Effect of earthquake and storm disturbances on bull kelp (Durvillaea ssp.) and analyses of holdfast invertebrate communities

• Main Author: Mondardini, Luca
• Format: Other/Unknown Material
• Language: English
• Published: University of Canterbury 2018
• Subjects: Holdfast; New Zealand; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10092/15095; https://doi.org/10.26021/7076

Marine wave-exposed intertidal rocky shores, in the temperate zone, are some of the most productive yet highly stressful biological habitats on earth. In the intertidal zone, marine species experience daily changes in desiccation, temperature and light conditions. Many large canopy-forming seaweeds, including some laminarian kelps and many fucoids, are well-adapted to these conditions, but are typically being limited in their upward distribution on the shore by desiccation tolerances. These rocky shores are also characterized by physical and biological disturbances, such as storm waves, invasions by non-native species and even tectonic events like vertical displacement following earthquakes. Where kelps and large fucoids dominate the biomass, they control and modify ecosystem functions, like productivity, wave attenuation and light levels. Southern bull kelps (Durvillaea spp.), which are actually fucoids, are some of the largest marine habitat formers on earth, often dominating wave exposed intertidal and shallow reefs throughout much of temperate Australasia and South America. Bull kelps support high local primary productivity, attenuate waves and provide food for grazing fish and habitat for invertebrates. A bull kelp is composed of a large holdfast firmly attached to the rocky substratum, a stipe and a flexible buoyant frond. Bull kelp can grow up to 10 m and live up to 10 years. Only a few species live on the stipe and fronds of bull kelp but their large holdfast can provide habitat for many invertebrates. In this thesis I explore, from intertidal reefs along the east coast of the South Island of New Zealand, how bull kelp (Durvillaea poha and D. antarctica) respond to simulated storm disturbances (Chapter 2), how their holdfast provide habitat for invertebrates (Chapter 3), and I describe impacts on bull kelp following a large earthquake and uplift of coastal reefs (Chapter 4). Firstly, I compared bull kelp responses between undisturbed control plots and three simulated disturbance intensities. To simulate ...