Size dependent competition was examined in two marine centric diatoms, Coscinodiscus sp. and Thal... more Size dependent competition was examined in two marine centric diatoms, Coscinodiscus sp. and Thalassiosira rotula at various 4 , 3 and Si concentrations. The growth responses for both species to nutrient levels were evaluated using two forms of nitrogen (NH 4 and NO 3) and silicon in both monoculture and mixed culture conditions. Under single species culture, the impact of Si did not depend on N forms for both diatoms. The increase of NH 4-N enhanced the growth of Coscinodiscus, but did not affect T. rotula. When NO 3-N was the nitrogen source, cell densities of both species were significantly enhanced by increasing Si concentrations, but only T. rotula density was affected by increasing N concentration. When Coscinodiscus sp. and T. rotula grew in the same culture, Coscinodiscus sp. dominated in both N forms. The scale of the dominance of Coscinodiscus sp. over T. rotula increased with decreasing N and Si concentrations. In the competition experiment, when 4 NH NO NH was the N source, both Coscinodiscus sp. and T. rotula were significantly affected by changes in N concentration, but only T. rotula was affected by Si. When NO 3 was the N source, neither Coscinodiscus sp. nor T. rotula was affected by Si, but T. rotula was enhanced by N levels. Regardless the N form, the impact of Si on neither Coscinodiscus sp. nor T. rotula depended on N concentration. Our results indicate that large diatom species have a competitive advantage over small species, and both large and small species were sensitive to NH 4-N limitation, but the small species was more sensitive to NO 3-N limitation than the large species.
This study investigated the effect of spawning activity on the ability of oysters to respond to a... more This study investigated the effect of spawning activity on the ability of oysters to respond to a simulated bacterial challenge, as a possible explanation for summer mortality. Using injection with a nonviable bacterial solution (NBS) of Vibrio harveyi, comparisons of ...
Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish... more Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish predation and nutrient input. In this study, we examined community effects of larval walleye and fertilizer type on plankton in ponds involving three densities (0, 250 000, and 500 000 fish/ha) of larval walleye (Stizosledion uitreum) and two fertilizer types (inorganic or organic). Walleye survival was not affected by fish density or fertilizer type, and more fish yield was gained in high fish density ponds. The best fish growth was obtained in ponds with low fish density and inorganic fertilizer. As fish density increased, the abundances of Daphniu, Diuptomus and nauplii, Secchi depth, NH,-N, NO,-N and chironomids were reduced, whereas primary productivity, Scenedesmus, flagellates, colonial algae, Anabaena, rotifers and pH were enhanced. Compared to organic fertilizer, inorganic fertilizer increased the levels of primary productivity, algal abundance, dissolved oxygen, pH and total phosphorus. Inorganic liquid fertilizer with N:P ratio at 20: 1 and a stocking density of 250 OOO-500 000 fry/ha is recommended for larval walleye culture. The stocking and fertilization protocol for larval walleye culture could be applied to the larval culture of other planktivorous fish species.
ABSTRACT Tremendous variation in survival and growth of percid fry stocked in ponds was addressed... more ABSTRACT Tremendous variation in survival and growth of percid fry stocked in ponds was addressed through manipulation of amounts and kinds of fertilizers added and stocking densities of fish. Ponds were filled with water from nearby eutrophic lakes less than one week prior to stocking. Survival in these ponds averaged 64%. whereas ponds filled one month before stocking averaged only 14%. Optimal inorganic fertilization was identified as weekly restoration to 600µg N/L (NH4 +NO3) and 30µg P/L as PO4 -3. Organic fertilization gave variable results and water qualities. In one experiment, low organic fertilization alone (28 kg alfalfa meal/ha/week) provided survival and growth comparable to optimal fertilization with inorganic nutrients. Although similar in results, inorganic fertilization was more cost effective than the alfalfa meal. Low fish predation from low stocking or survival allowed Daphnia to overgraze algae. This resulted in a crash in both algae and zooplankton in the ponds. Doubling the initial stocking density increased harvests from 150.000 to 300,000 fish/ha and increased yield from 45 to 100 kg/ha.
