The influence of consumer diversity and indirect facilitation on trophic level biomass and stability

Abstract

2005. The influence of consumer diversity and indirect facilitation on trophic level biomass and stability. Á/ Oikos 110: 556 Á/566.The relationship between species diversity and the stability and production of trophic levels continues to receive intense scientific interest. Though facilitation is commonly cited as an essential underlying mechanism, few studies have provided evidence of the impact that indirect facilitation may have on diversity Á/ecosystem functioning relationships. In this laboratory study, we examined the effect of zooplankton species diversity on trophic structure (total algal and zooplankton biomass) and temporal stability of total zooplankton biomass. We utilized four species of pond zooplankton grown in either monoculture or in polyculture. When comparing responses in polycultures with responses averaged across monocultures, a positive effect of diversity on total zooplankton biomass was observed. This occurred as a result of positive facilitative effects among competing zooplankton. Daphnia pulex , a biomass dominant in monoculture, was negatively affected by the presence of interspecific competitors. In contrast, Diaphanosoma brachyurum , a species that performed poorly in monoculture, was strongly and positively affected by the presence of interspecific competitors, driving positive diversity effects on total zooplankton biomass. Positive temporal covariances among zooplankton were detected in several polyculture replicates, increasing temporal variability of total zooplankton biomass. However, this destabilizing effect was weak relative to effects of high biomass yields in polyculture which caused temporal biomass variability (as measured by the coefficient of variation) to be lower in polyculture relative to monocultures. Zooplankton diversity effects on total algal biomass were not detected. However, increased zooplankton diversity significantly altered the size structure of algae, increasing the relative abundance of large, grazer-resistant algae.

Diversity of protists and bacteria determines predation performance and stability

“…This conclusion is further supported by the low magnitude of species DE within the predator community (Figure 4). Our results are consistent with observations made, for example, in some marine ecosystems, where the increase of consumer biomass with higher consumer richness was largely explained by the 'complementarity effect' rather than by 'selection effects' (Duffy et al, 2003;Steiner et al, 2005). Increasing prey diversity allows for a greater niche complementarity for the predators with regard to their feeding modes (Snyder et al, 2006), and hence, may reduce interspecific interference among predators (Byrnes and Stachowicz, 2009).…”

The effects of the psychiatric drug carbamazepine on freshwater invertebrate communities and ecosystem dynamics

“…Additionally, McMahon et al (2012) showed that declines in species richness induced by exposure to chlorothalonil reduced decomposition and water clarity and elevated primary production and dissolved oxygen in a mesocosm experiment. Further, zooplankton diversity can be critical to the algal community with high zooplankton diversity resulting in an increase in large, grazer resistant algae ( > 35 µm chlorophyll a; Steiner et al 2005). In this study, carbamazepine increased Elimia and decreased Helisoma standing biomass, increased invertebrate diversity and decreased Daphnia pulex abundance, which in turn affected ecosystem characteristics such as dissolved nutrient concentrations, primary production and decomposition.…”

“…Changes in diversity and species composition can profoundly alter ecosystem dynamics (Chaplin et al 1997, Steiner et al 2005, Wojdak 2005). utilized a mesocosm experiment to demonstrate the importance of both species richness and composition to productivity, respiration and decomposition in freshwater ecosystems.…”

“…Multiple studies have demonstrated how alterations in biodiversity and community structure influence ecosystem dynamics (e.g., Tilman et al 1997, Steiner et al 2005. However, many of these studies assessed relatively pristine ecosystems, despite their rare occurrence.…”

Effect of mesozooplankton feeding selectivity on the dynamics of algae in the presence of intermediate grazers—a laboratory simulation

“…Through complex trophic interactions, a highly diverse assemblage of grazers (with multiple feeding behaviors in a functional group) may have a null effect on the biomass of the lower trophic level, as direct consumption is balanced by indirect effects of predation. Due to the increased functional redundancy and weakened trophic effect, increasing the diversity of predator feeding behavior will consequently stabilize the system because the niche of an extinct species will soon be able to be occupied by others (Steiner et al 2005). Such a stabilization effect of predators with diverse feeding behaviors has also been studied in various systems, especially when predators engage in omnivory (Bruno & O'Connor 2005), cannibalism, or intraguild predation (Finke & Denno 2004).…”