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Rapid invasion of a sponge-dominated deep-reef by Caulerpa scalpelliformis (Chlorophyta) in Botany Bay, New South Wales

Journal Article


Abstract


  • We document the rapid spread of the green alga Caulerpa scalpelliformis (R. Brown ex Turner) C. Agardh following its establishment in Botany Bay. In February 1996 we estimated that this alga occupied at least 0.35 hectares of the substratum within the Bay. Coincident with the increase in algal cover on the deep-reef habitat has been a substantial decline in the cover of sessile invertebrates, predominantly sponges, colonial ascidians and bryozoans. Within 12 months of the appearance of the alga at Inscription Point, random photoquadrats (n = 15) revealed that it had reached an average cover of 56±11% with an estimated average fresh biomass of 5.2±1.1 kg m-2 (±sem). Over the same period the average cover of sessile invertebrates declined from 48 to 23%; a significant change by mixed-model nested ANOVA. No such decline was observed in reference sites at Henry Head at the northern entrance to the Bay. Within 12 months, the alga had spread to an additional location some 300m to the east of the originally monitored location, underscoring its ability to rapidly expand across continuous reef. Moreover, the appearance of small isolated plants at the northern entrance to the Bay, indicates that it is also capable of establishing on non-continuous reef.

Publication Date


  • 1997

Citation


  • Davis, A. R., Roberts, D. E., & Cummins, S. P. (1997). Rapid invasion of a sponge-dominated deep-reef by Caulerpa scalpelliformis (Chlorophyta) in Botany Bay, New South Wales. Austral Ecology, 22(2), 146-150. doi:10.1111/j.1442-9993.1997.tb00653.x

Scopus Eid


  • 2-s2.0-17444363438

Start Page


  • 146

End Page


  • 150

Volume


  • 22

Issue


  • 2

Abstract


  • We document the rapid spread of the green alga Caulerpa scalpelliformis (R. Brown ex Turner) C. Agardh following its establishment in Botany Bay. In February 1996 we estimated that this alga occupied at least 0.35 hectares of the substratum within the Bay. Coincident with the increase in algal cover on the deep-reef habitat has been a substantial decline in the cover of sessile invertebrates, predominantly sponges, colonial ascidians and bryozoans. Within 12 months of the appearance of the alga at Inscription Point, random photoquadrats (n = 15) revealed that it had reached an average cover of 56±11% with an estimated average fresh biomass of 5.2±1.1 kg m-2 (±sem). Over the same period the average cover of sessile invertebrates declined from 48 to 23%; a significant change by mixed-model nested ANOVA. No such decline was observed in reference sites at Henry Head at the northern entrance to the Bay. Within 12 months, the alga had spread to an additional location some 300m to the east of the originally monitored location, underscoring its ability to rapidly expand across continuous reef. Moreover, the appearance of small isolated plants at the northern entrance to the Bay, indicates that it is also capable of establishing on non-continuous reef.

Publication Date


  • 1997

Citation


  • Davis, A. R., Roberts, D. E., & Cummins, S. P. (1997). Rapid invasion of a sponge-dominated deep-reef by Caulerpa scalpelliformis (Chlorophyta) in Botany Bay, New South Wales. Austral Ecology, 22(2), 146-150. doi:10.1111/j.1442-9993.1997.tb00653.x

Scopus Eid


  • 2-s2.0-17444363438

Start Page


  • 146

End Page


  • 150

Volume


  • 22

Issue


  • 2