MEPS 532:101-109 (2015)  -  DOI: https://doi.org/10.3354/meps11343

Combined effect of warming and infection by Labyrinthula sp. on the Mediterranean seagrass Cymodocea nodosa

Ylva S. Olsen1,*, Carlos M. Duarte1,2,3

1The UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia
2Department of Global Change Research. IMEDEA (CSIC-UIB), Institut Mediterrani d’Estudis Avançats, Miquel Marquès 21, 07190 Esporles, Spain
3Faculty of Marine Sciences, King Abdulaziz University, PO Box 80207, Jeddah 21589, Saudi Arabia
*Corresponding author:

ABSTRACT: Global warming is predicted to alter host-pathogen relationships and increase disease outbreaks in terrestrial and marine environments. We evaluated the effect of warming on the susceptibility of Cymodocea nodosa to infection by Labyrinthula sp. (the causative agent of seagrass wasting disease) by monitoring disease symptoms and seagrass photobiology. Seagrass shoots were incubated at temperatures between 24 and 32°C, encompassing maximum summer seawater temperatures projected for the Mediterranean during the 21st century, and exposed to Labyrinthula sp. for 2 wk. The effect of temperature on pathogen growth was also tested by growing Labyrinthula sp. in liquid medium for 24 h. Disease severity, measured as lesion size, decreased with warming, but the presence of lesions had a negative effect on quantum yield, quantum efficiency, optimum irradiance and the maximum electron transport rate (ETRmax) in adjacent tissue across the full range of temperatures. The direct effect of increased temperature on photochemical efficiency was positive in terms of quantum yield, whereas compensation and optimum irradiances and ETRmax decreased slightly with warming. Warming stimulated Labyrinthula sp. growth up to a threshold of around 26 to 28°C, beyond which cell division and elongation of the ectoplasmic network decreased. At 32°C almost no growth was observed. Our results indicate that warming does not make C. nodosa more susceptible to infection by Labyrinthula sp. and that the disease is unlikely to pose a serious threat to C. nodosa, but that the pathogen is able to persist during forecasted warm periods.


KEY WORDS: Wasting disease · Pathogen · Host · Seagrass · Photosynthetic performance · Temperature · Climate change


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Cite this article as: Olsen YS, Duarte CM (2015) Combined effect of warming and infection by Labyrinthula sp. on the Mediterranean seagrass Cymodocea nodosa. Mar Ecol Prog Ser 532:101-109. https://doi.org/10.3354/meps11343

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