scholarly journals Response to Comment on Trophic strategy and bleaching resistance in reef-building corals

2021 ◽  
Vol 7 (23) ◽  
pp. eabi8666
Author(s):  
Inga E. Conti-Jerpe ◽  
Philip D. Thompson ◽  
Cheong Wai Martin Wong ◽  
Nara L. Oliveira ◽  
Nicolas N. Duprey ◽  
...  
Keyword(s):  
Improve Method ◽  
Coral Species ◽  
Risk Of Bias ◽  
Algal Symbionts ◽  
Trophic Strategy ◽  
Novel Method ◽  
Symbiotic Organisms ◽  
Scientific Questions ◽  
Trophic Niches

Recently, we published a novel method used to assess the trophic niches of different coral species and demonstrated that their nutrition varied considerably, with some species highly dependent on their photosynthetic algal symbionts and others able to feed on plankton to meet energetic requirements. Adjustments to the use of this tool are necessary when it is applied to other scientific questions and symbiotic organisms. We respond to a comment highlighting a risk of bias in the methods, discuss suggested adjustments, and propose further refinements to improve method robustness.

scholarly journals An updated assessment of Symbiodinium that associate with common scleractinian corals from Moorea (French Polynesia) reveals high diversity among background symbionts and a novel finding of clade B.

2016 ◽  
Author(s):  
Héloïse Rouzé ◽  
Gaël J Lecellier ◽  
Denis Saulnier ◽  
Serge Planes ◽  
Yannick Gueguen ◽  
...  
Keyword(s):  
Coral Species ◽  
French Polynesia ◽  
Molecular Tools ◽  
Quantitative Real Time Pcr ◽  
Algal Symbionts ◽  
Clade B ◽  
Highly Sensitive ◽  
Low Levels ◽  
First Time ◽  
High Diversity

The adaptative bleaching hypothesis (ABH) states that depending on the symbiotic flexibility of coral hosts (i.e., the ability of corals to “switch” or “shuffle” their algal symbionts), coral bleaching can lead to a change in the composition of their associated Symbiodinium community, and, thus, contribute to the coral’s overall survival. In order to determine the flexibility of corals, molecular tools are required to provide accurate species delineations, and to detect low levels of coral-associated Symbiodinium. Here, we used highly sensitive quantitative (real-time) PCR (qPCR) technology to analyse five common coral species from Moorea (French Polynesia), previously screened using only traditional conventional molecular methods, to assess the presence of low-abundance (background) Symbiodinium. Similar to other studies, each coral species exhibited a strong specificity to a particular clade, irrespective of the environment. In addition, however, each of the five species harboured at least one additional Symbiodinium clade, among clades A-D, at background levels. Unexpectedly, and for the first time in French Polynesia, clade B was detected as a coral symbiont. These results increase the number of known coral-Symbiodinium associations from corals found in French Polynesia, and likely indicate an underestimation of the ability of the corals in this region to associate with and/or “shuffle” different Symbiodinium clades. Altogether our data suggest that corals from French Polynesia may manage a trade-off between optimizing symbioses with a specific Symbiodinium clade(s), and maintaining associations with particular background clades that may play a role in the ability of corals to respond to environmental change.

scholarly journals Variation in susceptibility among three Caribbean coral species and their algal symbionts indicates the threatened staghorn coral, Acropora cervicornis, is particularly susceptible to elevated nutrients and heat stress

2021 ◽  
Author(s):  
Ana M. Palacio-Castro ◽  
Caroline E. Dennison ◽  
Stephanie M. Rosales ◽  
Andrew C. Baker
Keyword(s):  
Heat Stress ◽  
Coral Species ◽  
Coral Cover ◽  
Photochemical Efficiency ◽  
Acropora Cervicornis ◽  
Nutrient Inputs ◽  
Algal Symbionts ◽  
Algal Symbiont ◽  
Orbicella Faveolata ◽  
Significant Mortality

