Search

The growth feasibility of Lomentaria sp. in ocean water (OW) and inland saline water (ISW) at salinity 30‰ was tested in a series of four experiments. To grow Lomentaria sp., potassium chloride (KCl) was used to fortify ISW to approximately 100%, 66%, and 33% (ISW100, ISW66, and ISW33 respectively) of [K+] in OW and compared to two controls of OW and ISW. The results showed that the ISW66 medium resulted in the highest (P

Selenomethionine (SeMet) was supplemented to a fishmeal-based diet to investigate the toxic effects of excessive levels of dietary selenium (Se) in juvenile yellowtail kingfish ( Seriola lalandi ). For 10 weeks, the fish were fed one of five experimental diets; a basal diet containing 2.31 mg/kg of inherent Se or diets supplemented with SeMet to provide 4.91, 9.58, 15.43 or 20.87 mg/kg of Se. The results showed that the fish muscle proximate composition, feed conversion ratio and survival were not sensitive to dietary Se treatments; and no histopathological lesions were observed in heart and intestine tissues of the fish. The Se concentrations in liver and muscle tissues showed a strong linear positive relationship with the levels of Se in diets. Fish when fed the basal diet exhibited Se deficiency symptoms including myopathy, reduced feed intake, glutathione peroxidase activity and growth; whereas those fed the diets containing ≥ 4.91 mg Se/kg did not. While fish fed the 15.43 mg Se/kg diet did not show any toxic effects, the 20.87 mg Se/kg diet caused histopathological changes in liver and spleen as well as reduced feed intake, growth, haematocrit and hepatosomatic index, indicating Se toxicity. In conclusion, Se levels in liver and muscle tissues can be used as effective indicators of dietary Se exposure and dietary Se level between 15.43 and 20.87 mg/kg may be a threshold level in juvenile yellowtail kingfish.

Six strains of bacteria including Bacillus mycoides (A10) and Shewanella species (A12) isolated from healthy marron intestine, Bacillus species (PM1), Bacillus subtilis (PM3), Bacillus sp. (PM4) and Bacillus sp. (AQ) from commercial probiotic products were investigated for probiotic potential in marron culture. Antibiotic susceptibility tests indicated PM3 and PM4 were susceptible to all nine antibiotics evaluated. A10, A12 and AQ were resistant to class penicillins, whereas PM1 was resistant to class penicillin and macrolides. All strains were non-pathogenic for marron. Strong inhibition against Vibrio mimicus and Vibrio cholerae non-01 was exhibited by PM4 and PM3. A10 inhibited V. mimicus at 72 h of growth, but not V. cholerae non-01, whereas A12 inhibited V. cholerae non-01 but not V. mimicus, and AQ showed no inhibition activity. A wide range of enzymes were produced by A10 and AQ using the API ZYM test. Protease enzymes were produced by PM3, PM4, AQ and PM1. In order of effectiveness, the following bacteria have probiotic potential: B. subtilis (PM3), Bacillus sp. (PM4) and B. mycoides (A10). Further study is required to determine the bacterium or any combination that gives a multibeneficial effect on marron.

Effects of dietary selenium (Se) on immune competence of yellowtail kingfish, Seriola lalandi, were investigated. The fish were fed one of the three experimental diets including a control diet without Se supplementation and two diets supplemented with Se from Se-yeast (Selplex) at 2 and 4 mg/kg. After feeding for 6 wk, the fish were challenged by injecting Vibrio anguillarum and observed for 2 wk. Dietary Se had no effect on feed intake, feed conversion ratio, and survival over the course of 6-wk feeding; however, it significantly increased weight gain and Se content in muscle. Following the bacterial infection, the immune-stimulating effects of Se were observed in antibody, lysozyme, and bactericidal responses, and there was a corresponding increase in survival and hematocrit by Se. Under infectious condition, antioxidant capacity of fish as measured in terms of resistance of red blood cells to peroxidation and glutathione peroxidase activity also increased by supplementation of Se. Liver necrosis and kidney melano-macrophages were only seen in surviving fish fed the control diet after the challenge. Furthermore, there was evidence of myopathy in fish fed the diet without Se supplementation. This study suggests that Se, supplemented at 2 or 4 mg/kg, can improve growth and health of yellowtail kingfish.

Niobium diboride (NbB 2 ) is synthesized and consolidated by the spark plasma sintering technique. Elemental reactants such as niobium (Nb) and boron (B) were subjected to two stage heat treatment, initially at 1200 °C for synthesis and followed by densification at the temperatures in the range of 1700 °C to 1900 °C. High dense NbB 2 (~ 97.7%ρ th ) is obtained at 1900 °C after 15 min holding period. Load application during heat treatment stage is found to improve the sinterability of the niobium diboride compacts. Hardness, elastic modulus and indentation fracture toughness of the high dense NbB 2 are measured as 20.25 GPa, 539 GPa and 4 MPa m 1/2 respectively.

The densification behavior of boron carbide without sintering additives is reported for temperatures in the range of 1100 °C to 1800 °C by spark plasma sintering (SPS) technique together with the sintering parameters (Holding Time and Pulsed DC). The influence of porosity on mechanical properties (hardness, fracture toughness and elastic modulus) of boron carbide prepared by SPS is measured. Pulsed DC current is found to play a dominant role in the densification of boron carbide and in achieving near theoretical density at lower sintering temperature compared to conventional sintering techniques. Hardness, fracture toughness and elastic modulus of fully dense B 4 C are measured as 37.2 GPa, 2.8 MPa.m 1/2 and 570 GPa respectively. Microstructural analysis indicates the presence of deformation twins in boron carbide grains.

Different forms of selenium (Se) were supplemented to a fishmeal-based diet to investigate the digestibility and bioavailability of Se in yellowtail kingfish (Seriola lalandi). Five groups of fish in triplicate were fed a basal diet (containing 3.31 mg/kg Se) either unsupplemented or supplemented with 2 mg/kg Se from selenite, selenocystine (SeCys), selenomethionine (SeMet) or Se-yeast for 6 weeks. The basal unsupplemented diet resulted in significantly lower weight gain, red blood cell glutathione peroxidase (GPx) and bactericidal activities than the supplemented diets. Muscle Se concentration was increased by Se supplementation from SeCys, SeMet or Se-yeast, but not selenite. There was no difference in GPx activity of fish fed with any supplemented diets. The bioavailability of Se from SeMet and Se-yeast was similar for all measurements. The most digestible sources of Se were from SeMet and Se-yeast, whereas the least was from fishmeal. Se from SeMet or Se-yeast produced more weight gain, higher Se accumulation in muscle tissues and bactericidal activity in yellowtail kingfish than Se from SeCys or selenite. This study shows that SeMet and Se-yeast are the most bioavailable sources of Se to yellowtail kingfish and are recommended to be supplemented to fishmeal-based formulated diets for yellowtail kingfish.

