The Lagoon Slope descends from the upper slope to the floor of the lagoon. Fragile coral forms such as scroll shaped Montipora foliosa and branching Acropora are found here. There are also fragile branching Pocillopora damicornis and Seriatopora hystrix. Lagoon floors typically have large sediment deposits. Corals can be found growing on patch reefs, pinnacles and mounds. There are also large Acropora thickets.

The role of algae in the reef environment is very diverse. Red Algae in the form of coralline algae is an important framework binder that helps solidify coral structures. In a few areas they can even form Algal reefs where they are the dominant framework. The symbiotic dinoflagellate that lives inside reef building stony corals can also be considered a very important reef algae. Not all algae are beneficial to coral reefs. Ostreobium and filamentous algae can become problematic to corals. Nitrogen fixation from algal growth has also been discovered occurring in reefs. This is where dissolved nitrogen gas gets incorporated into growing algae and eventually increases the dissolved organic and inorganic nitrogen in the area.

Coral Distribution

Reef Building Stony Corals inhabit tropical ocean waters centered around the equator between 25 and 30 degrees north and south latitudes. This area can be divided into 4 separate provinces: The Pacific Province, The Indo-Pacific Province, The Indian Ocean Province and the Atlantic Province. The Pacific Province includes the Pacific Ocean from the western coastlines of North and South America to the Fiji and Marshall Islands of the western Pacific. Coral species diversity varies from 2 to 5 genera in the eastern pacific to 30 or 60 genera in the western pacific. The Eastern Pacific Region contains marginal habitats for stony corals due to cold water upwellings and a lack of underwater platforms. Corals in this area do not form true reef frameworks. The Galapagos Islands and Panama have the highest species diversity with up to 13 RBSC species. In a few locations Pocillopora colonies form reef-like frameworks. Acropora valida is the only Acropora species to ever be found in this region. The Central Pacific Region includes French Polynesia, Hawaii and American Samoa. This region contains numerous islands and over 100 coral atolls. Species diversity increases in the western parts of this region with the maximum being 174 RBSC species in American Samoa. The Western Pacific Region has the highest diversity in the Pacific Province with 200 RBSC species in Fiji. Water temperatures in Fiji vary from 20 C (68 F) to 30 C (86 F). Acropora are much more common as the dominant reef builders in this region when compared to reef structures in the eastern and central pacific regions. Kwajalein Atoll, located in the Marshall Islands, contains the worlds largest atoll lagoon.

The Indo-Pacific Province contains the areas located between the Indian Ocean to the west and the Pacific Ocean to the east. This area has the worlds highest diversity of RBSC species. Eastern Indonesia has 78 RBSC genera followed by the Philippines with 74, Eastern Australia with 73, the north coast of Papua New Guinea with 73, Western Australia has 69, northern Borneo has 65 while northwest Java and Taiwan have 59 genera. The southeastern region of this province includes the Coral Sea and its surrounding islands. This region contains the Great Barrier Reef, Papua New Guinea, the Solomon Islands, Vanuatu and New Caledonia. Reefs in this region are rich with Acropora species. The highest number of species is found at Eastern Papua New Guinea with over 400 species. The worlds largest barrier reef (Great Barrier Reef) as well as the worlds second largest (New Caledonia) is located in the region. The northeastern region of this province includes the Philippines Sea and the surrounding islands. This region includes Taiwan, the Philippines, Belau, Micronesia, Guam and Japan. Throughout the Philippine Islands there are 450 species of RBSC, while Belau and Micronesia have 250 species. The worlds northern-most area containing hermatypic stony corals can be found at Tateyama Bay on the main island of Japan. The northwestern region of this province contains the South China Sea and includes Malaysia, Singapore, Thailand and China. Coral diversity in the southern areas of this region can be over 400 species, but diversity drops to 50 species in the northern area. Surface water temperatures in Malaysia vary from 27 C (80.6 F) to 28 C (82.4 F). The South-Western region of this province includes the western coast of Australia and Indonesia. There are over 400 species of RBSC found inhabiting Indonesia with 250 species on the northwestern Australian coastline. There are few atolls in this region, but Taka Bone Rate in the Indonesian Flores Sea, is the worlds third largest atoll.