The hypotheses that larval fish density may potentially affect phytoplankton abundance through re... more The hypotheses that larval fish density may potentially affect phytoplankton abundance through regulating zooplankton community structure, and that fish effect may also depend on nutrient levels were tested experimentally in ponds with three densities of larval walleye, Stizostedion vitreum (0, 25, and 50 fish m' 3), and two fertilizer types (inorganic vs organic fertilizer). A significant negative relationship between larval fish density and large zooplankton abundance was observed despite fertilizer types. Larval walleye significantly reduced the abundances of Daphnia, Bosmina, and Diaptomus but enhanced the abundance of various rotifer species (Brachionus, Polyarthra, and Keratella). When fish predation was excluded, Daphnia became dominant, but Daphnia grazing did not significantly suppress blue-green algae. Clearly, larval fish can be an important regulator for zooplankton community. Algal composition and abundance were affected more by fertilizer type than by fish density. Inorganic fertilizer with a high N :P ratio (20 :1) enhanced blue-green algal blooms, while organic fertilizer with a lower N :P ratio (10 :1) suppressed the abundance of blue-green algae. This result may be attributed to the high density of blue-green algae at the beginning of the experiment and the fertilizer type. Our data suggest that continuous release of nutrients from suspended organic fertilizer at a low rate may discourage the development of blue-green algae. Nutrient inputs at a low N :P ratio do not necessarily result in the dominance of blue-green algae .
To understand the impact of young-of-the-year (YOY) fish on food web dynamics and water quality, ... more To understand the impact of young-of-the-year (YOY) fish on food web dynamics and water quality, we stocked larval walleye (9 mm TL) (Stizostedion vitreum) in six experimental ponds using two fish densities (10 and 50 fish m-3) with three replicates. At high fish density, the average abundances of cladocerans and copepods and the Secchi depth were lower whereas abundances of rotifers and algae, gross primary productivity (GPP), pH and total phosphorus concentration were higher than at low fish density. Fish impact on bacterial abundance, dissolved oxygen, nitrogen and phosphorus concentrations, however, was not significant. The within treatment measurements of all variables except GPP were significantly different over time. Our results indicate that YOY walleye predation at high density can affect plankton community by reducing large zooplankton biomass and water clarity, and increasing phytoplankton abundance. The impact of YOY piscivorous fish on plankton should be considered when biomanipulation is applied for improvement of water quality .
ASSTRACT Q~I. J. andCulver. D.A., 1992. trophic dynamics in fertilized Two fertilization methods.... more ASSTRACT Q~I. J. andCulver. D.A., 1992. trophic dynamics in fertilized Two fertilization methods. inoreanic fertilizers f IF) versus combined inareanic and oreanic fenilizen (IOF). were compared in f&r ponds with &o'replicates of each Irea&nt at B fi;h slockmg densitv of244 000 ha-'. Fish survival and total length averaeed 11.9%and 38.9 mm in the LF ponds. and 2.i% and 49.2 mm in the 10F ponds rerpecuv~ly. No si&ficant differences were found br the abundances of total zooplankton (P>O.lS) and phytoplankton (P>O.34) between the two treatments. but the mean dissolved oxygen at the bottom was significantly lower in the IOF ponds (6.8 r:~g O2 I-') than that in the IF ponds (IO.4 mg 0, I-' (P<O.OZI). The high fish mortnlity in the IOF ponds may have been due 10 low dissolved oxygen, or to ammonia toxicity. We suggest rhat in hatchery ponds filled with lake waler. the use of inorganic fenilizrr alone (N: P=20: I) will provide better results than the combined use of inorganic and orgamc fertilizers.
Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish... more Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish predation and nutrient input. In this study, we examined community effects of larval walleye and fertilizer type on plankton in ponds involving three densities (0, 250 000, and 500 000 fish/ha) of larval walleye (Stizostedion vitreum) and two fertilizer types (inorganic or organic). Walleye survival
... may make them subject to less physiological stress, and allow them to allocate more energy to... more ... may make them subject to less physiological stress, and allow them to allocate more energy to growth in inten-sive culture (Malison et al. ... 3). The low electivity index for Bosmina does not mean Bosmina is an unimpor-tant dietary item, but that the proportion of Bos-mina in fish ...
