Document Type
Article
Department/Program
Virginia Institute of Marine Science
Publication Date
8-2008
Journal
Ecology
Volume
89
Issue
9
First Page
2518
Last Page
2528
Abstract
The interactive effects of changing biodiversity of consumers and their prey are poorly understood but are likely to be important under realistic scenarios of biodiversity loss and gain. We performed two factorial manipulations of macroalgal group (greens, reds, and browns) and herbivore species (amphipods, sea urchin, and fish) composition and richness in outdoor mesocosms simulating a subtidal, hard-substratum estuarine community in North Carolina, USA. In the experiment where grazer richness treatments were substitutive, there were no significant effects of algal or herbivore richness on final algal biomass. However, in the experiment in which grazer treatments were additive (i.e., species-specific densities were held constant across richness treatments), we found strong independent and interactive effects of algal and herbivore richness. Herbivore polycultures reduced algal biomass to a greater degree than the sum of the three herbivore monocultures, indicating that the measured grazer richness effects were not due solely to increased herbivore density in the polycultures. Taking grazer density into account also revealed that increasing algal richness dampened grazer richness effects. Additionally, the effect of algal richness on algal biomass accumulation was far stronger when herbivores were absent, suggesting that grazers can utilize the increased productivity and mask the positive effects of plant biodiversity on primary production. Our results highlight the complex independent and interactive effects of biodiversity between adjacent trophic levels and emphasize the importance of performing biodiversity-ecosystem functioning experiments in a realistic multi-trophic context.
DOI
10.1890/07-1345.1
Keywords
amphipods; biodiversity; complementarity; diversity; ecosystem function; grazers; herbivory; macroalgae
Publication Statement
Copyright by the Ecological Society of America
Recommended Citation
Bruno, JF; Boyer, KE; Duffy, JE; and Lee, SC, Relative and interactive effects of plant and grazer richness in a benthic marine community (2008). Ecology, 89(9), 2518-2528.
10.1890/07-1345.1
