University Of Tasmania
131990 - Physiological response to temperature, light, and nitrates in the giant kelp Macrocystis pyrifera from Tasmania, Australia.pdf (867.31 kB)

Physiological response to temperature, light, and nitrates in the giant kelp Macrocystis pyrifera from Tasmania, Australia

Download (867.31 kB)
journal contribution
posted on 2023-05-20, 02:51 authored by Christopher MabinChristopher Mabin, Craig JohnsonCraig Johnson, Jeffrey WrightJeffrey Wright
Climate change is characterised by multiple abiotic forcings acting simultaneously on biotic systems. In marine systems, temperature appears to drive much of the observed change in biotic communities subject to climate change, but this may reflect the focus of most studies only on temperature without consideration of other environmental variables affected by climate change. The giant kelp Macrocystis pyrifera was once abundant in eastern Tasmania, forming extensive habitats of ecological and economic importance, but recent extensive population decline has occurred. Southerly incursion of warm oligotrophic East Australian Current (EAC) water has increased in frequency and intensity into this region, which has warmed ~4 times the global average, and the warming trend is predicted to continue. This study investigated the single and combined effects of temperature, light, and nitrate availability on the physiology of juvenile M. pyrifera sporophytes in a laboratory experiment. Determination of relative growth rate, photosystem II characteristics, pigments, elemental chemistry, and nucleic acid characteristics over 28 d showed that all experimental factors affected sporeling physiology. Temperature and light drove much of the observed variation related to performance characteristics, and rapid deterioration of kelp tissue was a consequence of temperature stress (high temperature), photoinhibition (high light), and low light, accompanied by impaired photosynthetic efficiency and increased RNA concentration, presumably associated with production of photoprotective proteins. Surprisingly, higher relative growth rates were observed in low-nitrate treatments. These findings suggest that negative effects of temperature on M. pyrifera populations will be mediated by local variation in light and nutrient conditions.


Australian Research Council


Publication title

Marine Ecology Progress Series








Institute for Marine and Antarctic Studies



Place of publication

Nordbunte 23, Oldendorf Luhe, Germany, D-21385

Rights statement

Copyright 2019 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

Repository Status

  • Open

Socio-economic Objectives

Oceanic processes (excl. in the Antarctic and Southern Ocean)