[capecoral]

"[Some websites really get down to the serious, useable information about corals. This site is one of them:]"

"CoralScience.org:

"Life on earth is always classified into systematic groups by biologists, on the basis of external appearance (e.g. birds and mammals), behavior (diurnal or nocturnal) or the characteristics of living cells (e.g. plant or animal cells). A fourth means of distinction is metabolism, which can be autotrophic or heterotrophic. These terms are commonly used in marine biology, especially when regarding bacteria."

"Autotrophy means that organisms use inorganic molecules (such as CO2 and bicarbonate) to build organic ones, such as carbohydrates [DOC]. Examples are plants, which convert CO2 into carbohydrates by using sun's energy, or sulphur bacteria, which utilize the chemical energy stored in sulphur to convert CO2 to organics. For plants, we call this photoautotrophy (photo: light, auto: self and trophy: feeding) and for bacteria, in this case, we call this chemoautotrophy (chemo: chemical reaction). Another term for photoautotrophy is photosynthesis, another word for chemoautotrophy is chemosynthesis. Autotrophic organisms are also called primary producers ["primary reducers"], as they are the first link in the food chain which leads to biomass production from inorganic molecules. [And thus they reduce these inorganics]"

"Heterotrophy means that organisms make direct use of organic molecules, which are either present in the environment, or have been produced by autotrophic organisms. The consumption of plants by snails or cows is a form of heterotrophic feeding. From CO2, carbohydrates have been formed by using sunlight, which the plants have converted into biomass; this is subsequently consumed and converted into animal biomass."

"The photosynthates which zooxanthellae provide their [coral] hosts with can deliver up to 100% of the daily required energy [but not growth] budget for corals. These are often deficient in nitrogen and phosphorus [which ARE required for growth], and are thought to be used as fuel for respiration and mucus secretion, rather than being assimilated into biomass [growth]. Zooxanthellae transfer glucose, glycerol, fatty acids, triglycerides and even amino acids [all these are DOC] to their [coral] hosts. [...] Unfortunately, photosynthates alone are not sufficient to build animal tissue. These elements [which ARE needed to build tissue] are ingested by corals by catching particulate organic matter (plankton, detritus) from the water, and by absorbing dissolved [DOC] molecules. Heterotrophy [feeding] is essential for all corals and can meet up to 100% of the daily required energy in corals which are bleached or inhabit deep or turbid waters [and thus get NO energy from light]."

"Dissolved organic matter (DOM) [DOC] forms an important food source for many corals and related animals such as Zoanthus [zoo's]. Already in 1960, scientists found that stony corals from the genus Fungia were able to take up radioactively labeled glucose from the water. This was demonstrated by subsequent tissue analysis."

"In science, DOM is often split into various elements such as DON (dissolved organic nitrogen) and DOC (dissolved organic carbon). Important examples are carbohydrates(DOC), amino acids (DON, often referred to as DFAA or dissolved free amino acids) and urea; as less poisonous variant of ammonia which is produced by many animals. [...] This indicates the importance of aquarium supplements for nutrient-poor aquaria, which contain many coral colonies and few fish [because fish-waste is food]. These are mostly aquaria from the aquaculture industry, as most hobbyists tanks are densely stocked with fish."

"It is intriguing that many corals also take up urea [pee] from the water, and they can do this in even greater quantities compared to nitrate (at least in nature). This indicates these animals may have adapted to the presence of higher animals on the reef, such as fish, which collectively produce large amounts of this nitrogen-rich compound [pee] on a daily basis."

"Particulate Organic Matter (POC): This group of particles usually describes detritus [waste]; the small remnants of feces and decayed organisms. In the aquarium, food which is not consumed and removed also becomes detritus. Detritus eventually precipitates [falls] on the ocean floor or aquarium bottom as sediment. This layer of organic material is partially degraded [eaten] by bacteria, and converted into inorganic molecules such as nitrate and phosphate. This process is called mineralization."

"The [POC] sediment which is present on coral reefs contains bacteria, protozoa and their excrements, microscopic invertebrates, microalgae and organics. These sedimentary sources can all serve as coral nutrients, especially for colonies which grow in turbid waters. Experiments during which sedimentary carbon was radioactively labeled showed that corals such as Fungia horrida and Acropora millepora readily took up sediment [as food]. The more sediment present, the more uptake [feeding] is measured; 50-80% of this material is converted into biomass [growth] by several species. This has also been found for the Caribbean species Montastrea franksi, Diploria strigosa and Madracis mirabilis; detritus is taken up by the polyps, and the available nitrogen is converted into biomass [growth]."

"Plankton: This group is sometimes regarded as the living component of POM. The term plankton is a common name for an astoundingly large group of organisms which can be categorized in different ways. Figure 7 shows a commonly accepted division into pico-, nano-, micro- and mesoplankton. These groups consist of (cyano)bacteria and protozoa (picoplankton), algae and protozoa (nanoplankton), microscopic crustaceans such as rotifers and large protozoa (microplankton) and countless other species of crustaceans (mesoplankton). Fish and invertebrate larvae can further be categorized into micro- and mesoplankton, depending on the species."

"Plankton was not considered as an important coral food source for many years; it was believed concentrations on the reef were too low to have any significant effect. In the meantime, more accurate estimations have been made, based on improved measuring techniques. These values are particularly high during summers, which is probably due to the abundance of phytoplankton. This leads to increased concentrations of zooplankton, as they feed on the extra available phytoplankton."

