The ciliated protozoan parasite Cryptocaryon irritans infecting marine fishes in Taiwan is described. Developmental characteristics and sequences of the ribosomal DNA regions such as part of 18 S, the entire first internal transcribed spacer, and part of 5.8 S of various Taiwan isolates of C. irritans were investigated. A total of 5 isolates was obtained from different fish-host species and localities, the majority from cultured fish species. C. irritans from Taiwan is able to shift its developmental characteristics, i.e. from non-adherent to adherent tomonts, from individualistic to aggregateforming tomonts, from infection of the gills only to infection of the gills and body. Thus, it is not possible to classify strains of C. irritans on the basis of these parameters. Premature tomonts that developed from dead fishes were able to produce theronts that could infect fish host. Isolates from Pingtung and the USA had identical nucleotide sequences while an isolate from Malaysia was identical to an Israel isolate. Percentage variation among pairs of Taiwan isolates showed a higher degree of variation than isolate sequences listed in GenBank. Sequence analysis revealed highly aberrant isolates in Taiwan, and a phylogenetic tree distinguished a marine and a low-salinity variant. C. irritans from marine fishes in Taiwan, therefore, display some characteristics not previously reported. Since manipulation of salinity in brackishwater ponds and marine cage sites is not feasible, there is a need to develop new strategies for the control and prevention of cryptocaryoniasis.

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Fish identification is generally challenging because of their unpronounced and overlapping morphological characters which is true in grouper species. In the Philippines, an updated, reliable and accurate inventory of this high value commercial groupers has not been carried out previously. Using molecular tools in the identification and inventory of fish species in the country is confined to few laboratories and experts in the country. In this study, 27 species of the Serranidae family were identified from the grouper samples collected from major fish landing sites and markets in the Philippines. The grouper species were molecularly identified using the cytochrome c oxidase I (COI) sequences for DNA barcoding. The accuracy of the inferred species-level taxonomy based on COI is supported with high similarity search (98-100%) both in BOLD and BLAST, well-distributed genetic distance values and cohesive clustering in the Neighbor-Joining Tree. Aside from reinforcing the classical methodology of grouper identification in the country, this pioneering study on molecular identification of Philippine groupers constitutes a significant contribution to the DNA barcode library of Philippine marine fishes and to the global barcode entries in general, which can be used when dealing with grouper taxonomy, biodiversity, stock assessment and trade. The results reveal the different localities where the grouper species can be possibly sourced out in the country for trade and aquaculture purposes. Several of the grouper species are included in the IUCN Red List of Threatened Species. As a tool for conservation ecology, this study signals the implementation of sustainable fisheries management regulation to protect in particular those which are listed under the IUCN.

Anguilla japonica and Anguilla marmorata share overlapping spawning sites, similar drifting routes, and comparable larval durations. However, they exhibit allopatric geographical distributions in East Asia. To clarify this ecological discrepancy, glass eels from estuaries in Taiwan, the Philippines, Indonesia, and China were collected monthly, and the survival rate of A. marmorata under varying water salinities and temperatures was examined. The composition ratio of these 2 eel species showed a significant latitude cline, matching the 24°C sea surface temperature isotherm in winter. Both species had opposing temperature preferences for recruitment. A. marmorata prefer high water temperatures and die at low water temperatures. In contrast, A. japonica can endure low water temperatures, but their recruitment is inhibited by high water temperatures. Thus, A. japonica glass eels, which mainly spawn in summer, are preferably recruited to Taiwan, China, Korea, and Japan by the Kuroshio and its branch waters in winter. Meanwhile, A. marmorata glass eels, which spawn throughout the year, are mostly screened out in East Asia in areas with low-temperature coastal waters in winter. During summer, the strong northward currents from the South China Sea and Changjiang River discharge markedly block the Kuroshio invasion and thus restrict the approach of A. marmorata glass eels to the coasts of China and Korea. The differences in the preferences of the recruitment temperature for glass eels combined with the availability of oceanic currents shape the real geographic distribution of Anguilla japonica and Anguilla marmorata, making them “temperate” and “tropical” eels, respectively.

Anguilla luzonensis, a recently identified tropical Anguilla species, was categorized as 'Near Threatened' in the International Union for Conservation of Nature (IUCN) Red List in 2014. However, its biogeographic distribution and dispersal mechanism remain unconfirmed. This study aimed to clarify the biotic and abiotic factors that may shape the eel's dispersal range, which could help to establish suitable conservation strategies. Glass eel distribution was investigated in Taiwan, Luzon, Mindanao, and Sulawesi. A. marmorata was used as a reference eel species for comparison. Although both species were found year-round, A. marmorata was found in all locations and was abundant at most sites. However, A. luzonensis was concentrated only on Luzon Island, mainly between June and October. It was rarely observed in Taiwan and Mindanao, and was not found in Sulawesi. The spawning site of A. luzonensis is probably located more northward in the North Equatorial Current (NEC), whereby the eel larvae avoid entering the Mindanao Current (MC). In addition, A. luzonensis typically spawns between February and May, and is preferentially transported into the Kuroshio from May to August, when the NEC bifurcation latitude reaches its southernmost position and the Kuroshio transport volume peaks. Furthermore, A. luzonensis has a shorter/narrower range of larval duration than A. marmorata, and its dispersal distance is therefore restricted. The life history traits of A. luzonensis, together with the oceanic current regime, may act together to concentrate its biogeographic distribution on Luzon Island.

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ABSTRACT--Attempts were made to cultivate Cryptocaryon irritans in vitro atAttachment of theronts and subsequent enlargement into trophonts were achieved in two experi ments using strips of trypticase soy agar (TSA, supplemented with 3% NaCl) as an attachment substrate in filtered seawater.In the third experiment, transformation of theronts into trophonts was achieved in an enriched liquid medium composed of 50% filtered seawater, 30% Leibovitz L-15 and 20% fetal calf serum without attachment onto the TSA. Sizes (mean of the trophonts, 114.6were from a recorded size range (50 to 700 vivo. Although only limited numbers of theronts (0.28-1.71%) transformed into trophonts, these results showed that the in vitro culture of C. irritans is potentially feasible as evidenced by the enlargement of the trophonts within the in vivo size range using either a solid medium as an attach ment substrate or a liquid medium without attachment.There is a need, however, to determine essential factors that influence the transformation of the trophonts into viable tomonts capable of producing theronts.

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