Effect of WSi2 addition on densification and properties of ZrB2 has been investigated. Samples of the following composition with controlled addition of WSi2 were prepared by hot pressing (1) ZrB2, (2) ZrB2+2·5%WSi2, (3) ZrB2+5%WSi2 and (4) ZrB2+10%WSi2. Hot pressing of monolithic ZrB2 at 1750°C resulted in achieving a density of only 80·1% ρth. Addition of WSi2 enhanced the densification and resulted in near theoretical density. Microstructural investigations revealed the presence of reaction product containing Si and Zr. An increase in WSi2 content led to an increase in hardness of the product. A slight increase in fracture toughness was observed with WSi2 addition. Crack deflection was observed in the microstructure. Oxidation study of the composite samples revealed that the oxidised layer is not adherent and resulted in spallation at the end of the test.

The aim of this study was to investigate the effects of different numbers of freeze–thaw cycles (0, 1, 2 and 3) on barramundi (Lates calcarifer) fillets. Quality and shelf life of fillets were evaluated using the microbiological and physiochemical analyses. The fillets were individually frozen on a polystyrene dish in an air blast freezer at −80C for 8 h, stored in a freezer at −20C for 20 days and then analysis was carried out on the 21st day from the beginning of frozen storage. The results obtained were compared with those of fresh fillets. This study revealed that the pH, total volatile base nitrogen, total viable counts, and L* and b* values of freeze-thawed fillets increased significantly (P

Six dietary treatments were prepared in a 3 × 2 factorial design (unsupplemented or supplemented with Se at 1 or 2 mg kg-1 × supplemented with vitamin E at 40 or 180 mg kg-1) and fed to yellowtail kingfish (Seriola lalandi) for 6 weeks to evaluate the effects of dietary Se and vitamin E on growth performance, immune and antioxidant responses and to investigate the potential interaction between these two micronutrients in this species. The results have revealed significantly interactive effects with positive physiological responses. Se significantly increased weight gain of fish fed diets low in vitamin E, but not high in vitamin E, whereas serum lysozyme activity was significantly improved by Se in diets high in vitamin E, but not low in vitamin E. Moreover, there was evidence of myopathy in fish deficient in both Se and vitamin E, but not single deficiency. There was no significant effect of dietary Se, vitamin E or their interaction on survival, antibody titre, feed intake, feed conversion ratio and fillet proximate composition; however, fillet Se and vitamin E were significantly responsive to dietary Se and vitamin E, respectively, and higher dietary Se intakes produced significantly higher red blood cell glutathione peroxidase activity.

A 90-day feeding trial was conducted to determine the effects of dietary organic selenium (OS) supplementation on immune responses, total selenium accumulation in various tissues and the digestive system health of marron Cherax cainii. A group of marron (initial weight 3.65 � 0.05 g) were fed 0.2 g kg � 1 of Sel-Plex as a source of OS and were compared to a control group of marron that were not fed OS. After 90 days of feeding OS, total haemocyte counts (THC) and the percentages of granular and semigranular cells in marron were significantly higher than in marron fed a control diet. However, dietary OS did not affect the proportion of hyaline cells. The marron fed OS had significantly lower bacteraemia and longer neutral red retention times than the control group. Total selenium levels in the haemolymph, hepatopancreas and muscle tissues of the OS-fed marron group were significantly higher (P < 0.05) than in control diet group. The highest total soluble selenium levels were found in the muscle tissues of OS-fed marron on the final day of the feeding trial. Amylase and protease activity, soluble protein, and numbers of microvilli were significantly higher (P < 0.05) in marron fed OS. These findings demonstrate the benefits of including 0.2 g kg � 1 OS in marron diet to enhance immune parameters, increase total selenium accumulation in muscle and improve marron digestive system health.

This study was conducted to compare the effects of dietary supplementation of selenium (Se, both inorganic and organic) and mannan oligosaccharide (MOS) on the growth, immune function, and antioxidant enzyme activities in the haemolymph of the marron Cherax cainii (Austin, 2002); 0.4 mg kg−1 of sodium selenate, 0.2 g kg−1 Sel-Plex®, or 0.4 % Bio-MOS® was added to the basal diet as sources of inorganic selenium (IS), organic selenium (OS), and MOS, respectively. After 90 days, marron fed all 3 supplemented test diets had significantly higher final weight, specific growth rate (SGR), survival, total haemocyte count (THC), percentage of hyaline cells, glutathione-S-transferase (GST), and glutathione peroxidase (GPx) activities than marron fed without any supplements. The marron fed OS showed significantly higher THC and percentage of hyaline cells than those fed IS and MOS. Marron fed MOS showed the highest final weight, SGR, and percentage of granular cells; however, there was no significant difference in the neutral red time retention between marron fed IS and OS, whereas marron fed OS resulted in the highest GPx activity and total Se levels in the haemolymph but the lowest lipid peroxidase activity; therefore, it is suggested that dietary supplementation with any source of Se and MOS is beneficial to improving growth, survival, and antioxidant activity.