Coral cover is declining worldwide due to multiple interacting threats. We compared the effects of elevated nutrients and temperature on three Caribbean corals: Acropora cervicornis, Orbicella faveolata, and Siderastrea siderea. Colonies hosting different algal types were exposed to either ambient nutrients (A), elevated NH4 (N), or elevated NH4 + PO4 (N+P) at control temperatures (26 °C) for > 2 months, followed by a 3-week thermal challenge (31.5 °C). A. cervicornis hosted Symbiodinium (S. fitti) and was highly susceptible to the combination of elevated nutrients and temperature. During heat stress, A. cervicornis pre-exposed to elevated nutrients experienced 84%-100% mortality and photochemical efficiency (Fv/Fm) declines of 41-50%. In comparison, no mortality and lower Fv/Fm declines (11-20%) occurred in A. cervicornis that were heat-stressed but not pre-exposed to nutrients. O. faveolata and S. siderea response to heat stress was determined by their algal symbiont community and was not affected by nutrients. O. faveolata predominantly hosted Durusdinium trenchii or Breviolum, but only corals hosting Breviolum were susceptible to heat, experiencing 100% mortality, regardless of nutrient treatment. S. siderea colonies predominantly hosted Cladocopium C1 (C. goreaui), Cladocopium C3, D. trenchii, or variable proportions of Cladocopium C1 and D. trenchii. This species was resilient to elevated nutrients and temperature, with no significant mortality in any of the treatments. However, during heat stress, S. siderea hosting Cladocopium C3 suffered higher reductions in Fv/Fm (41-56%) compared to S. siderea hosting Cladocopium C1 and D. trenchii (17-26% and 10-16%, respectively). These differences in holobiont susceptibility to elevated nutrients and heat may help explain historical declines in A. cervicornis starting decades earlier than other Caribbean corals. Our results suggest that tackling only warming temperatures may be insufficient to ensure the continued persistence of Caribbean corals, especially A. cervicornis. Reducing nutrient inputs to reefs may also be necessary for these iconic coral species to survive.

scholarly journals Conduction block of mammalian myelinated nerve by local cooling to 15–30°C after a brief heating

2016 ◽  
Vol 115 (3) ◽  
pp. 1436-1445 ◽  
Author(s):  
Zhaocun Zhang ◽  
Timothy D. Lyon ◽  
Brian T. Kadow ◽  
Bing Shen ◽  
Jicheng Wang ◽  
...  
Keyword(s):  
Striated Muscle ◽  
Conduction Block ◽  
Local Cooling ◽  
Myelinated Nerve ◽  
Axonal Conduction ◽  
Novel Method ◽  
Myelinated Nerves ◽  
Block Temperature ◽  
Scientific Questions ◽  
Urethral Striated Muscle

This study aimed at understanding thermal effects on nerve conduction and developing new methods to produce a reversible thermal block of axonal conduction in mammalian myelinated nerves. In 13 cats under α-chloralose anesthesia, conduction block of pudendal nerves ( n = 20) by cooling (5–30°C) or heating (42–54°C) a small segment (9 mm) of the nerve was monitored by the urethral striated muscle contractions and increases in intraurethral pressure induced by intermittent (5 s on and 20 s off) electrical stimulation (50 Hz, 0.2 ms) of the nerve. Cold block was observed at 5–15°C while heat block occurred at 50–54°C. A complete cold block up to 10 min was fully reversible, but a complete heat block was only reversible when the heating duration was less than 1.3 ± 0.1 min. A brief (<1 min) reversible complete heat block at 50–54°C or 15 min of nonblock mild heating at 46–48°C significantly increased the cold block temperature to 15–30°C. The effect of heating on cold block fully reversed within ∼40 min. This study discovered a novel method to block mammalian myelinated nerves at 15–30°C, providing the possibility to develop an implantable device to block axonal conduction and treat many chronic disorders. The effect of heating on cold block is of considerable interest because it raises many basic scientific questions that may help reveal the mechanisms underlying cold or heat block of axonal conduction.

scholarly journals Comment on Trophic strategy and bleaching resistance in reef-building corals

2021 ◽  
Vol 7 (23) ◽  
pp. eabd9453
Author(s):  
Martin Thibault ◽  
Anne Lorrain ◽  
Fanny Houlbrèque
Keyword(s):  
Stable Isotope ◽  
Environmental Changes ◽  
Risk Of Bias ◽  
Trophic Strategy

In an era of major environmental changes, understanding corals’ resistance to bleaching is as crucial as it is challenging. A promising framework for inferring corals’ trophic strategies from Stable Isotope Bayesian Ellipses has been recently proposed to this end. As a contribution to this framework, we quantify a risk of bias inherent in its application and propose three alternative adjustments.

scholarly journals Ecological factors rather than barriers to dispersal shape genetic structure of algal symbionts in horizontally-transmitting corals

