MEPS 587:105-115 (2018)  -  DOI: https://doi.org/10.3354/meps12406

ABSTRACT: In the 1930s, the wasting disease pathogen Labyrinthula zosterae is believed to have killed 90% of the temperate seagrass Zostera marina in the Atlantic Ocean. Despite the devastating impact of this disease, the host-pathogen interaction is still poorly understood, and few field studies have investigated factors correlating with the prevalence and abundance of L. zosterae. The present study measured wasting disease in natural populations of Z. marina on the Swedish west coast, and showed a strong correlation between the disease and both salinity and water depth. No infection was detected in Z. marina shoots from low-salinity (13-25 PSU) meadows, whereas most shoots carried the disease in high-salinity (25-29 PSU) meadows. Shallow (1 m) living Z. marina shoots were also more infected compared to shoots in deeper (5 m) meadows. In addition, infection and transplantation experiments showed that Z. marina shoots from low-salinity meadows with low pathogen pressure were more susceptible to L. zosterae infection. The higher susceptibility could not be explained by lower content of inhibitory defense compounds in the shoots. Instead, extracts from all Z. marina shoots significantly reduced pathogen growth, suggesting that Z. marina contains inhibitory compounds that function as a constitutive defense. Overall, the results show that seagrass wasting disease is common in natural Z. marina populations in the study area and that it increases with salinity and decreases with depth. Our findings also suggest that low-salinity areas can act as a refuge against seagrass wasting disease.

KEY WORDS: Labyrinthula zosterae · Eelgrass · Chemical defense · Host-pathogen interaction · Infection · Transplantation

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Cite this article as: Jakobsson-Thor S, Toth GB , Brakel J, Bockelmann AC, Pavia H (2018) Seagrass wasting disease varies with salinity and depth in natural Zostera marina populations. Mar Ecol Prog Ser 587:105-115. https://doi.org/10.3354/meps12406 Export citation Share:    Facebook - - linkedIn