A two-phased experiment was conducted to investigate the effects of dietary supplementation of customised probiotics on marron physiology. During the first phase marron were fed probiotic supplemented feed for 70 days, while in phase two the same marron were challenged with Vibrio mimicus and their physiological responses were investigated for 4 days post-challenged. The experiment was carried out in a purpose-built room, designed for aquaculture research, using 18 of 250 L cylindrical plastic tanks. Five species of isolated probiotic bacteria from commercial probiotic products and marron's intestine were tested in this experiment. The probiotic bacteria were (Bacillus sp.); A10 (Bacillus mycoides); A12 (Shewanella sp.); PM3 (Bacillus subtilis); and PM4 (Bacillus sp.), which were added to the formulated basal marron diet (34% crude protein, 8% crude lipid, 6% ash) at a concentration of 10(8) cfu/g of feed. Immune responses of marron fed probiotics were evaluated by investigating organosomatic indices, growth rate, survival, intermoult period, total haemocytes counts (THC), proportion of granular cells (GC), bacteraemia, bacteria load in the intestine and water quality. The results showed that dietary supplementation of probiotics in marron had no significant impact on growth, intermoult period and survival of the marron. However, their supplementation improved the physiological condition of marron in terms of significantly higher tail muscle indices, THC and proportion of granular cells (GC) and reduced bacterial load in the haemolymph. The addition of probiotics in marron diets also increased the bacteria load in the marron intestine. In addition, dietary supplementation of the customised probiotics was effective in improving the resistance of marron against V. mimicus as they had higher THC, higher proportion of GC and lower presence of bacteria in their haemolymph, after marron were challenged with V. mimicus. The results also showed that probiotic Bacillus mycoides (A10) and PM4 are the most beneficial dietary probiotics for marron health.

This paper presents the experimental results on synthesis of boron carbide from its elements. Boron to carbon ratio of 4:1 and a synthesis temperature of 1850°C was found optimum to obtain stoichiometric B4C. Higher boron in charge resulted in the formation of boron rich phase B8C along with B4C but was not effective in eliminating free carbon in the product. Effect of hot pressing parameters on densification of boron carbide was investigated and the optimum operating parameters to obtain B4C pellets with a density of ≥95% TD were identified. Mechanical and thermal properties were characterized and compared with literature values.

The effects of dietary selenium (Se) and vitamin E and their interaction in the nutrition of yellowtail kingfish, Seriola lalandi, were investigated. Six dietary treatments were prepared in a 3 × 2 factorial arrangement (not supplemented or supplemented with Se at 1 or 2 mg kg−1 × supplemented with vitamin E at 40 or 180 mg kg−1). A group of fish in triplicate were fed one of the six experimental diets for 6 weeks, and their growth performance, haematological and immune responses were measured. The results revealed positively interactive effects between dietary Se and vitamin E in yellowtail kingfish. Se significantly increased weight gain of fish fed diets low in vitamin E, but not high in vitamin E. Simultaneous supplementation of both micronutrients resulted in significant increase in serum bactericidal activity. There was no significant effect of Se or vitamin E on survival, feed intake, feed conversion ratio, haematocrit, white blood cell counts and fillet proximate composition. However, Se and vitamin E contents in fillets were significantly responsive to dietary Se and vitamin E, respectively. The supplemental level of Se at 2 mg kg−1 significantly increased red blood cell counts and haemoglobin concentrations, while lysozyme activity in skin mucus was significantly stimulated by vitamin E. The findings of Se and vitamin E supplementation in this study can be applied to improve growth and health indices of yellowtail kingfish.

The dietary selenium (Se) requirement of yellowtail kingfish (Seriola lalandi) in normal and infected conditions was investigated. The fish were fed one of five experimental diets; a control un-supplemented diet (3.35 mg/kg Se) or diets supplemented with Se to provide 4.86, 5.38, 5.85 or 6.38 mg/kg Se. After feeding for 6 weeks, the fish were challenged by Vibrio anguillarum immersion and then observed for 4 weeks. Supplementation of Se had no effect on feed intake, feed conversion ratio and survival over 6 weeks of feeding; however, it significantly increased growth and Se content in muscle tissues. The optimal Se level for maximal growth of yellowtail kingfish estimated by second order regression was 5.56 mg/kg. Following the bacterial challenge, the immune-stimulating effects of Se were demonstrated in lysozyme and bactericidal activities, and there was a corresponding increase in survival and antibody response by supplementation of Se at ≥2 mg/kg (measured Se of ≥5.38 mg/kg). Under normal and infectious conditions, antioxidant capacity of fish measured as glutathione peroxidase activity increased by supplementation of Se. During post-challenge period, haematocrits were higher in the fish fed Se supplemented diets than the fish fed the control diet, while more macrophage aggregates were seen in the control group than in the others. Furthermore, there was evidence of myopathy in fish fed the diet without Se supplementation. Therefore, the results indicated that the optimal dietary Se requirement of yellowtail kingfish is 5.56 mg/kg.

Solvent-extracted soybean meal (SBM) was fermented using baker's yeast Saccharomyces cerevisae at 30 °C for 5 days. Four isonitrogenous and isocaloric diets containing 75% SBM protein, either fermented or non-fermented (SBM and FSBM), and supplemented or not with organic Se (OS) (SBMOS and FSBMOS), were fed to triplicate groups of juvenile barramundi (Lates calcarifer) (initial weight of 5 g) for 75 days. A fishmeal (FM)-based diet formulated for juvenile barramundi was used as a reference diet. The growth of fish was significantly affected by either the interaction of SBM type or by the OS level. In fish fed diets supplemented with OS (SBMOS and FSBMOS), final weight (FW), specific growth rate (SGR) and weight gain (WG) were higher in fish fed the fermented SBM (FSBMOS) than in those fed the non-fermented SBM (SBMOS). The apparent digestibility coefficient (ADC) of protein was higher in the fish fed the fermented SBM, either supplemented or unsupplemented with OS. However, there were no significant differences in the ADC of dry matter (DM) and lipids among the tested diets and in comparison to the reference diet. The haematocrit and leucocrit of fish fed the FSBMOS diet were lower than those of fish fed the FM diet. Furthermore, glutathione peroxidase (GPx) activity was significantly influenced by OS supplementation in the experimental diets; GPx activity was greater in the fish fed diets supplemented with OS. Creatinine kinase (CK) of all groups of fish was higher than the CK of those fed the reference diet. These results suggest that with a proper nutritional level, OS supplementation may act as an important factor in enzymatic GPx activity and in the haematology and blood biochemistry status of juvenile barramundi fed fermented SBM-based diets, encouraging improvement of the overall growth performance.