The Indian Ocean Province includes the eastern and western areas of the Indian Ocean, The Red Sea and the Arabian Sea areas. Species diversity in this province is similar to the diversity found in the Western Pacific Region (Fiji to the Marshall Islands). The Red Sea Region has very high diversity with 50 RBSC genera, while the Arabian Sea has moderate diversity with 30 genera. The Indian Ocean Regions have high to moderate diversity. Reefs in this region are dominated by Acropora or Porites. Pocilloporidae are common in shallow water, while Faviidae are common at mid-depths. The eastern Indian Ocean includes the islands of Maldives, Lakshadweep, Nicobar, Andaman, Sri Lanka and the coastlines of India and Burma. These coastlines have little coral growth due to freshwater and sedimentary runoff. The Arabian Sea Region includes the Persian Gulf area and parts of the coastline bordering the Arabian Sea. The Persian Gulf area is considered a stressful environment for RBSC due to high salinities and extreme water temperatures. Salinities in some areas of the Persian Gulf can reach 50 ppt. No reefs form in these high salinities, but a few corals such as Porites nodifera can tolerate the salinity. The coastlines of the Arabian Sea experience cold water upwellings. The Western Indian Ocean Region includes the eastern coast of Africa and the western Indian Ocean. The African coast from south Somalia to northern Mozambique has fringing and patch reefs. The islands of Seychelles and Madagascar also have reefs. The Red Sea Region includes the Red Sea, the Gulf of Aqaba and the Gulf of Suez. The Red Sea has very little sedimentary input, low turbidity, high temeperature and a hard coastal substrate promoting widespread fringing reefs. There has been at least 194 species of RBSC species found in this sea.

The Atlantic Province includes the Caribbean region as well as the Atlantic Ocean. The diversity of RBSC in this province ranges from low to moderately low. In the Central and Eastern Caribbean regions there are over 20 RBSC genera, while the Atlantic Ocean Region has from 2 to 10 genera. There are only a few species of Acropora found in this Province. The Atlantic Ocean Region includes Bermuda, Brazil and the Western Coast of Africa. Coral reef development is found as far south as Rio de Janeiro in Brazil, while its northern most occurance is at Bermuda. The western coast of Africa has no reef development. The Eastern Caribbean Region contains a total of 38 species of RBSC. Good reef development occurs in the Netherlands Antilles. In the Central Caribbean Region extensive reef development occurs in the Bahamas, the north coast of Jamaica, Cuba and the Cayman Islands. The South-Western Caribbean Region includes the Caribbean coastlines of Mexico, Central America and Columbia. Reef development is limited due to freshwater runoff, but extensive reefs are found near offshore islands. The largest barrier reef in the Atlantic is found at Belize.

The Natural Light Environment

From the moonlite darkness of night to the daytime photoperiod, the natural light field that enters the water over a reef varies quite dramatically during the day. In summertime, light intensity reaches 60 % of its peak value for only about 6 to 7 hours at midday. Besides intensity, light also possesses a quality or color. This represents the distribution of wavelengths or energies of the individual light photons. Wavelength is extremelly important. For example, if we only had light of infrared wavelengths, the intensity would be meaningless to human eyes since we cannot percieve that color or quality of light. Corals would also not be able to use this light. A significant portion of surface sunlight actually happens to be infrared light. This light gets quickly absorbed by water as it travels into the ocean. The visible light spectrum occurs from violet light (400 nm lower end) to red light (700 nm upper end). The most intense peak area of sunlight at sea level occurs at 460 nm (blue light). There are two basic sources of light intensity at the seas surface. Direct Sunlight is light that travels directly from the sun to a particular point. Diffuse Skylight is the area of the sky that is away from the circular suns disk. It is blue when the atmosphere is clear and can be white when clouds are present. As you get closer to the suns disk, this scattered diffuse skylight becomes more intense and more white in color or quality. At high sun elevations in dry atmospheres, the minimum % of total light that is diffuse skylight is 10 %. This can reach 25 % of the total light in atmospheres that contain some humiditidy. In heavily clouded conditions diffuse skylight can become 100 % of the total light as the suns disk is completely obscured. Skylight is a greater factor at low sun elevation angles.

