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In the past, diatoms were considered the primary food source for copepods in both wild and aquaculture settings. However, recent studies have found that diatoms have defense mechanisms against predators, making them unsuitable as copepod feed. This study assessed the impact of addition of 100 μg L−1 of silicate to an inorganic nutrition formula containing 700 μg L−1 nitrogen, 100 μg L−1 phosphorus, and 100 μg L−1 iron. Our objective was to assess the impact of increased diatom abundance on copepod production. The experiment was carried out in 1000 L outdoor tanks over a period of 20 days, with adult Pseudodiaptomus annandalei copepods, introduced into each tank on the second day at an initial density of 10 ind. L−1. The results indicated that adding silicate reduced the prevalence of Chlorophyta, replaced by a higher proportion of Dinophyta, and eventually dominated by diatoms. While silicate had a positive effect on diatom culture, it had a negative effect on copepod production. Adding silicate to the inorganic fertilization method resulted in increased costs, leading to a significant increase in the unit production cost of copepods. [ABSTRACT FROM AUTHOR]

Copepods are commonly used as live feed for cultured fish larvae, but the current mass production method using organic fertilizers cannot meet the market demand for copepods. We evaluated the feasibility of applying an inorganic fertilization method, which is currently in use in freshwater and marine larviculture, to the mass production of copepods. For 30 days, and with five replicates of each treatment, we made comparative daily measurements of various parameters of (1) copepod cultures fertilized with commercially available condensed fish solubles (organic fertilization) and (2) other cultures in which the concentration of inorganic phosphorus was maintained at 100 μg P L−1 and that of inorganic nitrogen at 700 μg N L−1 (inorganic fertilization). With inorganic fertilization, pH fluctuated over a smaller range and much less filamentous algae grew in the tanks. The mean production of copepod nauplii over the course of the study was similar between the two treatments, but the combined density of copepodites and adult copepods was significantly higher with inorganic fertilization. Compared to commercial zooplankton products, copepods cultured with inorganic fertilization were smaller, were mixed with fewer (almost none) non-copepod contaminants, were also pathogen-free, and could be produced at the cheapest cost per unit output. Based on these results, we conclude that the inorganic fertilization method can profitably be adopted by commercial copepod producers to meet the demand from fish farmers, especially for small-sized copepods. [ABSTRACT FROM AUTHOR]

Previous studies have revealed that reproductive traits of the Oriental river prawn Macrobrachium nipponense (De Haan, 1849) (Palaemonidae) can differ markedly across populations, though the environmental factors responsible for such variation are unknown. We therefore conducted monthly surveys of these prawns to determine their reproductive traits over two years at four study sites in southern Taiwan. The temperature, dissolved oxygen concentration, conductivity, and turbidity in Long Luan Lake significantly differed from the other sites, yet levels of reproductive trait parameters were intermediate among all. The aforementioned environmental factors were similar between the two Sihchong River sites and Mudan Reservoir, yet the river populations had the highest values in all reproductive traits. The river's substratum was comprised of >60% of cobbles and boulders, whereas <5% of the substratum of the reservoir and lake consisted of such rocks. We therefore suggest that this difference in substrate composition may be linked to the significant differences in reproductive traits observed. Résumé: Des études précédentes ont révélé que les traits de reproduction de la crevette bouquet d'eau douce Macrobrachium nipponense (De Haan, 1849) (Palaemonidae) peuvent différer nettement dans les populations, bien que les facteurs environnementaux responsables pour cette variation soient inconnus. Aussi nous avons effectué des relevés mensuels des ces crevettes pour déterminer leurs traits reproducteurs pendant deux ans, sur quatre sites dans le sud de Taïwan. La température, la concentration d'oxygène dissous, la conductivité et la turbidité dans le Lac Long Luan diffèrent significativement des autres sites, alors que les niveaux des paramètres des traits reproducteurs ont été intermédiaires. Les facteurs environnementaux mentionnés plus haut on été similaires entre les deux sites de la rivière Sihchong et le bassin de retenue Mudan, de plus la population de la rivière avait les valeurs les plus élevées pour tous les traits reproducteurs. Le substratum de la rivière est formé par > 60% de galets et de rochers, tandis que < 5% du substratum du bassin de retenue et du lac consistent en de tels rochers. Nous suggérons donc que cette différence dans la composition du substrat pourrait être liée aux différences significatives observées dans les traits reproducteurs. [ABSTRACT FROM AUTHOR]

