wat is the el nino effect? how does it affect biodiversity?

El nino is abnormal warming of the surface water of pacific ocean. The warming of surface water effect formation of winds. It results in wet winters over southeastern US and drought in Indonesia and Australia.

El nino adversely affect biodiveristy. Increase in the temperature of ocean effects the population of phytoplanktons which form the first trophic level of aquatic food chain. So entire aquatic ecosystem will be effected and their will be loss of species which can not cope with this change. 

Also el nino causes drought in Australia and Indonesia. Prolonged drought effects the biodiversity as some of the species can be sensitive to lack of water even for short duration.