Translator Disclaimer
10 July 2012 Landuse intensity in stream catchments affects the benthic food web: consequences for nutrient supply, periphyton C:nutrient ratios, and invertebrate richness and abundance
Author Affiliations +
Abstract

Anthropogenic nutrient enrichment increases the supply ratio of N and P to aquatic ecosystems and can affect the identity of the limiting nutrient. Here we focus on how stream communities change along gradients of N and P supply and stream catchment landuse intensity. We used a survey approach in 41 southern New Zealand tributaries to investigate how much changes in water N and P concentrations are reflected in periphyton C∶nutrient ratios (C∶N or C∶P) and how much food quality (high food quality corresponds to low periphyton C∶nutrient) is reflected in the abundance and taxonomic richness of benthic invertebrate primary and secondary consumers. We measured streamwater nutrient state, periphyton nutrient ratios, biomass (as chlorophyll a in µg/cm2), algal taxon richness, and macroinvertebrate abundance, taxonomic composition, and richness. We also estimated stream habitat and catchment characteristics, such as current velocity, shading, substrate, geology, and landuse intensity. We calculated the Akaike information criterion (AIC) for each possible multiple linear regression model to select the best predictive models for each response variable. C∶nutrient ratios were more strongly negatively related to water-column N than P availability. Neither N nor P availability covaried with periphyton biomass. Lower periphyton C∶N partly explained higher grazer, but not predator, abundance. Increased % runoff from pasture and periphyton N∶P co-occurred with a decrease in invertebrate taxon richness. For example, a 4× increase in periphyton N∶P was related to the loss of ∼½ of invertebrate species, but with high uncertainty (R2  =  0.13). We conclude landuse intensity affects these southern New Zealand streams, and these effects are mediated by agricultural N runoff into streams (among other factors). Further shifts toward high-intensity farming within stream catchments may lead to losses of benthic species at all trophic levels.

The Society for Freshwater Science
Antonia Liess, Ariane Le Gros, Annika Wagenhoff, Colin R. Townsend, and Christoph D. Matthaei "Landuse intensity in stream catchments affects the benthic food web: consequences for nutrient supply, periphyton C:nutrient ratios, and invertebrate richness and abundance," Freshwater Science 31(3), 813-824, (10 July 2012). https://doi.org/10.1899/11-019.1
Received: 2 March 2011; Accepted: 1 April 2012; Published: 10 July 2012
JOURNAL ARTICLE
12 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top