This paper describes the results of an investigation on the saline and hypersaline zooplanktons f... more This paper describes the results of an investigation on the saline and hypersaline zooplanktons from Jinnan and Yinchuan regions during 1981--1984. 222 samples were collected from 7 localities ranging in salinity from 0.5--286. 57 species belonging to 16 families and 39 genera ...
Mortality is a major concern in larval fish rearing during exogenous feeding. An important cause ... more Mortality is a major concern in larval fish rearing during exogenous feeding. An important cause of mortality of larval yellowtail kingfish (Seriola lalandi) during the rotifer -Artemia weaning period was hypothesised as being due to larval sinking response after satiated feeding prior to dusk. This paper documents the effect of larval body density change under different Artemia feeding regimes and adds to the understanding of the cause of mortality of yellowtail kingfish larvae. The change in body density was used as a tool to determine the time of last feed in a day to ensure larvae were neutrally buoyant at dusk. An adaptive Artemia feeding regime was implemented, in which the amount of feed applied to the larvae was modified based on the body density. Larvae were denser than the seawater in which they were reared when fully satiated with Artemia. The time required to return to pre-feeding density significantly decreased with larval age. At 12 days post hatch (dph), the peak in body density of larvae fed Artemia to satiation was 1.0320 g cm − 3 and they did not return to a pre-feeding body density (1.0260 g cm − 3 ), for approximately 10 h. By 19 dph, larval body density only increased to 1.0275 g cm − 3 when larvae were fully satiated and they were neutrally buoyant again by 4 h. The decrease in larval body density when fully satiated at 16 dph demonstrated that overfeeding larvae with Artemia should be avoided prior to dusk before this age to maintain neutral buoyancy. The use of the adaptive regime reduced mortality by 20% compared with the control, from 13 to 17 dph, without sacrificing larval growth. Transition to Artemia feeding is a critical stage for yellowtail kingfish larvae and mortalities can be significantly reduced during this period by managing the timing of Artemia feeds throughout the day. The strategy of an adaptive feeding method may be considered a novel management tool to prevent larval sinking and associated mortality during the period of weaning from rotifers to Artemia during larval rearing.
Cryopreservation has been expected to improve the efficiency of hatchery operation by supplying g... more Cryopreservation has been expected to improve the efficiency of hatchery operation by supplying gametes on demand without live broodstocks and genetic improvement programs by achieving desired mating and establishing across-generation controls. The preservation of genetic materials of improved stocks and the original population is immensely important for oyster aquaculture industry to prepare the potential impacts from epidemic diseases and natural disasters. This review summarizes the research progress of sperm cryopreservation in oysters and discusses the scope of application of preserved sperm in aquaculture. A bulk of about 50 reports have been published on oyster sperm cryopreservation since 1971, nevertheless the application of this technique in aquaculture is limited. These studies primarily focused on the development of protocol for individual species by optimizing a set of interacting variables at different steps from sperm collection to post-thawing and fertilization. A number of approaches such as sperm motility, morphological integrity and fertility are used to evaluate the cryopreserved sperm quality but there are considerable variations in practice. We synthesized the outcomes in the existing literature in an attempt to suggest the standardization of sperm cryopreservation technique and provide directions for future research.
This study assessed the effects of the addition of vitamins (L-ascorbic acid), amino acids (glyci... more This study assessed the effects of the addition of vitamins (L-ascorbic acid), amino acids (glycine and taurine), and monosaccharides (glucose, fructose and galactose) on sperm cryopreservation using a non-programmable freezing technique in farmed greenlip abalone. The results showed that the addition of taurine, glycine or L-ascorbic acid significantly improved the post-thaw sperm motility, whereas the post-thaw sperm fertilization rates were improved by the addition of glycine or L-ascorbic acid. Flow cytometry analysis demonstrated that the addition of glycine significantly enhanced the post-thaw sperm plasma membrane integrity and acrosome integrity. Results from the investigation on monosaccharides demonstrated that glucose, fructose and galactose had a similar cryoprotective effect, resulting in a similar level of the post-thaw sperm fertilization rate, plasma membrane integrity, mitochondrial membrane potential and acrosome integrity. In this study, the highest postthaw fertilization rate of 96% was achieved by using the cryoprotective mediums containing 6% DMSO, 1% glucose and 0.6% glycine.
