Search

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]

Environmental impact assessment is a means of preventing and mitigating the adverse effects of economic development activities on the natural environment. It is meant to ensure that decision-makers have sufficient information to consider environmental impacts before proceeding with new projects. Despite their important role in public policy, verification of environmental impact assessments has seldom been conducted. In this study, we used principal component analysis (PCA) to identify the major sources of influence on the coastal waters adjacent to a major tourist facility (an aquarium) in southern Taiwan, followed by the construction of a structural equation model (SEM) to determine the direct and indirect effects of the abiotic factors on phytoplankton and zooplankton density and diversity. Based on the loadings of principal components 1–3, we identified that river input, suspended matter, and seasonal changes were the major factors affecting the coastal area. The SEM further suggested that phytoplankton density and diversity were affected directly by seasonal changes and suspended matter, but only indirectly by river input, owing to the latter's effect on suspended matter. In contrast, the SEM suggested that zooplankton density and diversity were affected directly by seasonal changes, but indirectly by both river input and suspended matter owing to their effects on phytoplankton density and diversity. Q2 was the season with the highest number of visitors to the aquarium, but none of the abiotic or biotic parameters showed particular differences, implying that the variations in those parameters in the adjacent coastal waters were not related to the visitors. We suggest that PCA and SEM be used in the future in other contexts to verify environmental impact assessments. [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]

To evaluate the effect of rainfall intensity on phytoplankton blooms, a continuous monitoring system was deployed during 2015 in a hyper-eutrophic lagoon in Taiwan. Intensive rainfall occurs during the wet summer months, from May to September. Salinity in the lagoon was found to decrease with increasing intensity of rainfall. The magnitude of phytoplankton blooms also increased linearly with increasing rainfall intensity. The chlorophyll a concentration rose by an order of magnitude during the heaviest rainfall. Blooms may be fueled by nutrient enrichment caused by drainage or run-off water from surrounding areas that is channeled into the lagoon during rainfall events. During bloom periods, the rates of net primary production and ecosystem respiration were high. However, this ecosystem was autotrophic for most of the year. As extreme rainfall is predicted to increase, the results of this study imply that the frequency and magnitude of phytoplankton blooms may increase in the future. [ABSTRACT FROM AUTHOR]

In 2009, the container ship Colombo Queen and the oil tanker W-O BUDMO grounded off Jialeshui and Houwan, respectively, in southern Taiwan. Water quality was monitored at each site to evaluate the environmental impact caused by the resulting oil spills. The results show that the PAHs, turbidity, and other nutrients increased shortly after oil spill, however levels of these parameters eventually returned to baseline levels. On the other hand, DO saturation, pH and chl. a decreased initially, reached maxima after 10 days, and returned to the baseline levels after 14 days. The chl. a concentration, pH and DO saturation fluctuated in a similar pattern at both sites during the oil spills, likely driven by algal blooms. In this study, we documented a full environmental recovery at coastal areas before, during and after the oil spills. [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]

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]

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]

Abstract: Before 2001, the ecological protection area in the Kenting National Park (KTNP), southern Taiwan, was poorly described. In this study, a set of four-year data (2001–2004) of seawater qualities at 19 sampling sites around the Nanwan Bay in the KTNP was used to explore anthropogenic impacts to ecological environment, especially coral reefs. The parameters of water quality were analyzed immediately after collection. The results showed that higher values of nutrients and suspended solids were attributed to the higher run-off around Nanwan Bay. The fluxes of nutrients and suspended solids were consistently correlated to rainfall. Hence, equations were developed to calculate nutrient fluxes and suspended solids by using only rainfall data. Our results show that suspended solids and ammonia were the dominant factors leading to the drop in coral coverage. In summary, the water quality in the intertidal zone of Nanwan Bay has been degraded and required greater attention. [Copyright &y& Elsevier]

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]

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.

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]

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]