Home About us Contact
|
Home About us Contact | ||
|
|
||
Different Salinities (different + salinity)
Selected AbstractsSedimentation of Soils from Three Physiographic Regions of Alabama at Different SalinitiesJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2009Gulnihal Ozbay This study evaluated the rate of sedimentation from water under various salinities, over a time period of 72 h. The particles come from soils that are commonly found in shrimp growing areas of Alabama: Black Belt Prairie, Piedmont Plateau, and Upper Coastal Plain. Different salinity treatments and settling times resulted in significant differences (P, 0.05) in the reduction of turbidity and TSS for each soil type. Solutions containing 2 ppt salinity had a similar rate of turbidity reduction as the solutions with 5, 10, or greater ppt treatments. Concentrations of turbidity and TSS decreased rapidly between 1 and 12 h of sedimentation; very little decline was observed during the time intervals 12,72 h. Higher salinity treatments yielded settling patterns similar to the 2 ppt salinity treatment. After 1 h, turbidity was removed by 65% in the control compared with 85% salinity treated samples. Variations in turbidity and TSS among the three sediments suggest that finer particles, the Piedmont Plateau soils, settled at a slower rate than larger particles. This difference occurs because the percentage of turbidity and TSS removed was significantly higher in mineralized waters compared to freshwater. Therefore, a small amount of salt, 2 ppt, can be used in pond aquaculture treatments to reduce the turbidity and TSS concentrations in shrimp ponds. [source] Growth and Feed Utilization of the Tilapia Hybrid Oreochromis mossambicus×O. niloticus Cultured at Different Salinities under Controlled Laboratory ConditionsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2001Manuel García-Ulloa Fish (2.32 g mean initial weight) were grown in 113-L aquaria at salinities of 0.5, 17 and 32 ppt at a density of 20 fish per tank. Mean specific growth, food conversion, and food consumption were determined at each salinity. There was no significant difference (P > 0.05) in growth among the treatments, although feed conversion and feed consumption were significantly improved (P , 0.05) when fish were grown at 17 and 32 ppt. [source] Changes in the community structure and activity of betaproteobacterial ammonia-oxidizing sediment bacteria along a freshwater,marine gradientENVIRONMENTAL MICROBIOLOGY, Issue 4 2006Thomas E. Freitag Summary To determine whether the distribution of estuarine ammonia-oxidizing bacteria (AOB) was influenced by salinity, the community structure of betaproteobacterial ammonia oxidizers (AOB) was characterized along a salinity gradient in sediments of the Ythan estuary, on the east coast of Scotland, UK, by denaturant gradient gel electrophoresis (DGGE), cloning and sequencing of 16S rRNA gene fragments. Ammonia-oxidizing bacteria communities at sampling sites with strongest marine influence were dominated by Nitrosospira cluster 1-like sequences and those with strongest freshwater influence were dominated by Nitrosomonas oligotropha- like sequences. Nitrosomonas sp. Nm143 was the prevailing sequence type in communities at intermediate brackish sites. Diversity indices of AOB communities were similar at marine- and freshwater-influenced sites and did not indicate lower species diversity at intermediate brackish sites. The presence of sequences highly similar to the halophilic Nitrosomonas marina and the freshwater strain Nitrosomonas oligotropha at identical sampling sites indicates that AOB communities in the estuary are adapted to a range of salinities, while individual strains may be active at different salinities. Ammonia-oxidizing bacteria communities that were dominated by Nitrosospira cluster 1 sequence types, for which no cultured representative exists, were subjected to stable isotope probing (SIP) with 13C-HCO3,, to label the nucleic acids of active autotrophic nitrifiers. Analysis of 13C-associated 16S rRNA gene fragments, following CsCl density centrifugation, by cloning and DGGE indicated sequences highly similar to the AOB Nitrosomonas sp. Nm143 and Nitrosomonas cryotolerans and to the nitrite oxidizer Nitrospira marina. No sequence with similarity to the Nitrosospira cluster 1 clade was recovered during SIP analysis. The potential role of Nitrosospira cluster 1 in autotrophic ammonia oxidation therefore remains uncertain. [source] Variation in toxin compositions of two harmful