Water Quality at the Aquarium

Taking care of the animals at the Greater Cleveland Aquarium means taking care of their homes. Sometimes that means cleaning the décor, and sometimes it means taking care of the water itself…this is where water quality testing comes in. I do most of the water quality testing here at the aquarium.  There are many interesting pieces of equipment (with fancy names) that go into testing, including a spectrophotometer, pH probe, refractometer, and titration kit.

Spectrophotometer                                                                       

We test for a number of things at different times. Nitrogen is one of the most frequent tests. The nitrogen cycle includes ammonia, nitrite, and nitrate. Bacteria convert the toxic ammonia from fish wastes to less toxic nitrite, and then to the much less toxic nitrate. We test all of these regularly, adding reagents that will react to the nitrogen, and using the spectrophotometer, a machine that reads the color change and converts it to a measure of ammonia, nitrite, or nitrate.

Blank ammonia test, sample ammonia test, sample nitrite test

Two more very important tests are pH and salinity. Evaporation can change the salinity of the water as the salt gets left behind in the smaller volume of water. When adding water back, it is important to know how much fresh and how much salt water to add to keep the salinity in the narrow range that is best for the animals. These are tested with the pH probe and refractometer directly.

pH probe                                                refractometer

Alkalinity is related to pH. It is a measure of the buffering capacity of the water; its ability to maintain a steady pH in the face of other changes. We measure this with a titration kit.

Alkalinity titration

Some animals have special needs, and their water gets additional tests. For example, elasmobranchs such as sharks and rays require iodine, so their water is tested for it. Corals and hard shelled invertebrates like snails require lots of calcium and magnesium to make their shells. These are tested ensure the water always has enough for them. These two tests also use titration methods.

A lot goes in to making sure our animals are healthy and happy. What many people don’t realize is that chemistry plays a large role here at the aquarium in addition to the manual labor and biology that takes place in every day operations. I am lucky enough to participate in these roles for work every day.

Keeping Moon Jellies

Look up and inside of the smokestack of the old powerhouse you will find a chimney full of Moon jellyfish. A lot of work and care goes into maintaining this unique exhibit. Here’s a quick look at what goes on behind the scenes of our jellyfish exhibit.

Photo: Jellyfish life cycle…Jellies have a very unique life cycle in that they reproduce through both sexual and asexual reproduction.

Culturing Jellyfish
We are happy to say that all of our jellyfish have been cultured right here at the GCA! We keep several plates of jelly polyps in flow through bins to catch and collect ephyrae. When the polyps asexually reproduce, they go through a process called strobilation. Once the ephyrae (stage 5 of the jellyfish life cycle) break off from the strobila they are pulled through to the bottom collection bin. There are several methods used to induce the strobilation process. The best way we’ve found here is through dramatic temperature swings. Dropping the temperature by 10-15 degrees for about 7-10 days has the polyps strobilating in no time! Once the strobilation process begins, we will find about 50-100 new epyrae each day. As the ephyrae slowly grow into medusa they will be moved into an appropriately sized tank and eventually make their way up to the chimney display. This process will take about 2-3 months.

Photo: Moon jelly culture set up at the Greater Cleveland Aquarium

Jellyfish Exhibit Design
Jellyfish are not very good swimmers and rely on ocean currents to get around. This means that the exhibit design and flow is very important when keeping jellies in aquariums. Jellyfish are typically kept in a round shaped exhibit, called a kreisel or pseudokriesel. The round shaped exhibit with a spray bar, help push the jellies in a circular motion to keep them suspended off the bottom.

Photo: Pseudokreisel built at the Greater Cleveland Aquarium

Jellyfish Diet
In the wild, most jellyfish eat zooplankton. Zooplankton is made of many tiny aquatic animals. Adult brine shrimp (Artemia nauplii) are most commonly used for captive diets. Unfortunately, adult brine shrimp don’t have much nutritional value for jellyfish but juvenile brine shrimp are. Our jellyfish are fed 48 hour hatched Artemia twice day that are enriched with a concentrate algae diet. They are also fed a krill shake once a week for variety. The idea of a krill shake is to blend up a mix of large, nutritious fish chucks that would normally big too large for the jellies to eat.

Photo: Artemia nauplii culture set up at the Greater Cleveland Aquarium

Don’t Moon Jellies Sting?
Although there are species of jellies that can have a fatal sting, the sting of a moon jelly is incredibly mild. A sting from a moon jelly usually results in an itchy, red rash and not considered a danger to humans. Here at the aquarium, we keep a spray bottle of diluted vinegar nearby to help stop and neutralize the sting.