Environment shapes invertebrate assemblage structure differences between volcanic spring-fed and runoff rivers in northern California
AffiliationUniv Arizona, Sch Nat Resources & Environm
Keywordsvolcanic spring-fed rivers
MetadataShow full item record
PublisherUNIV CHICAGO PRESS
CitationEnvironment shapes invertebrate assemblage structure differences between volcanic spring-fed and runoff rivers in northern California 2016, 35 (3):1010 Freshwater Science
Rights© 2016 by The Society for Freshwater Science.
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AbstractFlow variability plays an important role in structuring lotic communities, yet comparatively little is known about processes governing assemblage dynamics in stream ecosystems with stable environmental conditions, such as spring-fed rivers. Volcanic spring-fed rivers (hereafter spring-fed rivers) occur in geologically active landscapes of the western USA and around the globe. We sampled invertebrate assemblages and quantified primary productivity and habitat characteristics of spring-fed and runoff rivers in northern California over 4 seasons. We predicted that abiotic factors would be more stable and nutrient availability greater and that invertebrate density would be greater and diversity lower in spring-fed than in runoff rivers. Runoff rivers exhibited high variability in discharge and temperature, whereas spring-fed rivers were relatively stable with high naturally occurring nutrient levels. On average, NO3- and PO43- concentrations were 40x greater in spring-fed than in runoff rivers. Spring-fed rivers supported nearly 7 to 16x greater densities of invertebrates than runoff systems, depending on season. However, invertebrate species richness was greater in runoff rivers in all seasons. Spring-fed river invertebrate assemblages were strongly correlated with elevated nutrient concentrations and basal C sources, whereas runoff assemblages were associated with discharge variability and median substrate size. We suggest that strong differences in abiotic variability between spring-fed and runoff rivers play an important role in determining invertebrate assemblage structure. Because spring-fed rivers exhibit more stable temperatures throughout the year and lower temperatures during the summer than runoff rivers, they may provide essential refugia for coldwater taxa in a warming climate.
NoteONLINE: May 04, 2016
VersionFinal published version
SponsorsUS Bureau of Reclamation