Large-Scale Variation in Combined Impacts of Canopy Loss and Disturbance on Community Structure and Ecosystem Functioning

Abstract

Ecosystems are under pressure from multiple human disturbances whose impact may vary depending on environmental context. We experimentally evaluated variation in the separate and combined effects of the loss of a key functional group (canopy algae) and physical disturbance on rocky shore ecosystems at nine locations across Europe. Multivariate community structure was initially affected (during the first three to six months) at six locations but after 18 months, effects were apparent at only three. Loss of canopy caused increases in cover of non-canopy algae in the three locations in southern Europe and decreases in some northern locations. Measures of ecosystem functioning (community respiration, gross primary productivity, net primary productivity) were affected by loss of canopy at five of the six locations for which data were available. Short-term effects on community respiration were widespread, but effects were rare after 18 months. Functional changes corresponded with changes in community structure and/or species richness at most locations and times sampled, but no single aspect of biodiversity was an effective predictor of longer-term functional changes. Most ecosystems studied were able to compensate in functional terms for impacts caused by indiscriminate physical disturbance. The only consistent effect of disturbance was to increase cover of non-canopy species. Loss of canopy algae temporarily reduced community resistance to disturbance at only two locations and at two locations actually increased resistance. Resistance to disturbance-induced changes in gross primary productivity was reduced by loss of canopy algae at four locations. Location-specific variation in the effects of the same stressors argues for flexible frameworks for the management of marine environments. These results also highlight the need to analyse how species loss and other stressors combine and interact in different environmental contexts.

Influence of environmental factors and biogenic habitats on intertidal meiofauna

“…Macroalgae, in particular canopy algae such as Cystoseira sp., can reduce the impact of physical and biological factors, maintaining high levels of diversity in rocky shore habitats (Gibbons, 1988b;BenedettiCecchi et al, 2001;Crowe et al, 2013). Consistent with this, our results showed that the influence of thermal conditions (i.e.…”

Persistent natural acidification drives major distribution shifts in marine benthic ecosystems

“…Moreover, expected synergies of OA with warming and other stressors are likely to occur [41,42], which can result in even more drastic changes than the ones observed in this study. Fucoids and kelps, globally recognized as key structural and functional elements of marine benthic ecosystems [43], are in decline, with some local extinctions already documented [44]. Our results suggest an enhancement of the populations of these habitat-forming fleshy algae under acidified conditions, and especially of kelps at mesophotic depths.…”

Facilitation and the niche: implications for coexistence, range shifts and ecosystem functioning

“…in their use of resources) or by the sampling effecta greater probability of including species with strong effects as diversity increases (reviewed in Stachowicz, Bruno & Duffy 2007;Cardinale, Palmer & Collins 2002). Thus, the effects of facilitation on diversity discussed above may have considerable indirect effects on ecosystem functioning, in addition to the direct effects that foundation species often have on ecosystem function (Ellison et al 2005;Crowe et al 2013) by virtue of their high biomass and/or productivity.…”