Monitoring The Water Quality of Rehabilitated Coral Habitat

The New York Aquarium is using a Mantech MT100 analyser to monitor the health of rehabilitated live stony corals, confiscated by the US Fish and Wildlife Service and brought to the New York Aquarium in Coney Island after being illegally imported into the US.

Corals are marine animals composed of polyps which live in colonies. These polyps form hard calcium carbonate exoskeletons, forming coral reefs. These reefs provide habitats for at least 25% of the world’s marine life, protect coastlines from erosion and flooding, and provide space for fish nurseries. Acidification from CO2 and temperature changes across the world are affecting the health of the world’s remaining coral reefs.

“This is delicate, hands-on work” said aquarist Camilla Piechocki. “We monitor water chemistry, slowly reintroduce lighting, and mimic reef conditions to help them thrive. These animals are resilient, but the transition from illegal shipment to thriving exhibit is a complex process”. After time and care, the corals will become part of the Aquarium’s public reef exhibits. The New York Aquarium, run by the Wildlife Conservation Society, is no stranger to sea life care and rehabilitation. The Aquarium hosts plenty of marine life, including sharks, rays, sea lions, sea otters, harbor seals, invertebrates, penguins and more.

The coral propagation techniques the Aquarium use involve monitoring the quality of the water for hardness, pH, alkalinity and salinity using the Mantech MT100.

The Aquarium’s MT100 is configured to perform potentiometric hardness, pH, alkalinity and water temperature for temperature dependent calculations. These parameters can all be analyzed from one aliquot of sample or analyzed individually/in combination as needed. We spoke to Mark Kessel, Water Quality Manager at the Aquarium, to learn more about the water chemistry critical to coral health.

We spoke to Mark Kessel, Water Quality Manager at the Aquarium, to learn more about the water chemistry critical to coral health.

Calcium and Total Hardness
Calcium is important to sensitive aquatic invertebrates such as live corals. It’s used to build their hard skeletons and support their soft tissues. As we’ve learned from Kessel at the Aquarium, “Corals will assimilate the dissolved calcium in the water as aragonite (a crystalline form of calcium carbonate) to form their skeletons and polyps.”

Magnesium, the second most abundant cation found in seawater, also plays a crucial role by helping to maintain the water’s ionic balance and supporting coral health, growth, and metabolism. Calcium and magnesium must be regularly replenished in the water, as corals will remove these mineral salts over time.

pH
The skeletons of corals rely on calcium carbonate for the deposition of the mineral. For this to happen, the pH of that seawater is critical. Kessel tells us that “pH is also crucial to the internal and external transfer of ions in aquatic invertebrates, and in supporting the health of corals that house zooxanthellae (a photosynthetic dinoflagellate found in most corals) as part of a symbiotic relationship that provides corals with nutrients.”

Alkalinity
Alkalinity is another parameter critical to coral health, as the correct alkalinity helps in stabilizing pH. Balanced alkalinity also stabilizes inorganic carbonates such as carbon dioxide, calcium carbonate and sodium bicarbonate. Kessel shares that “All of these dissolved chemicals provide a complex network of ionic activity that directly relates to the physiology and health of most aquatic animals and supports a balanced pH.”

Salinity
Salinity is a measure of the concentration of dissolved salts in water, typically measured in parts per thousand. It is an important component of the coral’s environment, as corals are sensitive to changes in salinity. Changes could lead to stress, bleaching (loss of pigmentation due to the death of its symbiotic zooxanthellae) or even coral death. Kessel tells us “varying concentrations of trace elements and mineral salts play a big role in producing the diversity and radiance of the living coral reefs most of us have come to revere in our oceans and aquariums!”

26/9/2025