2016 ◽  
Author(s):  
SW Davies ◽  
FC Wham ◽  
MR Kanke ◽  
MV Matz
Keyword(s):  
Genetic Structure ◽  
Host Species ◽  
Coral Species ◽  
Spatial Scales ◽  
Horizontal Transmission ◽  
Ecological Factors ◽  
Local Environment ◽  
Transmission Strategy ◽  
Algal Symbionts ◽  
Genetic Structures

AbstractMany reef-building corals acquire their algal symbionts (Symbiodinium sp.) from the local environment upon recruitment. This horizontal transmission strategy where hosts pair with locally available symbionts could serve to increase coral fitness across diverse environments, as long as hosts maintain high promiscuity and symbionts adapt locally. Here, we tested this hypothesis in two coral species by comparing host and symbiont genetic structures across different spatial scales in Micronesia. Each host species associated with two genetically distinct Symbiodinium lineages, confirming high promiscuity in broadly dispersing hosts. However, contrary to our initial expectation, symbiont genetic structure was independent of physical barriers to dispersal between islands, unlike genetic structure of their hosts that was nearly perfectly explained by ocean currents. Instead, Symbiodinium consistently demonstrated genetic divergence among local reefs and between the two host species at each island, although not necessarily between distant islands. These observations indicate that Symbiodinium lineages disperse much more broadly than previously thought and continuously adapt to specific hosts and reef environments across their range, following the classical Baas Becking’s hypothesis: “Everything is everywhere, but the environment selects”. Overall, our findings confirm that horizontal transmission could be a mechanism for broadly dispersing coral species to enhance their local fitness by associating with locally adapted symbionts. Dramatic differences in factors driving the genetic structures of horizontally-transmitting corals and their Symbiodinium imply that viewing their combined genomes as a single entity (‘hologenome’) would not be useful in the context of their evolution and adaptation.

scholarly journals Multi-indicator evidence for habitat use and trophic strategy segregation of two sympatric forms of Arctic char from the Cumberland Sound region of Nunavut, Canada

2021 ◽  
Author(s):  
Kendra Lyn Ulrich ◽  
Ross F. Tallman
Keyword(s):  
Fatty Acid ◽  
Stable Isotope ◽  
Trophic Niche ◽  
Arctic Char ◽  
Trophic Levels ◽  
Fatty Acid Profiles ◽  
Δ13c And Δ15n ◽  
Sympatric Forms ◽  
Trophic Strategy ◽  
Trophic Niches

We analyzed Arctic Char stable isotope ratios and fatty acid composition from two geographically proximal Nunavut lakes, Qasigiyat and Iqalugaarjuit, to determine if anadromous and resident Arctic char occupied different trophic niches. Resident Arctic char had lower δ13C and δ34S, indicative of a freshwater feeding, compared to anadromous individuals. Significantly lower δ15N of residents suggests the ecotypes feed at different trophic levels. Significantly wider δ13C and δ15N ranges in residents implied a broader trophic niche or a wider range in baseline prey isotope values. Results also provide further evidence for resident use of the estuarine environment in Qasigiyat. Immature Arctic char occupy a different trophic niche than both resident and anadromous fish within Iqalugaarjuit, but this relationship is less clear in Qasigiyat. Distinct stable isotope and fatty acid profiles indicate that resident and anadromous Arctic char have distinct trophic niches, marine for anadromous, freshwater for resident. Immature Arctic char seem to occupy a distinct niche from both anadromous and resident fish, which likely relates to use of both freshwater and estuarine environments, depending on developmental stage. We show the first evidence of the fatty acid differences and niche segregation between sympatric anadromous and resident ecotypes in Arctic Char.

scholarly journals Trophic strategy and bleaching resistance in reef-building corals

2020 ◽  
Vol 6 (15) ◽  
pp. eaaz5443 ◽  
Author(s):  
Inga E. Conti-Jerpe ◽  
Philip D. Thompson ◽  
Cheong Wai Martin Wong ◽  
Nara L. Oliveira ◽  
Nicolas N. Duprey ◽  
...  
Keyword(s):  
Thermal Tolerance ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Coral Host ◽  
Nitrogen Stable Isotope ◽  
Polyp Size ◽  
Carbon And Nitrogen ◽  
Algal Symbionts ◽  
Trophic Strategy

Ocean warming increases the incidence of coral bleaching, which reduces or eliminates the nutrition corals receive from their algal symbionts, often resulting in widespread mortality. In contrast to extensive knowledge on the thermal tolerance of coral-associated symbionts, the role of the coral host in bleaching patterns across species is poorly understood. Here, we applied a Bayesian analysis of carbon and nitrogen stable isotope data to determine the trophic niche overlap between corals and their symbionts and propose benchmark values that define autotrophy, heterotrophy, and mixotrophy. The amount of overlap between coral and symbiont niche was negatively correlated with polyp size and bleaching resistance. Our results indicated that as oceans warm, autotrophic corals lose their competitive advantage and thus are the first to disappear from coral reefs.