Effects of salinity on the growth, survival, superoxide dismutase (SOD), catalase (CAT), glutathi... more Effects of salinity on the growth, survival, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and sodium-potassium adenosine triphosphatase (Na + K + -ATPase) activities of juvenile golden pompano Trachinotus ovatus were studied under a laboratory condition. Experimental fish were reared at the salinities of 10&, 18&, 26& and 34& for 30 days. Growth and survival of juvenile golden pompano were significantly affected by the rearing salinity. Fish reared at 34& achieved the highest specific growth rate, while the highest survival was obtained when fish were cultured at the salinity of 26&. The highest GPX activity was obtained when fish were cultured at 26&, and the lowest GPX activity was observed when fish reared at 34& salinity. The SOD activities of fish reared at 18& and 34& were significantly higher than those reared at 10& and 26&. The lowest of Na + K + -ATPase activity was obtained in fish reared at 34&, while the highest Na + K + -ATPase activity was obtained when fish reared at 18&. Results from present study indicate that juvenile golden pompano can be reared above 18& without sacrificing fish survival, and the best growth can be achieved when fish is reared at the salinity of 34&. The salinity of 10& may be too low for juvenile golden pompano as the growth, survival and SOD activity were reduced.
Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, Jan 18, 2015
Perfluorooctane sulfonate (PFOS) has been widely studied due to its global distribution, slow deg... more Perfluorooctane sulfonate (PFOS) has been widely studied due to its global distribution, slow degradation, high bioaccumulation and toxicological effects on vertebrates. However, the potential toxicity of PFOS to crustaceans is little known. The present study investigated the effects of PFOS on the immune responses and expression of immune-related genes in the Chinese mitten-handed crab Eriocheir sinensis. Crabs were exposed to 0, 0.01, 0.1, 1.0 and 10 mg/L of PFOS, and sampled on 1, 4, 7, 14 and 21 day respectively. The total hemocyte count and lysozyme activity in PFOS-treated crab were significantly lower than in the control. The exposure to 10 mg/L of PFOS led to a marked inhibition in phenoloxidase and superoxide dismutase activities. At other PFOS levels, phenoloxidase and superoxide dismutase showed an initial increase and a subsequent decrease over time. The alkaline and acid phosphatase activities were stimulated in 10 mg/L PFOS until 21d. The mRNA expression of immune rela...
This study investigated factors key to the development of sperm cryopreservation in the greenlip ... more This study investigated factors key to the development of sperm cryopreservation in the greenlip abalone Haliotis laevigata using a programmable freezing technique, including (1) permeable cryoprotectant agent (CPA) selection; (2) cooling rate;
Temperate abalone species in aquaculture have a grow-out period of approximately 3 years because ... more Temperate abalone species in aquaculture have a grow-out period of approximately 3 years because of their slow and heterogeneous growth rate. Abalone aquaculture is still a developing industry, and at least two major issues, nutrition and health, impede its development. Abalone are fed macroalgae on-farm in a number of countries, including China, Korea, South Africa and Chile. Formulated diets are crucial to the success of abalone aquaculture in countries where abalone do not grow readily when fed brown macroalgae or when access to macroalgae is insufficient for culture. Typically, the growth rate of abalone fed formulated diets is higher than abalone fed live macroalgae. However, due to a long production period, diets for abalone not only need to sustain high growth rates, but also maintain optimal health. Feeding live macroalgae improves the feeding activity, health and marketability of abalone. In this review, the nutritional requirements of abalone and dietary ingredients used in formulated diets will be discussed, together with the use of dried macroalgal meal as a dietary ingredient in formulated diets to improve the feeding activity, health and marketability of abalone in commercial production.
