Healthy and balanced environment supports different organisms on earth, and the human population depends on these organisms for a comfortable and healthy living. The natural and anthropogenic factors cause disturbance to the ecosystem. The natural disturbances to the ecosystems cannot be prevented; however, the ecosystems are resilient and return to the normalcy. The human-induced disturbances can be prevented by taking conscious efforts to adopt ecologically sound management measures. Society derives food, feed, fuel and drugs by exploiting marine ecosystem. The mainstay of coastal communities for their livelihood is ocean. The human-induced disturbances such as overexploitation, habitat destruction, pollution, bio-invasion and climate change affect the livelihood of fishers. The pressure on the marine resources is increasing steadily resulting in overexploitation. The resources of oceans are considered as common property resources and this consideration forms one of the major reasons for depletion of resources and degradation of the environment. Accidental and intentional discharges of pollutants especially persistent pollutants may pose greater ecological risks such as bio-magnification. Invasion of alien species results in loss of biodiversity and restructure the food-web. The climate change results in acidification, sea-level rise, and affect the marine ecosystem, which in turn affect the society. The human-induced or the accelerated ecological imbalance should be prevented by arousing the consciousness of human beings and proper implementation of national and international regulations. Educating the coastal and ocean user communities on the problems of imbalance in marine ecosystem and on how to ensure ecosystem sustainability is needed at this juncture. The conservation efforts will be successful only when user communities cooperate in this endeavour. Hence, encouraging co-management and the community participation of fishers should be made in marine resource management. This paper deals with the causes of ecological imbalance in ocean and its effect on ecosystem and the society.