raphidophytes, Chattonella antiqua and Chattonella marina, at different salinitiesENVIRONMENTAL TOXICOLOGY, Issue 2 2002Shahroz Mahean Haque Abstract Toxin compositions of the two species of raphidophytes, Chattonella antiqua (Hada) Ono and Chattonella marina (Subrahmanyan) Hara et Chihara, were investigated at different salinities under laboratory conditions. C. antiqua contained toxin components CaTx-I, CaTx-II, CaTx-III, and CaTx-IV, which corresponded to brevetoxin components PbTx-1, PbTx-2, PbTx-3, and oxidized PbTx-2. Similarly, C. marina included CmTx-I, CmTx-II, CmTx-III, and CmTx-IV corresponding to PbTx-2, PbTx-9, PbTx-3, and oxidized PbTx-2. Toxin yields in both species varied markedly with a change in salinity concentration. In C. antiqua CaTx-I, CaTx-II, and CaTx-III peaked at 25 P.P.t. with yields of 0.99, 0.42, and 2.90 pg/cell, but the highest yield (2.35 pg/cell) of CaTx-IV was attained at 30 P.P.t. The yields of all CaTx components decreased sharply at salinities exceeding 30 P.P.t. On the other hand, C. marina yielded higher proportions of CmTx-I (0.55 pg/cell) and CmTx-III (2.50 pg/cell) at 25 P.P.t. However, CmTx-IV was present in its highest amount (1.65 pg/cell) at 30 P.P.t., as seen in C. antiqua. A small amount of CmTx-II was also detected at 20 P.P.t.,35 P.P.t. Both species showed the highest ichthyotoxicities at 25 P.P.t., at which the maximum cell division rate was obtained. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 113,118, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10039 [source] Chronic copper toxicity in the estuarine copepod Acartia tonsa at different salinitiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Mariana M. Lauer Abstract Chronic Cu toxicity was evaluated in the euryhaline copepod Acartia tonsa. Male and female copepods were exposed (6 d) separately to different combinations of Cu concentration and water salinity (5, 15, and 30 ppt) using different routes of exposure (waterborne, waterborne plus dietborne, and dietborne). After exposure, groups of one male and three female copepods were allowed to reproduce for 24,h. In control copepods, egg production augmented with increasing water salinity. However, egg hatching rate did not change. Copper exposure reduced egg production and hatching rate in all water salinities tested, but the reproductive response was dependent on the route of Cu exposure. Median effective concentration (EC50) values for egg production after waterborne exposure were 9.9, 36.8, and 48.8,µg/L dissolved Cu at water salinities of 5, 15, and 30 ppt, respectively. For waterborne plus dietborne exposure, they were significantly higher (40.1, 63.7, and 109.9,µg /L, respectively). After dietborne exposure, approximately 40% decrease in egg production was observed, independently of Cu concentration and water salinity tested. At water salinities of 5 and 30 ppt, egg hatching rate reduced after waterborne exposure, together or not with the dietborne exposure. At water salinity of 15 ppt, Cu toxicity was only observed after dietborne exposure. Data indicate that egg production is a more reliable reproductive endpoint to measure chronic Cu toxicity in copepods than egg hatching rate in a wide range of water salinities. They also suggest that both water salinity and route of Cu exposure should be taken into account in the development of a chronic biotic ligand model version for estuarine and marine environments. Environ. Toxicol. Chem. 2010;29:2297,2303. © 2010 SETAC [source] Acute copper toxicity in the euryhaline copepod Acartia tonsa: implications for the development of an estuarine and marine biotic ligand modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Grasiela Lopes Leães Pinho Abstract Copepods (Acartia tonsa) were exposed (48 h) to waterborne, diet-borne (non-Cu-equilibrated and Cu-equilibrated food), and waterborne plus diet-borne Cu in either the absence or the presence of food (diatom Thalassiosira weissflogii). Toxicity tests were run in different salinities (5, 15, and 30 ppt) together with measurements of physicochemical parameters and total and dissolved Cu concentrations in the experimental media. Results show that most of the toxic Cu fraction was in the dissolved phase. In general, Cu toxicity was higher in low (5 ppt) than in high salinity (30 ppt), regardless of the pathway of Cu exposure tested. In the absence of food, data clearly indicate that differences in waterborne Cu toxicity can be explained by changes in water chemistry. However, addition of food (either non-Cu-equilibrated or Cu-equilibrated) to the experimental media protected against acute Cu toxicity in salinities 5 and 15 ppt, suggesting that A. tonsa requires extra energy to cope with the stressful condition imposed by Cu exposure associated with the ionoregulatory requirements in low salinities. For diet-borne exposure, a very high Cu concentration was necessary to precontaminate the diatoms to a level resulting in copepod mortality. Therefore, availability of food exerted a more important positive impact in protecting against acute Cu toxicity than its potential negative impact via contamination resulting in toxicity. Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters. In this context, the euryhaline copepod A. tonsa would be a suitable model species with which to perform experiments to validate and calibrate any future saltwater BLM. Environ. Toxicol. Chem. 2010; 29:1834,1840. © 2010 SETAC [source] Biogeochemistry of a gypsum-encrusted microbial ecosystemGEOBIOLOGY, Issue 3 2004D. E. CANFIELD ABSTRACT Gypsum crusts containing multicolored stratified microbial populations grow in the evaporation ponds of a commercial saltern in Eilat, Israel. These crusts contain two prominent cyanobacterial layers, a bright purple layer of anoxygenic phototrophs, and a lower black layer with active sulphate reduction. We explored the diel dynamics of oxygen and sulphide within the crust using specially constructed microelectrodes, and further explored the crust biogeochemistry by measuring rates of sulphate reduction, stable sulphur isotope composition, and oxygen exchange rates across the crust,brine interface. We explored crusts from ponds with two different salinities, and found that the crust in the highest salinity was the less active. Overall, these crusts exhibited much lower rates of oxygen production than typical organic-rich microbial mats. However, this was mainly due to much lower cell densities within the crusts. Surprisingly, on a per cell-volume basis, rates of photosynthesis were similar to organic-rich microbial mats. Due to relatively low rates of oxygen production and deep photic zones extending from 1.5 to 3 cm depth, a large percentage of the oxygen produced during the day accumulated into the crusts. Indeed, only between 16% to 34% of the O2 produced in the crust escaped, and the remainder was internally recycled, used mainly in O2 respiration. We view these crusts as potential homologs to ancient salt-encrusted microbial ecosystems, and we compared them to the 3.45 billion-year-old quartz barite deposits from North Pole, Australia, which originally precipitated gypsum. [source] Salt-responsive outer membrane proteins of Vibrio anguillarum serotype O1 as revealed by comparative proteome analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009D.-Y. Kao Abstract Aims:,Vibrio anguillarum is a universal marine pathogen causing vibriosis. Vibrio anguillarum encounters different osmolarity conditions between seawater and hosts, and its outer membrane proteins (OMPs) play a crucial role in the adaptation to changes of the surroundings. In the present study, proteomic approaches were applied to investigate the salt-responsive OMPs of V. anguillarum. Methods and Results:, Lower salinity (0·85% NaCl) is more suitable for growth, survival and swimming motility of the bacterium. Comparative two-dimensional electrophoresis (2-DE) analysis reveals six differentially expressed protein spots among three different salinities, which were successfully identified as OmpU, maltoporin, flagellin B, Omp26La, Omp26La and OmpW respectively. Conclusions:, OmpW and OmpU were highly expressed at 3·5% salinity, suggesting their role in the efficient efflux of NaCl. Maltoporin was downregulated in higher salinity, indicating that higher osmolarity inhibits carbohydrate transport and bacterial growth. Omp26La, the homologue of OmpV, functions as a salt-responsive protein in lower salinity. Significance and Impact of the Study:, To the best of our knowledge, this is the first report describing salt stress-responsive proteins of V. anguillarum using proteomic approaches. Our results provide a useful strategy for delineating the osmoregulatory mechanism of the marine pathogens. [source] Nutritional condition of Anguilla anguilla starved at various salinities during the elver phaseJOURNAL OF FISH BIOLOGY, Issue 2 2005A. Rodríguez The effects of food deprivation and environmental salinity (<1, 10 and 20) on survival, fish morphology, organization of the digestive system and body lipid reserves in European eel