Competition between the species was asymmetrical and, in both species, per capita effect of competition was stronger from H. ulvae than from H. ventrosa, regardless of sediment type.
We examined the potential for a trait-mediated indirect interaction (TMII), whereby a behavioural response to a predator (crab Cancer borealis) alters the per capita effect of a reacting species (sea urchin Strongylocentrotus droebachiensis) on its algal food (kelp Saccharina latissima), in field and laboratory experiments.
In contrast, plant ecologists have demonstrated that α, the per capita effect of neighbors, may respond to the abiotic environment.
Second, climate change could alter the per capita effects of these heterospecifics on the focal species.
Instead, our experiment focuses on whether changes in precipitation alter the per capita effects of competition, α.
We tested for the fixed effects of treatment, status and their interaction on digging (poisson distribution, log-link, scaling parameter adjusted using the deviance method), entering the number of individuals observed as a covariate, to arrive at per capita effects.
We tested for the fixed effects of treatment (medium or large predator), status and their interaction on attacks (poisson distribution, log-link, scaling parameter adjusted using the deviance method), entering the number of individuals observed as a covariate, to arrive at per capita effects.
In the medium and long terms, GDP per capita effects, however, become negative (−£20 and −£47 respectively) as efficiency measures with longer repayment periods are introduced (including solid wall insulation and glazing replacement).
8 The GDP per capita effects of the household energy scenario are initially positive (£2) as relatively cheap insulation and ventilation investment in the initial phases yields proportionally high gains in efficiency (Table 2).
First, because we found little evidence that altered precipitation will modify per capita competitive effects, indirect effects of climate change are more likely to be caused by changes in the composition of the resident community.
When modelled in combination with GDP per capita, the effect of this variable keeps its significance, but the main effect of GDP per capita becomes not significant.