scholarly journals An updated assessment ofSymbiodiniumspp. that associate with common scleractinian corals from Moorea (French Polynesia) reveals high diversity among background symbionts and a novel finding of clade B

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2856 ◽  
Author(s):  
Héloïse Rouzé ◽  
Gaël J. Lecellier ◽  
Denis Saulnier ◽  
Serge Planes ◽  
Yannick Gueguen ◽  
...  
Keyword(s):  
Coral Species ◽  
French Polynesia ◽  
Molecular Tools ◽  
Quantitative Real Time Pcr ◽  
Algal Symbionts ◽  
Clade B ◽  
Highly Sensitive ◽  
Low Levels ◽  
First Time ◽  
High Diversity

The adaptative bleaching hypothesis (ABH) states that, depending on the symbiotic flexibility of coral hosts (i.e., the ability of corals to “switch” or “shuffle” their algal symbionts), coral bleaching can lead to a change in the composition of their associatedSymbiodiniumcommunity and, thus, contribute to the coral’s overall survival. In order to determine the flexibility of corals, molecular tools are required to provide accurate species delineations and to detect low levels of coral-associatedSymbiodinium. Here, we used highly sensitive quantitative (real-time) PCR (qPCR) technology to analyse five common coral species from Moorea (French Polynesia), previously screened using only traditional molecular methods, to assess the presence of low-abundance (background)Symbiodiniumspp. Similar to other studies, each coral species exhibited a strong specificity to a particular clade, irrespective of the environment. In addition, however, each of the five species harboured at least one additionalSymbiodiniumclade, among clades A–D, at background levels. Unexpectedly, and for the first time in French Polynesia, clade B was detected as a coral symbiont. These results increase the number of known coral-Symbiodiniumassociations from corals found in French Polynesia, and likely indicate an underestimation of the ability of the corals in this region to associate with and/or “shuffle” differentSymbiodiniumclades. Altogether our data suggest that corals from French Polynesia may favor a trade-off between optimizing symbioses with a specificSymbiodiniumclade(s), maintaining associations with particular background clades that may play a role in the ability of corals to respond to environmental change.

scholarly journals An updated assessment of Symbiodinium that associate with common scleractinian corals from Moorea (French Polynesia) reveals high diversity among background symbionts and a novel finding of clade B.

2016 ◽  
Author(s):  
Héloïse Rouzé ◽  
Gaël J Lecellier ◽  
Denis Saulnier ◽  
Serge Planes ◽  
Yannick Gueguen ◽  
...  
Keyword(s):  
Coral Species ◽  
French Polynesia ◽  
Molecular Tools ◽  
Quantitative Real Time Pcr ◽  
Algal Symbionts ◽  
Clade B ◽  
Highly Sensitive ◽  
Low Levels ◽  
First Time ◽  
High Diversity

The adaptative bleaching hypothesis (ABH) states that depending on the symbiotic flexibility of coral hosts (i.e., the ability of corals to “switch” or “shuffle” their algal symbionts), coral bleaching can lead to a change in the composition of their associated Symbiodinium community, and, thus, contribute to the coral’s overall survival. In order to determine the flexibility of corals, molecular tools are required to provide accurate species delineations, and to detect low levels of coral-associated Symbiodinium. Here, we used highly sensitive quantitative (real-time) PCR (qPCR) technology to analyse five common coral species from Moorea (French Polynesia), previously screened using only traditional conventional molecular methods, to assess the presence of low-abundance (background) Symbiodinium. Similar to other studies, each coral species exhibited a strong specificity to a particular clade, irrespective of the environment. In addition, however, each of the five species harboured at least one additional Symbiodinium clade, among clades A-D, at background levels. Unexpectedly, and for the first time in French Polynesia, clade B was detected as a coral symbiont. These results increase the number of known coral-Symbiodinium associations from corals found in French Polynesia, and likely indicate an underestimation of the ability of the corals in this region to associate with and/or “shuffle” different Symbiodinium clades. Altogether our data suggest that corals from French Polynesia may manage a trade-off between optimizing symbioses with a specific Symbiodinium clade(s), and maintaining associations with particular background clades that may play a role in the ability of corals to respond to environmental change.

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