Coral reef fish are collected from the wild and exhibited in aquaria worldwide. Some of the fish spawn in captivity; however, the eggs are usually neglected. In this study, we collected the eggs spawned naturally in the exhibit tanks, hatched and cultured them indoor in 2000-L fibreglass tanks (initial density = 18 000 egg tank−1). We applied an inorganic fertilization method commonly used in freshwater fish culture in raising these coral reef fish larvae. We maintained inorganic phosphorus concentration at 100 μg P L−1 and inorganic nitrogen at 700 μg N L−1 daily in the fertilized group ( n = 4), while the control tanks ( n = 4) were fed with rotifers (10 ind mL−1). Chlorophyll a at particle sizes of both 0.45-20 μm and >20 μm, as well as NH3-N, NO3-N, and PO4-P concentrations were significantly higher in the fertilized group than the control. Zooplankton in the size groups of 10-50 μm (mainly flagellates) and 50-100 μm (mainly ciliates) were abundant (about 10~60 ind mL−1) during 3-7 days in fertilized tanks. The average larval fish survival rate at 21 day after hatch in fertilized group was consistently higher than the control in two trials. The experiments demonstrated that the inorganic fertilization approach can be successfully adapted for coral reef fish culture in an aquarium to achieve sustainable exhibits. [ABSTRACT FROM AUTHOR]

Copepods are proven nutritious food sources for the mariculture/larviculture industry, however, unreliable methods for mass production of copepods are a major bottleneck. In this study, we modified a previously reported inorganic fertilization method (N: 700 μg L−1 and P: 100 μg L−1) by the addition of iron (Fe: 10 μg L−1, using FeSO4·7H2O) (+Fe treatment) and compared its suitability for copepod culture (Pseudodiaptomus annandalei) to the original method (control). The experiment was conducted outdoors in 1000 L tanks for 15 days. The addition of iron prolonged the growth phase of the phytoplankton and resulted in the production of significantly more small phytoplankton (0.45–20 μm, average 2.01 ± 0.52 vs. 9.03 ± 4.17 µg L−1 in control and +Fe, respectively) and adult copepods (control: 195 ± 35, +Fe: 431 ± 109 ind L−1), whereas copepodid-stage was similar between treatments (control: 511 ± 107 vs. +Fe: 502 ± 68 ind L−1). Although adding iron increased the cost of production by 23% compared to the control, the estimated net profit was 97% greater. We concluded that inorganic fertilization, with the addition of iron (Fe: 10 μg L−1), could be an effective method for the mass production of copepods for larviculture. [ABSTRACT FROM AUTHOR]

A major constraint in successful larviculture of groupers has been the small gape of the larvae and hence the requirement for small prey at first feeding. In this study, we examined how maintaining a phosphate concentration of 100 μg P L−1 and an inorganic nitrogen (N) level of 700 μg N L−1 via weekly fertilization with inorganic fertilizers affected phytoplankton, zooplankton and giant grouper larval survival in relation to a control group that was provided with rotifers immediately after larvae hatched. Unicellular algae, zooplankton within the size ranges of 10-50 μm and 50-100 μm and survival of giant grouper larvae were all significantly higher in the fertilized treatment compared with the control. Stomach analysis revealed that ciliates and flagellates were actively consumed by larval fish in the fertilized group, whereas few rotifers were consumed in the control. We conclude that the inorganic fertilization method provides high densities of suitable-sized prey for larval groupers at the onset of exogenous feeding before they are able to consume larger, commercially available rotifers and copepods. [ABSTRACT FROM AUTHOR]

