Metabolomics and traditional indicators unveil stress of a seagrass (Cymodocea nodosa) meadow at intermediate distance from a fish farm

Abstract

Seasonal variation of structural, physiological and growth indicators and the metabolome of the seagrass Cymodocea nodosa, as well as biogeochemical conditions of underlying sediment were studied in two meadows growing at increasing distance downstream from a fish farm in the Aegean Sea in order to assess seagrass performance under stress. Horizontal rhizome production decreased significantly with proximity to the fish farm (0.67 and 1.57 g DW m-2 d-ACCEPTED MANUSCRIPT 1 close and far from the fish-farm, respectively). This coincided with observed effects on ecophyiological indicators, such as rhizome nitrogen, leaf carbon and leaf δ 13 C, which were elevated with proximity to the fish-farm. Seasonality was shown by some indicators being elevated in either in the warm (C of all tissues and leaf δ 34 S) or the cold period (N of all tissues). Growth promoting metabolites (sucrose, fructose, myo-inositol, heptacosane, tetracosane, stigmasterol, catechin and alpha-tocopherol) were lower close to the zone, whereas metabolites involved with stress-response (alanine, serine, proline, putrescine, ornithine, 3,4dihydroxybenzoic acid and cinnamic acid) were higher. We found that growth-promoting metabolites were positively correlated with horizontal rhizome production, whereas the metabolites related to stress were negatively correlated. Metabolomic fingerprinting of seagrass provides opportunities for early detection of environmental degradation in marine ecological studies.

Sand supplementation favors tropical seagrass Thalassia hemprichii in eutrophic bay: implications for seagrass restoration and management

“…This phenomenon could be attributed to two reasons. First, increased ammonium assimilation was induced by the higher nitrogen content in sediments with smaller particle sizes [22]. Second, the adverse effects of lower oxygen conditions.…”

“…The enhancement of rETR max and Ek ETR may partially offset the negative effects of reduced light irradiance on C balance and improve high light tolerance. In particular, seagrass beds worldwide have faced increased eutrophication caused by a large input of nutrients from anthropogenic activity [4,22,69]. Considering the large variation of seagrass leaf light absorption [70,71], the leaf light absorption needs to be measured.…”

“…Metabolomics has been instrumental in connecting the genotype and phenotype of vascular plants under adverse environmental conditions, and has been applied in seagrass research [19][20][21] providing new insights into diverse cellular pathways to identify stress tolerance biomarkers. Much is known about the effect of environmental stress on the primary metabolites of seagrass [22,23] and the total content of key secondary metabolites [24]. However, little is known about the response of key secondary metabolite compositions by applying targeted metabolomics techniques.…”

“…This failure might be attributed to the desiccation exposure during low tide and sediment composition (mud vs. sand) [29]. Nevertheless, limited studies have considered the effect of sediment type on seagrass physiology [22], especially flavonoids, which are the key secondary metabolites. Flavonoids have been implicated in plant resistance to many stress factors [30].…”

Climate-Friendly Seafood: The Potential for Emissions Reduction and Carbon Capture in Marine Aquaculture

“…Coastal mariculture operations can impact seagrass ecosystems through direct disturbance or shading, leading to losses of up to half the sediment carbon stock (Lovelock et al 2017 , Trevathan-Tackett et al 2018 ). In addition, localized nutrient enrichment commonly associated with fed finfish mariculture causes metabolic stress and reduced seagrass growth (de Kock et al 2020 ), poor recruitment (Díaz-Almela et al 2008 ), and, ultimately, seagrass loss around pens (e.g., Delgado et al 1999 , Ruiz et al 2001 , Herbeck et al 2014 , Cullain et al 2018 , Thomsen et al 2020 ), leading to decreases in both stored blue carbon and ongoing sequestration potential (Apostolaki et al 2011 , Jiang et al 2018 , Liu et al 2020 ).…”