Species-Specific Effects on Ecosystem Functioning Can Be Altered by Interspecific Interactions

Abstract

Biological assemblages are constantly undergoing change, with species being introduced, extirpated and experiencing shifts in their densities. Theory and experimentation suggest that the impacts of such change on ecosystem functioning should be predictable based on the biological traits of the species involved. However, interspecific interactions could alter how species affect functioning, with the strength and sign of interactions potentially depending on environmental context (e.g. homogenous vs. heterogeneous conditions) and the function considered. Here, we assessed how concurrent changes to the densities of two common marine benthic invertebrates, Corophium volutator and Hediste diversicolor, affected the ecological functions of organic matter consumption and benthic-pelagic nutrient flux. Complementary experiments were conducted within homogenous laboratory microcosms and naturally heterogeneous field plots. When the densities of the species were increased within microcosms, interspecific interactions enhanced effects on organic matter consumption and reduced effects on nutrient flux. Trait-based predictions of how each species would affect functioning were only consistently supported when the density of the other species was low. In field plots, increasing the density of either species had a positive effect on organic matter consumption (with no significant interspecific interactions) but no effect on nutrient flux. Our results indicate that species-specific effects on ecosystem functioning can be altered by interspecific interactions, which can be either facilitative (positive) or antagonistic (negative) depending on the function considered. The impacts of biodiversity change may therefore not be predictable based solely on the biological traits of the species involved. Possible explanations for why interactions were detected in microcosms but not in the field are discussed.

Species contributions to ecosystem process and function can be population dependent and modified by biotic and abiotic setting

“…Indeed, as observed here, the functional role of species is not necessarily expressed to the same extent when species are in mixture, relative to when they are in monoculture. This is because the presence of interspecific interactions can positively or negatively affect the trait expression of individual species, altering per capita contributions to ecosystem functioning [ 71 ]. While the specific abiotic and/or biotic factors that lead to variation in trait expression are not easy to predict [ 22 , 72 ], the relationship between functional diversity and ecosystem properties has a strong theoretical base [ 73 ] and species responses to specific circumstances are well known.…”

The distinctive character of lumpy limestones (Early Jurassic, Lusitanian Basin, W Portugal)

“…This is probably the main difference that explains the singularity and restricted geographical and stratigraphic occurrence of the lumpy limestones. Commonly, long‐term and well‐established borrowing communities often suffer from competition, predation, or exhausted resources such as nutrients, oxygen, or even space (e.g., Clare, Spencer, Robinson, & Frid, ; Möller, ; Rönn, Bonsdorff, & Nelson, ; Wilson, ). In contrast, pioneer infauna settling in defaunated recovering environments can find optimal circumstances to develop under minimized stress, following a positive facilitating colonization model ( sensu Connell & Slatyer, ).…”

Influence of sugarcane growth stages on bird diversity and community structure in an agricultural-savanna environment

“…Phenotypic traits of species play a critical role in determining their contribution to ecosystem services and functioning ( Clare et al., 2016 ; Norberg et al., 2001 ; Tilman, 2001 ). Functional diversity describes the variation of these traits ( Mason et al., 2005 ; Tilman, 2001 ), and may, therefore, be useful for understanding how their persistence or loss may affect ecosystem-level processes ( Petchey and Gaston, 2006 ).…”