The influences of a tidal cycle on the distribution of autotrophic plankton were investigated in a hyper-eutrophic lagoon designated as a scenic area. Results showed that the highest concentrations of picoplankton and phytoplankton were found in the middle and inner part of the lagoon, irrespective of the tides. The MDS result also revealed that phytoplankton communities, dominated by Ceratium furca, were similar among stations in the inner bay during both flood tides and ebb tides. The time series sampling results at the inlet-outlet channel revealed that almost the same amounts of phytoplankton and picoplankton were carried through the channel during flood and ebb tides, with no trend in nutrient fluctuations except for phosphate which had a net loss from the lagoon. The results showed that tidal cycles do not effectively flush away phytoplankton and picoplankton from the lagoon, and the blooming of phyto- and picoplankton is inevitable should the situation stay the same. Steps are needed to alleviate the eutrophication condition instead of depending on the natural process such as tidal cycle. [ABSTRACT FROM AUTHOR]

Abstract: Over-fertilization, low dissolved oxygen concentration, high pH, unionized ammonia, fish stocking density, and cannibalism are all possible causes of variations in larval percid survival and growth in earthen ponds. In this study, we examined the phosphorus fertilization effect over three different production years (2001–2003) by comparing fish raising success in ponds fertilized with phosphoric acid to restore phosphate concentrations to 30 μg P l−1 each week with other ponds restored to only 20 μg P l−1 each week, while restoring the inorganic nitrogen level in both sets to 600 μg N l−1 weekly. At the end of the 5–6 wk production period, there were no significant differences between the two treatments in mean fish length, weight, survival, number harvested ha−1, nor total biomass yield ha−1 (P >0.05). Phytoplankton and zooplankton densities were higher in 30 μg P l−1 ponds than in 20 μg P l−1 ponds (P <0.05) in 2001, but not in 2002. Significantly lower Secchi depths and higher pH (P <0.05) were observed in 30 μg P l−1 ponds, while dissolved oxygen and temperature values were similar between treatments, as were soluble reactive phosphorus, total phosphorus, nitrate–nitrogen, and ammonium–nitrogen concentrations (P >0.05). We conclude that weekly fertilization to the levels of 20 μg P l−1 and 600 μg N l−1 provides sufficient prey for larval percids, and it also reduces the risk of extreme pH and low dissolved oxygen that can cause increased fish mortality. [Copyright &y& Elsevier]

Dumping of approximately two million tonnes of steel slag in a shallow (ca. 40 m), sandy-bottom area in southern Taiwan from 1984 to 1989 has caused major changes of the substrate. After cessation of slag disposal, the demersal fish community in the area was monitored for 9 years (1990–1998). Species richness and the Shannon diversity index at the disposal site and a control site were significantly different, while the number of individuals and the Index of Multivariate Dispersion, as a measure of relative variation, were not. Splitting the data according to three 3-year periods did not reveal significant differences in any of the univariate community metrics. However, multivariate analysis revealed significant temporal differences, dispersion becoming smaller over time. It is concluded that slag disposal created a reef-like habitat and the associated fish fauna had a higher diversity than that seen on the sandy bottom present originally, partly caused by increased habitat complexity and partly by diversion of fishing activities because of potential gear damage. However, in the long run the ecological benefits may not last because the habitat is gradually being covered up again by sand. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved. [ABSTRACT FROM PUBLISHER]

Examines the impact of the 1999 earthquake on mountain stream fishes in Taiwan. Size composition of the population of two dominant endemic fishes; Reason for the visibility of large adults in the pool after the earthquake; Reduction of the number of juveniles.