The present study examined the effect of simulated transport on marron, Cherax cainii, (Austin, 2002) after a 10 week feeding trial using basal diet or customised probiotic, Bacillus mycoides supplemented diet by measuring intestinal bacterial population, total haemocyte count (THC), bacteraemia, morbidity, dehydration and mortality. Packing steps followed the established standard packing method for live transportation of marron. Each treatment group consisted of six polystyrene boxes (65 ?? 30 ?? 40 cm3 ), and each box contained 30 marron from each feeding group. The sealed boxes were placed on a trolley at room temperature to give the effect of transportation. Boxes were opened at 24th and 48th hour post simulated transport and marron from each treatment group were returned to the culture tank. After temperature acclimation, the marron were observed for mortality and samples were collected to assess marron health and immunity. The results demonstrated that no mortality was observed at 24 h of transport both in basal diet and probiotic diet fed marron, however at 48h of transport the survival of probiotic fed marron was significantly higher (100 ?? 0.0%) compared to survival (93.3 ?? 2.8%) of basal diet fed marron. The higher survival rate of probiotic fed marron was also sustained by superior health and immune status indicated by higher intestinal bacterial population, higher total haemocyte count and lower haemolymph bacteria (bacteraemia) level. In brief, supplementation with host origin customized probiotic B. mycoides significantly improved marron tolerance to a live transport stress test, which resulted in no mortality up to 48h of transport.

We conducted a seven-year survey (years 2009 - 2015) of the Lake Saimaa signal crayfish population. Lake Saimaa is the largest single waterbody in Finland, with a productive fishery and crayfishery. The signal crayfish were introduced to Lake Saimaa in mid-1990’s and a commercial fishery was initiated in the mid-2000s. At first, there was a small proportion of noble crayfish among the catch, but after 2007, an acute crayfish plague epidemic eradicated them, and the signal crayfish stock started showing frequent gross symptoms of chronic crayfish plague infection (e.g., melanised lesions, eroded uropods and pleopods, lost appendages with melanised stumps). This stock now shows gross symptoms of the infection at a rate of 45% to 79% of the annual trap catch, in addition to showing signs of eroded swimmeret symdrome (ESS) at a rate of 2.8 to 15.4%. The CPUE has remained rather low, between one and three crayfish throughout the survey, while the proportion of the commercial grade catch has been between 35% and 68% of the total catch. The signal crayfish populations in Lake Saimaa are still rather fragmented, and production is low. It appears that the Lake Saimaa signal crayfish population has developed slowly and is producing less than expected.

A feeding experiment was conducted to evaluate the effect of partial and complete replacement of freshwater shrimp ( Caridina nilotica ) (Roux) protein with boiled taro leaves [ Colocasia esculenta (L.) Schott] in diets of Nile tilapia ( Oreochromis niloticus Linnaeus) cultured in Kenya under semi-intensive conditions. Four formulated isonitrogenous test diets with protein levels of 23% were prepared in which taro leaf meal replaced the freshwater shrimp meal at 100% (D2), 67% (D3), 33% (D4) and 0% (D5). These diets were evaluated on the basis of growth performance of Nile tilapia, cost‐efficiency of the farming operations and water stability of the diets against a commercial diet (D1) and a test diet with no shrimp meal (D2). Though all the diets remained intact till they were ingested by the fish, the commercial diet had a significantly higher (P 2 ponds located at three different sites having 5 ponds each. Three randomly selected ponds received one experimental diet in such a way that each replicate was allocated to one site. All the ponds were initially stocked with tilapia fingerlings of 35.3 g and standard length 9.7 ± 0.2 cm at the rate of 1.4 fish/m 2 . At the end of the trial, the daily weight gain (DWG) and the total mean weight gain of tilapia fed with diets D1 and D2 were significantly higher (P 0.05) were observed in apparent food conversion ratio (AFCR), specific growth rate (SGR), and survival among any tilapia. Water quality parameters were similar among all ponds irrespective of diets received. At the final harvest, the size distribution showed that fish fed with D1 and D5 had a more uniform size distribution while those fed with D3 had a spread distribution. Cost benefit analysis indicated that D1 was the least cost effective (profit index = $2.75), while D2 (profit index = $12.20) was the most effective when taro leaves were sourced in situ . It was concluded that at 23% protein level, taro leaf protein could effectively replace shrimp meal protein in fertilized ponds without compromising growth performance, survival, and AFCR.

Integrated farming methods, where filter feeders are used to absorb suspended particles have been used for treating nutrients and particulate wastes from prawn culture system. This study investigated the effects of integrating varying stocking densities of blue mussels ( Mytilus e dulis ) with western king prawns ( Penaeus latisulcatus ) on the water quality and animals growth rates under a closed recirculating aquaculture system. The experiment was conducted using fifteen indoor recirculating systems which tested four different mussel and prawn stocking ratios (replicates of three) with a control of having prawns only. The four mussel densities and prawn biomass ratios were 0.25, 0.50, 1.00 and 2.00. Mussels in the system removed significant ( P

Feed rate is one of the important variables considered for the improvement in production of prawns. The effects of four feeding rates on growth, water quality and the nutrient budget of Penaeus latisulcatus were investigated for 98 days. The specific growth rate (SGR) at 3.0% feed rate was significantly higher than at all higher feed rates, and there was no significant difference in SGR between 4.5%, 6% and 7.5%. Total ammonia nitrogen concentrations in all treatments remained low in the safe range for prawn culture. Dissolved inorganic nitrogen and nitrate nitrogen were significantly higher (P < 0.05) in prawn tanks received feed rates of 6.0% and 7.5%. Total phosphorus and the soluble reactive phosphorus linearly increased with the progression of the trial and feeding rates. Nutrient conversion rates were significantly higher (P < 0.05) in prawns receiving the feeding rate of 3.0% than feeding rates of 6.0% and 7.5%. The lowest food conversion ratio was recorded at feeding rates of 3% and 4.5%. Nutrient budget showed that 6.01–15.99% nitrogen and 4.53–9.29% phosphorus of the nutrient inputs were retained in the prawn biomass. The results indicated that the growth and nutrient conversion rate may not increase with the increase above 3.0% of biomass per day.

