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National Committee on Marine Sciences (NCMS)

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    The harmful raphidophyte Chattonella (Raphidophyceae) in Western Pacific: Its red tides and associated fisheries damage over the past 50 years (1969–2019)
    Lum, Wai Mun; Benico, Garry; Doan-Nhu, Hai; Furio, Elsa; Leaw, Chui Pin; Leong, Sandric Chee Yew; Lim, Po Teen; Lim, Weol Ae; Lirdwitayaprasit, Thaithaworn; Lu, Songhui; Nguyen, Nguyen Van; Orlova, Tatiana Yu.; Rachman, Arief; Sakamoto, Setsuko; Takahashi, Kazuya; Teng, Sing Tung; Thoha, Hikmah; Wang, Pengbin; Yñiguez, Aletta T.; Wakita, Kazumi; Iwataki, Mitsunori (Elsevier, 2021-07)
    Red tides and associated fisheries damage caused by the harmful raphidophyte Chattonella were reassessed based on the documented local records for 50 years to understand the distribution and economic impacts of the harmful species in the Western Pacific. Blooms of Chattonella with fisheries damage have been recorded in East Asia since 1969, whereas they have been only recorded in Southeast Asia since the 1980s. Occurrences of Chattonella have been documented from six Southeast Asian countries, Indonesia, Malaysia, Philippines, Singapore, Thailand and Viet Nam, with mass mortalities mainly of farmed shrimp in 1980–1990s, and farmed fish in 2000–2010s. These occurrences have been reported with the names of C. antiqua, C. marina, C. ovata, C. subsalsa and Chattonella sp., owing to the difficulty of microscopic species identification, and many were not supported with molecular data. To determine the distribution of C. marina complex and C. subsalsa in Southeast Asia, molecular phylogeny and microscopic observation were also carried out for cultures obtained from Indonesia, Malaysia, Japan, Philippines, Russia, Singapore and Thailand. The results revealed that only the genotype of C. marina complex has been detected from East Asia (China, Japan, Korea and Russia), whereas both C. marina complex (Indonesia and Malaysia) and C. subsalsa (Philippines, Singapore and Thailand) were found in Southeast Asia. Ejection of mucocysts has been recognized as a diagnostic character of C. subsalsa, but it was also observed in our cultures of C. marina isolated from Indonesia, Malaysia, Japan, and Russia. Meanwhile, the co-occurrences of the two harmful Chattonella species in Southeast Asia, which are difficult to distinguish solely based on their morphology, suggest the importance of molecular identification of Chattonella genotypes for further understanding of their distribution and negative impacts.
    We thank Drs Yuuki Kosaka, Winnie Lik Sing Lau, Ing Kuo Law and Toh Hii Tan for their sampling assistances. We thank Dr. Sadaaki Yoshimatsu for providing a culture strain TAI-93, and Drs Mineo Yamaguchi and Haruo Yamaguchi for support on maintenance and rDNA analysis of the culture. This work was carried out under international collaboration of the IOC/WESTPAC-HAB project and Core-to-Core Program (B. Asia-Africa Science Platforms) of the Japan Society for the Promotion of Science (JSPS). This work was partially supported by Japanese JSPS Kakenhi 19H03027 and 19KK0160 (MI), Malaysian MOHE HICOE IOES and FRGS (PTL), Vietnamese VAST NVCC17.02/21-21 (HD-N), and the Japanese Fund-in-Trust (MEXT).
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    Trans-Arctic asymmetries, melting pots and weak species cohesion in the low-dispersal amphiboreal seaweed Fucus distichus
    Neiva, João; Assis, Jorge; Fragkopoulou, Eliza; Pearson, Gareth A.; Raimondi, Peter T.; Anderson, Laura; Krause-Jensen, Dorte; Marbà, Núria; Want, Andrew; Selivanova, Olga; Nakaoka, Masahiro; Grant, W. Stewart; Konar, Brenda; Roleda, Michael Y.; Sejr, Mikael K.; Paulino, Cristina; Serrão, Ester A. (Frontiers Media SA, 2024-04-18)
    Amphiboreal taxa are often composed of vicariant phylogroups and species complexes whose divergence and phylogeographic affinities reflect a shared history of chronic isolation and episodic trans-Arctic dispersal. Ecological filters and shifting selective pressures may also promote selective sweeps, niche shifts and ecological speciation during colonization, but these are seldom considered at biogeographical scales. Here we integrate genetic data and Ecologic Niche Models (ENMs) to investigate the historical biogeography and cohesion of the polymorphic rockweed Fucus distichus throughout its immense amphiboreal range, focusing on trans-Arctic asymmetries, glacial/interglacial dynamics, and integrity of sympatric eco-morphotypes. Populations were sampled throughout the Pacific and the Atlantic, from southern rear-edges to the high-Arctic. They were genotyped for seven microsatellites and an mtDNA spacer, and genetic diversity and structure were assessed from global to local scales. ENMs were used to compare niche divergence and magnitude of post-glacial range shifts in Pacific versus Atlantic sub-ranges. Haplotypic and genotypic data revealed distinct and seemingly isolated Pacific vs Arctic/Atlantic gene-pools, with finer-scale regional sub-structuring pervasive in the Pacific. MtDNA diversity was highly structured and overwhelmingly concentrated in the Pacific. Regionally, Alaska showed the highest intra-population diversity but the lowest levels of endemism. Some sympatric/parapatric ecotypes exhibited distinct genotypic/haplotypic compositions. Strikingly, niche models revealed higher Pacific tolerance to maximum temperatures and predicted a much more consolidated presence in the NE Atlantic. Glacial and modern ranges overlapped extensively in the Pacific, whereas the modern Atlantic range was largely glaciated or emerged during the Last Glacial Maximum. Higher genetic and ecogeographic diversity supports a primary Pacific diversification and secondary Atlantic colonization, also likely reflecting the much larger and more stable climatic refugia in the Pacific. The relic distribution and reduced ecological/morphological plasticity in the NE Atlantic are hypothesized to reflect functional trans-Arctic bottlenecks, recent colonization or competition with congeners. Within the Pacific, Alaska showed signatures of a post-glacial melting pot of eastern and southern populations. Genetic/ecotypic variation was generally not sufficiently discontinuous or consistent to justify recognizing multiple taxonomic entities, but support a separate species in the eastern Pacific, at the southern rear-edge. We predict that layered patterns of phylogeographic structure, incipient speciation and niche differences might be common among widespread low-dispersal amphiboreal taxa.
    The authors thank Marta Valente (CCMAR), André Silva and Diogo Brito for sequencing and genotyping work and all the people involved in sample collection. Samples from Logy Bay were kindly collected by Kyle R. Millar. DK-J and NM thank Hurtigruten’s FRAM cruise for help with sampling along the Greenland west coast. Greenland sampling was also connected with campaigns for the MarineBasis component of the Greenland Ecosystem Monitoring (GEM) Programme in Nuuk and Young Sound, which is acknowledged.