Longfin batfish Platax teira is one of the most important finfish species in Asian aquaculture. However, knowledge on early ontogeny and reproduction of this species in captivity are scarce and incomplete. In this study, the embryonic, larval and juvenile development of P. teira are described and illustrated for the first time. The effect of temperature (27, 30 and 33 °C) on hatching rate, yolk-sac volume and oil globule volume was demonstrated. Cannibalism control via aeration adjustment for the enhancement of larval survival was also examined. Fertilized eggs were spherical, buoyant and had a diameter of 1.29 ± 0.05 mm (mean ± SD). Embryonic development lasted 16 h at 26.2 °C. Newly hatched larvae were 2.81 ± 0.24 mm in total length ( L T ) with 24 myomeres and had an oil globule in the ventroposterior area of the yolk sac. Early larvae had xanthophores appeared all over the body, except for the tip of the notochord. Larvae completed yolk absorption within 3 days post hatching (dph) at 3.41 ± 0.11 mm L T . Larvae were fed initially on rotifers Brachionus ibericus , followed by Artemia nauplii and finally weaned onto an artificial diet. From 8 dph, the larger larvae (over 4 mm L T ) began to exhibit cannibalistic behaviour. Transformation of larvae to the juvenile stage was completed at 23.80 ± 1.98 mm L T , all fins had the adult complement of rays and spines. A statistical model: Y  = 2.4968e 0.0786 x , where Y is mean L T (mm) and X represents dph, explained 96.45% of variation in growth ( P  < 0.001, R 2  = 0.9645). The hatching rate, yolk-sac volume and oil globule volume of newly hatched larvae were significantly ( P  < 0.05) decreased when the incubation temperature increased. Only 2–6% of embryos hatched at 33 °C, while the hatching rate was 63 ± 6% at 27 °C. Larvae reared in aeration rate of 300 mL min −1 attained the highest survival rate at 70.00 ± 7.20%, but remained significantly ( P  < 0.05) lower in cannibalism: 24.44 ± 4.16% compared with 66.67 ± 5.44% in 20 mL min −1 . These results indicate that the optimal incubation temperature recommended is approximately at 27 °C, and aeration at 300 mL min −1 could enhance larval survival by reducing cannibalism. [ABSTRACT FROM AUTHOR]

Bluestreak cleaner wrasse, Labroides dimidiatus , is one of the top ten most exported fish to the global trade in marine aquarium fish and a key species for reef fish diversity. However, knowledge on reproduction and early ontogeny of this species in captivity are scarce and incomplete. Daily spawning, early development and appropriate rearing condition (temperature and salinity) for the larviculture of L. dimidiatus were studied for the first time. We raised wrasse larvae by using an inorganic fertilization method to produce natural assemblages of phytoplankton and zooplankton, and compared it to the higher N: P ratio group and traditional rotifer-fed group. A single male dominated a harem of three females, spawning between late afternoon and dusk. L. dimidiatus spawned 305 times from 1 May 2011 to 30 April 2012, 86.9 ± 10.1% of which resulted in fertilized eggs. Fecundity ranged from 53 to 25,108 eggs per spawn with average hatching rate of 72.2 ± 22.6%. Fertilized eggs were spherical, buoyant and had a diameter of 0.68 ± 0.02 mm. Embryonic development lasted 19 h at 27.3 °C. Newly hatched larvae were 1.81 ± 0.06 mm in total length (L T) and had an oil globule in the ventroanterior area of the yolk sac. First feeding took places at 3 days post hatch (dph) which is marked by the widening of the gut. At 41 dph, transformation of larvae to the juvenile stage was completed at 12.60 ± 0.98 mm L T. On the scanning electron microscope observations, the fertilized egg membrane was smooth and lack surface sculpturing. The distribution density of pores was 61 pores 100 μm−2. The micropyle was circular or oval-shaped, and the diameter was 6.90–7.13 μm. Several neuromasts were found on the head and body surface of newly hatched larvae. The results showed that unicellular algae, zooplankton within the size ranges of 48–150 μm and larval survival of L. dimidiatus were all significantly (P < 0.05) higher in the fertilized treatment (maintaining the inorganic nitrogen and phosphorus concentrations of 700 μg N L−1 and 100 μg P L−1, respectively) compared with the others. These results indicated that the optimal conditions for embryo incubation and larval rearing of L. dimidiatus were combinations of temperature 27 °C and salinity 33 psu. Our results of this study may provide a keystone for further studies to determine the successful mass-scale production of juvenile L. dimidiatus. [Display omitted] • Y ear-round natural spawning, early development and ultrastructure of Labroides dimidiatus were reported for the first time. • The optimal rearing conditions for the eggs and larvae of L. dimidiatus are recommended to be 27 °C and 33 psu, respectively. • Controlling the amount and ratio of N and P by inorganic fertilization increase the important initial prey for larviculture. • Present results indicate that L. dimidiatus is a potential species for captive-bred marine ornamental fish. [ABSTRACT FROM AUTHOR]