"Other branched SPS corals are however capable of catching more zooplankton per unit of weight compared to species with larger polyps [LPS]. It seems that polyp size is not a solid predictor of capture efficiency, but rather determines maximum prey size."

"The species Pocillopora damicornis and Pavona gigantea which inhabit the Gulf of Panama were found to mainly feed on isopods, amphipods and crab zoea [all plankton]."

"Individual polyps of the Atlantic species Madracis mirabilis and Montastrea cavernosa are able to capture and ingest 0.5 to 2.0 prey per hour. On a colony level, these numbers get big pretty quickly. A small Seriatopora colony of 14 ml in volume is able to capture 10,000 Artemia in 15 minutes! This however requires very high aquarium zooplankton concentrations of 10,000 to 20,000 Artemia per liter."

"Other results show that an aquarium concentration of 2000 nauplii/liter (about 5000 nauplii /gallon) is ideal for stony corals such as Pocillopora damicornis. To reach this concentration, it will take a daily amount of one million nauplii for the average 500 liter (130 USG) aquarium."

"Next to fish, protein skimmers also are voracious particle predators. All forms of mechanical filtration will decrease available nutrients, unfortunately. Without this filtration however, water quality declines quickly. Water changes, phosphate reactors, refugia with Chaetomorpha macro algae [and other solid-algae solutions that we will point out] and denitrification reactors all work well to allow plankton populations to persist, however these are often quite labor intensive. Keeping many organisms in a small aquarium, be it corals or fish, simply degrades water quality quickly. In nature, the ratio between biomass to water volume is much lower. [And in the ocean, algae is 90% of all biomass except bacteria]. Next to this, many waste products are quickly converted into new biomass such as plankton and sponges. This also occurs in the aquarium, to some extent, however this does not outweigh the amount of nutrients which is introduced on a daily basis."

"[Bacteria and protozoa] play an important role in the marine food chain. In terms of biomass and photosynthesis, these organisms form the most important part of pelagic plankton. On the reef, bacterial concentrations sometimes lie around one million per milliliter! For cyanobacteria, the number fluctuates around 10,000-100,000 per ml, and for flagellates around 10,000 per ml. As these microbes grow fast, they are highly important for the nitrogen and carbon cycles in the ocean. For the model species Stylophora pistillata, if has been found that [eating] microbes yields almost three times as much nitrogen as ammonia, nitrate and amino acids together."

"Montipora capitata colonies have been found to increase their plankton feeding rates after bleaching, which completely satisfies their daily metabolic requirements."

"Although it may seem that feeding and photosynthesis are two separate processes, they are in fact intricately linked. Nutrient exchange between corals and symbiotic algae is diverse, and this is increased by extra light and feeding. More feeding stimulates zooxanthellae growth and buildup of pigments such as chlorophyll. This makes the coral a more effective 'solar cell', which is able to convert more light into chemical energy. This benefits both the coral and the algae. It has become clear from CORALZOO-experiments that corals grow less than expected under high intensity lighting. This is most likely due to [lack of food]. French scientists found that this limitation can be reduced by providing extra nutrition in the form of zooplankton. This in fact occurs in nature as well, mostly during summers, when ample light and zooplankton particles are available. This situation can be simulated in the aquarium as well, by providing extra plankton in combination with T5 or metal halide lighting."

"After eight weeks of zooplankton feeding (such as Artemia nauplii), calcification [growth] rates of Stylophora pistillata doubled. As tissues grew faster compared to the skeleton, this led to fleshier corals. When these corals received less light, a decline in growth rate could be prevented by providing additional plankton. This fact is interesting for aquarists who do not want to make use of heavy lighting above the aquarium, for obvious reasons."

"Coral feeding quickly leads to increased tissue production and protein concentration. This increase was about 2-8x for Stylophora pistillata after three weeks of zooplankton feeding! Next to proteins, lipid content also increased. Both saturated and unsaturated fatty acids increased in Galaxea fascicularis tissue after feeding with Artemia nauplii. More light actually decreased tissue fat contents [this is bad]. Although this seems contradictory, these corals probably invested more fatty acids into growth and zooxanthellae production to enhance usage of extra light."

"[Here is] an overview of the studies discussed in this article, which shows the diverse effects of feeding on coral physiology. Fed corals display (1) twofold greater protein concentrations and photosynthetic rates per unit skeletal surface area; (2) twofold higher dark and light calcification rates; (3) twofold greater organic matrix synthesis in the dark and a 60% increase during daytime."

"For Stylophora pistillata, zooxanthellae tissue concentrations doubled within several weeks of zooplankton feeding, both at low and high light levels."

"Stony corals such as Leptoseris and Montipora spp. also occur in the mesophotic zone, even though light levels be may as low as 1% of the sunlight irradiance experienced at the surface! This shows that even zooxanthellate corals can adapt to very low light intensity levels, as long as this is compensated by heterotrophy such as plankton feeding."

"It must be noted that major differences exist between the fastest growing coral, and the most attractive one. Most aquarists favor bright colors, which arise by coral host pigmentation. Brown zooxanthellate pigments such as chlorophyll are considered to be unattractive. These last pigments do provide the energy for increased growth, in contrast to brightly colored pigments which act as sunscreens. Producing them also goes at the expense of coral growth. [Thus, increase feeding when you want growth, and decrease feeding when you want colors.]"