Living in the intertidal; desiccation and shading reduce seagrass growth, but high salinity or population of origin have no additional effect
- Published
- Accepted
- Subject Areas
- Ecology, Ecosystem Science, Marine Biology
- Keywords
- Stress, Desiccation, Light, Salinity, Zostera noltii, Intertidal seagrass, population of origin, morphotypic variation, ecotypic variation
- Copyright
- © 2018 Suykerbuyk et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Living in the intertidal; desiccation and shading reduce seagrass growth, but high salinity or population of origin have no additional effect. PeerJ Preprints 6:e26509v1 https://doi.org/10.7287/peerj.preprints.26509v1
Abstract
The limiting effects of stressors like desiccation, light and salinity on seagrass growth and distribution are well-studied. However, little is known about their interactive effects, and such interactive effects might differ among populations that are adapted to different local conditions. In two laboratory experiments we tested a) if growth and development of intertidal, temperate Zostera noltii is affected by emergence time (experiment 1 and 2), and b) how this is affected by an additional, second stressor, namely shading (experiment 1) or high salinity (25, 30 and 35 PSU, experiment 2). In addition, we tested c) whether the effects of emergence time and salinity varied between three different European seagrass populations (Saint-Jacut / France, Oosterschelde / The Netherlands, and Sylt / Germany), which are likely adapted to different salinity levels (experiment 2). In both experiments, emergence of 8 hours per tidal cycle (of 12 hours) had a negative effect on seagrass relative growth rate (RGR), and aboveground biomass. Emergence furthermore reduced either rhizome length (experiment 1) or belowground biomass (experiment 2). Shading (experiment 1) resulted in lower RGR and a two-fold higher above ground / below ground (AG/BG) ratio. We found no interactive effects of emergence and shading stress. Salinity (experiment 2) did not affect seagrass growth or morphology of any of the three populations. The three tested populations differed greatly in morphology but showed no differential response to emergence or salinity level (experiment 2). Our results indicate that the two applied stressors: emergence time (desiccation stress) and shading, simply add-up (no synergistic or antagonistic effect), making the plants still vulnerable to such combination, whereas Z. noltii of different populations seem tolerant to variations in salinity within the tested range. Secondly, our results indicate that the three tested populations show morphotypic rather then ecotypic variation, at least regarding the salinity and emergence, as there were no interactive effects with origin. Intruigingly, North-west European Z. noltii beds generally do not extend downwards to the subtidal, while our study shows that the shorter emergence periods towards the subtidal are more favourable. In our study areas, where light is ample, the lower depth limit may be determined by increasing sediment dynamics.
Author Comment
This is a submission to PeerJ for review.