Gracilaria is the most importance source of raw material for the extraction of the polysaccharide agar. Despite its worldwide importance, few papers have addressed the effect of different life stages on the biomass and agar production. Gracilaria cliftonii Withell, Millar & Kraft (1994) has been identified as a potential species for aquaculture due to its high agar yield (> 60%). However, information related to seasonal variations in biomass and abundance of the species has not yet been determined. The present study reports the seasonality of biomass, abundance, occurrence and plant length variations of different life stages from G. cliftonii from Western Australia. The biomass and abundance of tetrasporophyte and carposporophyte stages of G. cliftonii in autumn was significantly higher (p < 0.05) than other seasons, while the biomass of the vegetative stage was significantly higher in spring and summer. Biomass and abundance were found to be dependent on nitrate and nitrite concentration, while male biomass was dependant (p < 0.05) on rainfall and osmolality. The present study provided new information on the phenology of Gracilaria from a different location of the world and demonstrates that variations in biomass, abundance and plant length of G. cliftonii are influenced by environmental parameters.

Integrating recirculating aquaculture systems with seaweeds is one of the strategies that can minimise wastes and risk of disease outbreaks. This study investigated the effect of integrating green seaweed ( Ulva lactuca ) with western king prawns ( Penaeus latisulcatus ) at varying stocking densities on the water quality, nutrient conversion rates and nutrient budget under closed recirculating culture system. The experiment was conducted using fifteen indoor tank recirculating systems and tested four different stocking ratios of prawns and seaweed with a control having prawns only. The four stocking ratios of seaweed and prawn biomass were 2, 4, 8 and 16 per tank. The mean concentrations of total ammonia nitrogen (TAN), NO 3 − –N and PO 4 3− –P in the prawn and seaweed tanks were significantly lower (P U. lactuca was highly efficient in removing the inorganic nutrients from the culture systems with TAN removal rate of 59–81% and PO 4 3− –P removal rate of 50–55%. Integrating seaweed with prawns did not significantly alter the specific growth rate (SGR) and survival rate of the prawns (P > 0.05). Ratio of C:P in seaweed tissues decreased with increasing seaweed stocking densities while C:N ratio showed an adverse trend. The nutrient conversion rate into total biomass (prawns plus seaweed) in the integrated systems was significantly higher at the highest seaweed stocking density (2.00 kg m − 2 ). Nutrient budget revealed that seaweed retained about 6.5–29.7% nitrogen and 1.6–13.5% phosphorus inputs while values for prawns were 28.0–31.9% and 13.5–14.6%, respectively. Seaweed also removed dissolved inorganic nitrogen effectively in the closed recirculating aquaculture system.

The effect of different nutrient media on growth, physicochemical, and agar properties of the marine algae Gracilaria cliftonii was investigated in ocean water (OW) and inland saline water (ISW). G. cliftonii fronds were cultured in 500-mL and 25-L containers with different nutrient media: Aquasol, Total, Guillard f2, Walnes, and Modified-Provasoli's Enriched Seawater in OW and ISW at 35 ppt. Specific growth rate (SGR) was higher in OW than ISW irrespective of nutrient media in both volumes. Growth of G. cliftonii in Guillard f2-supplemented OW was significantly higher than other nutrient media in both water types. Nutrient media had no influence on growth and agar properties. However, f2−supplemented OW resulted in significantly higher agar yield (58.3% db) as compared to other media. Either f2 or Walnes media are preferred nutrient sources for culturing G. cliftonii in ocean and inland saline water.

Seasonality in yield, physical and chemical properties of the native agar from different life stages of Gracilaria cliftonii was investigated over a period of six seasons (autumn 2008–winter 2009). Agar yield and its properties varied as a function of seasons and life stages but there was no significant correlation between environmental factors and agar properties (p > 0.05). Native agar varied from 53.6% to 59.6% dry basis over the study period. Agar yield of the tetrasporophyte was significantly higher in autumn 2008 than spring 2009. Gelling temperature of agar varied between 34 and 36 °C, whereas melting point varied from 77 to 84.3 °C. Sulphate of the agar from different life stages of G. cliftonii varied from 5.9% to 6.6% dry basis but was not influenced by seasons (p > 0.05). The present study demonstrated that agar yield and its properties are influenced both by seasons and reproductive status of the thallus.

The efficacy of dietary supplementation of mannan oligosaccharide (MOS) (Bio-Mos®, Aqua Grade; Alltech, Lexington, KY, USA) was evaluated on survival, growth, physiological and immunological parameters of marron, Cherax tenuimanus. Marron were fed six different isonitrogenous and isocalorific diets supplemented with 0, 0.05, 0.1, 0.2, 0.4, and 0.8% of MOS for a duration of 112 d and examined for survival and growth every 28 d. Physiological and immunological indicators were measured every 56 d. After 112 d, survival was the highest when marron were fed 0.2 and 0.4% MOS supplemented diets. Wet tail muscle index (TMIwet) and dry tail muscle index (TMIdry) of marron fed MOS supplemented diets were significantly higher (P < 0.05) than marron fed diet without MOS. Osmoregulatory capacity was highest in marron fed 0.4% MOS. Marron fed MOS supplemented diets had lower (P < 0.05) bacteraemia than marron fed diet without MOS. Hemolymph clotting time was the lowest and granular cells were the highest in marron fed 0.2 and 0.4% MOS. The results suggest that feeding 0.2–0.4% MOS in the diet increases the health status of marron.

This paper presents the results of experimental investigations carried out on the synthesis of pure ZrB2 by boron carbide reduction of ZrO2 and densification with the addition of HfB2 and TiSi2. Process parameters and charge composition were optimized to obtain pure ZrB2 powder. Monolithic ZrB2 was hot pressed to full density and characterized. Effects of HfB2 and TiSi2 addition on densification and properties of ZrB2 composites were studied. Four compositions namely monolithic ZrB2, ZrB2 + 10% TiSi2, ZrB2 + 10% TiSi2 + 10% HfB2 and ZrB2 + 10% TiSi2 + 20% HfB2 were prepared by hot pressing. Near theoretical density (99.8%) was obtained in the case of monolithic ZrB2 by hot pressing at 1850 °C and 35 MPa. Addition of 10 wt.% TiSi2 resulted in an equally high density of 98.9% at a lower temperature (1650 °C) and pressure (20 MPa). Similar densities were obtained for ZrB2 + HfB2 mixtures also with TiSi2 under similar conditions. The hardness of monolithic ZrB2 was measured as 23.95 GPa which decreased to 19.45 GPa on addition of 10% TiSi2. With the addition of 10% HfB2 to this composition, the hardness increased to 23.08 GPa, close to that of monolithic ZrB2. Increase of HfB2 content to 20% did not change the hardness value. Fracture toughness of monolithic sample was measured as 3.31 MPa m1/2, which increased to 6.36 MPa m1/2 on addition of 10% TiSi2. With 10% HfB2 addition the value of KIC was measured as 6.44 MPa m1/2, which further improved to 6.59 MPa m1/2 with higher addition of HfB2 (20%). Fracture surface of the dense bodies was examined by scanning electron microscope. Intergranular fracture was found to be a predominant mode in all the samples. Crack propagation in composites has shown considerable deflection indicating high fracture toughness. An oxidation study of ZrB2 composites was carried out at 900 °C in air for 64 h. Specific weight gain vs time plot was obtained and the oxidized surface was examined by XRD and SEM. ZrB2 composites have shown a much better resistance to oxidation as compared to monolithic ZrB2. A protective glassy layer was seen on the oxidized surfaces of the composites.

