WISRD Research & Engineering Journal

Ex situ coral growth: A technical report on tank lightning and water chemistry parameters for growth of small polyp stony (SPS) coral microfragments in a marine aquarium 4 M. Papadopoulos, H. Witsken, Dr. K. Griffis, J.A. Wise 1. Introduction Growing coral in a lab setting can be challenging. For optimal coral health and growth, it is vital to have stable water chemistry, especially with regards to pH, salinity, alkalinity, and temperature. While small amounts of nitrate are required for coral growth, tanks should be properly cycled so that nitrogenous compounds such as ammonia, nitrite, and other components of the nitrogen cycle are in the zero range; even slightly unbalanced levels of nitrate can lead to growth of undesirable algae. Additionally, proper levels of dissolved calcium are essential for coral skeleton growth, such as is seen in large and small polyp stony (SPS) corals, but both a stable pH and correct levels of dissolved magnesium are required in the prevention of precipitation of calcium carbonate. Another crucial aspect of coral growth ex-situ is light. The SPS corals we are growing include photosynthetic endosymbionts, microalgae referred to as zooxanthellae, which rely on the light of certain wavelengths and intensity to transform light energy into chemical energy. This relationship is truly mutually beneficial, as the zooxanthellae are protected within the stony skeletons of the coral, and in turn the coral polyps supplement their diets with sugar molecules created by these photosynthetic partners. 2. Water Chemistry 2.1 What is Tested and Ideal Parameters It is important to monitor the following water parameters. If a parameter is out of range, it can cause stress to the coral polyps, which in many cases can lead to the death of the organisms. This is especially true for the most sensitive SPS corals. Table 1 shows the most widely agreed upon parameters to test, as well as their optimal ranges, as established by coral reef keepers. In all cases, we attempted to stay in the typical target values that most successful tanks report as being optimal. Table 1. Water chemistry parameters tested and target levels. Targets from liveaquaria.com. Parameter Suggested Level Salinity (given as specific gravity, a unitless value) 1.023 - 1.025 Temperature 72 - 78˚F

4 Sponsored by the Wildwood Institute for STEM Research and Development (WISRD) and the Mariner Ocean Research Institute (MORI)

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