As light travels through seawater it can become absorbed or scattered. The combined affects of absorption and scattering is called attenuation. Light gets absorbed in seawater by the physical water itself, dissolved yellow pigments, photosynthetic biological organisms and inanimate particulate matter. Pure water is a weakly blue colored liquid due to its absorption of yellow, orange and red light. A 1 meter (3.28 feet) layer of water will absorb 35 % of light at wavelengths of 680 nm (red). Another form of absorbtion occurs from dissolved yellow pigments (gilvin) that are derived from the decomposition of plant tissue. This is why some coastal areas have green or in extreme cases brown colored water. Inanimate particulate matter (tripton) can also absorb light. Gilvin and tripton absorb more blue light than they do green or red. Phytoplankton can also absorb light primarily with their chlorophyll a pigments. Most of the areas with coral reefs have clear blue ocean water where orange, yellow and red light gets absorbed by the physical water itself. Water is acting as a filter which allows blue, violet and ultraviolet light to penetrate deeply. Dirty coastal water can severly limit the penetration of ultraviolet, violet and blue light. Radiance is a measure of direct sunlight arriving from a particular angular direction. For example, the direct sunlight from the suns disk minus diffuse skylight from the sky is a radiance measure. Irradiance would be the total light from the suns disk plus diffuse skylight. When quantifying artificial light bulbs, radiance values from the bulb should be measured. Irradiance measurements can bias the results with the reflective attributes of nearby structure.

The attenuation of light travelling through seawater changes the spectral qualities of light. This is why photometers biased to sealevel light qualities that determine foot-candles, meter-candles or lux should be avoided. Quantum based sensors give a more accurate count of photons, but do not describe the quality or spectral distribution of the light field. This can be approximated with spectroradiometers that have bandwidth resolutions of 10 to 5 nm. These meters are unfortunately very expensive. In Jamaica at a depth of 10 m (32.8 feet), red light is decreased by a factor of 100. This virtually makes it non-existant at this depth. PAR light represents the total number of light quanta in the visible part of the spectrum (400 to 700 nm). At Discovery Bay in Jamaica, a surface PAR value of 1,925 micro-Einsteins/square meter per second was measured. At a depth of 15 m (49 feet) PAR was 392 micro-E/m2s. This means that at 15 m (49 feet) depth, irradiance was ~20 % of surface irradiance. At a reef in the Great Barrier Reef, irradiance at a depth of 10 m (32.8 feet) was found to be about 24.5 % of the surface irradiance. The depth distribution of RBSC were studied at Thochu Islands in the South China Sea. Corals were rare in the shallow intertidal waters due to wave action, strong sedimentation and a moving sand substrate. The maximum RBSC species diversity occurred at depths that had 10 to 30 % of surface irradiance, which happened to be 10 (32.8 feet) to 15 m (49 feet) depths. Shallow water areas with very intense light are occupied by only a few species of corals that have a competitive edge. Greater diversity occurs in light fields with peak intensities from 200 to 600 microE/m2s. This means that intense very high shallow water PAR values should not be what the aquarist strives for if the most diverse habitat of RBSC corals is being reproduced. This explains the awesome reef tanks with only 4.5 watts per gallon of lighting. In very clear waters, light irradiance at 10 meters depth is actually about 50 % of its irradiance at 1 meter depth. This means that violet/blue/green light intensity at 10 m depth is still more than 50 % of its surface intensity.

The zooxanthellae (phytoplankton) that inhabit RBSC, utilize light collecting pigments called photorecptors. These pigments have physical limitations that affect the type and quantity of light they absorb and convert into chemical energy. There are basically two types of pigments within the zooxanthellae: chlorophyls and carotenoids. Chlorophyls a and c primarily absorb blue light, some red and little green or yellow. The carotenoids found within these algae absorb primarily blue light. Algae from low light areas absorb more of the available light field than algae from intense light fields. Almost all RBSC species are also found inhabiting the mid-depth regions where red light is basically non-existant. This means that the corals can adapt and survive without red light. A primarily blue light field with equal amounts of violet and green light is what most of the RBSC experience in nature. They are also exposed to some amounts of UV-A due to its ability to penetrate water to mid-depths. Studies of corals have found that low levels of blue light can achieve peak photosynthesis values similar to what is achieved from peak sunlight (white light). Light at wavelengths of 460 and 420 nm have also been found to enhance algae due to factors independent of photosynthesis.

Algae have a peak rate of photosynthesis that they can achieve that is called the saturation point. The more intense the light is, the earlier the saturation point is reached. What happens is that there are simply too many photons being captured and they cannot all be converted into chemical energy. Too much captured light can actually damage and photoinhibit the photosynthesis apparatus. Algae also possess the ability to adapt to changing light fields and can change their saturation points based on the health and level of adaptability achieved. Light saturation intensity levels for Acropora digitifera in 1 meter (3.28 feet) of water was 407 microE/m2s. The average saturation intensity for corals at 1 meter (3.28 feet) depth at Davis Reef on the GBR was 340 microE/m2s. This is only 22 % of the peak incident irradiance. These shallow water corals are utilizing only 22 % of the available irradiance.

