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Correctly delimiting species and populations is a prerequisite for studies of connectivity, adaptation and conservation. Genomic data are particularly useful to test species differentiation for organisms with few informative morphological characters or low discrimination of cytoplasmic markers, as in Scleractinians. Here we applied Restriction site Associated DNA sequencing (RAD-sequencing) to the study of species differentiation and genetic structure in populations of Pocillopora spp. from Oman and French Polynesia, with the objectives to test species hypotheses, and to study the genetic structure among sampling sites within species. We focused here on coral colonies morphologically similar to P. acuta (damicornis type β). We tested the impact of different filtering strategies on the stability of the results. The main genetic differentiation was observed between samples from Oman and French Polynesia. These samples corresponded to different previously defined primary species hypotheses (PSH), i.e., PSHs 12 and 13 in Oman, and PSH 5 in French Polynesia. In Oman, we did not observe any clear differentiation between the two putative species PSH 12 and 13, nor between sampling sites. In French Polynesia, where a single species hypothesis was studied, there was no differentiation between sites. Our analyses allowed the identification of clonal lineages in Oman and French Polynesia. The impact of clonality on genetic diversity is discussed in light of individual-based simulations., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Octocrylene (OC) is an ingredient used in many sunscreens and cosmetics worldwide. Our group evaluated the toxicity of OC in corals. Adult Pocillopora damicornis coral was treated with OC at concentrations of 5, 50, 300, and 1000 μg/L. Most polyps were closed at concentrations of 300 μg/L and higher. Further, metabolomic profiling provided crucial information regarding OC accumulation in coral tissues and OC toxicity. First, we demonstrated that OC was transformed into fatty acid conjugates via oxidation of the ethylhexyl chain, yielding very lipophilic OC analogues that accumulate in coral tissues. Second, the differential analysis of coral profiles revealed higher levels of 15 acylcarnitines, suggesting abnormal fatty acid metabolism related to mitochondrial dysfunction. The formation of OC analogues suggests that OC concentrations measured in the environment, and organisms may have been largely underestimated. Overall, these results call for an in-depth evaluation of OC toxicity and the reevaluation of the actual OC accumulation rate in the ocean's food chain, including OC-fatty acid conjugates.

In this study, we tested the tolerance of tissue balls (TBs, 100-400 μm in diameter) from the coral Pocillopora damicornis produced using mechanical excision to exposure to cryoprotectant (CPA) solutions. TBs were treated for 20 min at room temperature with individual, binary, ternary or quaternary CPA solutions with a total molarity from 2.0 to 5.0M. Four CPAs were used: ethylene glycol (EG), dimethylsulfoxide (Me2SO), methanol (Met) and glycerol (Gly). In some experiments, the molarity of the CPA solutions was increased and decreased in a stepwise manner. The tolerance of TBs following CPA treatment was evaluated using two parameters. The Tissue Ball Regression (expressed in μm/h) measured the diameter regression of TBs over time. The % Undamaged TBs quantified the proportion of TBs, which remained intact over time after the CPA treatment. TBs tolerated exposure to binary solutions with a total molarity of 4.0 M containing 2.0 M EG+2.0 M Met and 2.0 MEG+2.0 M Gly. TBs displayed tolerance to ternary solutions with a total molarity up to 3.0 M, containing each CPA at 1.0 M. Quaternary solutions with a total molarity of 4.0M containing each CPA at 1.0 M were not tolerated by TBs. When the molarity of the CPA solutions was increased and decreased in a stepwise manner, TBs withstood exposure to a CPA solution with a total molarity of 4.5 M, containing 1.5 M EG+1.5 M Gly+1.5 M Me(2)SO. This study confirmed the interest of using TBs to test CPA solutions, with the objective of developing a vitrification-based cryopreservation protocol., (Copyright © 2015 Elsevier Inc. All rights reserved.)

In this study, the tolerance of tissue balls (TBs, 100-300 μm in diameter) from the coral Pocillopora damicornis produced using mechanical excision to exposure to cryoprotectant (CPA) solutions was tested. TBs were treated for 20 min at room temperature with solutions of ethylene glycol (EG), methanol (Met), glycerol (Gly) or dimethyl sulfoxide (Me2SO) at concentrations between 1.0 and 4.5M. Two parameters were used to evaluate the survival of TBs following CPA treatment. The Undamaged Duration of Tissue Balls (expressed in h) corresponded to the time period during which the membrane surface of TBs remained smooth and their motility was preserved. Tissue Ball Regression (expressed in μm/h) corresponded to the size reduction of TBs over time. TBs tolerated exposure to all CPAs tested at the three lower concentrations employed (1.0 M, 1.5 M and 2.0 M). No survival was achieved following exposure to a 4.5 M CPA solution. At concentrations of 3.0 and 4.0 M, higher Undamaged Duration of Tissue Balls and lower Tissue Ball Regression were obtained following treatment with EG compared to the other three CPAs. Our experiments show that TBs constitute a good experimental material to evaluate CPA toxicity on corals using large numbers of samples. Performing preliminary experiments with TBs may allow reducing the number of tests carried out with less easily available coral forms such as planulae, thereby preserving larval stocks., (Copyright © 2014. Published by Elsevier Inc.)

In this study, we investigated the tolerance of Pocillopora damicornis apexes to treatments with solutions containing penetrating and non-penetrating cryoprotective agents (CPAs). CPAs were employed individually or in binary, tertiary or quaternary solutions. In some experiments apexes were treated successively with two CPA solutions with increasing total concentration. P. damicornis apexes withstood exposure for up to 30 min to solutions containing 0.6-0.8 M sucrose (Suc) or trehalose (Tre). When apexes were treated with binary cryoprotectant solutions containing Suc and ethylene glycol (EG), methanol (Meth), dimethyl sulfoxide (Me(2)SO) or glycerol (Gly), the CPAs employed in combination with Suc could be ranked in the following order of decreasing tolerance: EG>Meth>Me(2)SO>Gly. P. damicornis apexes tolerated exposure to complex CPA solutions containing Suc, Me(2)SO, EG and/or Meth with a total molarity of 2.45 M. In experiments where two successive CPA solutions were employed, apexes withstood treatment with the second, more concentrated solution at 0°C for up to 10 min. These preliminary results pave the way to the development of a cryopreservation protocol for P. damicornis apexes., (Copyright © 2014 Elsevier Inc. All rights reserved.)