Dwarf eelgrass (Zostera noltii) leaf fatty acid profile during a natural restoration process: Physiological and ecological implications

Abstract

A B S T R A C TSeagrass beds are among the most relevant ecosystem engineers, providing essential ecosystem services for the surrounding coastal communities. Alongside, these ecosystems are among the most threaten in the world, and thus several restoration projects have been developed in the past years. Seagrasses are important sources of essential fatty acids (FA) for animals, which are unable to synthetize them. During the seagrass growth and photochemical maturation, there is a membrane remodelling, where some fatty acids are synthetized. When analysing the FA changes at different development stages, one of the first noticeable changes is the increase in C16:1t (trans-hexadecenoic acid), associated to an increase in the chloroplast membrane fluidity, essential for the efficient energy transduction processes to occur in the thylakoids. Also, interesting to observe are the high levels of omega-3 and -6 (30-43% and 18-31% of total fatty acid content, respectively) present in this seagrass, reinforcing the nutritional value of this species as source of essential fatty acids for the primary consumers. Additionally, it is possible to observe that in the more mature plants there is a high leaf concentration of C18:3. Recent reports suggest that C18:3 can act as a direct scavenger of reactive oxygen species (ROS), indicating a lower stress level, as suggested by the higher photochemical efficiency previously observed. Moreover, it is also interesting to observe that total long-chain polyunsaturated fatty acids (LC-PUFAs) content show a significant increase with the biomass development. These LC-PUFAs are not produced by higher plants and their production in animals occurs at low rates, suggesting they may have as origin the microalgae in the grass surface, adding another important ecosystem service to these prairies, as support for microalgae development and carriers of LC-PUFAs into the food web.This membrane remodelling appears to be on the basis of the photochemical maturation of these seagrasses observed in previous studies and can be used as potential and efficient tool to monitor the development stage of the prairies and its physiological status in future restoration processes. Moreover, it becomes evident that highly developed seagrass beds are crucial food source providers in terms of essential fatty acids to the estuarine heterotrophic life.

LipidTOX: A fatty acid-based index efficient for ecotoxicological studies with marine model diatoms exposed to legacy and emerging contaminants

“…As above mentioned, diatoms are also a source of essential fatty acids (Jónasdóttir, 2019). Additionally, fatty acids have also proved to be a suitable source of biomarkers towards environmental stresses (Duarte et al, 2018c;Duarte et al, 2019a;Duarte et al, 2020d;Feijão et al, 2020c) but also of contaminant exposure, especially in marine diatoms (Cruz de Carvalho et al, 2020c;Duarte et al, 2020b;Feijão et al, 2020a;Franzitta et al, 2020;Silva et al, 2020a). This reinforces the potential of integrating these very important molecules from these key organisms into an unifying index, that can be further applied in risk assessment and ecotoxicological studies.…”

“…One of the most relevant compounds that phytoplankton make available to the rest of the trophic web are fatty acids, namely long-chain polyunsaturated fatty acids (LC-PUFA) (Jónasdóttir, 2019). Fatty acids have been proved to be a suitable source of biomarkers towards environmental stresses (Duarte et al, 2018c;Duarte et al, 2019a;Duarte et al, 2020d;Feijão et al, 2020c) including contaminant exposure, especially in marine diatoms (Cruz de Carvalho et al, 2020c;Feijão et al, 2020a;Franzitta et al, 2020;Silva et al, 2020a). However, fatty acid profiles constitute a dataset composed of several quantitative variables that are not of easy understanding by a non-expert audience.…”

Sources of variability in seagrass fatty acid profiles and the need of identifying reliable warming descriptors

“…With the aim of evaluating the potential sources of variability in seagrass leaf FA composition at different environmental conditions, we realized that only relatively few studies have investigated variations in FA composition along natural environmental gradients 34 , 46 , 47 , while the majority have been conducted in mesocosms with artificial induced changes. Remodelling in FA profiles related to a heat stress, such as a reduction in PUFA, in total Fatty acids, and an increase in SFA 34 , 47 , is connected to the healthy functioning of photosynthetic activity, and consequently, to the plant resilience to the environmental changes.…”

“…Furthermore, the material collected for analyses is often inconsistent for seagrasses, even within samples belonging to the same species: most authors referred to generic leaf biomass of the same shoot both in Posidonia oceanica and Zostera noltii (e.g. 47 , 48 . and 49 , 50 respectively), while recently only young leaves were considered (e.g.…”