Tipping points in saltmarshes – the scramble for high land

Ms Peri Coleman1, Ms Faith Coleman2

1Delta Environmental Consulting, St Kilda, Australia, 2EcoProTem, Tintinara, Australia

Abstract

Recent studies in South Australia have revealed a significant loss of the shrubby samphire, Tecticornia arbuscula, from coastal saltmarshes. Field observations suggested that SA saltmarshes are reaching a “tipping point” in relation to sea level rise, and that the loss of shrubby samphire is only one of many ecological changes that may soon become apparent.

Until recently, modelled habitat retreat scenarios have tended to simply relocate existing habitats, containing all the species presently found in them, upslope. Our observations suggest that the component species within a habitat vary widely in their adaptation mechanisms and these mechanisms are likely to result in altered species compositions within “migrated” habitats.

As an example, the adaptation mechanisms of four species (Avicennia marina, Sarcocornia quinqueflora, Tecticornia arbuscula and Tecticornia halocnemoides) are presented, to highlight the intricate competitive pressures that are likely to alter the character of our coastal saltmarshes as they adapt to sea level rise. While these four species occur at the lowest elevations of the saltmarshes, the impacts of increased tidal flooding are evident in the higher marsh as well. There is a paucity of information on adaptive mechanisms used by saltmarsh plant species and this prevents any meaningful predictions on likely habitat change. Research on a number of species would be useful, and in this regard several species that have been observed to have changing distribution patterns within saltmarshes are brought forward as fruitful for research.

Biography

Peri Coleman (M AppSc – Environmental Management and Restoration) has extensive experience in identifying marine and terrestrial flora and fauna of the mainland states and Tasmania, conducting biological surveys, and producing reports and educational materials. Peri owns, and is senior consultant for, Delta Environmental Consulting. She is a member of the South Australian Coast Protection Board and chairs the Jeffries Buckland Park Community Consultation Committee. Peri has a strong commitment to research, with several recent papers accepted for international publication. She is a fellow of the Royal Society of South Australia and member of the International Society for Salt Lake Research.