Dynamics of Dipsastraea pallida-symbiont association following bleaching events across the northern Persian Gulf and Gulf of Oman

Oladi, Mahshid; Rouzbehani, Soudabeh; Ahmadzadeh, Faraham; Ghazilou, Amir

doi:10.1007/s13199-021-00773-5

Cited by 7 publications

(3 citation statements)

References 59 publications

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“…The ecological and metabolic interactions between coral hosts and their associated bacterial assemblages are believed to be crucial in maintaining the stability and functionality of intact coral holobionts [9]. In order to survive future bleaching events, corals have the ability to increase their chances of recovery by shifting their symbionts (Symbiodiniaceae and bacteria), a mechanism commonly referred to as the adaptive bleaching hypothesis [10].…”

Section: Introductionmentioning

confidence: 99%

The Symbiodiniaceae and Bacterial Dynamic Composition of the Coral Echinopora gemmacea on Wuzhizhou Island

Li,

Zhu

et al. 2023

JMSE

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Coral’s susceptibility to bleaching is determined by the strength of the intricate mutual relationships among coral symbionts. However, there is limited knowledge about how the symbiotic members of the scleractinian coral Echinopora gemmacea respond to changes in their surrounding environmental conditions. In this study, we conducted a survey of seawater characteristics in the south and north zones of Wuzhizhou (WZZ) Island, measured symbiotic microalgal density and chlorophyll-a content in the corals, and performed metabarcoding of the Symbiodiniaceae and bacteria communities within coral tissue. Our findings demonstrated that the seawater in the north zone of WZZ Island had higher levels of turbidity, temperature, salinity, and dissolved oxygen content compared to the south zone. This indicated that the corals in the two zones were subjected to distinctive environmental conditions. Analysis of the Symbiodiniaceae composition revealed that Cladocopium sp. C1 and Cladocopium sp. C17 were the dominant species in the southern E. gemmacea, whereas Durusdinium sp. D1a and Cladocopium sp. C17 prevailed in the northern E. gemmacea. Consequently, symbiotic microalgal density and chlorophyll-a content were diminished in the northern E. gemmacea. Furthermore, correlation network analysis revealed the presence of intricate bacterial interactions that potentially mediate coral’s adaptation to environmental stress. This study provides insights into the differences in symbiotic members, including Symbiodiniaceae and bacteria, within E. gemmacea, and contributes to fundamental knowledge for coral conservation efforts.

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Section: Introductionmentioning

confidence: 99%

The Symbiodiniaceae and Bacterial Dynamic Composition of the Coral Echinopora gemmacea on Wuzhizhou Island

Li,

Zhu

et al. 2023

JMSE

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“…Low abundance Symbiodiniaceae may also confer environmental stress resistance to their host by supplying a source of genomic innovation, enhancing the resilience of host-symbiont communities (Bay et al 2016;Ziegler et al 2018). Studies have proposed that corals may acclimatise or adapt to warmer oceans through rearrangements of symbiont community compositions favouring thermally tolerant species (Buddemeier and Fautin 1993;Baker et al 2004;Berkelmans and Van Oppen 2006;Cunning et al 2018;Claar et al 2020), a phenomenon observed following temperature-induced coral bleaching (Berkelmans and Van Oppen 2006;LaJeunesse et al 2009;Cunning et al 2015;Oladi et al 2021). However, some tolerant symbiont species are considered less compatible with the nutritional needs of their host (Stat and Gates 2011;Pettay et al 2015;Matthews et al 2017;Gabay et al 2018;Sproles et al 2020), and perturbed symbiont communities tend to return to their original composition over time if stress is alleviated (Thornhill et al 2006;Stat et al 2009b;McGinley et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Colony self-shading facilitates Symbiodiniaceae cohabitation in a South Pacific coral community

et al. 2022

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The ecological success of tropical corals is regulated by symbiotic dinoflagellate algae (Symbiodiniaceae). Corals can associate with multiple Symbiodiniaceae species simultaneously, yet the conditions that permit Symbiodiniaceae cohabitation are not understood. We examined how corals self-shade their own tissues causing within-colony light gradients that drive Symbiodiniaceae photoacclimatory processes and positional genetic disparity. Paired light ‘exposed’ and ‘shaded’ samples from 20 coral species were collected from a shallow coral reef (Rarotonga, Cook Islands). Through active chlorophyll fluorometry, rapid light curves revealed that exposed Symbiodiniaceae exhibited 50% higher values in minimum saturating irradiances and demonstrated a shift towards preferential nonphotochemical quenching [1 – Q], consistent with higher overall light exposure. High-throughput or targeted DNA sequencing of ITS2 and psbAncr markers demonstrated that corals harboured distinct and/or differentially abundant Symbiodiniaceae ITS2 sequences (typically rare in relative abundance) or multiple ITS2 intragenomic variant profiles across shaded vs exposed regions. In Hydnophora cf. microconos, within-colony symbiont genetic disparity was positively correlated with the magnitude of difference in [1 – Q] utilisation. Together, these results suggest that within-colony light gradients produce distinct optical niches that enable symbiont cohabitation via photoadaptation, a phenomenon that is expected to increase the adaptive capacity of corals under future climates.