The Photosynthetic Action Spectrum (PAS) defines how photosynthetic organisms respond to light at specific wavelengths. It can be very valuable when analyzing natural underwater light fields with their varying wavelength qualities. PUR or Photosynthetically Useable Radiation is a wavelength biased method that has been utilized in the study of RBSC. A simple example can illustrate how PUR values can be more viable than PAR values. Lets place an organism that has pigments that do not absorb much yellow light into a light field that is all yellow. PAR would give a reading equivalent to the yellow light intensity. PUR would result in a very low value since it is biased with the organisms ability to absorb light at specific wavelengths. Coral scientist have also developed a metric called Photosynthetically Stored Radiation PSR which is similar to PAS.

The pigments previously discussed have been algal pigments that only occur within the zooxanthellae. There are also coral pigments located in the coral animal tissue. All of the non-brown coloration that humans percieve is due to coral pigments. The brown coloration is from zooxanthellae pigmentation. Coral Bleaching refers to a loss or shrinkage of this zooxanthellae pigmentation. In extreme cases the coral will turn white and still remain alive, while minor cases cause a lighter color or white patches to appear on the coral. These zooxanthellae can be expelled from the coral or can degenerate within the coral. A quick bleaching that occurs in just a few days is probably due to an extreme environmental event. Scientist have determined that warm water is the primary cause of bleaching but extreme cold water, reduced salinity, high temperature with intense solar radiation and even a bacterial infection have been found to cause bleaching. The opposite of bleaching is called coloring. This occurs when a coral darkens its brown color, recovers from a bleaching event or even regains its colorful coral pigmentation. A coral that is slowly turning white on areas receiving direct light, while remaining dark brown in low light areas is probably recieving too much light. A coral that is turning dark on areas recieving direct light, while turning white in low light areas is probably not recieving enough light. These slow to develop changes in color are due to photoadaptation.

I have defined the colorful coral pigments into three different types: reflecting; fluorescing and growth pigments. Growth pigments only develop in new growth areas and can disappear as the new area ages. Fluorescing pigments fluoresce or transform UV-A and Violet light into visible light from blue to red. Reflecting pigments will reflect a specific wavelength of light. The first scientifically indentified pigment has been called pocilloporin, which is a pink pigment found within Pocillopora damicornis. This pigment fits my definition of a reflecting pigment. It absorbs green and yellow light while reflecting back pink light. You can only see the pigment if you illuminate it with some reddish light. The development of the pigment increases with the increasing intensity of visible light the coral recieves. It is also possible that exposure to UV light can increase the production of the pigment. However, the pigment does not function as a UV protectant and it is not connected to algal photosynthesis. Science has yet to determine its function. Other pocilloporin-like reflecting pigments are pink in Seriatopora hystrix and Stylophora pistillata as well as the purple in an Acropora digitifera.

Fluorescing pigments have been found to occur in every color of the visible light spectrum. The most common and easy to produce pigment is the green fluorescing pigment. Fluorescing pigments that require more light to be reproduced are the pink and blue fluorescing pigments in Acropora. I do not think its correct for aquarist to subjectively call fluorescing pigments non-desirable. The coral animal is developing them for some reason that is presently unknown. Overall there appear to be numerous types of pigments in these corals. Most pigments require a specific amount of light intensity and a specific light quality to be developed. This is easily demonstrated by examining a colorful RBSC from its top and then flipping it over and examining it from below. They are usually brown on the bottom low light side and very colorful on the top. This is a normal coloration and corals that are white in the bottom area may have suffered bleaching. Many corals also possess pigments in their polyps that are different from pigments in the main coral body. The "tricolor" Acropora have fluorescent green pigment in their polyps while also possessing a reflective purple pigment in their main body. Some Pocillopora and Stylophora have also possessed a dual reflecting and fluorescing pigment combination. RBSC also possess UV absorption substances called S320. Their function is to absorb UV-B light. These pigments are however colorless and there should be no reason to expose the corals to biologically damaging UV-B. UV-A and violet light however, may help stimulate pigments and will clearly make fluorescent pigments more visible.

