Journal of Marine Sciences / 2012 / Article / Fig 2

Research Article

Kelp Forests versus Urchin Barrens: Alternate Stable States and Their Effect on Sea Otter Prey Quality in the Aleutian Islands

Figure 2

Relative frequency distributions of sea urchins (Strongylocentrotus polyacanthus) collected in remnant kelp forest and urchin barren communities in the central and western Aleutian Islands. Relative frequency percentages are determined using counts from sea urchins in kelp forests ( 𝑛 = 3 0 8 ) and urchin barrens ( 𝑛 = 4 5 6 9 ). The dotted line indicates the minimum size threshold for sea otter predation on urchins (30 mm).