Size dependent competition was examined in two marine centric diatoms, Coscinodiscus sp. and Thal... more Size dependent competition was examined in two marine centric diatoms, Coscinodiscus sp. and Thalassiosira rotula at various 4 , 3 and Si concentrations. The growth responses for both species to nutrient levels were evaluated using two forms of nitrogen (NH 4 and NO 3) and silicon in both monoculture and mixed culture conditions. Under single species culture, the impact of Si did not depend on N forms for both diatoms. The increase of NH 4-N enhanced the growth of Coscinodiscus, but did not affect T. rotula. When NO 3-N was the nitrogen source, cell densities of both species were significantly enhanced by increasing Si concentrations, but only T. rotula density was affected by increasing N concentration. When Coscinodiscus sp. and T. rotula grew in the same culture, Coscinodiscus sp. dominated in both N forms. The scale of the dominance of Coscinodiscus sp. over T. rotula increased with decreasing N and Si concentrations. In the competition experiment, when 4 NH NO NH was the N source, both Coscinodiscus sp. and T. rotula were significantly affected by changes in N concentration, but only T. rotula was affected by Si. When NO 3 was the N source, neither Coscinodiscus sp. nor T. rotula was affected by Si, but T. rotula was enhanced by N levels. Regardless the N form, the impact of Si on neither Coscinodiscus sp. nor T. rotula depended on N concentration. Our results indicate that large diatom species have a competitive advantage over small species, and both large and small species were sensitive to NH 4-N limitation, but the small species was more sensitive to NO 3-N limitation than the large species.
This study investigated the effect of spawning activity on the ability of oysters to respond to a... more This study investigated the effect of spawning activity on the ability of oysters to respond to a simulated bacterial challenge, as a possible explanation for summer mortality. Using injection with a nonviable bacterial solution (NBS) of Vibrio harveyi, comparisons of ...
Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish... more Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish predation and nutrient input. In this study, we examined community effects of larval walleye and fertilizer type on plankton in ponds involving three densities (0, 250 000, and 500 000 fish/ha) of larval walleye (Stizosledion uitreum) and two fertilizer types (inorganic or organic). Walleye survival was not affected by fish density or fertilizer type, and more fish yield was gained in high fish density ponds. The best fish growth was obtained in ponds with low fish density and inorganic fertilizer. As fish density increased, the abundances of Daphniu, Diuptomus and nauplii, Secchi depth, NH,-N, NO,-N and chironomids were reduced, whereas primary productivity, Scenedesmus, flagellates, colonial algae, Anabaena, rotifers and pH were enhanced. Compared to organic fertilizer, inorganic fertilizer increased the levels of primary productivity, algal abundance, dissolved oxygen, pH and total phosphorus. Inorganic liquid fertilizer with N:P ratio at 20: 1 and a stocking density of 250 OOO-500 000 fry/ha is recommended for larval walleye culture. The stocking and fertilization protocol for larval walleye culture could be applied to the larval culture of other planktivorous fish species.
ABSTRACT Tremendous variation in survival and growth of percid fry stocked in ponds was addressed... more ABSTRACT Tremendous variation in survival and growth of percid fry stocked in ponds was addressed through manipulation of amounts and kinds of fertilizers added and stocking densities of fish. Ponds were filled with water from nearby eutrophic lakes less than one week prior to stocking. Survival in these ponds averaged 64%. whereas ponds filled one month before stocking averaged only 14%. Optimal inorganic fertilization was identified as weekly restoration to 600µg N/L (NH4 +NO3) and 30µg P/L as PO4 -3. Organic fertilization gave variable results and water qualities. In one experiment, low organic fertilization alone (28 kg alfalfa meal/ha/week) provided survival and growth comparable to optimal fertilization with inorganic nutrients. Although similar in results, inorganic fertilization was more cost effective than the alfalfa meal. Low fish predation from low stocking or survival allowed Daphnia to overgraze algae. This resulted in a crash in both algae and zooplankton in the ponds. Doubling the initial stocking density increased harvests from 150.000 to 300,000 fish/ha and increased yield from 45 to 100 kg/ha.