Steve Tyree - ccoberg@ez2.net (909-677-0073 voice mail/fax) DE (www.masla.com/home000.htm) DE Publishing (www.masla.com/depublish.htm) The League of Coral Reef Farmers (www.masla.com/home001.htm)

A. palmata is a shallow reef coral - rarely found below depths of 30 feet - don't you mean A. cervicornis ? A. cervicornis can also occur in some shallow areas with weak current. What specific reference are you refering to ?

A. cervicornis is the lower depth Caribbean species - A. palmata is a surface reef crest coral species but you are right, A. cervoicornis can be found in shalllower depths as well. That must of been the Reef Environment section. I see where I noted that A. palmata forms zones in the upper strong current areas. To be more specific they have to frame the quote for me.

It seems to me that the water temp has a big impact on species diversity, do you feel that higher water temps would be beneficial to reef aquariums?

Higher temps over 85 F seem to cause problems. Temps from 80 to 86 F which might seem high to some are more normal for these corals. My tanks run at those temps. The benifits from running lower temps 74-78 F are that disease outbreaks (RTN) occur less often but the drawback is that growth is slowed.

Are there any methods that you know of that will stimulate branching of fragments? I ask particulrily in reference to montipora digitata frags that have developed quite a large base, >1" in diameter, but show no signs of branching yet.

Are you sure it is a Montipora digitata ?

hmm, not positive :/, but think it is.

Most digitata grow branches fairly easily. What is the current like over the coral ? > it's quite high, ~300gph in a 10g tank My guess is the current is too high. Thin branches need low current values. Thats why staghorn thickets grow in lagoons and not on the upper fore reef.

Your name is used as a positive reference for Leng Sy's method.. do you still support Leng's Method and and think it is a break through method?

Leng's method worked very well for the reef tank I setup. Since setting it up I have done more research and think I know how it works. There is some interesting stuff going on with the macroalgae 24 hour light period. I know he has taken some criticism over his marketing methods, but that is his method.

Have there been any attempts to grow corals with two photoperiods daily (ie: 5am - 11am + 5pm - 11pm)? What results?

I attempted that with regards to coral spawning research, but have not done any growth studies. My guess is that like larval growth, coral growth also has some physical limitations. Some have suggested that most calcification occurs at night, but that is still debatable.

Regarding 4.5 watts per gallon, this makes little sense, as 4.5 watts per gallon on a ten gallon tank is about the irradiance of a forty watt bulb - corals don't work like this - it does not figure into what you later discuss in terms of saturation values - agree?

A 10 gallon tank is not very tall. Distance from the bulb is extremelly critical. I am sure that many 10 gallon tanks have a couple of fluorescents over them.

What is the optimum setup for keeping Acropora?

If you read my book there really is no such animal. RBSC occur in very wide habitats. It really depends on what type of environment you are trying to replicate. Water current varies dramatically in nature as does light intensity.

What 3-4 SPS are the easiest to grow if someone is starting out (or is that a stupid question)?

That is a very good suggestion. Do what happens in nature. Use the pioneer corals of the Pacific that were mentioned in the presentation. Pocillopora damicornis, Stylophora pistillata and P. verrucosa.

Would you care to expound on how you thinks Leng's method works?

Not really. But Leng had an advisor who had a PhD at UCLA.

What type of reef environment is the easy to reproduce in the tank?

I would suggest a middepth lagoon. That has low current and low light. Lots of Acropora staghorn thickets. Of course you could go cryptic with hardly no light at all :>

Are you saying that N2 fixation by cyanobacteria in lagoonal sediments is a bad thing, Steve?

It depends on your definition of bad thing :>. Nitrogen fixation will add nitrogenous nutrients to a system. Systems that have high levels of nitrogen (ammonia, nitrite and nitrate) will want to avoid that. Systems that have low levels wont mind.

You've talked about Frame-Builders & Frame-Binders, you indicated the primary binders are coraline algae. Can you expain this a little further?

In the majority of cases, reef building stony corals are the primary framework builders of a reef. They however need to be glued together to prevent being ripped off the reef from strong waves. Coralline algae grows over dead coral skeleton and provides it with an armor kind of coating. This drastically increase its ability to survive pounding wave action. The corallines also cement things together by attaching to them.

What degree kelvin lamps (MH) would you recommend to increase pigments in SPS corals?