Anguilla anguilla during the transition from glass eel to elver, were evaluated. Fasted elvers kept in fresh water were able to withstand starvation for >60 days, while those in brackish environments (salinity 10 and 20) reached the level of irreversible starvation at 37 and 35 days, respectively. The high level of lipid reserves contained in liver inclusions and the abdominal cavity (perivisceral deposits) in elvers might explain their long resistance to starvation and differences in fasting tolerance under different salinities. Fasting resulted in a significant reduction of the elvers' condition factor and body depth. There were severe histopathological changes in the digestive system and musculature, such as the alteration of the liver organization, and hepatic glycogen and lipid content, shrinkage of enterocytes and reduction of their height, pancreas degeneration, autolysis of the oesophageal and intestinal mucosa and disarrangement of myofibrils and degeneration of trunk musculature. Degeneration of the oesophageal and intestinal mucosa as a consequence of fasting might have impaired digestive and osmoregulatory functions in feed-deprived fish, directly affecting the tolerance to starvation and survival. Length of food deprivation was associated with a significant increase in mortality, coefficient of variation, cannibalism and point of no return at high salinities. Mortality was dependent on food deprivation and salinity concentrations. Environmental salinity directly influenced the ability of elvers to withstand starvation; once glass eels metamorphosed into elvers, they tolerated starvation better in fresh water than in brackish environments. [source] Gene expression profiling of Dunaliella sp. acclimated to different salinitiesPHYCOLOGICAL RESEARCH, Issue 1 2010Minjung Kim SUMMARY To investigate which genes may be important for growth under extreme conditions such as very low or high salinities, a survey of the Dunaliella sp. transcriptome was performed with a cDNA microarray which had been generated previously representing 778 expressed sequence tags. The comparative microarray analysis indicated that 142 genes differed in expression levels by more than twofold in cells grown at extreme salinities (0.08 M and 4.5 M NaCl) when compared with cells grown at intermediate salinity (1.5 M NaCl). Of these genes, 28 had increased expression and 57 were suppressed in cells grown at low salinity. In cells grown at high salinity, 43 genes showed increased expression and 69 genes showed suppressed expression. However, we did observe a large overlap in the expression of extreme salinity-responsive genes based on Venn diagram analysis, which found 55 genes that responded to both of the two extreme salinity conditions. Further, we found that several genes had similar expression levels under low and high salinities, including some general stress response genes that were upregulated in both extreme salinity conditions. For confirmation of the validity of the cDNA microarray analysis, expression of several genes was independently confirmed by the use of gene-specific primers and real-time polymerase chain reaction. The present study is the first large-scale comparative survey of the transcriptome from the microalga Dunaliella sp. acclimated to extreme salinities, thus providing a platform for further functional investigation of differentially expressed genes in Dunaliella. [source] Tolerance of Soil Flagellates to Increased NaCl levelsTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 4 2002FLEMMING EKELUND ABSTRACT. The ability of heterotrophic flagellates to survive and adapt to increasing salinities was investigated in this study. Whole soil samples were subjected to salinities corresponding to marine conditions and clonal cultures were used to perform growth and adaptation experiments at a wide range of different salinities (0,50 ppm). More morphotypes tolerant to elevated NaCl levels were found in road verge soil that was heavily exposed to de-icing salt than in less exposed soils, though there were fewer tolerant than intolerant morphotypes in all soils examined. Heterotrophic flagellates isolated on a freshwater medium from a non-exposed soil were unable to thrive at salinities above 15 ppt, and showed reduced growth rates even at low salt salinities (1,5 ppt). The findings suggest that heterotrophic soil flagellates are less tolerant to NaCl than their aquatic relatives, possibly due to their long evolutionary history in soil, and support the idea that identical morphospecies