Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea

Pappas, Melissa; He, Song; Hardenstine, Royale S.; Kanee, Hana; Berumen, Michael L.

doi:10.1007/s12526-017-0715-2

Cited by 22 publications

(30 citation statements)

References 67 publications

(94 reference statements)

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“…DeBoer and collaborators [10] showed that giant clams that harbor Symbiodinium (formerly known as "clade A"), a typical temperature-and light-resistant algal genus in corals, are more sensitive to thermal and light stress than those that harbor Cladocopium. This result is, however, inconsistent with a recent report on tridacnids of the Red Sea, where Symbiodinium was found as the unique algal genus in clams that lived in high temperature and salinity conditions [16]. The role and potential flexibility of the Symbiodiniaceae assemblage of giant clams need clarification in order to better understand the threats and adaptive capacity of these important reef organisms.…”

Section: Introductioncontrasting

confidence: 87%

“…While Tridacna crocea is predominantly associated with one algal genus at a time (Symbiodinium, Cladocopium, or, less frequently, Durusdinium), Tridacna squamosa and Tridacna maxima typically harbor multiple genera simultaneously [10,11], except in the Red Sea where they exclusively associate with Symbiodinium spp. [16]. This species-specific symbiosis with Symbiodiniaceae can be disrupted by environmental change that-similar to corals-can lead the expulsion or apoptosis of the photosynthetic symbionts [17][18][19][20] and cause clam bleaching and, subsequently, death.…”

Section: Introductionmentioning

confidence: 99%

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Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

et al. 2020

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Background: Giant clams and scleractinian (reef-building) corals are keystone species of coral reef ecosystems. The basis of their ecological success is a complex and fine-tuned symbiotic relationship with microbes. While the effect of environmental change on the composition of the coral microbiome has been heavily studied, we know very little about the composition and sensitivity of the microbiome associated with clams. Here, we explore the influence of increasing temperature on the microbial community (bacteria and dinoflagellates from the family Symbiodiniaceae) harbored by giant clams, maintained either in isolation or exposed to other reef species. We created artificial benthic assemblages using two coral species (Pocillopora damicornis and Acropora cytherea) and one giant clam species (Tridacna maxima) and studied the microbial community in the latter using metagenomics. Results: Our results led to three major conclusions. First, the health status of giant clams depended on the composition of the benthic species assemblages. Second, we discovered distinct microbiotypes in the studied T. maxima population, one of which was disproportionately dominated by Vibrionaceae and directly linked to clam mortality. Third, neither the increase in water temperature nor the composition of the benthic assemblage had a significant effect on the composition of the Symbiodiniaceae and bacterial communities of T. maxima. Conclusions: Altogether, our results suggest that at least three microbiotypes naturally exist in the studied clam populations, regardless of water temperature. These microbiotypes plausibly provide similar functions to the clam host via alternate molecular pathways as well as microbiotype-specific functions. This redundancy in functions among microbiotypes together with their specificities provides hope that giant clam populations can tolerate some levels of environmental variation such as increased temperature. Importantly, the composition of the benthic assemblage could make clams susceptible to infections by Vibrionaceae, especially when water temperature increases.

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Section: Introductioncontrasting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

et al. 2020

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“…The composition of these associated algal symbionts might therefore also impact the susceptibility to (high) light levels, as different genera of Symbiodiniaceae (in symbiosis) exhibit different physiological and ecological patterns, including sensitivity to light and temperature (Rowan et al, 1997;Berkelmans and Van Oppen, 2006). However, a previous study on Red Sea giant clams and their associated Symbiodiniaceae (Pappas et al, 2017) reports that T. maxima in the region exclusively associated with Symbiodinium spp. (previously clade A), which was thus assumed to represent an optimal group for the local environmental conditions.…”

