{"title":"Differential strategies developed by two light-dependent scleractinian corals to extend their vertical range to mesophotic depths","authors":"Gonzalo Pérez-Rosales, Héloïse Rouzé, Michel Pichon, Pim Bongaerts, Nelly Bregere, Jérémy Carlot, Valeriano Parravicini, Laetitia Hédouin","doi":"10.1007/s00338-024-02544-2","DOIUrl":null,"url":null,"abstract":"<p>Mesophotic coral ecosystems are characterised by the presence of photosynthetic scleractinian corals despite the decreasing amounts of light available with depth. To better understand physiological strategies across a broad depth gradient, we studied the biological trait responses of <i>Pocillopora</i> cf. <i>verrucosa</i> from 6 to 60 m depth and <i>Pachyseris “speciosa”</i> spp. from 20 to 90 m depth at four islands of French Polynesia. Specifically, we characterised associated Symbiodiniaceae communities, photophysiological traits (Symbiodiniaceae density and chlorophyll concentrations), micro-morphology and trophic plasticity (autotrophy vs heterotrophy inferred from stable isotopes). Our results showed that both taxa can live at mesophotic depths without significant genetic structuring in their generic Symbiodiniaceae communities, mainly composed of <i>Cladocopium</i> and <i>Durusdinium</i>. Yet, the prevalence of Symbiodiniaceae ITS2 profiles revealed location-based variations that sometimes interact with depth and highlight putative shallow- or depth-tolerant taxa. For both taxa, symbiont density and chlorophyll pigment concentrations increased with increasing depth. We also found a change in their skeletal micro-morphology with an increase in the inter-corallite distance for <i>Pocillopora</i> cf. <i>verrucosa</i> and a decrease in the height of septa for <i>Pachyseris “speciosa”</i> spp. with depth. Finally, we found no isotopic evidence of switching to a more heterotrophic diet as their primary energy source, although host–tissue δ<sup>13</sup>C ratios became more negative with depth in both corals. Overall, our findings show similarity (across the two species) and species-specific strategies (biological trait patterns with increasing depth) underlying the capacity of symbiotic scleractinian corals to live in low-light environments.</p>","PeriodicalId":10821,"journal":{"name":"Coral Reefs","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Coral Reefs","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1007/s00338-024-02544-2","RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MARINE & FRESHWATER BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Mesophotic coral ecosystems are characterised by the presence of photosynthetic scleractinian corals despite the decreasing amounts of light available with depth. To better understand physiological strategies across a broad depth gradient, we studied the biological trait responses of Pocillopora cf. verrucosa from 6 to 60 m depth and Pachyseris “speciosa” spp. from 20 to 90 m depth at four islands of French Polynesia. Specifically, we characterised associated Symbiodiniaceae communities, photophysiological traits (Symbiodiniaceae density and chlorophyll concentrations), micro-morphology and trophic plasticity (autotrophy vs heterotrophy inferred from stable isotopes). Our results showed that both taxa can live at mesophotic depths without significant genetic structuring in their generic Symbiodiniaceae communities, mainly composed of Cladocopium and Durusdinium. Yet, the prevalence of Symbiodiniaceae ITS2 profiles revealed location-based variations that sometimes interact with depth and highlight putative shallow- or depth-tolerant taxa. For both taxa, symbiont density and chlorophyll pigment concentrations increased with increasing depth. We also found a change in their skeletal micro-morphology with an increase in the inter-corallite distance for Pocillopora cf. verrucosa and a decrease in the height of septa for Pachyseris “speciosa” spp. with depth. Finally, we found no isotopic evidence of switching to a more heterotrophic diet as their primary energy source, although host–tissue δ13C ratios became more negative with depth in both corals. Overall, our findings show similarity (across the two species) and species-specific strategies (biological trait patterns with increasing depth) underlying the capacity of symbiotic scleractinian corals to live in low-light environments.
期刊介绍:
Coral Reefs, the Journal of the International Coral Reef Society, presents multidisciplinary literature across the broad fields of reef studies, publishing analytical and theoretical papers on both modern and ancient reefs. These encourage the search for theories about reef structure and dynamics, and the use of experimentation, modeling, quantification and the applied sciences.
Coverage includes such subject areas as population dynamics; community ecology of reef organisms; energy and nutrient flows; biogeochemical cycles; physiology of calcification; reef responses to natural and anthropogenic influences; stress markers in reef organisms; behavioural ecology; sedimentology; diagenesis; reef structure and morphology; evolutionary ecology of the reef biota; palaeoceanography of coral reefs and coral islands; reef management and its underlying disciplines; molecular biology and genetics of coral; aetiology of disease in reef-related organisms; reef responses to global change, and more.