Establishment of the introduced kelp Undaria pinnatifida following dieback of the native macroalga Phyllospora comosa in Tasmania, Australia

By J. Valentine, Craig R. Johnson. 2004

122 citations recorded by the source corpus.

The Asian kelp Undaria pinnatifida has recently invaded the coastlines of several countries across both hemispheres. Although the occurrence and subsequent spread of the alga has been well documented, the processes underpinning establishment and spread remain poorly understood. Recent work involving canopy manipulations has demonstrated that disturbance to the native algal canopy facilitates establishment of U. pinnatifida sporophytes at high densities, however, the kelp’s response to a natural disruption of the native algal canopy has not been assessed. In summer/autumn 2001, we examined the response of U. pinnatifida to the significant dieback of a common native canopy forming macroalga (Phyllospora comosa) on the east coast of Tasmania. The response of U. pinnatifida and native algae to the dieback was observed during the season for growth of U. pinnatifida sporophytes (spring 2001) and compared with adjacent areas where dieback did not occur. Undaria pinnatifida sporophytes established at high densities (6.75 ± 1.99 stipes m–2) in dieback areas, but remained rare or entirely absent in control areas where the native canopy was intact. The dieback also resulted in bleaching of encrusting algae and increased cover of understorey algae and sediment. The results support the findings of our recent artificial disturbance experiments, confirming the importance of disturbance events for the successful establishment of U. pinnatifida at high densities.

Subfields: Ecology, Oceanography

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Citations in the corpus

Climate change cascades: Shifts in oceanography, species' ranges and subtidal marine community dynamics in eastern Tasmania (2011, background): “Valentine and Johnson (2004) suggested that an unusual dieback of the shallow sublittoral brown macroalga Phyllospora comosa along the east coast of Tasmania in 2001 may have been in response to above-average seawater temperatures coupled with nutrient stress.”
Climate change and disease: bleaching of a chemically defended seaweed (2011, background): “Algal bleaching is often caused by exposure to high levels of solar radiation (e.g. Scrosati & DeWreede, 1998; Valentine & Johnson, 2004), however, initial observations of this phenomenon in D. pulchra suggest that it is not ‘photo-bleaching’.”
The role of kelp species as biogenic habitat formers in coastal marine ecosystems (2017, background): “…structure of understorey 700 assemblages, but such disturbances can also provide opportunity for the recruitment and growth of 701 non-native species (Valentine and Johnson, 2003), potentially with detrimental effects on the 702 diversity and habitat structure of these systems (Bax et al., 2001).”
A Global Review of the Distribution, Taxonomy, and Impacts of Introduced Seaweeds (2007, background): “In the Tasman Sea, sea urchins cannot keep up with annual growth of Undaria and they actually facilitate its spread by consuming native perennial seaweeds and opening space for settlement (Edgar et al. 2004; Valentine & Johnson 2003, 2005).”
Impacts of climate change in a global hotspot for temperate marine biodiversity and ocean warming (2011, background): “radiata in eastern Tasmania in 2001 was attributed to above-average seawater temperatures coupled with nutrient stress during calm sea conditions (Valentine and Johnson, 2004).”
Recovery of canopy-forming macroalgae following removal of the enigmatic grazing sea urchin Heliocidaris erythrogramma (2010, background): “…caused by the sea urchin consuming canopy-forming brown algae (e.g. Johnson et al., 2004; Shepherd, 1974; Constable, 1989; Connolly, 1986; reviewed by Keesing, 2006), however high sediment loads may also restrict macroalgal growth in such situations (e.g. Valentine and Johnson, 2004, 2005a,b).”
Introduced Macroalgae – a Growing Concern (2006, background): “For example, the establishment of U. pinnatifida in Australia was facilitated by reduced native macroalgal cover (Valentine & Johnson, 2003; 2004).”