maybe not a desirable part, depending on your point of view. The ecosystem IS capable of dealing with people, though the result may not be to your liking. Perhaps the result is the extinction of species not resistant to phosphate laden water. It would not be the first time that an ecosystem changed to adapt to new conditions, nor would it be only the millionth time. The wholesale collapse of entire ecosystems has happened before, and not exclusively or even predominately due to humans.

The human species is multiplying far faster than the it's collective societies efforts to reduce per capita impact on the environment, and this is unlikely to change in the next century or two. A change in the balance of the ecosytem is therefore inevitable (though the one constant in ecosystems is their changing balance). The best thing you can due to prevent environmental change from human activity is to not have children - but few people comply. A kayak paddling couple with three children is going to do far more long term damage to the ecosystem than a childless couple who washes their boat every hour with the worst sort of detergent.