Juvenile western king prawn P. latisulcatus were fed 105 colony-forming units (CFU)/mL of two probiotics Pseudomonas synxantha and P. aeruginosa for 28 days. P. latisulcatus were then challenged with V. harveyi at 0 (control), 103, 105, and 107 CFU/mL. During the seven days of challenge, disease resistance of the probiotic-fed prawns was compared with that of prawns not fed probiotics. The immunological responses of the prawns did not improve during the challenge period in terms of total haemocyte count, hyalinocyte, semi-ganulocyte, granulocyte, clotting time, bacteraemia, and intestinal bacterial load. Overall, when prawns were challenged with V. harveyi, the LT50 values got shorter as V. harveyi concentration increased. LT50 values of prawns fed probiotics were significantly longer (P < 0.05) than those not fed probiotics. At a V. harveyi concentration of 103 CFU/mL, the 100% survival of the prawns fed probiotics was three times more likely than those of the prawns not fed probiotics.

Effluent water from intensive prawn aquaculture systems typically has a high concentration of dissolved nutrients such as nitrogen and phosphorus. A study was conducted for 42 days to investigate the nutrient flow in a system where brown seaweed ( Sargassum sp. ) was integrated into western king prawn ( Penaeus latisulcatus) culture. Three treatments namely, western king prawn monoculture (5.48 ± 0.29 g), Sargassum sp. monoculture and seaweed/prawn integrated culture were tested for nutrient flow among feed, water and species cultured. The results showed that by integrating seaweed into prawn culture, the concentrations of total ammonium nitrogen (TAN), nitrite–nitrogen (NO 2 − ) and nitrate–nitrogen (NO 3 − ), dissolved inorganic nitrogen (DIN), total nitrogen (TN), phosphate (PO 4 3− ) and total phosphorus (TP) were significantly lower (p Sargassum sp. with western king prawn culture did not significantly alter the nitrogen and phosphorus conversion rates from feed into prawns (approximately 17.69–18.99 and 13.79–14.47%, respectively). The specific growth rate (SGR) and survival rate of the prawns in integrated treatment did not significantly differ (p > 0.05) from the prawn monoculture. The mean biomass of Sargassum sp. in integrated culture increased at the rate of 3.16 ± 0.74% g day −1 after 7 days of the study, which was significantly higher than in the monoculture system (5.70 ± 0.82% g day −1 ). The results suggest that integrating Sargassum sp. into western king prawn culture can benefit prawn farming by assisting in the maintenance of optimum water quality and thereby, reducing environmental impacts on surrounding areas.

The aim of this experiment was to determine the effects of dietary supplementation of Bio-Mos® as a source of mannan oligosaccharide (MOS) on the growth, survival, immunity and digestive enzyme activity of freshwater crayfish, Cherax destructor (yabby). A basal diet and another diet with 0.4% of Bio-Mos® supplemented to the basal diet were formulated. Each diet was provided to eight yabbies (35.14 ± 0.48 g, initial weight) replicated 3 times in individual 250-L plastic cylindrical tanks for a duration of 56 days. Each tank was provided with an independent recirculating water system filtered with a biological filtration. Growth parameters such as weight, specific growth rate and average weekly gain of Bio-Mos®-fed yabbies were higher (P < 0.05) than yabbies fed the control diet. Total haemocyte count, granular cells and semi-granular cells were also higher in the yabbies fed Bio-Mos® diet. Protease activity was higher in hepatopancreas, and amylase activity was higher in the guts of yabbies fed Bio-Mos® diet. The results implies that supplementation of MOS through Bio-Mos® can effectively improve growth and immunological condition of yabbies.

Development of shrimp aquaculture has been associated with increases in infectious diseases and environmental degradation. An effective alternative to chemicals and antibiotics used for the prevention of these problems is to administer probiotics into the rearing system. Three bacterial genera, Bacillus, Vibrio, and Pseudomonas, are commonly administered as probiotics in shrimp aquaculture. Candidate probiotics are species specific and need to be tested for their effectiveness for certain species in in vitro and in vivo. Supplementation into feed is more effective in conveying probiotics into animals compared to direct application into rearing systems. Overdosage or prolonged administration of probiotics can induce immunosuppression. A cell-density of 105 colony-forming units (CFU) per ml is widely recommended. A combination of probiotics results in better outcomes for the host than individual probiotics. Probiotics improve water quality while reducing pathogenic bacteria. Probiotics show positive effects through an improvement in the physiological and immune responses of shrimps. Probiotics are increasingly becoming important and more common in any organic shrimp farming.

The aim of this experiment was to determine the effects of dietary supplementation with mannan oligosaccharide (MOS; BioMos, Alltech, USA) on the gut microbiota and histology of marron, Cherax tenuimanus. Marron were fed six different diets supplemented with 0%, 0.05%, 0.1%, 0.2%, 0.4%, and 0.8% of MOS for a duration of 112 days. Total bacteria in the gut were highest when marron were fed diets which included 0.1% to 0.4% BioMos, whereas total bacteria/Vibrio spp. ratio was highest in the marron fed 0.4% BioMos diet only. The marron fed 0.2% and 0.4% BioMos diets showed normal morphology and higher densities of microvilli, and thicker layer of gut epithelium than other inclusion rates. The results suggest that application of 0.2% to 0.4% of MOS in the diet improves digestive system health in marron.

