Determining the mechanism by which fish diversity influences production

Abstract

Understanding the ability of biodiversity to govern ecosystem function is essential with current pressures on natural communities from species invasions and extirpations. Changes in fish communities can be a major determinant of food web dynamics, and even small shifts in species composition or richness can translate into large effects on ecosystems. In addition, there is a large information gap in extrapolating results of small-scale biodiversity-ecosystem function experiments to natural systems with realistic environmental complexity. Thus, we tested the key mechanisms (resource complementarity and selection effect) for biodiversity to influence fish production in mesocosms and ponds. Fish diversity treatments were created by replicating species richness and species composition within each richness level. In mesocosms, increasing richness had a positive effect on fish biomass with an overyielding pattern indicating species mixtures were more productive than any individual species. Additive partitioning confirmed a positive net effect of biodiversity driven by a complementarity effect. Productivity was less affected by species diversity when species were more similar. Thus, the primary mechanism driving fish production in the mesocosms was resource complementarity. In the ponds, the mechanism driving fish production changed through time. The key mechanism was initially resource complementarity until production was influenced by the selection effect. Varying strength of intraspecific interactions resulting from differences in resource levels and heterogeneity likely caused differences in mechanisms between the mesocosm and pond experiments, as well as changes through time in the ponds. Understanding the mechanisms by which fish diversity governs ecosystem function and how environmental complexity and resource levels alter these relationships can be used to improve predictions for natural systems.

How natural capital delivers ecosystem services: A typology derived from a systematic review

“…This is also observed for freshwater fishing, both in natural ecosystems and in aquaculture ponds or managed lakes stocked with mixed species of fish (e.g. Carey and Wahl, 2011;Lapointe et al, 2014;Rahman et al, 2008;Schindler et al, 2010). For food crops, intra-species genetic diversity (e.g.…”

Loss of Rare Fish Species from Tropical Floodplain Food Webs Affects Community Structure and Ecosystem Multifunctionality in a Mesocosm Experiment

“…That is, increases in ecosystem functioning with increasing diversity are the result of limited functional redundancy among species or that higher diversity increases the probability of “selecting” taxa with greater individual influences on ecosystem functioning. This is especially the case for studies that manipulate diversity within a single trophic level, although these mechanisms have also been shown to operate in simplified multitrophic systems [33]. In ecosystems with natural patterns of commonness and rarity, the relative abundance or biomass of species may mediate the roles of complementarity and the selection effect (i.e.…”

“…Indirect effects in multitrophic systems limit the ability to attribute ecosystem-level consequences to complementarity and the selection effect, which are more readily interpretable for biodiversity within a single trophic level and directly associated ecosystem responses. Similarly, in this experiment, we manipulated species richness within and among trophic levels, whereas other multitrophic BEF studies typically manipulate diversity within a single trophic level [20], [33], [35] but see [34], [36]. Therefore, as loss of the rarest species occurred simultaneously across multiple components of this complex food web, observed influences on ecosystem processes and multifunctionality are likely the combined result of indirect effects of manipulated taxa (i.e.…”

Longer food chains and crowded niche space: effects of multiple invaders on desert stream food web structure

“…). However, the impact of invasive predators and competitors is not consistent for all recipient systems and is influenced by ecosystem complexity (Case ; Carey & Wahl , ) and evolutionary history (Kitchell et al. ; Shea & Chesson ).…”