Metabolic and oxidative stress responses of the jellyfish Cassiopea to pollution in the Gulf of Aqaba, Jordan.

Physiological responses of jellyfish to pollution are virtually overlooked. We measured the activity of two glycolytic enzymes (pyruvate kinase (PK) and lactate dehydrogenase (LDH)), lipid peroxidation (LPO), protein and chlorophyll a content in the jellyfish Cassiopea sp. from polluted and reference sites along the Gulf of Aqaba, Jordan. In jellyfish from polluted sites, low PK/LDH ratios and high LDH activity clarify their reliance on anaerobic metabolism. PK and LDH were positively correlated in the jellyfish. While medusae from polluted sites showed no signs of oxidative stress damage, protein content was significantly lower. This might suggest protein utilization for energy production needed for maintenance. Unchanged LPO in polluted sites indicates the ability of jellyfish to keep reactive oxygen species under control. Overall these results suggest that the jellyfish seems to tolerate the current levels of pollution at the studied sites and they might be anaerobically poised to live at such habitats.