Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
  • Problem Description
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Five matlab script files (.m) are added as supplemental files to this dataset. They are for the data analysis and results/figures of the results paper. Some of these are run step-wise. Note that because Chamber 1 malfunctioned in all three deployments, the scripts regularly exclude that chamber in data processing and analyses. Users replicating these methods who have better luck with their chamber 1 will want to add in code modified from analysis of the other chambers to analyze those data.

In brief, a custom field deployable benthic chamber system was used to collect sediment oxygen demand (SOD) data in situ from small replicate patches of sediment throughout a diel oxygen cycle. Chambers were "batch" style incubation chambers that periodically flushed the overlying water with water from the external environment to start another incubation, and SOD could be calculated from the slopes of each incubation. Upon completion of the 24 hour deployment, the chambers were extracted, oxygen data offloaded from the chamber loggers, and the faunal community in each chamber identified and counted (1mm sieve).

The data file s the compiled data for every high-quality chamber incubation among all three deployments, the product of data processing, filtration, and consolidation done in MATLAB scripts 2, 3 and 4. This sheet is used in MATLAB script 5 for data analysis. It contains the start date and time of the incubation, the elapsed time since the start of the deployment (dayfrac), the chamber number out of 5 replicate chambers, the SOD (sediment oxygen demand) in mmol m-2 d-1, the Initial DO (dissolved oxygen) of that incubation in mg L-1, the total biomass of fauna within the chamber in grams, the deployment number, and the overall study sample number.

DO data processing involved manual selection of oxygen slopes from raw oxygen data for each deployment to generate a data set of sediment oxygen demand (SOD) values. Data were compiled into a master data sheet which was then used to compare SOD with the dissolved oxygen levels at the time of the slope and the faunal community in the particular chamber.

* Added Matlab script files as supplemental files

NSF Award Abstract:
Marine sediments are important habitats for abundant and diverse communities of organisms that are important as food sources for higher trophic levels, including commercially important species. Through burrowing, constructing tubes, and feeding on sediments, these animals modify their physical and chemical environments to such an extent that they are considered ecosystem engineers. Bioturbation, the mixing of sediments by animals, is important in regenerating nutrients and transporting pollutants and carbon bound to mineral grains. Despite its importance, our ability to predict bioturbation rates and patterns from the community structure is poor, largely due to a lack of understanding of the mechanisms by which animals mix sediments. This project builds on earlier work showing that animals extend burrows through muddy sediments by fracture to test the hypothesis that the mechanical properties of sediments that affect burrowing mechanics also affect sediment mixing. More broadly, this project examines the relative contributions of (i) the functional roles of the organisms in the community, (ii) the mechanical properties of sediments, and (iii) factors that might increase or decrease animal activity such as temperature and food availability to bioturbation rates. Burrowing animals modify the physical properties of sediments, and this project quantifies these changes and tests the hypothesis that these changes are ecologically important and affect community succession following a disturbance. In addition to this scientific broader impact, this project involves development of instrumentation to measure sediment properties and includes a substantial education plan to introduce graduate, undergraduate, and middle school students to the important role that technology plays in marine science.

Through burrowing and feeding activities, benthic infauna mix sediments and modify their physical environments. Bioturbation gates the burial of organic matter, enhances nutrient regeneration, and smears the paleontological and stratigraphic record. However, current understanding of the mechanisms by which infaunal activities mix sediments is insufficient to predict the impacts of changes in infaunal community structure on important sediment ecosystem functions driven by bioturbation. This project tests specific hypotheses relating infaunal communities, bioturbation, and geotechnical properties with the ultimate goal of understanding the dynamic changes and potential feedbacks between infauna and their physical environments. This project integrates field and lab experiments to assess the relative importance of infaunal community structure and activities to bioturbation rates. Additionally, this project builds on recent work showing that muddy sediments are elastic gels through which worms extend burrows by fracture to propose that geotechnical properties of sediments mediate bioturbation by governing the release of particles from the sediment matrix during burrow extension. Finite element modeling determines how the release of particles by fracture during burrowing depends on the fracture toughness (cohesion) and stiffness (compaction) of sediments and complements laboratory experiments characterizing the impact of geotechnical properties on burrowing behaviors. The proposed research also aims to determine whether impacts of infauna on geotechnical properties are ecologically important. Changes in infaunal communities and geotechnical properties following an experimental physical disturbance address the hypothesis that ecosystem engineering of bulk sediment properties facilitates succession.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.