Biology subjects

Sawall, Y.

Publications and source records attributed to Sawall, Y..

3 recordsLinked to original sources

bioRxiv2026

Improving coral oxidative stress assessments through compartment-specific lipid peroxidation measurements and increased methodological standardization

Lipid peroxidation (LPO) is widely used as a biomarker of oxidative stress in coral bleaching research, yet its measurement remains poorly standardized across the field. A systematic review of the coral LPO literature reveals substantial variation in methodological approaches, including tissue fraction analysis, lysis protocols, assay choice, and normalization metrics, confounding cross-study comparison and obscuring the biological interpretation of results. We experimentally investigate two key sources of variation: the use of bulk holobiont vs separated host and algal symbiont fractions, and the choice of normalization metric. To do so, we used Montastraea cavernosa (n = 6 colonies) exposed to ambient (28 {degrees}C), heat stress (30.5 {degrees}C), and heat stress + artificial upwelling (AU; heat stress intermitted by daily pulses of cooler water, 30.5/27.5 {degrees}C) conditions in a controlled mesocosm experiment. Using a TBARS-based MDA assay with a lysis buffer optimized for coral tissue, we measured LPO separately in coral host and algal symbiont fractions across four time points throughout the day. Host MDA remained stable across all treatments and time points, consistent with either sufficient antioxidant buffering capacity or thermal acclimation over the experimental period. Algal symbiont MDA, in contrast, exhibited pronounced diel and treatment-specific dynamics, and the two fractions responses were decoupled from one another. Normalizing MDA to coral surface area instead of total protein content produced largely consistent diel and treatment patterns, but the two metrics diverged at specific time points, indicating that normalization choice is not interchangeable and can itself affect interpretation. Together, our literature review and empirical results demonstrate that host and algal symbiont LPO dynamics are not comparable when aggregated and argue for host-symbiont fraction separation and consistent, explicitly reported normalization as minimum standards for interpretable and cross-comparable coral LPO measurement.

biochemistry↗

bioRxiv2024

Temperature drives seagrass recovery across the Western North Atlantic

Climate-driven shifts in herbivores, temperature and nutrient runoff threaten coastal ecosystem resilience. However, our understanding of ecological resilience, particularly for foundation species, remains limited due to a rarity of field experiments that are conducted across appropriate spatial and temporal scales and that investigate multiple stressors. This study aimed to evaluate the resilience of a widespread tropical marine plant (turtlegrass) to disturbances across its geographic range and how this is impacted by environmental gradients in (a)biotic factors. We assessed the resilience (i.e. recovery) of turtlegrass to a simulated disturbance (complete above- and belowground biomass removal) over a year. Contrary to temperate studies, higher temperature generally enhanced seagrass recovery. While nutrients and light availability had minimal impact, combined high levels of nutrients and herbivore grazing (meso and megaherbivore) reduced aboveground recovery. Our results suggest that the resilience of some tropical species, especially in cooler subtropical waters, may initially increase with warming.

ecology↗

bioRxiv2018

mtDNA recombination indicative of hybridization suggest a role of the mitogenome in the adaptation of reef building corals to extreme environments

mtDNA recombination following hybridization is rarely found in animals and was never until now reported in reef-building corals. Here we report unexpected topological incongruence among mitochondrial markers as evidence of mitochondrial introgression in the phylogenetic history of Stylophora species distributed along broad geographic ranges. Our analyses include specimens from the Indo-Pacific, the Indian Ocean and the full latitudinal (2000 km) and environmental gradient (21{degrees}C-33{degrees}C) of the Red Sea (N=827). The analysis of Stylophora lineages in the framework of the mitogenome phylogenies of the family Pocilloporidae, coupled with analyses of recombination, shows the first evidence of asymmetric patterns of introgressive hybridization associated to mitochondrial recombination in this genus. Hybridization likely occurred between an ancestral lineage restricted to the Red Sea/Gulf of Aden basins and migrants from the Indo-Pacific/Indian Ocean that reached the Gulf of Aden. The resulting hybrid lives in sympatry with the descendants of the parental Red Sea lineage, from which it inherited most of its mtDNA (except a highly variable recombinant region that includes the nd6, atp6, and mtORF genes) and expanded its range into the hottest region of the Arabian Gulf, where it is scarcely found. Noticeably, across the Red Sea both lineages exhibit striking differences in terms of phylogeographic patterns, clades-morphospecies association, and zooxanthellae composition. Our data suggest that the early colonization of the Red Sea by the ancestral lineage, which involved overcoming multiple habitat changes and extreme temperatures, resulted in changes in mitochondrial proteins, which led to its successful adaptation to the novel environmental conditions.

evolutionary biology↗