The hypotheses that larval fish density may potentially affect phytoplankton abundance through re... more The hypotheses that larval fish density may potentially affect phytoplankton abundance through regulating zooplankton community structure, and that fish effect may also depend on nutrient levels were tested experimentally in ponds with three densities of larval walleye, Stizostedion vitreum (0, 25, and 50 fish m' 3), and two fertilizer types (inorganic vs organic fertilizer). A significant negative relationship between larval fish density and large zooplankton abundance was observed despite fertilizer types. Larval walleye significantly reduced the abundances of Daphnia, Bosmina, and Diaptomus but enhanced the abundance of various rotifer species (Brachionus, Polyarthra, and Keratella). When fish predation was excluded, Daphnia became dominant, but Daphnia grazing did not significantly suppress blue-green algae. Clearly, larval fish can be an important regulator for zooplankton community. Algal composition and abundance were affected more by fertilizer type than by fish density. Inorganic fertilizer with a high N :P ratio (20 :1) enhanced blue-green algal blooms, while organic fertilizer with a lower N :P ratio (10 :1) suppressed the abundance of blue-green algae. This result may be attributed to the high density of blue-green algae at the beginning of the experiment and the fertilizer type. Our data suggest that continuous release of nutrients from suspended organic fertilizer at a low rate may discourage the development of blue-green algae. Nutrient inputs at a low N :P ratio do not necessarily result in the dominance of blue-green algae .
To understand the impact of young-of-the-year (YOY) fish on food web dynamics and water quality, ... more To understand the impact of young-of-the-year (YOY) fish on food web dynamics and water quality, we stocked larval walleye (9 mm TL) (Stizostedion vitreum) in six experimental ponds using two fish densities (10 and 50 fish m-3) with three replicates. At high fish density, the average abundances of cladocerans and copepods and the Secchi depth were lower whereas abundances of rotifers and algae, gross primary productivity (GPP), pH and total phosphorus concentration were higher than at low fish density. Fish impact on bacterial abundance, dissolved oxygen, nitrogen and phosphorus concentrations, however, was not significant. The within treatment measurements of all variables except GPP were significantly different over time. Our results indicate that YOY walleye predation at high density can affect plankton community by reducing large zooplankton biomass and water clarity, and increasing phytoplankton abundance. The impact of YOY piscivorous fish on plankton should be considered when biomanipulation is applied for improvement of water quality .
ASSTRACT Q~I. J. andCulver. D.A., 1992. trophic dynamics in fertilized Two fertilization methods.... more ASSTRACT Q~I. J. andCulver. D.A., 1992. trophic dynamics in fertilized Two fertilization methods. inoreanic fertilizers f IF) versus combined inareanic and oreanic fenilizen (IOF). were compared in f&r ponds with &o'replicates of each Irea&nt at B fi;h slockmg densitv of244 000 ha-'. Fish survival and total length averaeed 11.9%and 38.9 mm in the LF ponds. and 2.i% and 49.2 mm in the 10F ponds rerpecuv~ly. No si&ficant differences were found br the abundances of total zooplankton (P>O.lS) and phytoplankton (P>O.34) between the two treatments. but the mean dissolved oxygen at the bottom was significantly lower in the IOF ponds (6.8 r:~g O2 I-') than that in the IF ponds (IO.4 mg 0, I-' (P<O.OZI). The high fish mortnlity in the IOF ponds may have been due 10 low dissolved oxygen, or to ammonia toxicity. We suggest rhat in hatchery ponds filled with lake waler. the use of inorganic fenilizrr alone (N: P=20: I) will provide better results than the combined use of inorganic and orgamc fertilizers.
Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish... more Plankton abundance which greatly affects larval fish growth and survival can be regulated by fish predation and nutrient input. In this study, we examined community effects of larval walleye and fertilizer type on plankton in ponds involving three densities (0, 250 000, and 500 000 fish/ha) of larval walleye (Stizostedion vitreum) and two fertilizer types (inorganic or organic). Walleye survival
... may make them subject to less physiological stress, and allow them to allocate more energy to... more ... may make them subject to less physiological stress, and allow them to allocate more energy to growth in inten-sive culture (Malison et al. ... 3). The low electivity index for Bosmina does not mean Bosmina is an unimpor-tant dietary item, but that the proportion of Bos-mina in fish ...
