The First Report of Eel Larvae Ingesting Rotifers

Tanaka, Hideki; Kagawa, Hirohiko; Ohta, Hiromi; Okuzawa, Koichi; Hirose, Kei

doi:10.2331/fishsci.61.171

Cited by 53 publications

(29 citation statements)

References 3 publications

(2 reference statements)

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“…Most important for understanding the ecology of leptocephali in relation to their larval survival is that they appear to feed on the type of particulate organic material (POM) called marine snow. This has been indicated by observations of their gut contents (Otake et al 1993;Mochioka and Iwamizu 1996;Miller et al 2011a) and their trophic position (Miller et al 2013a) even if small leptocephali may also feed on individual organisms, as has been observed in the laboratory (Tanaka et al 1995) or hypothesized from DNA barcoding of gut contents . Feeding on marine snow that is linked to primary production in the euphotic zone makes it likely that the availability of food for leptocephali is influenced by fluctuations in primary productivity (Knights 2003;Bonhommeau et al 2008aBonhommeau et al , 2008bMiller et al 2016).…”

Section: Introductionmentioning

confidence: 87%

The ecology of oceanic dispersal and survival of anguillid leptocephali

Miller

Tsukamoto

2017

Can. J. Fish. Aquat. Sci.

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Recruitment declines of anguillid eels are difficult to understand because both anthropogenic impacts on juveniles and adults and oceanic changes affecting larval survival or dispersal may be contributing. Anguillid larvae may passively disperse widely from offshore spawning areas but late-stage larvae or glass eels apparently must swim directionally to reach recruitment habitats. Their long larval durations vary among tropical (ϳ3-4 months) and temperate species (5 months to >1 year). The bodies of anguillid leptocephali are filled with transparent gelatinous material, possibly reducing predation rates and providing an energy reserve for swimming and metamorphosis. Leptocephali feed on marine snow making their first-feeding success linked to primary producers contributing to marine snow production. Alternations between ubiquitous cyanobacteria dominating in low-nutrient conditions and eukaryotic phytoplankton such as diatoms that are important for marine snow production dominating in high-nutrient conditions may influence early-larval survival at first-feeding due to many eggs simultaneously hatching within sympatric spawning areas. Fewer spawning eels resulting from population reductions and variations in early-larval survival may offer some explanations for lower and fluctuating recruitment in recent decades.Résumé : Les baisses du recrutement d'anguillidés sont difficiles à comprendre parce que des impacts de l'activité humaine sur les juvéniles et les adultes et des changements océaniques influant sur la survie et la dispersion des larves pourraient y participer. Les larves d'anguillidés peuvent se disperser largement de manière passive à partir de lieux de frai au large, mais les larves tardives ou les civelles doivent apparemment nager de manière directionnelle pour atteindre les habitats de recrutement. Leurs longues périodes larvaires sont différentes pour les espèces de climat tropical (de 3 à 4 mois) et tempéré (de 5 mois à >1 an). Les corps de leptocéphales d'anguillidés sont remplis d'une matière gélatineuse transparente, ce qui réduit possiblement les taux de prédation et fournit une réserve d'énergie pour la nage et la métamorphose. Les leptocéphales se nourrissent de neige marine, de sorte que la réussite après la résorption est reliée aux producteurs primaires qui contribuent à la production de neige marine. Des alternances de cyanobactéries ubiquistes dominantes dans des conditions pauvres en nutriments et de phytoplancton eucaryote comme des diatomées, importantes pour la production de neige marine, dominant dans des conditions riches en nutriments pourraient influencer la survie précoce des larves après la résorption en raison des nombreux oeufs qui éclosent simultanément dans des lieux de frai sympatriques. La baisse du nombre d'anguilles reproductrices découlant de la réduction des populations et des variations de la survie précoce des larves pourrait constituer une piste pour expliquer le recrutement plus faible et variable des récentes décennies. [Traduit par la Rédaction]

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Section: Introductionmentioning

confidence: 87%

The ecology of oceanic dispersal and survival of anguillid leptocephali

Miller

Tsukamoto

2017

Can. J. Fish. Aquat. Sci.

