A most unusual barrens: Complex interactions between lobsters, seaurchins and algae facilitates spread of an exotic kelp in eastern Tasmania

摘要: Sea urchin (Heliocidaris erythrogramma) 'barrens' in central eastern Tasmania differ from typical barrens elsewhere that they seasonally support dense cover of the introduced kelp Undaria pinnatifida. Sporophytes this establish stands only when native algal canopy is reduced, and experimental removal algae results greatly increased U. pinnatifida sediment. Urchin barrens are integral to widespread establishment because grazing sediment on barrens prevents canopy-forming from colonizing, but insufficient prevent proliferation of U. pinnatifida. Estimates population growth situ rates lobster predation on urchins reveal fishing lobsters can account for increases densities, ostensibly levels enabling barrens formation. Lobsters far more important predators H. erythrogramma than fishes. Thus, fishing of rock may ultimately area.