This paper describes the results of an investigation on the saline and hypersaline zooplanktons f... more This paper describes the results of an investigation on the saline and hypersaline zooplanktons from Jinnan and Yinchuan regions during 1981--1984. 222 samples were collected from 7 localities ranging in salinity from 0.5--286. 57 species belonging to 16 families and 39 genera ...
Mortality is a major concern in larval fish rearing during exogenous feeding. An important cause ... more Mortality is a major concern in larval fish rearing during exogenous feeding. An important cause of mortality of larval yellowtail kingfish (Seriola lalandi) during the rotifer -Artemia weaning period was hypothesised as being due to larval sinking response after satiated feeding prior to dusk. This paper documents the effect of larval body density change under different Artemia feeding regimes and adds to the understanding of the cause of mortality of yellowtail kingfish larvae. The change in body density was used as a tool to determine the time of last feed in a day to ensure larvae were neutrally buoyant at dusk. An adaptive Artemia feeding regime was implemented, in which the amount of feed applied to the larvae was modified based on the body density. Larvae were denser than the seawater in which they were reared when fully satiated with Artemia. The time required to return to pre-feeding density significantly decreased with larval age. At 12 days post hatch (dph), the peak in body density of larvae fed Artemia to satiation was 1.0320 g cm − 3 and they did not return to a pre-feeding body density (1.0260 g cm − 3 ), for approximately 10 h. By 19 dph, larval body density only increased to 1.0275 g cm − 3 when larvae were fully satiated and they were neutrally buoyant again by 4 h. The decrease in larval body density when fully satiated at 16 dph demonstrated that overfeeding larvae with Artemia should be avoided prior to dusk before this age to maintain neutral buoyancy. The use of the adaptive regime reduced mortality by 20% compared with the control, from 13 to 17 dph, without sacrificing larval growth. Transition to Artemia feeding is a critical stage for yellowtail kingfish larvae and mortalities can be significantly reduced during this period by managing the timing of Artemia feeds throughout the day. The strategy of an adaptive feeding method may be considered a novel management tool to prevent larval sinking and associated mortality during the period of weaning from rotifers to Artemia during larval rearing.
Cryopreservation has been expected to improve the efficiency of hatchery operation by supplying g... more Cryopreservation has been expected to improve the efficiency of hatchery operation by supplying gametes on demand without live broodstocks and genetic improvement programs by achieving desired mating and establishing across-generation controls. The preservation of genetic materials of improved stocks and the original population is immensely important for oyster aquaculture industry to prepare the potential impacts from epidemic diseases and natural disasters. This review summarizes the research progress of sperm cryopreservation in oysters and discusses the scope of application of preserved sperm in aquaculture. A bulk of about 50 reports have been published on oyster sperm cryopreservation since 1971, nevertheless the application of this technique in aquaculture is limited. These studies primarily focused on the development of protocol for individual species by optimizing a set of interacting variables at different steps from sperm collection to post-thawing and fertilization. A number of approaches such as sperm motility, morphological integrity and fertility are used to evaluate the cryopreserved sperm quality but there are considerable variations in practice. We synthesized the outcomes in the existing literature in an attempt to suggest the standardization of sperm cryopreservation technique and provide directions for future research.
This study assessed the effects of the addition of vitamins (L-ascorbic acid), amino acids (glyci... more This study assessed the effects of the addition of vitamins (L-ascorbic acid), amino acids (glycine and taurine), and monosaccharides (glucose, fructose and galactose) on sperm cryopreservation using a non-programmable freezing technique in farmed greenlip abalone. The results showed that the addition of taurine, glycine or L-ascorbic acid significantly improved the post-thaw sperm motility, whereas the post-thaw sperm fertilization rates were improved by the addition of glycine or L-ascorbic acid. Flow cytometry analysis demonstrated that the addition of glycine significantly enhanced the post-thaw sperm plasma membrane integrity and acrosome integrity. Results from the investigation on monosaccharides demonstrated that glucose, fructose and galactose had a similar cryoprotective effect, resulting in a similar level of the post-thaw sperm fertilization rate, plasma membrane integrity, mitochondrial membrane potential and acrosome integrity. In this study, the highest postthaw fertilization rate of 96% was achieved by using the cryoprotective mediums containing 6% DMSO, 1% glucose and 0.6% glycine.
