Coastal erosion are harmful to coastal cities a sthey are near by to sea and they damage the city completely and compare to town and village their population are high hence they are harmful to cities of coastal areas.

role of mangrooves-mangrooves are very important as they  protect shorelines from damaging storm and hurricane winds, waves, and floods. Mangroves also help prevent erosion by stabilizing sediments with their tangled root systems. They maintain water quality and clarity, filtering pollutants and trapping sediments originating from land.

mangrooves are an endangered species because they ar emore useful to animals and fish and hence they have been endangered species.

why they should be protect- they should be protected because 
provides nurseries for fishprotects the coastline from strong winds and wavesprovides soil stabilization, stimulate nutrient retention and water quality improvement through filtration of sediments and pollutantsallows absorption of carbon dioxide