The Ecosphere is a miniature, fully enclosed aquatic habitat containing small marine shrimp, algae, and microorganisms within filtered seawater. This system operates as a materially closed ecosystem, meaning no external substances like food or air are ever added. The only input the system accepts from the outside world is energy, which must be provided as light. The survival of the shrimp is entirely dependent on this energy source to drive internal biological processes. Without sunlight, the delicate balance of food production and gas exchange collapses, leading to the eventual death of the shrimp and the entire system.
Sunlight Powers the Primary Producers
Sunlight fuels the entire food chain within the Ecosphere. The base of this miniature ecosystem is composed of primary producers, primarily algae and photosynthetic bacteria. These organisms capture light energy to perform photosynthesis, converting carbon dioxide and water into chemical energy, or food.
This chemical energy is utilized by the producers for growth and metabolism, and it becomes the sole source of sustenance for the shrimp. The shrimp graze on the algae and the biofilm of bacteria, transferring the stored energy up the food chain. When light is removed, photosynthesis ceases, stopping all new food production. The shrimp begin to starve, consuming the existing, finite supply of microorganisms until energy reserves are depleted.
Maintaining the Essential Gas Exchange
Light is necessary for maintaining the balance of gases within the sealed environment. Photosynthetic producers, such as algae, generate oxygen as a byproduct of converting light energy into chemical energy. This oxygen dissolves into the water, replenishing the supply needed for the rest of the ecosystem.
The shrimp, along with aerobic bacteria, rely on this dissolved oxygen for cellular respiration to survive. Respiration releases carbon dioxide back into the water, which the algae then use to restart photosynthesis. This continuous, light-driven cycle of oxygen production and carbon dioxide consumption maintains a breathable aquatic environment for the shrimp.
The Cascading Failure of the Closed System
The removal of sunlight triggers a rapid, two-pronged failure in the closed system that inevitably kills the shrimp. The immediate effect is the complete shutdown of photosynthesis, halting the production of fresh oxygen. The shrimp and decomposer bacteria continue to respire, quickly consuming the limited supply of dissolved oxygen remaining in the water.
Suffocation and Anoxia
Within a short period, the water becomes anoxic, meaning the oxygen concentration drops to a lethal level, causing the shrimp to suffocate. This immediate cause of death is typically faster than starvation, though the lack of food is a long-term certainty. Compounding this issue, the decomposer bacteria become compromised in the low-oxygen environment, slowing their ability to process waste.
Toxic Waste Buildup
Organic waste products, including feces and decaying matter from dead microorganisms, are normally broken down into usable nutrients by the bacteria and absorbed by the algae. Without a functioning biological filter, this waste rapidly accumulates as ammonia and other toxic compounds. The buildup of these toxins quickly poisons the water, ensuring the death of any shrimp that survived the initial suffocation.