Friday, November 25, 2011

Reef Update

The Coral Reef Exhibit has been running well, the water cleared and the chemistry has stabilized. It is now the new home for several corals, anemones, and fishes. As the system matures, each animal will find its home within the exhibit and learn how to interact with their tank mates. Already the bubble-tip anemone has moved several times. Anemones can be very mobile and often move about at night to find the most suitable combination of light and current.

 A bubble-tip anemone on exhibit about 16 inches across

Similarly, soft corals have the ability to move as well, but not nearly as fast or as often as anemones. Soft corals are just that, soft; they lack the calcareous skeletons of stony or hard corals that create reef structures. Soft corals are also generally less reliant upon symbiotic zooxanthellae as hard corals and therefore do not need as much light.
Two different species of hairy mushroom corals in the exhibit.
Corals can vary widely as to flow requirements, light levels, and feeding behavior, and positioning is critical. Often one species will aggressively defend or even take over the space of another by stinging or even sending out digestive filaments that kill its competitors' polyps. Frogspawn corals (Euphyllia spp.), such as the one shown below, are considered aggressive and thus must be given space. 

Frog spawn corals may be aggressive towards other coral species.
Once the corals and anemones were positioned (for now), the fishes were added. Fishes also can be aggressive towards each other, so it is important to consider their potential conflicts, now and as they (some of them) get larger. Certain species like to bury, others such as clownfishes associate with an anemone or coral. Other fishes such as engineer gobies make burrows, while many species prefer the crevices and cracks within rocks or hard coral skeleton. To further complicate matters, some fishes have a tendency to pick and nip at coral polyps. Unfortunately, many angelfish and butterfly fishes are not considered "reef friendly" for this reason and cannot be put in the exhibit despite their beauty. We did add a flame angel (Centropyge loriculus) as the one pictured here, despite the risk (considered low).
Flame angelfish 
We also added two firefish (Nemateleotris magnifica), a small, peaceful and attractive coral reef fish, pictured below. 

One of our two new Firefish

Saturday, November 5, 2011

Reef tank modifications

We recently renovated our coral reef tank to add more substantial filtration. We added a large sand filter, a much more powerful pump, and several additional returns to dramatically improve water flow, essential to proper coral growth.
         The white pipes are returns that have valves to control strength of flow and fittings that can be angled to control direction of flow.

The first step in the process was to drain the exhibit and remove the animals. Corals and anemones attach strongly to the rocks, so their entire rock has to be removed or they have to be separated, which can damage the soft tissue. When possible we removed the entire rock, but several of the large bubbletip anemones were attched to the walls and had to be pried off. Next the fishes were captured. Most hid until there was very little water left. The corals, fishes and anemones were then put in a holding tank with enough lighting to maintain the corals/anemones. While the exhibit was still damp, I power washed the inside with a pressure washer to remove unwanted polyps and algae. Then all the old substrate was removed and discarded.
                                        Tomato clown in a bubbletip anemone in coral holding

After the tank was thoroughly cleaned and dried, work on the life support upgrades began. The new pump is three times more powerful, and eliminates the use of additional powerheads for flow, so we reduced electric use. The new pump's power allowed for a sand filter where waste is physically removed. The additional flow also let us put several more returns (where the water returns to the tank after filtration) and valves to control the flow precisely. Then the new substrate (cleaned and sterilized sand mixed with crushed coral) was added. Several pieces of coral were epoxied to the interior of the exhibit for looks and settlement areas for live coral and anemones, clean rocks were added, and then it was filled with water.
                                                The new pump and sand filter behind coral

The moment of truth comes when the new system is turned on again filled with water. There were inevitable problems and leaks in such a large undertaking and there were in this case. No need for details, but I spent all day today drying out from an early soaking. The final step is to let the water in the system clear, adjust the flow, then add the fishes, anemones, and corals back. There are a few exciting additions/changes there though: Omaha Zoo sent us some bubbletips, Jenkinson's Aquarium is sending some Montipora capricornis frags, we are getting a large number of Convict gobies from Houston Zoo that will all be new to our Coral Reef exhibit. We are excited for the new animals and hope you will be too.