Variation in flexural, morphological, and biochemical leaf properties of eelgrass (Zostera marina) along the European Atlantic climate regions
Seagrasses need to withstand hydrodynamic forces; therefore, mechanical properties such as flexibility or breaking resistance are beneficial for survival. The co-variation of leaf breaking properties with biochemical traits in seagrasses has been documented, but it is unknown if the same patterns apply to leaf flexural properties. To interpret changes in the ecological function of seagrass ecosystems based on acclimation responses to environmental changes, it is necessary to understand the factors that affect flexural leaf properties. Here, morphological and flexural leaf properties of the perennial type of Zostera marina across different environmental conditions along European Atlantic climate regions are presented together with C:N ratio and neutral detergent fibre content as descriptors of biochemical leaf composition. Eelgrass leaves from cold regions were ~ threefold more elastic and ~ tenfold more flexible, were also narrower (1.7-fold), and contained ~ 1.9-fold higher fibre content than from plants growing in warmer regions. Eelgrass also showed acclimation to local conditions such as seasonality, water depth, and hydrodynamic exposure. Leaves collected from exposed or shallower locations or during winter were more flexible, suggesting an avoidance strategy to hydrodynamic forcing, which is generally higher under those conditions. Flexural rigidity was almost equally controlled by bending modulus (35%) and leaf thickness (37%), indicating functional differences compared to leaf breaking described in the literature. Overall, the findings indicate that Zostera marina has a high flexural plasticity and high acclimation capacity to some climate change effects such as sea level rise and increase in storm frequency and intensity.
We are thankful to C. Barañano and E. Fernández-Suárez from the University of Vigo (Spain) and to A. Silva, J. Silva and M. Costa, from the Center of Marine Sciences of Algarve (Portugal), for collecting samples and providing abiotic data. F. Kanzler and the SeaArt team is thanked for collecting the samples in Lübeck bay and E. Infantes assisted in sample collection at the Swedish locations and transport to the Centre of Marine Science of Algarve for further processing. R. Santos is thanked for his kindly financial contribution to the chemical analysis. MP acknowledges funding by the German Science Foundation (Grant No. PA 2547/1-1) and by the Royal Swedish Academy of Sciences (KVA travel grant). This study received Portuguese national funds from FCT—Foundation for Science and Technology through project UID/Multi/04326/2019 and through fellowship SFRH/BPD/119344/2016 granted to CBS.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The collection of seagrass specimen for this study was conducted under permission from the respective authorities. All applicable international, national, and institutional guidelines for the use of plants were followed.
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