Stream detritus dynamics: Regulation by invertebrate consumers

Area of Science:

• Ecology
• Environmental Science
• Aquatic Biology

Background:

• Aquatic insects are vital components of forest stream ecosystems.
• Detritus processing is a fundamental ecosystem service in streams.
• Understanding the impact of disturbances on stream communities is crucial.

Purpose of the Study:

• To investigate the effects of insecticide treatment on aquatic insect populations.
• To assess the consequences of insect reduction on detritus breakdown and organic matter dynamics.
• To determine the role of macroinvertebrate consumers in stream ecosystem functioning.

Main Methods:

• Insecticide application in a treated Appalachian forest stream.
• Comparison with an adjacent untreated reference stream.
• Measurement of insect drift, densities, leaf detritus breakdown rates, and organic matter transport.

Main Results:

• Insecticide treatment caused massive downstream insect drift and reduced insect densities to <10% of the reference stream.
• Leaf detritus breakdown rates were reduced in the treated stream.
• Transport of particulate organic matter was significantly lower post-treatment in the treated stream.

Conclusions:

• Aquatic macroinvertebrates, particularly insects, are critical regulators of detritus processing rates.
• Disruption of insect populations significantly affects nutrient cycling and organic matter availability in downstream communities.
• Insecticide disturbances have cascading effects on stream ecosystem functions.