A new composite of TiB2 with CrSi2 has been prepared with excellent oxidation resistance. Dense composite pellets were fabricated by hot pressing of powder mixtures. Microstructural characterization was carried out by XRD and SEM with EDAX. Mechanical and physical properties were evaluated. Extensive oxidation studies were also carried out. A near theoretical density (99.9% TD) was obtained with a small addition of 2.5 wt.% CrSi2 by hot pressing at 1700 °C under a pressure of 28 MPa for 1 h. The microstructure of the composite revealed three distinct phases, (a) dark grey matrix of TiB2, (b) black phase – rich in Si and (c) white phase – Cr laden TiB2. Hardness and fracture toughness were measured as 29 ± 2 GPa and 5.97 ± 0.61 MPa m1/2, respectively. Crack branching, deflection and bridging mechanisms were responsible for the higher fracture toughness. With increase in CrSi2 content, density, hardness and fracture toughness values of the composite decreased. Thermo gravimetric studies revealed the start of oxidation of the composite at 600 °C in O2 atmosphere. Isothermal oxidation of these composites showed better oxidation resistance by formation of a protective oxide layer. TiO2, Cr2O3 and SiO2 phases were identified on the oxidized surface. Effects of CrSi2 content, temperature and duration of oxidation on the oxide layer formation are reported. Activation energy of the composite was calculated as ∼110 kJ/mol using Arrhenius equation. Diffusion controlled mechanism of oxidation was observed in all the composites.

Six isonitrogenous and isocalorific diets supplemented with five different levels of beta-1,3-glucan (0.08%, 0.1%, 0.2%, 0.4% and 0.8%) were formulated and tested for marron (Cherax tenuimanus) growth, survival, organosomatic indices, osmoregulatory capacity and immunological parameters (total and differential haemocyte counts, haemolymph clotting time and bacteraemia). The sixth diet without any beta-1,3-glucan was used as a control. Each diet was provided to 18 marron (0.47 +/- 0.02 g initial weight) replicated 3 times in individual 250 L fiberglass cylindrical tanks. Each tank was provided with a biological filtration recirculating water system. After 84 days of culture, the survival and yield were higher in the marron fed 0.1% beta glucan supplemented diet. The different levels of beta glucan did not alter any of the physiological parameters of marron. However, dietary supplementation with beta glucan resulted in significantly higher (P0.05) total haemocyte count (THC) and granular cells. The bacteraemia rank was lower in all diets having beta glucan supplemented with more than or equal to 0.1% compared to the control and 0.08% beta glucan supplemented diets. Results suggest that dietary beta-1,3-glucan at a minimum concentration of 0.1-0.2% can improve the immune system of marron.

This paper presents the results of investigation carried out on synthesis and densification of monolithic HfB 2 and the effect of TiSi 2 as sinter additive. Pure phase HfB 2 was prepared by boron carbide reduction of HfO 2 and hot pressed to full density with the addition of TiSi 2 . Isothermal oxidation study of this composite was carried out at 850 °C up to 64 h. Formation of HfB 2 was seen at 1200 °C but pure HfB 2 was formed at a much higher temperature of 1875 °C in vacuum. Hot pressing of HfB 2 at 1850 °C and 35 MPa pressure gave a compact of 80% TD. Addition of TiSi 2 helped in achieving a much higher density at a lower temperature of 1600 °C and a pressure of 20 MPa. A fully dense composite of HfB 2 and TiSi 2 was obtained with 15% TiSi 2 . Hardness and fracture toughness of this composite were 27.4 ± 1.9 GPa and 6.6 ± 0.2 MPa m 1/2 , respectively. Considerable deflection was observed in the crack propagation in composites. Oxidation studies indicated the formation of HfO 2 , SiO 2 , TiO 2 and HfSiO 4 with some glassy phase and the composite with 15% TiSi 2 was seen to be completely covered with a protective glassy layer.

The effects of dietary mannan oligosaccharide (MOS) (Bio-Mos, Alltech, USA) on the growth, survival, physiology, bacteria and morphology of the gut and immune response to bacterial infection of tropical rock lobsters (Panulirus ornatus) juvenile were investigated. Dietary inclusion level of MOS at 0.4% was tested against the control diet (trash fish) without MOS inclusion. At the end of 56 days of rearing period, a challenged test was also conducted to evaluate the bacterial infection resistant ability of the lobsters fed the two diets. Lobster juvenile fed MOS diet attained 2.86 +/- 0.07 g of total weigh and 66.67 +/- 4.76% survival rate which were higher (P < 0.05) than the lobsters fed control diet (2.35 +/- 0.14 g total weight and 54.76 +/- 2.38% survival rate, respectively) thus providing the higher (P < 0.05) specific growth rate (SGR) and average weekly gain (AWG) of lobsters fed MOS diet. Physiological condition indicators such as wet tail muscle index (Tw/B), wet hepatosomatic index (Hiw) and dry tail muscle index (Td/B) of the lobsters fed MOS supplemented diet were higher (P < 0.05) than that of the lobsters fed the control diet. Bacteria in the gut (both total aerobic and Vibrio spp.) and gut's absorption surface indicated by the internal perimeter/external perimeter ratio were also higher (P < 0.05) when the lobsters were fed MOS diet. Lobsters fed MOS diet were in better immune condition showed by higher THC and GC, and lower bacteraemia. Survival, THC, GC were not different among the lobsters fed either MOS or control diet after 3 days of bacterial infection while bacteraemia was lower in the lobsters fed MOS diet. After 7 days of bacterial infection the lobsters fed MOS diet showed higher survival, THC, GC and lower bacteraemia than the lobsters fed the control diet. The experimental trial demonstrated the ability of MOS to improve the growth performance, survival, physiological condition, gut health and immune responses of tropical spiny lobsters juveniles.

