Figure 5.

Mean red urchin and adult kelp stipe density (±s.e.) for all rocky reef survey sites (a) 2 years before SSWD (2013–2014) and (b) 2 years after SSWD (2015–2016). Point sizes are scaled to the mean biomass of urchins at each site. Dark green circles indicate sites occupied by sea otters; red symbols indicate sites where sea otters are absent. The trophic interactions between species are illustrated for each scenario; solid lines show direct negative interactions, and dashed lines show indirect positive interactions.