may differ considerably with respect to physiology [source] Effects of dietary protein and lipid levels on growth and energy productive value of pacific white shrimp, Litopenaeus vannamei, at different salinitiesAQUACULTURE NUTRITION, Issue 4 2010X.Z. ZHU Abstract A 8-week feeding experiment was conducted to evaluate the effect of different dietary protein and lipid levels on growth and energy productive value of juvenile Litopenaeus vannamei, at 30 and 2 ppt, respectively. Nine practical diets were formulated to contain three protein levels (380, 410 and 440 g kg,1) and three lipid levels (60, 80 and 100 g kg,1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The effects of salinity and an interaction between dietary protein level and lipid level on growth and energy productive value of shrimp were observed under the experimental conditions of this study. At 30 ppt seawater, shrimp fed with 440 g kg,1protein diets had significantly higher weight gain (WG) than those fed with 380 g kg,1 protein diets at the same dietary lipid level, and the 60 g kg,1 lipid group showed higher growth than 80 g kg,1and 100 g kg,1 lipid groups at the same dietary protein level. At 2 ppt seawater, the growth of shrimp was little affected by dietary protein treatments when shrimp fed the 80 and 100 g kg,1 lipid, shrimp fed the 80 g kg,1 lipid diets had only slightly higher growth than that fed 60and 100 g kg,1 lipid diets when fed 380 and 410 g kg,1 dietary protein diets. A significant effect of salinity on growth of shrimp was detected with the growth responses at 30 ppt > 2ppt (P < 0.05). Final body lipid content, body protein content and energy productive value of shrimp was significantly higher in animals exposed to 30 ppt than in shrimp held at 2 ppt. [source] Effects of salinity on the growth and proximate composition of selected tropical marine periphytic diatoms and cyanobacteriaAQUACULTURE RESEARCH, Issue 9 2010Helena Khatoon Abstract Marine periphytic cyanobacteria and diatoms have been examined as a potential source of feed supplement for rearing aquatic larvae in the aquaculture industry. Culture of the periphytic diatom Amphora sp., Navicula sp., Cymbella sp. and the cyanobacteria Oscillatoria sp. at different salinities showed significant changes in biomass and specific growth rates. Diatoms growth was significantly higher at 35 g L,1, while for cyanobacteria growth was better at 25 g L,1. Significantly higher levels of protein and lipid were found in diatoms at low salinities (15,25 g L,1) and an increase in carbohydrate at high salinities (30,35 g L,1). Conversely, cyanobacteria showed a significantly higher lipid content at 30,35 g L,1 compared with other salinity levels but no significant changes were observed in the protein and carbohydrate contents at different salinity levels. The present findings can be taken into consideration when culturing marine periphytic Amphora sp., Navicula sp., Cymbella sp. and Oscillatoria sp. to provide appropriate levels of protein, lipid and carbohydrate as feed supplement as well as for bioremediation in aquaculture. [source] Osmoregulation, growth and moulting cycles of the giant freshwater prawn (Macrobrachium rosenbergii) at different salinitiesAQUACULTURE RESEARCH, Issue 9 2010Do Thi Thanh Huong Abstract The giant freshwater prawn, Macrobrachium rosenbergii, is a species with a high commercial value in aquaculture. Two experiments were performed to determine the effects of salinities on the osmoregulation, growth and molting cycles of M. rosenbergii during growout. The first experiment was designed to determine whether these animals are capable of adapting to the changes in salinity seen in salinity intrusions in tropical deltas, with an incremental increase in salinity of 3, per day from 0, to 30, Haemolymph osmolality was rapidly regulated up to salinities of 15, , whereas animals conformed at higher salinities. The second experiment determined the growth, moulting cycle, osmolality, muscle water content and mortality during a 4-month experiment at 0,, 15, or 25, salinity. The weight gains in 0, and 15, were not significantly different and were comparable to the growth rates achieved in production farms with body mass increases of 2.6 and 2.3-fold their initial body mass, respectively, after 4 months. The 25, group suffered from low growth, high mortality and a significantly lower moulting frequency. These data show that this species can be reared in brackish water up to 15,, allowing for farming in the large areas impacted by salt