Wetlands are transitional areas where land is covered by water, either seasonally or permanently, influencing their biological, physical, and chemical characteristics. They exist between dry land and deeper water bodies like rivers and streams, forming a crucial link in the landscape. The removal of wetlands disrupts this fundamental connection, leading to significant impacts on the health and stability of connected waterways.
Wetland Functions for Rivers and Streams
Wetlands perform multiple functions that benefit rivers and streams, acting as natural filters and water regulators. They purify water by trapping sediments and retaining excess nutrients and pollutants, such as heavy metals.
They absorb excess water during heavy rainfall and snowmelt, reducing downstream flooding. These ecosystems store water, slowly releasing it into connected waterways, which maintains streamflow during dry periods.
Dense root systems of wetland plants stabilize soil, preventing erosion along shorelines and streambanks. Wetlands recharge underground aquifers, contributing to groundwater supplies that feed rivers and streams.
Alterations to Water Quality
The removal of wetlands degrades the water quality of rivers and streams. Their absence leads to increased sediment loads as soil, no longer held in place by wetland vegetation, erodes. This increased sedimentation can smother aquatic organisms and reduce water clarity.
Without wetlands to absorb and process them, higher levels of pollutants enter rivers and streams. These pollutants include excess nutrients like nitrogen and phosphorus from agricultural runoff, as well as pesticides. The influx of nutrients can cause algal blooms, which deplete dissolved oxygen levels when the algae decompose, harming aquatic life.
Changes in water temperature and oxygen levels can also occur, as wetlands help regulate these factors by providing shade and facilitating natural aeration processes.
Changes in Water Flow and Hydrology
Wetlands play a significant role in regulating water flow and hydrological balance.
They act as natural reservoirs, absorbing large volumes of water during high precipitation and flooding. This absorption reduces the intensity and frequency of floods downstream by temporarily holding water and slowing its velocity.
When wetlands are removed, this natural flood control is lost, leading to more severe and frequent flooding events in connected river systems.
During dry seasons, wetlands slowly release stored water, which maintains baseflow in rivers and streams. Their removal can result in reduced water levels during droughts, impacting overall water availability.
This also affects groundwater recharge, as wetlands facilitate surface water seepage into underground aquifers, influencing regional water balance.
Degradation of Aquatic Habitats
The removal of wetlands degrades aquatic habitats and contributes to biodiversity loss.
Wetlands serve as crucial nursery grounds, spawning areas, and feeding grounds for many aquatic species, including fish, amphibians, and invertebrates.
Their removal leads to habitat fragmentation, where continuous natural areas are broken into smaller, isolated patches. This fragmentation can prevent species from moving freely between habitats, disrupting their life cycles and reducing genetic exchange.
Altered water quality and flow regimes from wetland loss further stress aquatic ecosystems, contributing to biodiversity decline and disrupting food webs.