Krill excretion boosts microbial activity in the Southern Ocean

PLoS One. 2014 Feb 19;9(2):e89391. doi: 10.1371/journal.pone.0089391. eCollection 2014.

Abstract

Antarctic krill are known to release large amounts of inorganic and organic nutrients to the water column. Here we test the role of krill excretion of dissolved products in stimulating heterotrophic bacteria on the basis of three experiments where ammonium and organic excretory products released by krill were added to bacterial assemblages, free of grazers. Our results demonstrate that the addition of krill excretion products (but not of ammonium alone), at levels expected in krill swarms, greatly stimulates bacteria resulting in an order-of-magnitude increase in growth and production. Furthermore, they suggest that bacterial growth rate in the Southern Ocean is suppressed well below their potential by resource limitation. Enhanced bacterial activity in the presence of krill, which are major sources of DOC in the Southern Ocean, would further increase recycling processes associated with krill activity, resulting in highly efficient krill-bacterial recycling that should be conducive to stimulating periods of high primary productivity in the Southern Ocean.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonium Compounds / metabolism
  • Animals
  • Antarctic Regions
  • Biomass
  • Euphausiacea / chemistry
  • Euphausiacea / physiology*
  • Flow Cytometry
  • Heterotrophic Processes / physiology
  • Mass Spectrometry
  • Microbiota / physiology*
  • Oxygen Consumption / physiology
  • Water Microbiology*

Substances

  • Ammonium Compounds

Grants and funding

This research is a contribution to projects ICEPOS (REN2002-04165-CO3-O2) and ATOS (POL2006-00550/CTM), funded by the Spanish Ministry of Science and Innovation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.