Environmental Stress, Chemical Defences and Disease in the Habitat Forming Kelp Ecklonia Radiata

Over the last few decades, the negative impact of environmental stress on marine systems, such as global climate change or environmental pollution, has become more prevalent. The impacts of such anthropogenic factors are particularly important when habitat-forming species, such as kelp, are affected. Near Sydney, coastal development and urbanisation, and rising ocean surface temperatures caused by the further South penetration of the East Australian Current can cause potential stress to the surrounding marine life.

These environmental changes have been associated with emerging diseases and there are predictions that increases in environmental stress may lead to a general increase of disease in marine habitats. There is some global evidence supporting this prediction for corals, sea grasses and seaweeds.  In particular, in the local red seaweed Delisea Pulchra environmental stress leads to decrease in chemical defences which facilitate infection by pathogenic bacteria.  Such chemical defences are generally important for the interaction of organisms with their environment, and their loss can affect interactions with natural enemies ranging from herbivores to pathogens to fouling organisms.

In this project, Rebecca Neumann of UNSW Australia – SIMS 2011 Thyne Reid Doctoral Fellowship tested whether environmental stressors (changes in temperature, pollutants) will affect chemical defence and microbial communities on kelp, leading to a greater incidence of disease. Further examining the effects of any resulting disease on the health and performance of seaweeds. Using habitat-forming kelp Ecklonia Radiata as a model species.  E. Radiata is the most abundant seaweed on sub tidal rocky reefs of Australia and New Zealand where it forms highly productive and species-rich ecosystems. These experiments will be conducted in the field along the coast of Sydney accompanied by controlled laboratory assays.

This research should help make predictions, and determine underlying mechanisms, regarding the susceptibility of this key habitat forming macroalga to environmental stress.

Ecklonia Radiata

Habitat-forming kelp Ecklonia Radiata. Photo credit: Rebecca Neumann.