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“…These population shifts, which occur either through switching (Boulotte et al, 2016;Rouzé et al, 2019) or especially shuffling (Baker 2003;Berkelmans and van Oppen 2006;Jones and Berkelmans 2010;Cornwall et al 2023),may occur when corals are thermally stressed and bleach. Many of these studies have detected symbionts from the genus Durusdinium within post-heat-stressed corals (Huang et al, 2020;Kao et al, 2018;Oladi et al, 2021;Williamson et al, 2021). Symbionts from this genus often maintain higher levels of thermal tolerance when in coral hosts and maintain this tolerance when in culture, supporting adaptive bleaching claims (Chen et al, 2020;Dougan et al, 2022;Howells et al, 2020;Palacio-Castro et al, 2023;Strader et al, 2022).…”

Section: The Impacts Of Climate Change On Coral Healthmentioning

confidence: 99%

Partner Switching and Metabolic Carbon Flux under Thermal Stress in the Cnidarian-Dinoflagellate Symbiosis

Heit

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Reef corals depend heavily on their symbiotic relationship with dinoflagellates of the family Symbiodiniaceae, which are their primary source of metabolic energy and hence allow them to survive in oligotrophic tropical seas. The symbiotic relationship between these two partners is exceptionally sensitive to environmental change, however, and global warming is known to induce dysbiosis (i.e., breakdown of the symbiosis) in a process referred to as ‘coral bleaching’. The adaptive bleaching hypothesis posits that the host may acquire a new dominant Symbiodiniaceae species after a bleaching event, either from a shift in the relative abundance of the resident symbionts (‘shuffling’) or the uptake of new symbionts from the environment (‘switching’), better equipping the holobiont (i.e., the whole symbiosis) for the new environmental regime. However, different symbiont types may have different nutritional implications for the coral, potentially limiting the potential for partner shuffling or switching. Energy-rich carbon compounds are primarily provided by the symbiont to their coral host as glucose, glycerol, and lipids. Yet, it is poorly understood how climate change impacts this carbon translocation and how symbiont identity influences the response. This thesis, therefore, addressed this topic, using the sea anemone Exaiptasia diaphana (‘Aiptasia’), a globally adopted model system for the study of the cnidarian-dinoflagellate symbiosis.First, I aimed to quantify and compare pools of carbon-based metabolites under thermal stress in the host and symbiont, focusing on glucose, glycerol, and total carbohydrates (Chapter 2). It was hypothesized that thermal stress (33 °C) would cause a decline in the pools of these various metabolites, likely due to decreased photosynthetic function of the symbiont and carbon translocation to the host, combined with elevated catabolism in the host under thermal stress. Metabolites were measured using a range of commercially available metabolite-specific assay kits. As predicted, total carbohydrates in the symbionts decreased in abundance at high temperature, however, host and symbiont glucose and glycerol pools either remained constant or even increased under thermal stress relative to controls. This latter observation is consistent with gluconeogenesis (i.e., the synthesis of glucose from the likes of glycerol) in response to increased metabolic demands at high temperatures. The increased pools of glycerol, on the other hand, are consistent with the use of this metabolite as an osmolyte or moderator of cellular stress. While the test-kit approach used here was associated with a considerable amount of inter-sample variability, it nevertheless confirmed and added to previous observations gained using much more expensive, technically complex metabolomics methods.I then compared the synthesis and translocation of photosynthates in Aiptasia under low, control, and high temperature (15, 25, 33 oC), when colonized by either Breviolum minutum, which is the only known symbiont of Aiptasia through the Indo-Pacific region (the source of the Aiptasia used here), Durusdinium trenchii or Breviolum psygmophilum (Chapter 3). D. trenchii is a thermally tolerant but opportunistic species not typically associated with Aiptasia, while Breviolum psygmophilum is often associated with temperate and sub-tropical species, including Aiptasia in the western Atlantic Ocean. I hypothesized that B. minutum would translocate more photosynthate to its host at the control temperature but that D. trenchii and B. psygmophilum would out-perform B. minutum at high and low temperatures, respectively. To test this, a radiotracer (NaH14CO3) was used to measure photosynthetic fixation and translocation. Contrary to expectations, anemones hosting D. trenchii bleached completely at both low and high temperatures. However, the population density of B. psygmophilum increased at low temperature relative to B. minutum and controls, and anemones containing B. psygmophilum did not bleach as extensively as those containing B. minutum at high temperature, confirming the reputation of the former as a ‘thermal generalist.’ With respect to carbon metabolism, B. psygmophilum performed similarly or slightly out-performed B. minutum across all temperatures, though both species provided the most nutritional benefit at the low temperature. However, at the high temperature, symbiont density had a major influence on total carbon flux to the host, lessening the impact of bleaching. Specifically, a low symbiont population density facilitated proportionally higher rates of symbiont-cell specific photosynthesis and translocation, presumably due to reduced competition for CO2, such that heat-stressed anemones continued to receive similar amounts of photosynthate to controls.In summary, this thesis demonstrates that both thermal stress and symbiont type impact carbon flux and metabolism in the cnidarian-dinoflagellate symbiosis. Most interestingly, my findings highlight the potential importance for more research on the cellular processes that underlie the physiology of thermal generalists such as B. psygmophilum and the potential for such generalists to aid the adaptation of reef corals to climate change, either through natural processes or the development of tools for coral reef conservation.

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Dynamics of Dipsastraea pallida-symbiont association following bleaching events across the northern Persian Gulf and Gulf of Oman

Cited by 7 publications

References 59 publications

The Symbiodiniaceae and Bacterial Dynamic Composition of the Coral Echinopora gemmacea on Wuzhizhou Island

The Symbiodiniaceae and Bacterial Dynamic Composition of the Coral Echinopora gemmacea on Wuzhizhou Island

Colony self-shading facilitates Symbiodiniaceae cohabitation in a South Pacific coral community

Partner Switching and Metabolic Carbon Flux under Thermal Stress in the Cnidarian-Dinoflagellate Symbiosis

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