What is ozone and how does it affect any ecosystem?

Hint: Ozone is a form of oxygen. The molecule of ozone contains three oxygen atoms ($O_3$). The region of stratosphere, at an altitude of 16-50 km over the equator and at a slightly lower altitude elsewhere, having a thick sheet of ozone is called ozonosphere.

Complete answer:
The Ozone layer in the stratosphere acts as a shield to protect all types of life on the earth from harmful ultraviolet radiations.
Absorption of UV radiations by ozone layers is proportional to its thickness. As the thickness of ozone is more above poles than at equator, therefore, the maximum amount of UV radiations pass through the atmosphere to reach the earth surface in the tropics. This amount of UV radiation reaching the earth decreases towards the poles. The concentration of ozone in the stratosphere also changes with reason.
Ozone hole is the decline in thickness of the ozone layer over an area called the ozone hole. It was first noticed in Antarctica (1985) by Dr. Joe C. Forman and his colleagues.
Chlorofluorocarbons (CFCs) are mainly responsible for ozone depletion in the stratosphere.
Due to ozone depletion, more UV radiations reach the earth which cause many harmful diseases in humans. Like:
a) The incidence of cataract, skin cancer, herpes, affects the immune system have increased tremendously over the years
b) In humans eye cornea absorbs UV-B radiation, and a high dose of it causes inflammation of cornea called snow blindness cataract, such exposure may permanently damage the cornea.
c) Incidence of genetic mutations have become more common leading to hike in genetic disorders
d) Also photosynthesis will be inhibited as it affects photosynthetic chemicals.
e) Mortality of young animals has also increased over the years
Due to harmful UV-radiations both aquatic and terrestrial food chains will be disturbed.

Note:Chlorofluorocarbon produces active chlorine in the presence of UV radiations. They destroy ozone, convert it into oxygen. Besides CFCs used as coolants in air conditioners and refrigerators, cleaning solvents, aerosol propellants, nitrogen oxides and hydrocarbons are also responsible for ozone depletion.