Structural complexity governs seagrass acclimatization to depth with relevant consequences for meadow production, macrophyte diversity and habitat carbon storage capacity

Enríquez, S., Olivé, I. , Cayabyab, N. and Hedley, J. D. (2019) Structural complexity governs seagrass acclimatization to depth with relevant consequences for meadow production, macrophyte diversity and habitat carbon storage capacity. Scientific Reports, 9, 14657. (doi: 10.1038/s41598-019-51248-z) (PMID:31601973) (PMCID:PMC6787196)

Abstract

Analyses of the integrated seagrass response to depth support the previously documented low plasticity and consistent shade-adapted leaf physiology of a habitat-builder that dominates well-illuminated reef environments. Two structural responses, "canopy-opening" and "below-ground-mass-depletion", govern the photoacclimatory response and facilitate, respectively, light penetration within the canopy and functional adjustments in whole-plant carbon balances. Conversely, "canopy-closing" may also explain dense canopies formed close to the waterline, as they provide shade and photoprotection to a susceptible leaf physiology under high-light. Canopy light attenuation is primarily regulated by the leaf area index (LAI), which is governed by changes in shoot size and density. Shoot density diminishes non-linearly with depth, while shoot size increases to a maximum followed by a decline. The initial increase in shoot size, which resembles a self-thinning response, increases LAI and meadow production in shallow depths. These seagrass structural adjustments have relevant ecological implications. Canopy-thinning allows macrophyte diversity to increase with depth, while seagrass production and carbon storage diminish exponentially, and are maximal only in a shallow coastal fringe. The results support the universality of plant self-thinning, from phytoplankton to complex canopies, likely the consequence of simple physical laws related to light limitation and pigment self-shading within photosynthetic structures and communities.

• Item Type: Articles
• Additional Information: This work has been supported by the CONACYT (grant-129880) and DGAPA (grant-IN206710) to SE. Two fellowships from the Mexican Secretaría de Relaciones Exteriores to NC, and from the Spanish Asociación Universitaria Iberoamericana de Postgrado to IO provided financial support to visit SE laboratory in Mexico.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Olive Samarra, Dr Irene
• Authors: Enríquez, S., Olivé, I., Cayabyab, N., and Hedley, J. D.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Scientific Reports
• Publisher: Nature Research
• ISSN: 2045-2322
• ISSN (Online): 2045-2322
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Scientific Reports 9(1):14657
• Publisher Policy: Reproduced under a Creative Commons License