7. Macrofaunal Burrows and Irrigation in Marine Sediment: Microbiological and Biogeochemical Interactions

  1. Erik Kristensen,
  2. Ralf R. Haese and
  3. Joel E. Kostka
  1. E. Kristensen and
  2. J. E. Kostka

Published Online: 23 MAR 2013

DOI: 10.1029/CE060p0125

Interactions Between Macro- and Microorganisms in Marine Sediments

Interactions Between Macro- and Microorganisms in Marine Sediments

How to Cite

Kristensen, E. and Kostka, J. E. (2005) Macrofaunal Burrows and Irrigation in Marine Sediment: Microbiological and Biogeochemical Interactions, in Interactions Between Macro- and Microorganisms in Marine Sediments (eds E. Kristensen, R. R. Haese and J. E. Kostka), American Geophysical Union, Washington, D. C.. doi: 10.1029/CE060p0125

Publication History

  1. Published Online: 23 MAR 2013
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9780875902746

Online ISBN: 9781118665442

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Keywords:

  • Interactions between macro- and microorganisms in marine sediments

Summary

Construction and maintenance of burrows by macrofauna have large implications for the microbiology and biogeochemistry of marine sediments. Although a wealth of new information has become available during the last few decades, there are still significant gaps in our knowledge. In this chapter, we review the current understanding of how the structure and function of irrigated burrows affect the composition of microbial com- munities and associated biogeochemical processes. Although a general relationship is observed between burrow depth and diameter (inhabitant width), it is difficult to classify burrow architecture in relation to the function and trophic mode of macrofaunal inhabi- tants. Trophic mode (suspension-feeding versus deposit-feeding) appears to control burrow wall structure and irrigation rate and thus the exchange of solutes between sediment porewaters and the overlying water. The associated translocation of electron acceptors into and inhibitory metabolites out of the sediment in turn affects diagenetic reactions. It is well established that irrigated burrows enhance total microbial metabolism by stimulating oxic (e.g. respiration) and suboxic (e.g. nitrification-denitrification and iron reduction) reactions in the surrounding sediment. In contrast, the impacts of burrow- generated changes to diffusion scales on anoxic processes like sulfate reduction are less clear. Sediments surrounding burrow structures likely support unique microbial communi- ties that differ from those in surficial sediments due to large differences in environmental conditions. Biogeochemical evidence clearly indicates that the activity and abundance of microorganisms are elevated around burrows. However, the mechanisms controlling microbially mediated geochemical reactions in the burrow zone remain understudied, and very little information is available to assess the impacts of burrow environments on the community structure or diversity of microorganisms. Therefore, we cannot yet gener- alize about direct relationships between burrows, irrigation and the distribution of micro- organisms. However, much progress is already being made through the use of new and exciting experimental tools, such as microsensors and cultivation-independent molecular techniques.