The Impact of Hypoxia on Bioturbation Rates in the Louisianna Continental Shelf, Northern Gulf of Mexico

Abstract

Variation in the spatial and temporal extent of hypoxia in coastal bottom waters of the northern Gulf of Mexico leads to changes in benthic community structure and sediment physical properties. Past and present benthic community structure determines what types of biogenic structures are present in the sediment as well as faunal mixing rates. Therefore, hypoxia has an important effect upon bioturbation. This study focuses upon the effects of hypoxia on bioturbation specifically on the continental shelf of Louisiana, where hypoxia has become an important issue due to its seasonal reoccurrence and increasing expansion across the northern Gulf of Mexico over the past 30 years. In this project, characteristics of biogenic structures in the sediment including number, diameter, and depth are correlated with benthic communities dwelling in hypoxic, intermittently hypoxic, and normoxic conditions using non-destructive Computed Tomography (CT) imagery of sediment cores and Sediment Profile Imaging (SPI) photography. Biogenic structures are also correlated with sediment physical properties, bioturbation rates, and bioturbation behaviors (dilator or compactor) of benthic invertebrate fauna. Initial data for this project was collected during two cruises along the continental shelf of Louisiana, the first in April 2009 and the second in September 2009. Four different "provinces" were chosen for sampling using bottom water oxygen concentration data from the Louisiana Universities Marine Consortium (LUMCON) and archived sediment type data. These four sampling sites represent normoxic and hypoxic provinces with a consistent sediment type. The provinces consist of a normoxic site (NO) that has experienced hypoxia less than 25% of the time and briefly hypoxic (BH), frequently hypoxic (FH) and hypoxic (HO) sites that have experienced hypoxia greater than 25% of the time.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2009
Accession Number
ADA513744

Entities

People

  • Kevin B. Briggs
  • Kevin M. Yeager
  • Robert Diaz
  • Shivakumar Shivarudrappa
  • Valerie A. Hartmann

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Abstracts
  • Acoustic Properties
  • Bottom Waters
  • Cameras
  • Chemistry
  • Communities
  • Continental Shelves
  • Images
  • Louisiana
  • Low Density
  • Materials
  • Mechanical Properties
  • Military Research
  • Photographs
  • Photography
  • Urban Areas
  • Water

Fields of Study

  • Environmental science

Readers

  • Auditory Neuroscience/Auditory Physiology.
  • Coastal Oceanography
  • Oceanography.