Productivity–diversity relationships for stream in

Authors: Jonathan D Tonkin Russell G Death José Barquín

Publish Date: 2013/02/19

Volume: 47, Issue: 1, Pages: 109-121

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Abstract

More productive environments typically have more species although the specific form of this relationship is unclear and can vary with spatial scale This relationship has received little direct attention in lotic systems and thus the nature of the relationship is unclear as is any effect of spatial scale We examined the link between stream primary productivity and macroinvertebrate diversity in Spain and New Zealand and hypothesized that macroinvertebrate diversity would increase loglinearly with increasing productivity in both regions We sampled 24 streams in Cantabria Spain and 24 in the central North Island New Zealand Algal primary productivity was approximately three times higher in Spanish streams but taxonomic richness of invertebrates did not differ between the regions Richness and Shannon diversity only responded to productivity in the New Zealand streams exhibiting the predicted loglinear increase In the Spanish streams only the total number of individuals increased with productivity However when plotted on the same axes richness in the Spanish streams simply occurred on the linear portion of the graph to the right of the New Zealand streams We speculate that productivity in the Spanish streams never became low enough to constrain diversity but did in the New Zealand streams Combining results from the two regions there is no evidence of a decline in diversity with higher productivityWe are grateful to Jessica Costall for help with fieldwork This manuscript was improved by comments from Angus McIntosh Ian Henderson Christopher Robinson and two anonymous reviewers A Massey University Doctoral Scholarship supported JDT during the study

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