Ecosphere (aquarium)

Biota

The manufacturer did not reveal the species of any of the components of the Ecosphere. However, Hawaiian aquarists readily recognized the filamentous alga as a Chaetomorpha species, the snails as common Malaysian trumpet snails (either Melanoides tuberculata or Tarebia granifera) and the shrimp as Halocaridina rubra. H. rubra is native to Hawaii, where it and other tiny shrimp inhabit anchialine pools. These are puddles or ponds located near shores and surrounded with lava rock. The pores and chambers of the lava allow seawater to seep into the pools, where it mixes with freshwater from springs or rain. Anchialine shrimp are noted for their great adaptability: they survive in pools of undiluted seawater and in brackish ponds; they tolerate water temperatures over 85 degrees Fahrenheit (near 30 degrees C) when the tropical sun heats up the shallowest anchialine pools, and they also thrive in cool water.

Prior to 2003, the EcoSpheres contained at least one Malaysian trumpet snail at the time of purchase. However, the system is self-sustaining without the snails. (The main function of the snails was aesthetic, as they cleaned scum from the glass.) The Gorgonia coral in EcoSpheres was dead and played no active biological role in the system; however it did increase the surface area for beneficial bacteria and algae, and the calcium carbonate in the coral acted as a pH buffering agent.

Concerns

In 2010 the National Science Foundation reported that the shrimp’s sole habitat is shrinking, with over 90% of Hawaii’s anchialine pools having disappeared due to development, and this species of shrimp is disappearing along with them.

Comparable objects and systems

Commercially packaged aquarium kits, including algae, intended to be left open or closed, are available in Hawaii. The customer can use these to create an aquarium comparable to the EcoSphere.

It is possible to purchase Halocaridina rubra shrimp from Hawaiian aquarium dealers and create home-made sealed aquaria with no other special supplies. Sand, gravel, crushed shell, and very well cycled filtered water from a successful saltwater aquarium, diluted with an equal volume of distilled or reverse-osmosis water, with the lowest attainable ammonia content, provides a suitable brackish water mixture. A small inoculation of live Spirulina algae may be introduced for food. Certain ubiquitous algae and bacteria are likely to be carried by the shrimp themselves and will soon colonize the walls of the container. There is a risk that pathogens also may be introduced.

Closed jar systems like the Ecosphere degrade with time. They are "self-sustaining" only in comparison to systems which degrade much more quickly.

The advantage of an aquarium closed with a lid (rather than a permanently sealed plug, which was found in the base of an EcoSphere) is that if the system goes out of equilibrium, the owner can remedy conditions and prevent a complete die-off. Intervention to maintain good water quality allows a larger number of shrimp to live in the open system than can survive in the relatively poor quality closed environment.

Freshwater closed systems are often attempted by hobbyists, and as experimental projects or demonstrations for biology classes. These require nothing more than a large glass jar with an airtight lid, a few cups of lake or river water, and mud or other substrate from the same body of water. Kept indoors at room temperatures, with exposure to sunlight from a window, such systems have been found to contain living organisms even after several decades. The original level of diversity always falls drastically, sometimes exhibiting interesting patterns of population flux and extinction. Multicellular organisms fare poorly. Eventually an equilibrium of micro-organisms is established.

Make magazine Volume 10 contained instructions for creating a self-contained fresh-water "biosphere", which contained a freshwater amano shrimp, snails, amphipods, ostracods, copepods, rigid hornwort, duckweed, pond scum (for microorganisms), and small rocks or shells (as a pH buffer).

In their paper "The Emergence of Materially-closed-system Ecology", Joe Hanson and Clair Folsome described the creation of Ecosphere-like closed ecosystems. Their containers were half-filled with 50% water brought to a salinity of 11 parts per thousand by the addition of "Instant Ocean", with the rest of the container filled with unmodified air. They used algae collected from the ponds of Halocaridina rubra shrimp, and 3 to 16 Halocaridina rubra shrimp (and their associated microbial populations). The container size was not stated. However, in similar, 2,000 ml setups the authors noted that while the survival rate of shrimp varies it averages 4 shrimp per 2,000 ml of container when not carbon, sulfur, or phosphorus limited; or 1 to 8 shrimp per 1,000 ml when limited. They also noted that the shrimp population in all ecosystems declined from the starting number to a steady state within 60 days.

In the media

The ecosphere was reviewed by Carl Sagan in a 1986 Parade magazine article entitled "The World That Came in the Mail". The article is reprinted as a chapter in Sagan's last book, Billions and Billions.