SREL Reprint #2178
Information length: spatial and temporal parameters among stream bacterial assemblages
J VAUN McARTHUR
Savannah River Ecology Laboratory, Aiken, South Carolina 29802 USA
R. CARY TUCKFIELD
Westinghouse Savannah River Company, Savannah River Technology Center, Aiken, South Carolina 29808 USA
Abstract. Bacteria, while known to be an integral part of all ecosystems, are seldom studied except as a single taxonomic
unit. Few ecological studies even acknowledge the extraordinary functional and species diversity of bacteria. Recent research
has elucidated some important facts about bacteria in stream ecosystems. For instance, the dynamics of bacterial genornes
within a stream suggest that populations of these organisms are more stable temporally than spatially. We develop predictive
models and testable hypotheses based on the information spiraling concept to describe the ecology of stream bacteria and to
define 2 new terms: colonization distance and information length. Colonization distance (Dc) is the maximum distance
downstream from original colony establishment at which a new colony of bacteria can be established. Information length (L1)
is defined as the maximum length over whidi a gene has an effect on an ecosystem process independent of a specific host.
These terms are modeled relative to the average temporal energy load (joules/min) in the stream. Energy inputs that exceed
biologically defined limits of use result in ecosystem energy leaks regardless of information length. Our models predict that
information length should be shorter in montane streams than in Coastal Plain streams of southeastern USA. Furthermore,
assuming equal average energy load between streams, the stream with the largest energy load variance will leak more energy
downstream. Therefore, temperate streams should be less efficient than tropical streams at utilizing energy within a reach.
Key words: information spiraling concept, information length, colonization distance, energy load, bacteria, lotic.
SREL Reprint #2178
McArthur, J V. and R.C. Tuckfield. 1997. Information length: spatial and temporal parameters among stream bacterial assemblages. Journal of the North American Benthological Society 16:347-357.
