Leaf Breakdown Rates and Aquatic Insects in Piedmont Headwater Stream
Abstract
One of the primary energy sources for freshwater streams is terrestrial leaf litter. Leaves that fall into the water float downstream and naturally form accumulations against obstructions referred to as leaf packs. Leaf packs begin to break down progressively through leaching, microbial activity, and various benthic macroinvertebrates. These nutrients support an aquatic food web and studies have shown that a diversity in leaf species entering the stream leads to a continuum of resources for healthy ecosystem functioning. Currently, there is a trend of loss of biodiversity in riparian habitats due to climate change and urbanization. Our objective is to determine what communities of stream organisms are supported by two different types of leaf packs. We hypothesized that differing leaf species will have different breakdown rates and therefore support different benthic macroinvertebrate communities. This study was conducted at Miller’s Fork Creek, a headwater stream, fed from filtered groundwater in Clinton, SC. Thirty pre-weighed leaf packs of the leaf species, Acer rubrum and Quercus stellata, were installed in the stream along with a temperature logger recording every six hours. Water quality and habitat assessments were conducted to describe the conditions in Miller’s Fork Creek. After 10-, 33-, and 66- days, leaf packs were retrieved, benthic macroinvertebrates were collected during the washing process, and leaf packs were air dried. Using a muffle furnace, leaves were burned at 500°C and the Ash Free Dry Mass was calculated to precisely measure the breakdown rate coefficient. Benthic macroinvertebrates were identified to family level and diversity indices were calculated comparing communities by leaf type and time deployed in the stream. Our results showed that the species A. rubrum had a faster breakdown rate than the species Q. stellata and that the community of benthic macroinvertebrate were different by leaf type. These results aid in the understanding of the need for a healthy riparian habitat with diverse species to supply a continuum of resources. Our study adds to the understanding of how global climate change affects carbon cycling. These results are a part of an ongoing research effort to create best management practices to conserve and protect the drinking water supply for Clinton, SC.
Keywords
Leaf pack, Macroinvertebrate, Breakdown rate, Stream, Riparian habitat, Nutrient cycling, Ecology
Leaf Breakdown Rates and Aquatic Insects in Piedmont Headwater Stream
CLC Ballroom
One of the primary energy sources for freshwater streams is terrestrial leaf litter. Leaves that fall into the water float downstream and naturally form accumulations against obstructions referred to as leaf packs. Leaf packs begin to break down progressively through leaching, microbial activity, and various benthic macroinvertebrates. These nutrients support an aquatic food web and studies have shown that a diversity in leaf species entering the stream leads to a continuum of resources for healthy ecosystem functioning. Currently, there is a trend of loss of biodiversity in riparian habitats due to climate change and urbanization. Our objective is to determine what communities of stream organisms are supported by two different types of leaf packs. We hypothesized that differing leaf species will have different breakdown rates and therefore support different benthic macroinvertebrate communities. This study was conducted at Miller’s Fork Creek, a headwater stream, fed from filtered groundwater in Clinton, SC. Thirty pre-weighed leaf packs of the leaf species, Acer rubrum and Quercus stellata, were installed in the stream along with a temperature logger recording every six hours. Water quality and habitat assessments were conducted to describe the conditions in Miller’s Fork Creek. After 10-, 33-, and 66- days, leaf packs were retrieved, benthic macroinvertebrates were collected during the washing process, and leaf packs were air dried. Using a muffle furnace, leaves were burned at 500°C and the Ash Free Dry Mass was calculated to precisely measure the breakdown rate coefficient. Benthic macroinvertebrates were identified to family level and diversity indices were calculated comparing communities by leaf type and time deployed in the stream. Our results showed that the species A. rubrum had a faster breakdown rate than the species Q. stellata and that the community of benthic macroinvertebrate were different by leaf type. These results aid in the understanding of the need for a healthy riparian habitat with diverse species to supply a continuum of resources. Our study adds to the understanding of how global climate change affects carbon cycling. These results are a part of an ongoing research effort to create best management practices to conserve and protect the drinking water supply for Clinton, SC.