 Human beings have played a role in the ecology of Presque Isle since at least the Erielhonan . The natural drift of sand is hindered or stopped by breakwaters , permanent structures , and roads . Roads also do not absorb rainwater , causing erosion , and break up natural habitats . Excavations such as those to make the waterworks basins or the marina have destroyed habitats , but yearly artificial replenishment with sand helps to create new ones . One area within the park is closed to all public use from April to November to minimize the impact of humans : it is the easternmost part of the park , Gull Point . 
