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National Committee on Marine Sciences (NCMS)

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    Restriction site-associated DNA sequencing reveals local adaptation despite high levels of gene flow in Sardinella lemuru (Bleeker, 1853) along the northern coast of Mindanao, Philippines
    Labrador, Kevin; Palermo, Joseph Dominic; Agmata, Altair; Ravago-Gotanco, Rachel; Pante, Ma. Josefa (Frontiers Media SA, 2022-02-24)
    Stock identification and delineation are important in the management and conservation of marine resources. These were highlighted as priority research areas for Bali sardinella (Sardinella lemuru) which is among the most commercially important fishery resources in the Philippines. Previous studies have already assessed the stocks of S. lemuru between Northern Mindanao Region (NMR) and Northern Zamboanga Peninsula (NZP), yielding conflicting results. Phenotypic variation suggests distinct stocks between the two regions, while mitochondrial DNA did not detect evidence of genetic differentiation for this high gene flow species. This paper tested the hypothesis of regional structuring using genome-wide single nucleotide polymorphisms (SNPs) acquired through restriction site-associated DNA sequencing (RADseq). We examined patterns of population genomic structure using a full panel of 3,573 loci, which was then partitioned into a neutral panel of 3,348 loci and an outlier panel of 31 loci. Similar inferences were obtained from the full and neutral panels, which were contrary to the inferences from the outlier panel. While the full and neutral panels suggested a panmictic population (global FST ∼ 0, p > 0.05), the outlier panel revealed genetic differentiation between the two regions (global FST = 0.161, p = 0.001; FCT = 0.263, p < 0.05). This indicated that while gene flow is apparent, selective forces due to environmental heterogeneity between the two regions play a role in maintaining adaptive variation. Annotation of the outlier loci returned five genes that were mostly involved in organismal development. Meanwhile, three unannotated loci had allele frequencies that correlated with sea surface temperature. Overall, our results provided support for local adaptation despite high levels of gene flow in S. lemuru. Management therefore should not only focus on demographic parameters (e.g., stock size and catch volume), but also consider the preservation of adaptive variation.
    We would like to acknowledge the assistance provided by Ma. Rio Naguit, Asuncion De Guzman, Jerry Garcia, Jhunrey Follante, Joshep Mercene, and John Christopher Azcarraga in sample collection and initial processing. We also acknowledge the research staff of the Marine Molecular Ecology and Evolution Laboratory (MMEEL), as well as the Marine Genomics and Molecular Genetics Laboratory (MGMGL) and its head, Arturo Lluisma, for providing valuable input in the conduct of the experiment and analysis of the data. Finally, we extend our gratitude to Demian Willette, Laura David, and Jonas Quilang for their valuable feedback on the manuscript.
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    Co-occurrence of a marine heatwave and a reported tomato jellyfish (Crambione mastigophora Maas, 1903) bloom in March 2020 at El Nido, Palawan, Philippines
    Quilestino-Olario, Raven; Concolis, Brenna Mei M.; Atup, Dale Patrick D.; Cortes, Aiza; Yñiguez, Aletta T.; Edullantes, Brisneve (The Plankton Society of Japan/The Japanese Association of Benthology, 2023-05-31)
    Globally, observations on marine species during marine heatwaves (MHWs) help outline the scope of the MHW’s possible biological effects. In line with this effort, this paper presents a 2020 MHW that coincided with a reported ‘tomato jellyfish’ (Crambione mastigophora Maas, 1903) bloom on 23 March 2020 in the Corong-Corong Bay of Palawan, Philippines. Detecting a moderate MHW from 21 March to 04 April 2020, the analysis of sea surface temperatures revealed that most areas surrounding the bloom site attained their peak positive anomalies on the same day as the reported bloom. Certain physical mechanisms present in the first quarter of 2020 may have played a role in the occurrence of both events: the presence of cyclonic eddies and parallel monsoonal winds alongshore can induce upwelling which promotes biological productivity in surface waters, while the observed weakening of winds have been associated with anomalous warming of the sea surface. Further studies are still highly recommended to determine the exact causes of the jellyfish bloom and what conditions make it more likely to happen during MHWs. However, if the C. mastigophora is hypothetically able to continually bloom amidst warming temperatures, the increasing trend of MHW frequency and intensity in the West Philippine Sea (where the reported bloom site is situated) may consequently yield more future co-occurrences. This paper aims to hopefully contribute to the existing knowledge of possible biological impacts associated with extreme marine events, especially in the Philippine context where both jellyfish blooms and MHWs are understudied.
    The authors would like to express sincere gratitude to the anonymous reviewers whose comments and suggestions helped improve and clarify this manuscript. The authors would also like to thank Mr. Alimar Amor for his permission on the still photos in Figs 1c and 1d from his recorded jellyfish bloom video on 23 March 2020. This paper is also made through the funding of DOST̶ Philippine Council for Industry, Energy, and Emerging Technology Research and Development under the Survey of Heatwaves in the Philippine Seas project (DOST Project No. 9615).