The Missing Ingredient for a Successful Reef Aquarium

Phytoplankton are very important to marine organisms, because as primary producers in the oceans, phytoplankton are crucial to the development and survival of most, if not all marine animals at some level. Phytoplankton are tiny floating organisms (such as unicellular algae, diatoms and dinoflagellates) which serve the same role in the food chains of the oceans as vegetation serves on land; namely small things eat them, which are in turn eaten by bigger things, and so on as the food chain progresses. Many coral reef animals such as clams and other bi-valves, soft corals, sponges and feather duster worms feed directly on phytoplankton, and even those that do not, such a most stony corals, rely ultimately on the nutrition gained from phytoplankton and other marine algae eaten by the zooplankton they feed on. Some essential nutrients gained from marine algae, phytoplankton in particular, cannot be synthesized by animals, and are therefore extremely important components of a healthy diet.

The most important of these nutrients are the class of lipids known as long chain omega-3 fatty acids. One of the major breakthroughs in the aquaculture of marine animals was the discovery that these fatty acids were an essential part of the diet, and without them, nutritional deficiencies or arrested development are common problems.

Many reef-dwelling animals for sale in aquarium stores are sediment feeders which specialize in eating phytoplankton, but until recently, live phytoplankton was not easily available to feed them, and unfortunately what was available was stored in a way that eliminated the nutritional value of the phytoplankton. The poor record of survival in aquaria for many of these animals is most likely a direct consequence of their starvation without phytoplankton being available to feed on. Even animals which contain symbiotic zooxanthellae, such as corals and giant clams cannot gain all of their nutritional requirements from light alone. The symbiotic algae only provides sugar as a nutrient, and although sugar alone may provide 100 % of the animals energy needs it does not provide the other nutrients needed to grow, reproduce, fight off disease, repair tissue and many other needs. For example, researchers on the Great Barrier Reef in Australia showed that 75% of the phytoplankton passing over the reef was captured and eaten by giant clams (T.gigas); furthermore, juvenile clams were found to obtain 65% of their energy needs from feeding on phytoplankton rather then photosynthesis.

Phytoplankton provides a great benefit to most reef animals. Phytoplankton form the basis of marine food webs in general, and are an essential component of the diet for many reef inhabitants (such as feather duster worms, soft corals, clams, tunicates, and zooplankton), they are probably the least common element included in feeding an aquarium