Ecological Benefits of Reduced Hydrologic Connectivity in Intensively Developed Landscapes

A broad perspective on hydrologic connectivity is necessary when managing stream ecosystems and establishing conservation priorities. Hydrologic connectivity refers to the water-mediated transport of matter, energy, or organisms within or between elements of the hydrologic cycle. The potential negative consequences of enhancing hydrologic connectivity warrant careful consideration in human-modified landscapes that are increasingly characterized by hydrologic alteration, exotic species, high levels of nutrients and toxins, and disturbed sediment regimes. While connectivity is integral to the structure and function of aquatic ecosystems, it can also promote the distribution of undesirable components. Here we provide examples illustrating how reduced hydrologic connectivity can provide greater ecological benefits than enhanced connectivity does in highly developed, human-modified ecosystems; for example, in urban landscapes, restoration efforts can sometimes create population sinks for endangered biota. We conclude by emphasizing the importance of adaptive management and balancing trade-offs associated with further alterations of hydrologic connectivity in human-modified landscapes.