Persistence of sea urchin (Heliocidaris erythrogramma) barrens on the east coast of Tasmania: inhibition of macroalgal recovery in the absence of high densities of sea urchins

Abstract

Cover sheet Cover sheet Title Persistence of sea urchin (Heliocidaris erythrogramma) barrens on the east coast of Tasmania: inhibition of macroalgal recovery in the absence of high densities of sea urchins Author Valentine, JP, Craig Johnson Bibliographic citation Bibliographic citation Valentine, JP; Johnson, Craig (2005). Persistence of sea urchin (Heliocidaris erythrogramma) barrens on the east coast of Tasmania: inhibition of macroalgal recovery in the absence of high densities of sea urchins.

Do native grazers from Patagonia, Argentina, consume the invasive kelp Undaria pinnatifida?

“…Our laboratory experiments show that A. dufresnii and P. Magellanicus from Golfo Nuevo actually feed on Undaria, but they are unlikely to play a role in the control of the seaweed because the high rates of recruitment and growth of Undaria, but field experiments using grazer exclosures and enclosures are needed to test this hypothesis. The inability of sea urchins to control Undaria has previously been reported for Heliocidaris erythrogramma in Tasmania (Valentine & Johnson, 2003;Valentine & Johnson, 2005a, b) and is now confirmed in Golfo Nuevo in the present paper. This fact must be taken into account at the time of propose conservation policies for the control of the dispersal of Undaria in the study zone.…”

“…It has been proposed that the successful settlement and dispersal of Undaria would be favored by the presence of disturbed substrata (Valentine & Johnson, 2003;Valentine & Johnson, 2005a, b), but little is known about the factors involved in this disturbance.…”

“…In Tasmania, where Undaria is an invasive species, the sea urchin Heliocidaris erythrogramma has been observed grazing on its blades (Valentine & Johnson, 2003;Valentine & Johnson, 2005a, b). In other parts of the world, preferential feeding on Undaria has been reported for the sea urchins Evechinus chloroticus and Strongylocentrotus nudus, the gastropod Turbo smaragdus, and the crab Pugettia producta , which is known to be associated with kelps (Kittaka et al, 1983;Sinner et al, 2000;Thornber et al, 2004).…”

Stable isotopes reveal a consistent consumer–diet relationship across hundreds of kilometres

“…Understanding geographical variation in the diet of H. erythrogramma is useful because its diet has profound implications for the influence it exerts on rocky reef ecosystems. H. erythrogramma exerts an especially strong influence on rocky reefs in some areas of eastern Australia, where it can denude kelp-dominated ecosystems (Valentine & Johnson 2005, Wright et al 2005, but in southern and western Australia, it generally exerts a minor influence (Connell & Irving 2008).…”

“…Heliocidaris on the eastern coast of Australia apparently exhibits a wider range of feeding behaviour, with evidence that it feeds on drift algae and that it adopts a mobile grazing behaviour (Valentine & Johnson 2005, Wright et al 2005. This latter behaviour is associated with extensive defoliation of kelp forests.…”