Rising Temperature Is a More Important Driver Than Increasing Carbon Dioxide Concentrations in the Trait Responses of Enhalus acoroides Seedlings

Abstract

Increasing temperature and CO2 concentration are among the most important factors affecting marine ecosystems under climate change. We investigated the morphological, biochemical, and physiological trait responses of seedlings of the tropical seagrass Enhalus acoroides under experimental conditions. Trait responses were greater under temperature effects than increasing CO2 concentration. Seedlings under rising temperatures showed enhanced leaf growth, lower leaf nutrient content, and stimulated down-regulating mechanisms in terms of photo-physiology. Increasing CO2 concentrations did not show any significant effects independently. There was a significant interaction for some of the trait responses considered, such as leaf number and carbon content in the roots, and trends of higher starch concentrations in the leaves and lower rETRmax under combined enriched CO2 and high temperature, even though none of these interactions were synergistic. Understanding the single and interactive trait responses of seagrass seedlings to increasing temperature and CO2 concentration is of importance to determine the relative responses of early life stages of seagrasses, which may differ from adult plants, in order to form a more holistic view of seagrass ecosystem health under climate change.

A trait-based framework for seagrass ecology: Trends and prospects

“…This can be illustrated using the example of temperature. An increase in temperature within the optimal range fosters leaf growth ( Thalassia hemprichii : Viana et al., 2020 ; Enhalus acoroides : Artika et al., 2020 ) and leaf size ( Z. marina : Young Kim and Seob Choi, 2004 ; Ondiviela Eizaguirre et al., 2018 ; DuBois et al., 2019 ; Halodule wrightii : Sordo et al., 2011 ; Zostera noltei : Ondiviela Eizaguirre et al., 2018 ; T. hemprichii : Viana et al., 2020 ; Cymodocea serrulata : Viana et al., 2020 ; E. acoroides : Artika et al., 2020 ; Artika et al., 2021 ; Zostera capensis : Beltrand et al., 2022 ). However, when the optimal temperature for a species is surpassed, heat stress reduces these two traits ( Posidonia oceanica : Traboni et al., 2018 ; Halophila ovalis : Ontoria et al., 2020 , Halophila stipulacea : Viana et al., 2020 ).…”

Optimizing Seagrass Detection in Lampung Selatan: Leveraging Machine Learning Algorithms and Sentinel-2A Imagery

“…The distinctive root and leaf characteristics of E. acoroides help in the identification and understanding of this species. Knowledge of these characteristics is important in ecological studies and management of seagrass meadow ecosystems, as it allows for the identification and monitoring of E. acoroides populations within the studied environment [28].…”

How Does Ocean Acidification Affect the Early Life History of Zostera marina? A Series of Experiments Find Parental Carryover Can Benefit Viability or Germination

“…A major concern for bed establishment from seeds is that CO 2 availability increased germination but did not statistically increase seedling production nor survival. For Posidonia oceanica seedlings, CO 2 enrichment increases the rate of the dark reaction in photosynthesis resulting in increased growth and storage capacity, carbon reserves in the below-ground tissues and lowered nitrogen content in leaves (Artika et al, 2021). Direct effects of CO 2 may be masked by epiphytic growth, herbivory, or simultaneously co-occurring heat or light stress.…”