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“…The age of the leptocephalus at the onset of metamorphosis (T m ) was determined from the number of DGIs between the primordium (P) and MC where the increment pattern and Sr/Ca ratios dramatically changed (Otake et al 1994Tzeng and Tsai 1994;Tzeng 1995;Kuroki et al 2005;Arai et al 2002a). To estimate the T m , 13 days (adjustment factor, N 0 ) was added to the number of DGIs because a previous study found that no increment was deposited in the core of the otolith during the yolk-sac stage, and otolith growth increment deposition only commences once a larva begins feeding 13 days after hatching (Tanaka et al 1995). The duration of the metamorphosis stage was determined by counting the number of DGIs between the onset of a marked increase in the otolith increment width and its maximum peak.…”

Section: Otolith Microstructural Analysesmentioning

confidence: 99%

Effects of metamorphosis timing and the larval growth rate on the latitudinal distribution of sympatric freshwater eels, Anguilla japonica and A. marmorata, in the western North Pacific

et al. 2013

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Background: Early life history traits of the temperate eel Anguilla japonica and tropical eel Anguilla marmorata were examined to determine the possible reason why these two species have similar spawning areas and oceanic larval transport in the North Equatorial Current and yet are recruited to different but partly overlapping continental growth habitats in northern East Asia. To understand the segregative migration of these two sympatric eel species, their glass eels were collected from nine estuaries in the Philippines, Taiwan, Japan, and China. The age at metamorphosis from leptocephalus to glass eel (T m ), the age at estuarine arrival (T t ), the time between metamorphosis and estuarine arrival (T t−m ), and the growth rate (G t ) of glass eels were calculated from daily growth increments in their otoliths. Results: Results indicated that the G t was faster and the T m was younger in A. marmorata than in A. japonica. On the other hand, fish length and the T t at estuarine arrival were larger in A. japonica than in A. marmorata, indicating that elvers of A. japonica experience a longer oceanic drift than those of A. marmorata. In addition, the T t−m also indicated that A. japonica experienced a longer coastal migration than A. marmorata.

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“…However, despite the availability of artificially matured male and female eels, the life cycle of anguillids has still not been completed in captivity. Indeed, researchers have successfully fertilised and hatched eggs of Japanese (A. japonica; e.g., Yamamoto & Yamauchi 1974;Yamamoto et al 1975;Tanaka et al 1995) and European eels (Prokhorchik 1986), but larvae never survived for more than a few weeks, possibly as a result of aberrant yolking or lack of appropriate food (Yamauchi & Yamamoto 1982;Kurokawa et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Induced spawning and early ontogeny of New Zealand freshwater eels{Anguilla dieffenbachiiandA. australis)

Lokman

Young

2000

New Zealand Journal of Marine and Freshwater Research

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Knowledge on the reproductive biology of New Zealand freshwater eels (Anguilla australis Richardson and A. dieffenbachii Gray) is limited to changes associated with gametogenesis in the adults; details pertaining to embryonic and larval development are not available, but are of obvious benefit for a better understanding of the eel life history and for artificial propagation programmes, whether for aquaculture or conservation purposes. Therefore, eels were artificially matured and eggs fertilised with sperm from either species to investigate early ontogeny. Only eggs from A. australis hatched successfully after c. 45 h of incubation at room temperature, yielding larvae of c. 2.5 mm in length. Larvae survived for up to 5 days, by which time they had attained a length of 5.3 mm. Scanning electron microscopy of 1-and 2-day-old larvae revealed the presence of prominent free neuromasts on the head and along the flanks. Although hatching of New Zealand eels was achieved for the first time, it is strongly recommended that hormone treatment be initiated immediately following capture, well before ovarian atresia starts.

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The First Report of Eel Larvae Ingesting Rotifers

Cited by 53 publications

References 3 publications

The ecology of oceanic dispersal and survival of anguillid leptocephali

The ecology of oceanic dispersal and survival of anguillid leptocephali

Effects of metamorphosis timing and the larval growth rate on the latitudinal distribution of sympatric freshwater eels, Anguilla japonica and A. marmorata, in the western North Pacific

Induced spawning and early ontogeny of New Zealand freshwater eels{Anguilla dieffenbachiiandA. australis)

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