Land reclamation can be harmful to surrounding corals and marine life. Corals are usually moved to another place when land is to be reclaimed. The corals might not be able to survive in that foreign habitat, and thus dies.

In some countries, where the project is in large-scale, they do not even bother to re-plant the corals elsewhere, instead just reclaim the land on their habitat, causing them to die immediately.

Marine life, such as fishes, might not have enough food after the underwater plantations are destroyed due to reclamation of land. This also affects the food chain.

The waters might also be polluted from the soil used to reclaim land, causing the fishes to die and blocking out sunlight, depriving the aquatic plants of necessary sunlight. Marine habitats are also destroyed, as mentioned earlier; therefore, the marine creatures would be forced to move to another new habitat. Some might not be able to adapt, and thus die out. Some would just die without even finding a new habitat, as they cannot move long distances in water.

Of course, the reasons and examples look tempting to us humans, but marine life is life too.