Section: Light-dependent Calcification and Production In Red Sea Gianmentioning

confidence: 99%

Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>

et al. 2019

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Abstract. Tropical giant clams of the subfamily Tridacninae, including the species Tridacna maxima, are unique among bivalves as they live in a symbiotic relationship with unicellular algae and generally function as net photoautotrophs. Light is therefore crucial for these species to thrive. Here we examine the light dependency of calcification rates of T. maxima in the central Red Sea as well as the patterns of its abundance with depth in the field. Red Sea T. maxima show the highest densities at a depth of 3 m with 0.82±0.21 and 0.11±0.03 individuals m−2 (mean ± SE) at sheltered and exposed sites, respectively. Experimental assessment of net calcification (µmol CaCO3 cm−2 h−1) and gross primary production (µmol O2 cm−2 h−1) under seven light levels (1061, 959, 561, 530, 358, 244, and 197 µmol quanta m−2 s−1) showed net calcification rates to be significantly enhanced under light intensities corresponding to a water depth of 4 m (0.65±0.03 µmol CaCO3 cm−2 h−1; mean ± SE), while gross primary production was 2.06±0.24 µmol O2 cm−2 h−1 (mean ± SE). We found a quadratic relationship between net calcification and tissue dry mass (DM in gram), with clams of an intermediate size (about 15 g DM) showing the highest calcification. Our results show that the Red Sea giant clam T. maxima stands out among bivalves as a remarkable calcifier, displaying calcification rates comparable to other tropical photosymbiotic reef organisms such as corals.

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“…Giant clams on shallow reefs allow for the establishment of a diverse in-situ reservoir of interacting fungal, bacterial, and micro-algal communities (Baker 2003;Neo et al 2015 (Baillie et al 2000;DeBoer et al 2012;Ikeda et al 2017;Ikeda et al 2016;Pappas et al 2017;Trench et al 1981). Similar to coral symbiosis, it is assumed that the genotypic composition of Symbiodiniaceae in giant clams is influenced by environmental or physical parameters (e.g.…”

Section: Paving the Way For Comprehensive Biodiversity Assessment Of mentioning

confidence: 99%

Peer Review #3 of "Towards an in-depth characterization of Symbiodiniaceae in tropical giant clams via metabarcoding of pooled multi-gene amplicons (v0.2)"

2019

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High-throughput sequencing is revolutionizing our ability to comprehensively characterize freeliving and symbiotic Symbiodiniaceae, a diverse dinoflagellate group that plays a critical role in coral reef ecosystems. Most studies however, focus on a single marker for metabarcoding Symbiodiniaceae, potentially missing important ecological traits that a combination of markers may capture. In this proof-of-concept study, we used a small set of symbiotic giant clam (Tridacna maxima) samples obtained from nine French Polynesian locations and tested a dual-index sequence library preparation method that pools and simultaneously sequences multiple Symbiodiniaceae gene amplicons per sample for in-depth biodiversity assessments. The rationale for this approach was to allow the metabarcoding of multiple genes without extra costs associated with additional single amplicon dual indexing and library preparations. Our results showed that the technique effectively recovered very similar proportions of sequence reads and dominant Symbiodiniaceae clades among the three pooled gene amplicons investigated per sample, and captured varying levels of phylogenetic resolution enabling a more comprehensive assessment of the diversity present. The pooled Symbiodiniaceae multi-gene metabarcoding approach decribed here is readily scalable, offering considerable analytical cost savings while providing sufficient phylogenetic information and sequence coverage.

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Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea

Abstract: Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea.

Cited by 22 publications

References 67 publications

Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>

Peer Review #3 of "Towards an in-depth characterization of Symbiodiniaceae in tropical giant clams via metabarcoding of pooled multi-gene amplicons (v0.2)"

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Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea

Abstract: Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea.

Cited by 22 publications

References 67 publications

Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Light-dependent calcification in Red Sea giant clam &lt;i&gt;Tridacna maxima&lt;/i&gt;

Peer Review #3 of "Towards an in-depth characterization of Symbiodiniaceae in tropical giant clams via metabarcoding of pooled multi-gene amplicons (v0.2)"

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Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>