Dissolved Oxygen, Temperature
Pacific American Foundation (PAF)
Case Study Description
Located on the island of Oahu, Hawaii, the Waikalua Loko l’a fishpond was constructed more than 400 years ago. Fishermen realized creating water barriers would lead to more consistent and abundant fish harvests. The Pacific American Foundation (PAF) is focused on re-commissioning Waikalua Loko l’a.
Due to runoff, excessive nutrients have caused dense algae growth which deprives the fishpond of oxygen levels needed for survival. More than 50 years have passed since the Waikalua Loko l’a pond inhabited aquatic life, meaning water temperature and dissolved oxygen levels must undergo testing and data analysis to assess the pond’s water quality and overall ability to sustain aquafarming.
PAF is seeking help from Aquasend® and the Aquasend Beacon® to determine the viability of the pond and to determine the carrying capacity of Waikalua Loko l’a.
How Waikalua Loko I’a Supports Aquafarming
The pond operates with stationary gates called makahas, located in the canal and built into the seaward wall of the pond. Maintaining the original design created by Hawaiian ancestors, the gates are designed with small vertical standing wood poles held together with rope to let smaller fish into the pond. The fish would be fed, grow and become trapped in the fishpond due to their larger size.
This fishpond’s brackish water is a mixture of salt and fresh water. North Pacific saltwater from a bay actively circulates the pond while surrounding freshwater streams, Kawa and Kane`ohe, percolate the soil to enter the pond. Prior to Hawaii’s statehood, there were nearly 500 natural fishponds across the Hawaiian Islands. As time has passed the number of fishponds has decreased to less than 100. Restoring Waikalua Loko I’a is not only important to the aquaculture industry, but also in preserving rich cultural and natural heritage.
Importance of Data Measurement
Water temperature and dissolved oxygen (DO) levels are critical environmental factors for determining the success of fishponds. If fluctuations in temperature and dissolved oxygen are not accounted for, this can lead to overpopulation decreasing the fish survival rate due to low oxygen levels.
Aquasend® deployed three Aquasend Beacons® in Waikalua Loko l’a through its partnership in the Xylem Innovation Labs’ Incubator Program. The buoys were installed across Waikalua Loko l’a water and will record data on both moving and stagnant water points.
Aquasend Beacon®: Real-Time Data
To maintain operating fishponds, the primary asset must be protected: water quality. Dissolved oxygen (DO) and temperature are the two most important factors in water quality.
The Aquasend Beacon® will continuously monitor Waikalua Loko l’a dissolved oxygen (DO) and temperature levels throughout the day to assess the pond’s fish density. Aquasend’s® advanced water technology will give PAF a better understanding of water conditions to determine carrying capacity and more.
The Beacon buoys will collect data and remain in the Waikalua Loko l’a fishpond for three months. The data from Aquasend Beacons® will provide the Pacific American Foundation with fundamental information required to begin the process of safely inhabiting the pond with native mullet and milkfish.