AUTHOR=Richards Christina L. , Langanke Kristen L. , Mounger Jeannie , Fox Gordon A. , Lewis David B. 

TITLE=Trait Response to Nitrogen and Salinity in Rhizophora mangle Propagules and Variation by Maternal Family and Population of Origin

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.756683

DOI=10.3389/fmars.2021.756683

ISSN=2296-7745

ABSTRACT=Many coastal foundation plant species thrive across a range of environmental conditions, often displaying dramatic phenotypic variation in response to environmental variation. We characterized the response of propagules from six populations of the foundation species Rhizophora mangle L. to full factorial combinations of two levels of salinity (15 ppt and 45 ppt) reflecting the range of salinity measured in the field populations, and two levels of nitrogen (N; no addition and amended at approximately 3 mg N per pot each week) equivalent to comparing ambient N to a rate of addition of 75 kg per hectare per year. The response to increasing salinity included significant changes, i.e. phenotypic plasticity, in succulence and root to shoot biomass allocation. Propagules also showed plasticity in maximum photosynthetic rate and root to shoot allocation in response to N amendment, but the responses depended on the level of salinity and varied by population of origin. Generally, survival was lower in high salinity and high N, but the impact varied among populations. Overall, this study revealed significant phenotypic plasticity in response to salinity and N level. Propagules from different populations and maternal families within populations differed in all traits measured except photosynthesis. Variation in phenotypic plasticity and propagule survival in R. mangle may contribute to adaptation to a complex mosaic of environmental conditions and response to climate change.