Increase in salinity of inland water sources is adversely affecting aquatic and terrestrial ecosystems around the world including Australia. Inland saline water (ISW) with similar ionic profile to ocean water has potential for culturing marine species. Gracilaria species are commercially important as they are a source of agar. One of the native species Gracilaria cliftonii has been reported for high agar yield of 52%dw. The aim of this research was to investigate the feasibility of culturing G. cliftonii in different ionic profiles of ISW under laboratory conditions. The growth rate of G. cliftonii under different ionic profiles ranged from 0.9 to 2.5 %day−1. Gracilaria cliftonii carbohydrate content decreased while protein content increased in culture conditions when compared to natural populations. Agar yield, gel strength and melting point decreased while gelling temperature and sulphate content increased in culture conditions when compared to natural populations. Strong correlation (R 2 > 0.8, P

Agar extraction process was developed for Gracilaria cliftonii by investigating the effects of various extraction variables and alkali treatments on agar yield and properties. The tested variables were soaking time, soaking temperature, seaweed to water ratio of, extraction temperatures and extraction time. Alkali treatments were carried out in alkali concentrations of 1%, 2%, 3% and 5% in a water bath at 60, 70 and 80 °C prior to agar extraction. The results showed that agar yield was significantly affected by all the tested variables. The agar yield was maximised when extraction process was carried out with 1 h soaking time at 30 °C with seaweed to water ratio of 1:150 and extracted for 3 h at 100 °C. The alkali-temperature combinations significantly influenced agar yield and properties. Irrespective of temperature, alkali treatments at 3% and 5% significantly increased the gel strength.

This paper presents the results of detailed studies carried out on the densification of TiB2 with CrB2 as sinter additive by hot pressing. The dense compacts were characterized by measurement of hardness, indentation fracture toughness, flexural strength, coefficient of thermal expansion and electrical resistivity. Oxidation characteristics were investigated between 600 °C and 1000 °C and isothermal oxidation kinetics at 850 °C. Phase identification and surface morphology analysis of hot pressed and oxidized samples were done using XRD and SEM. A high density of 96.61% Τ.D was obtained with the addition of 2.5% CrB2 by hot pressing at 1750 °C under 35 MPa pressure. Hardness values of composites with 2.5–10% CrB2 were close to 24 GPa and fracture toughness in the range of 3–5 MPa m1/2. Coefficient of thermal expansion of the composite with 10% CrB2 was measured in the range of 6.21–7.43 × 10−6/K from room temperature to 1000 °C. Electrical resistivity of TiB2 + 10%CrB2 was measured as 32.83, 75.97 and 120 μΩ cm at 25 °C, 500 °C and 900 °C, respectively. Observed nature of oxidation was parabolic for all composites. Formation of continuous and thick glassy film was observed with increased CrB2 content in the composite. TiO2 and CrBO3 phases were identified on the oxidized surface which are responsible for the improved oxidation resistance of this composite.

Experimental investigations were carried out on synthesis of chromium diboride through boron carbide reduction of Cr2O3. The products obtained were characterized by X-ray diffraction and the process optimized to prepare single-phase CrB2 powder. Densification of CrB2 was investigated by pressureless sintering and hot pressing. A maximum of 93% ρth was obtained by pressureless sintering at 1850 °C after a prolonged duration of 360 min. However, near theoretical density was achieved by hot pressing at 1600 °C and 35 MPa pressure for 2 h. The hardness and fracture toughness of fully dense CrB2 was measured as 22 GPa and 3.5 MPa m1/2, respectively. The mode of fracture in pressureless sintered samples is intergranular whereas that in hot pressed is transgranular.

Epiphytism in Gracilaria is a common phenomena observed in natural populations and under culture conditions. Generally, epiphytes are attached superficially to the surface of the host however, genera such as Polysiphonia spp. and Ceramium spp. can penetrate into the host tissue affecting its growth and hence productivity. The present paper aims to identify and quantify epiphyte abundance and characterise their attachment and penetration on the natural populations of Gracilaria cliftonii collected from Shoalwater Marine Park, Perth, Western Australia. G. cliftonii samples were collected monthly for 1 year and their epiphytes were identified. Histological studies of G. cliftonii were also performed on epiphyte attachment sites. Twenty-four species of macroalgae epiphytes were recorded, 21 belonging to Rhodophyta and 3 to Chlorophyta. Hypnea episcopalis and Polysiphonia forfex were the dominant (p < 0.05) species during the sampling period. The maximum epiphytic load was observed in October (40%), however, the maximum diversity of epiphytes was recorded in September and February (n = 14). Light and scanning electron microscopy studies of the epiphyte attachment sites revealed that P. forfex and Ceramium isogonum penetrated into the cortex and outer medulla of G. cliftonii, while Bryopsis plumosa and Laurencia clavata altered the cellular structure of the cell wall of G. cliftonii.

Three trials were conducted to determine the effects of mannan oligosaccharide (Bio-Mos ® ) on the immune responses of marron. In the first trial marron were challenged with Vibrio mimicus infection, in the second with NH 3 exposure and in the third, the marron were exposed to air during a simulated live transportation trial. For V. mimicus infection and live transportation trials, marron (10.44 ± 0.20 g and 4.44 ± 0.20 g initial weights, respectively) were fed three different diets containing 0% (control diet), 0.2% and 0.4% Bio-Mos ® for 30 days and 112 days respectively before challenge, whereas for the NH 3 exposure trial, marron (94 ± 2.17 g initial weight) were reared with the control diet and 0.4% Bio-Mos ® diet for 42 days before exposure to NH 3 . Marron were examined for survival and total haemocyte count (THC), differential haemocyte count (DHC), haemolymph clotting time, bacteraemia and lysosomal membrane stability as indicators of immune responses during the course of the challenge. Survival of marron infected with bacteria and exposed to NH 3 , were significantly improved when fed Bio-Mos ® . THCs were significantly reduced in marron fed the control diet when they were infected with bacteria and subjected to live transportation while it remained unchanged in the marron fed the Bio-Mos ® supplemented diets. THCs of marron fed any of the diets were reduced when they were exposed to NH 3 but the THCs were higher ( P ® diets. Vibrio spp. in haemolymph of marron fed the control diet significantly increased when they were infected with V. mimicus and challenged with NH 3 but it remained unchanged in the marron fed the Bio-Mos ® diets. Haemolymph clotting time was higher in marron fed the control diets when subjected to live transportation and 3 days of exposure to NH 3 . After 96 h infection marron fed the Bio-Mos ® diets had longer NRR time than those fed the control diet. All the findings demonstrated the ability of Bio-Mos ® to improve the survival, health status and immunity of marron under the bacterial infection and stress conditions caused by air and NH 3 exposures.