That's not even mentioned in my book :> I have stated many times that 6500 K are the bare minimum. They will work fine, but they appear to be weak in violet light. That's why I recommend supplmental actinics. Some of the newer 10,000 K also have a weak violet problem. With 20,000 K you do not need supplemental actinic lighting. But they all three can work.

How much skimming do you use, and what do you think of using less skimming or even removing skimming?

I have been skimmerless since the start of the year. Thats one thing I learned from my consultation with Leng Sy. It can work, but you need to be careful. I still recommend skimmers for most applications, but those that what to try the more natural methods can still experiment and even get by without a skimmer.

Is there a site you can refer us to for the basics of Leng's method?

I thing it is ecosystems.com or ecosystemsaquarium.com or something similar. My consultation with Leng was over 2 years ago and I have been too busy with other projects to keep up with what he is currently doing.

Is it true about soft corals in with hard corals in a tank that when the soft corals shed their mucus it helps the sps corals in some way?

Thats a new one to me. What is the basis for this theory ? Is the mucus a food for the SPS ?

Would you mind telling us about your Sponge Filters? Have you done any further work on setting up a new sponge filtration aquarium?

I am currently setting up a 600 gallon sponge filter system. Should be ready to write the book and recommend the system by spring of next year. Still fine tuning it, but it is very interesting. Any specific questions concenring it ?

What about those high temps, when we are keeping corals from cool climates, such as Yellow Scrolls?

The cool climate corals are probably those from Tonga ? The corals from Jakarta, and Solomons are from very warm waters. Yellow scrolls are Turbinaria I guess and they do occur in warm water too.

Where one might aquire sponges for use in a naturally filtered aquariu? Could they be aquired from the uncured transhipped rock?

They can be acquired that way, but 90 % will not survive. It looks like sponge farming will be real easy to do so hopefully that will provide sponges. Their is direct import too, but they usually pick too large of sponges from shallow water.

What type of currents do you recommend for encrusting and plating species, such as montipora's, enchinopora's, porites, and merulina's?

Thats actually a very interesting question. I have found references that state they need strong current and weak current. Scrolling corals typically require moderate to weak current, but thats not always the case. Encrusting Montipora and plates grow that way in strong current but they also take on that form in low lighting environments. The best guide is to see if sediments are collecting on the coral. Current is too weak then. Also, pigmentation can also fade if current is too low as Dana and others have determined.

Are you using carbon filtration on the skimmerles tank?

There is no plumbing on the tanks. None at all. And no bags of carbon in the main reef either :>

Obviously the question then begs, why go skimmerless in the 1st place?

So someone wants me to rag on skimmers ? :> I have been avoiding that but since you ask - They require power to operate and I got kicked out of my apartment in Los Angeles because the skimmer collection cup kept overflowing. Their price is a little high too.

Regarding the Leng system, how much nutrient export are you achieving (via macroalgae harvesting I presume) compared to the nutrient export you were achieving with skimmers?

I am not running Lengs system. I did consultation for him and converted one of his reefs to an RBSC system. I have not been to his main facility in well over a year. So I do not even know how it is currently running.

The Low Flow/ Low Light area. How do you decide how big it needs to be in comparison to the tank?

Thats one of the items I am trying to fine tune right now. At first my guess was that for every liter of primary producing animals (RBSC) there would be one liter of living sponge or squirt. It appears though that these RBSC really shed a lot of slime :>

What I meant to ask is how are you doing nutrient export in your skimmerless tank (ref to previous Q)?

There is no nutrient export currently. Right now the tanks require nutrient import via raw tap water and I have began experimenting with supplemental sponge feeding to get the sponges growing faster. Eventually I will be harvesting excess sponge growth as well as coral growth. That is the pipe dream anyway :>

Have you found any positive results from adding plankton to your sponge systems?

Yes I have been experimenting with Bob Starks magic ferry dust (flash dried phytoplankton) as well as live phytoplankton. It looks like that is an item that can assist the filter while coral populations are low.

Would lighting a 100 gal sump with about 180lbs of live rock benefit the rest of the system (1 110 gal, 1 90 gal, and 6 35 gal with 100 gal common sump) ?

I do not know why you would light the sump. Its an added cost due to energy requirements. If you want to keep the light demanding organisms on the rock alive then you will probably need the light. If you assume that the live rock in the systems has plenty of these organisms already, then flip the rocks over and keep em dark. Its much cheaper and may eventually allow you to disconnect the skimmer.