Successful natural spawning of Chaetodontoplus septentrionalis in captivity from 19 March to 11 May, 2008 is described for the first time. A single male dominates a harem of two females, spawning with each at dusk, from 10 min before to 20 min after sunset. Each female laid an average 119 × 103 eggs during the spawning period. Fertilized eggs were spherical, buoyant and had a diameter of 0.83 ± 0.02 mm (mean ± SD). Embryonic development lasted 15–18 h at 28.1 °C. Newly hatched larvae were 1.60 ± 0.07 mm in total length (TL) with 27 myomeres. Larvae completed yolk absorption within 3 days post hatching (ph) at 3.01 ± 0.08 mm TL. Ten days ph, the larvae had attained 3.95 ± 0.12 mm TL. Larvae were fed either 100% s-type rotifers ( Brachionus rotundiformis), 100% copepods ( Microsetella sp.), a combination of the two (50%:50%) or without live feed (starved control) to determine the effect of live feed on the survival rate. The survival was significantly ( P<0.001) higher in larvae fed a combination of diet than the others. These results indicate that C. septentrionalis is a potential species for captive breeding programs and the use of a combination of diet (s-type rotifers and copepods) may be a suitable first food for the larvae. [ABSTRACT FROM AUTHOR]

Orange-spotted grouper (Epinephelus coioides) is one of the most important aquaculture species in tropical and subtropical Asia. Traditionally, rotifer are fed to the larvae after they hatched. However, larval survival rate has been very low, and prey of suitable size during the first week after hatching is a major constraint. In this study, we raised grouper larvae by using an inorganic fertilization method to produce natural assemblages of phytoplankton and zooplankton, and compared it to a traditional rotifer-fed group. The results showed higher larval survival rate in inorganic fertilization group, albeit not significantly different due to high variation. Using next-generation sequencing to examine the fish stomach content from inorganic fertilization group, we found that copepods and choanoflagellates were actively consumed, whereas rotifers were not. The results imply that the inorganic fertilization method can produce desirable forage species for the grouper larvae, and it can be an alternative way in grouper larviculture worldwide. • We raised grouper larvae using an inorganic fertilization method. • Fish stomach content analysis showed that copepod and choanoflagellate were selectively consumed. • Survival rate is comparable to traditional rotifer-fed larvae. • This can be an alternative way in grouper larviculture worldwide. [ABSTRACT FROM AUTHOR]

A three-dimensional, high-resolution numerical model with tide-generating and wind forces was used to simulate a passive tracer to study the water mass flushing rate in a coastal lagoon— Tapeng Bay. Model results show that north–northwesterly monsoons in winter can suppress ebb tidal currents flowing northwestward and concurrently suppress lagoon water exchanges with open shelf water, leading to a poor flushing rate. By contrast, both the westerly and southeasterly prevailing wind conditions in summer allowed lagoon water to mix, producing long-distance motion in the form of tidal residual currents from the southeast toward the northwest of the bay. This wind stress disturbance induced a horizontal mixing of the longitudinal lagoon water and led to greater water mass exchanges between Tapeng Bay and the open shelf. Therefore, tide-generating forces and suitable monsoons crucially influence the residence time of water mass in coastal lagoons. • For more accurately assess water exchange in Tapeng Bay, a high-resolution numerical model is used to simulate the water residence time under different Asian monsoon conditions; it is verified. • The observations, including CTD and ADCPs sampling, usefully help the study. • The model results suggest that it is not appropriate to use a box model to estimate residence times for coastal lagoons worldwide, particularly where the lagoons are not well-mixed water. [ABSTRACT FROM AUTHOR]