Habitat Degradation

Aquatic and terrestrial habitats are increasingly degraded and lost as greater percentages of watershed areas are made impervious. The following sections focus upon these impacts which include habitat degradation, habitat loss, and habitat fragmentation.

Habitat degradation is the diminishment of habitat quality and its ability to support biological communities. It stems from the adverse effects of urban development, such as increases in impervious surfaces within watersheds. Its adverse effects can be immediate or cumulative.

Habitat loss is the outright destruction of habitat, such as filling a wetland or channelizing a section of stream. Its impacts upon biological communities are immediate and catastrophic.

Habitat fragmentation is the piecemeal disassembly of terrestrial habitats into discontinuous, oftentimes isolated, patches as a consequence of development. Its adverse effects are cumulative and not immediately noticeable. Habitat fragmentation stems from habitat loss.

Observable Health Indicators

Some of the indicators of stream health degradation include:

• population shifts to aquatic organisms tolerant of poor water quality and poor habitat

• less riparian vegetation

• reduced macroinvertebrate, fish, and amphibian diversity

• lower plant and amphibian density

• increased sediment and stormwater runoff

• fewer snags in channels to dissipate energy

• channel instability

Resources

Looking for the tools to protect your local watershed and ideas on how to manage urban development? For fact sheets and literature on watershed protection and imperviousness, discussion of land-use planning and management techniques, and model ordinances, check out the following resources:

• Center for Watershed Protection
• EPA Office of Water: Watershed Protection
• NEMO
• Smart Growth Network
• Save Our Streams
• Biological Indicators of Watershed Health
• Save Our Streams: Curriculum Materials for Environmental Educators Montgomery County Schools, Maryland