Wave action modifies the effects of consumer diversity and warming on algal assemblages

Abstract

Abstract. To understand the consequences of biodiversity loss, it is necessary to test how biodiversity-ecosystem functioning relationships may vary with predicted environmental change. In particular, our understanding will be advanced by studies addressing the interactive effects of multiple stressors on the role of biodiversity across trophic levels. Predicted increases in wave disturbance and ocean warming, together with climate-driven range shifts of key consumer species, are likely to have profound impacts on the dynamics of coastal marine communities. We tested whether wave action and temperature modified the effects of gastropod grazer diversity (Patella vulgata, Littorina littorea, and Gibbula umbilicalis) on algal assemblages in experimental rock pools. The presence or absence of L. littorea appeared to drive changes in microalgal and macroalgal biomass and macroalgal assemblage structure. Macroalgal biomass also decreased with increasing grazer species richness, but only when wave action was enhanced. Further, independently of grazer diversity, wave action and temperature had interactive effects on macroalgal assemblage structure. Warming also led to a reversal of grazer-macroalgal interaction strengths from negative to positive, but only when there was no wave action. Our results show that hydrodynamic disturbance can exacerbate the effects of changing consumer diversity, and may also disrupt the influence of other environmental stressors on key consumer-resource interactions. These findings suggest that the combined effects of anticipated abiotic and biotic change on the functioning of coastal marine ecosystems, although difficult to predict, may be substantial.

Size‐balanced community reorganization in response to nutrients and warming

“…This led to an increase in the mean (+3.5 °C) and standard deviation (±0.8 °C) of temperature, thereby imitating the range of possible warming of up to +6 °C expected for global oceanic waters by the end of the century (IPCC ). Consistent with other experiments performed in this particular array of outdoor mesocosms, fluctuations in experiment temperatures are unlikely to be as great as those observed in natural rockpools in the UK (Morris & Taylor, ; Mrowicki & O'Connor, ). As the actual temperature observed varied between mesocosms, the mean temperatures for each mesocosm over time were used as continuous covariates in the subsequent analysis.…”

Warming affects predatory faunal impacts upon microbial carbon cycling

“…Our study builds upon previous studies which demonstrate that crabs play a key role in coastal sediments, controlling accumulation of microbial biomass and the preservation of organic matter (Canuel et al, ; Fanjul et al, ; Spivak et al, ). This reinforces the concept of the benthic fauna as a “gearbox” that regulates microbial activity in marine sediments (Hunter et al, ; van Nugteren, Herman et al, ; van Nugteren, Moodley et al, ) and support the observation that the responses of faunal communities to rising ocean temperature will have cascading effects upon benthic primary producers (Mrowicki & O'Connor, ; O'Connor et al, ).…”

“…Stable isotope ( 13 C) pulse‐chase experiments were conducted during February and March 2015 using outdoor flow‐through mesocosms at Queen's University Marine Laboratory (Portaferry, Northern Ireland, Mrowicki & O'Connor, ). We assembled 20 mesocosms containing intertidal sediment manipulating two factors: (a) presence of Carcinus (two levels, present [single crab] and absent); and (b) temperature (two levels, ambient and warming [ambient +2°C]).…”

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

“…However, the expression of functional traits within species is unlikely to be homogenously distributed, as individuals behave differently depending on the biotic and/or environmental conditions they experience [22–26]. Such context-dependent changes in trait expression, including, for example, responses to temperature [27], hydrodynamic regimes [28,29], resource availability and quality [30–32], or biotic interactions (e.g. predation [33,34]; competition [35]), can mean that the functional role of an individual may fundamentally change over time and across space, with corresponding transient effects on ecosystem properties [25,36,37].…”