Jelly Population Explosion

Jelly Population Explosion: How Competition Can Affect Population Size

• In some ecosystems, jelly populations have increased so much that it is called a population explosion.
• This increase in population can affect human activities and the ecosystems we depend on.
• Scientists are trying to understand why these population increases occur and how to avoid causing them.
• Moon jellies are one of the most common types of jelly in Northern and Southern Benguela.
• A team of ecologists studied two ocean ecosystems near the southwestern coast of Africa—Northern Benguela and Southern Benguela.
• The jelly population increased in Northern Benguela but remained relatively stable in Southern Benguela.
• Laws prevented people from catching too many fish in Southern Benguela, while there were no limits placed on fishing in Northern Benguela.
• Without laws limiting the number of fish they could catch in Northern Benguela, people caught huge numbers of sardines and other fish there, causing the fish populations to decrease.
• Jellies and sardines eat the same food: zooplankton, which is why a decrease in the size of the fish populations in Northern Benguela affected the jelly population.
• With fewer zooplankton eaten by the sardines, the zooplankton population increased—leaving more zooplankton for the jellies to eat.
• This allowed the jellies to reproduce more, leading to more births than deaths, and causing the jelly population to increase.
• This is an example of an indirect effect, where a change to the sardine population caused the zooplankton population to change, which caused the jelly population to change.