Effects of salinity on the growth, survival, superoxide dismutase (SOD), catalase (CAT), glutathi... more Effects of salinity on the growth, survival, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and sodium-potassium adenosine triphosphatase (Na + K + -ATPase) activities of juvenile golden pompano Trachinotus ovatus were studied under a laboratory condition. Experimental fish were reared at the salinities of 10&, 18&, 26& and 34& for 30 days. Growth and survival of juvenile golden pompano were significantly affected by the rearing salinity. Fish reared at 34& achieved the highest specific growth rate, while the highest survival was obtained when fish were cultured at the salinity of 26&. The highest GPX activity was obtained when fish were cultured at 26&, and the lowest GPX activity was observed when fish reared at 34& salinity. The SOD activities of fish reared at 18& and 34& were significantly higher than those reared at 10& and 26&. The lowest of Na + K + -ATPase activity was obtained in fish reared at 34&, while the highest Na + K + -ATPase activity was obtained when fish reared at 18&. Results from present study indicate that juvenile golden pompano can be reared above 18& without sacrificing fish survival, and the best growth can be achieved when fish is reared at the salinity of 34&. The salinity of 10& may be too low for juvenile golden pompano as the growth, survival and SOD activity were reduced.
Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, Jan 18, 2015
Perfluorooctane sulfonate (PFOS) has been widely studied due to its global distribution, slow deg... more Perfluorooctane sulfonate (PFOS) has been widely studied due to its global distribution, slow degradation, high bioaccumulation and toxicological effects on vertebrates. However, the potential toxicity of PFOS to crustaceans is little known. The present study investigated the effects of PFOS on the immune responses and expression of immune-related genes in the Chinese mitten-handed crab Eriocheir sinensis. Crabs were exposed to 0, 0.01, 0.1, 1.0 and 10 mg/L of PFOS, and sampled on 1, 4, 7, 14 and 21 day respectively. The total hemocyte count and lysozyme activity in PFOS-treated crab were significantly lower than in the control. The exposure to 10 mg/L of PFOS led to a marked inhibition in phenoloxidase and superoxide dismutase activities. At other PFOS levels, phenoloxidase and superoxide dismutase showed an initial increase and a subsequent decrease over time. The alkaline and acid phosphatase activities were stimulated in 10 mg/L PFOS until 21d. The mRNA expression of immune rela...
This study investigated factors key to the development of sperm cryopreservation in the greenlip ... more This study investigated factors key to the development of sperm cryopreservation in the greenlip abalone Haliotis laevigata using a programmable freezing technique, including (1) permeable cryoprotectant agent (CPA) selection; (2) cooling rate;
Temperate abalone species in aquaculture have a grow-out period of approximately 3 years because ... more Temperate abalone species in aquaculture have a grow-out period of approximately 3 years because of their slow and heterogeneous growth rate. Abalone aquaculture is still a developing industry, and at least two major issues, nutrition and health, impede its development. Abalone are fed macroalgae on-farm in a number of countries, including China, Korea, South Africa and Chile. Formulated diets are crucial to the success of abalone aquaculture in countries where abalone do not grow readily when fed brown macroalgae or when access to macroalgae is insufficient for culture. Typically, the growth rate of abalone fed formulated diets is higher than abalone fed live macroalgae. However, due to a long production period, diets for abalone not only need to sustain high growth rates, but also maintain optimal health. Feeding live macroalgae improves the feeding activity, health and marketability of abalone. In this review, the nutritional requirements of abalone and dietary ingredients used in formulated diets will be discussed, together with the use of dried macroalgal meal as a dietary ingredient in formulated diets to improve the feeding activity, health and marketability of abalone in commercial production.
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