Aurelia aurita
"Aurelia aurita" lives in ocean water temperatures ranging from ; with optimum temperatures of . It prefers temperate seas with consistent currents. It has been found in waters with salinity as low as 6 parts per thousand.
The relation between summer hypoxia and moon jellyfish distribution is prominent during the summer months of July and August where temperatures are high and dissolved oxygen (DO) is low. Of the three environmental conditions tested, bottom DO has the most significant effect on moon jellyfish abundance. Moon jellyfish abundance is the highest when bottom dissolved oxygen concentration is lower than 2.0 mg L -1. Moon jellyfish show a strong tolerance to low DO conditions, which is why their population is still relatively high during the summer. Generally, hypoxia causes species to move from the oxygen depleted zone, but this is not the case for the moon jellyfish. Furthermore, bell contract rate, which indicates moon jellyfish feeding activity, remains constant although DO concentrations are lower than normal. During July and August it is observed that moon jellyfish aggregations of 250 individuals consumed an estimated 100% of the mesozooplankton biomass in the Seto Inland Sea. Other major fish predators that are also present in these coastal waters do not seem to show the same high tolerance to low DO concentrations that the moon jellyfish exhibit. The feeding and predatory performance of these fish significantly decreases when DO concentrations are so low. This allows for less competition between the moon jellyfish and other fish predators for zooplankton. Low DO concentrations in the coastal waters such as the Tokyo Bay in Japan and Seto Inland Sea prove to be advantageous for the moon jellyfish in terms of feeding, growth, and survival.
Warm core ring
Many fish species’ life cycle involves two distinct habitats. The adults live in warmer temperate waters south of Cape Hatteras, NC while the juveniles are found in estuaries of cooler waters north of Cape Hatteras. Warm Core Rings play an important role in the transport of larvae between the two habitats. Species like the bluefish (Pomatomus saltatrix) and pearly razorfish (Xyrichtys novacula) spawn near the western edge of the Gulf Stream just south of Cape Hatteras. Because of the convergence of the Gulf Stream from the south and cooler coastal water current from the north, most water around Cape Hatteras flows into the Gulf Stream. The larvae released near this convergence is swept into the Gulf Stream and flows north. Since the larvae are planktonic, they don’t swim into the center of the Gulf Stream but stay near the western edge. This is beneficial for when warm core rings form. Warm core rings are formed when the crest of a meander breaks off from the Gulf Stream. Any larvae in the crest of the meanders are then entrapped in the warm core ring. Once the warm core ring breaks way, it takes a southwesternly path towards the coast. The interaction between warm core rings and the continental shelf creates a weakening of the ring and enables the larvae to escape and continue their journey to nearby estuaries. The warm core rings formed along the northeastern states can last between 4 and 5 months. During this time the larvae grow so that by the time they reach the estuaries, they are able to swim away from the warm core ring into the estuaries.