How do you deal with humidity in your aquarium room?

The humidity is eating away at the dry wall in my room (6 gal evaporated daily) I have a nice hole in the dry wall of my shop due to splashes from the sump I just removed (spare system). That is a good question and I would recommend covering the tops of the reefs to prevent evaporation from increasing or maybe installing a fan that exchanges air with other nearby dry locations in the house/apartment.

Do you think 1 55watt 6500k PC + 1 75watt super atinic VHO will suffice to light up a 30x12x18 (inches) reef keeping SPS?

A 28 gallon tank with 130 watts of lighting. Thats 4.6 watts per gallon. Should do okay, but I would recommend not trying the very shallow water SPS that typically are brought in from FIJI. They need 400 watters. Might try some slightly bronwish Jakarta corals. They can color up in time.

The live sponge filters you are working with, are the sponges the boring types as (they would be the ones located in the cryptic region of the rock) or the area you are trying to recreate?

Boring sponges actually are only paritally cryptic. These are the only sponges that possess symbiotic zooxanthellae so they obviously need some light. In fact they typically are found in shallow water boring the heck out of the RBSC. The cryptic sponges I am using do not have many symbiotic photosynthetic organisms living in them. These sponges get all their food from dissolved organics and bacteria.

What exactly do you mean by raw tap water?

Tap water that is not RO/DI'd in anyway. When you do not add any food into the reef system (which is what I basically do) phosphate for example can become limited. So you need to add it to keep photosynthesis running. Thats why the raw tap water. Also, we do not know which trace elements are important to sponges yet.

What thickness of a sand substrate do you reccomend?

Up till now I have not been utilizing a sand substrate. I am examining the operation of a reefs cryptic and non-cryptic organisms. Sediments will only complicate the picture right now. The sponges themselved do create a very fine detritus and that is where sediments can play a functional role in the sponge system. The problem with sediments is that they trap dissolved organic matter. Then you have to consume it somehow. My goal is to have the macro organisms consume as much as possible, but sediments will be added later on.

I am running an sps tank with no sump, only a backpack skimmer and powerheads. Can I place sponges in dark, low movement areas behind rocks to achieve the same filtration effect??

Yes, that can work as long as sediments are not continually flushed up behind the rocks. Sediments clog most of the cryptic sponges.

What kind of monster (skimmer) are/were you using Steve, something from one of those Dutch museums? A 6 metre behemoth? ;-) (referring to you saying it was expensive, etc.)

I was using a 7 foot RK2 skimmer in my facility. It was expensive to buy an operate but did a fine job. Sold it but the guy that bought it is storing it in my facility. So its still there just not hooked up.

What is your source of live phytoplankton?

I believe its Wasatch Mariculture. The operation in Salt Lake City.

Steve, I heard a rumor that you add small amounts of bleach to your tank. Is there any truth to that? If so, please explain.

Gee the rumors you hear :> I might as well let you know now that I am not a space alien or a member of the CIA (same thing maybe :>). Perhaps that was some sort of joke concerning the fact that I have and still use minor amounts of ozone in coral import systems to prevent any new diseases from coming in. Ozone it is theorized causes the creation of bleach in a tank. But you do not need to bleach corals to get them colored.

You spouse an anti-complexity approach; you touched on pigmentantion of SPS and lighting, but, in relation to these statements, how does your approach gibe with the needs of Tridacna clams?

The requirements with respect to lighting for clams is probably similar to the requirements of SPS. I remember once I had this awesome metallic electric blue crocea clam that was screaming under a 20,000 K light. In fact even Jeff Macare said "dude look at that clam". I sold it to Bob Mankin and he has kept it to himself ever since :>. Pigmentation or lighting is definitely not simple issues. And in fact what you term simple is actually much more complex than you could possibly imagine. Just because humans built it does not mean its complex. In fact generally the opposite is true :>

What advice would you give to a budding coral farmer?

Right now, stick with what you can distribute locally. That means xenia and soft corals. Local markets are not very strong for SPS. And try to get cash from a store if you sell them livestock.

OK, time for one more question to end this fantastic meeting .... What do you see to be the advantages of a sponge filter system?

Primarily, low costs and ease of operation. I have gone up to 7 to 8 days without even visiting my shop. No plumbing. And its good from a farmers point of view since the number of farmed organisms is much more diverse.

Thanks for the great talk, Steve!

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