water intrusions in tropical deltas. [source] Effect of EPA/DHA ratios on the growth and survival of Galaxias maculatus (Jenyns, 1842) larvae reared under different salinity regimesAQUACULTURE RESEARCH, Issue 9 2010Patricio Dantagnan Abstract Despite the importance of certain highly unsaturated fatty acids in osmotic regulation, few studies have been addressed to determine the essential fatty acid requirements for a given species cultured under different salinities. As Galaxias maculatus is a diadromic species, the present study aimed to determine the effect of salinity on the optimum dietary EPA/docosahexaenoic (DHA) ratio for survival and growth during the larval stages. Larvae were fed for 20 days with rotifers containing two different EPA/DHA ratios (low: 0.64 and high: 2.18) at three different salinities (0, 10 and 15 g L,1). The results of this study showed a marked effect of water salinity on larval dietary lipid utilization in G. maculatus larvae. These results suggested that G. maculatus larvae reared at higher salinities may have a higher dietary requirement for DHA, whereas larvae reared at 0, showed higher requirements for EPA. The overall results of the present study indicate that even small changes in salinity can determine the optimum dietary EPA/DHA ratio and the quantitative essential fatty requirements of fish. This may have important repercussions and affect the rearing performance of G. maculatus cultured under different salinities. [source] Growth, salinity tolerance and microsatellite analysis of the F2 reciprocal hybrids of Oreochromis niloticus×Sarotherodon galilaeus at different salinitiesAQUACULTURE RESEARCH, Issue 9 2010Biao Yan Abstract Oreochromisniloticus (O), the sixth generation of Genetic Improvement of Farmed Tilapia, shows rapid growth but poor salt tolerance, while Sarotherodon galilaeus (S) exhibits opposite traits. To combine the traits, F1 progeny was obtained through artificial fertilization. Fertile F1 produced F2 by natural spawning. The mean survival times, the median survival time (ST50) or the survival rate of hybrids was greater than O. niloticus in a gradual or an acute salinity change. Plasma osmolarity, [Na+] and [Cl,] of the hybrids fluctuated in 32 g L,1 water during a 24-h period, but eventually reached levels similar to fish in freshwater. O. niloticus,×S. galilaeus, (OS F2) or S. galilaeus,×O. niloticus, (SO F2) showed the fastest growth at 22.5 g L,1, equal to about 78.2% or 69.7% of O. niloticus at 0 and 3.87 or 3.45 times that of S. galilaeus at their individual optimum growth. Growth in OS F2 was 12% faster than SO F2. Microsatellite analysis showed that F2 had more alleles, a higher polymorphism information content and greater observed and expected heterozygosity than O. or S. Population differentiation was not detected between F1 and F2. All the results indicated that F2 could be exploited for commercial production under saline conditions. [source] Protein requirements of Nile tilapia (Oreochromis niloticus) fry cultured at different salinitiesAQUACULTURE RESEARCH, Issue 8 2010Edvino Larumbe-Morán Abstract Effect of isolipidic (62.7 ± 5.0 g kg,1) diets with protein levels of 204.6 (T20), 302.3 (T30), 424.6 (T40) or 511.0 g kg,1 (T50) on growth and survival in Nile tilapia (Oreochromis niloticus Linnaeus 1758) fry cultured for 70 days at one of four salinities (0, 15, 20 and 25 g L,1) was evaluated. A bifactorial (4 × 4) design was used with 16 treatments run in triplicate and 20 fry (0.25 ± 0.04 g) per replicate under semi-controlled conditions. Four independent, recirculating systems (one per salinity level) were used, each one with 12 circular tanks (70 L capacity), filters and constant aeration. The different salinities had no significant effect on growth. Weight gain improved significantly as dietary protein content increased, although organisms fed the T50 diet had a lower growth rate. Survival was highest (98.33%) in the T50/15 (protein/salinity levels) treatment and lowest (71.0%) in the T20/20 treatment, with no pattern caused by the variables. The T40/25, T40/20 and T50/0 treatments produced the most efficient growth and feed utilization values while the T20 treatments at all the salinities resulted with the lowest performance. With the exception of the T50 treatments, a non-significant tendency to increased weight gain was observed as water salinity increased, suggesting that the salinity of the culture environment does not influence dietary protein requirements in Nile tilapia O. niloticus fry. [source] Experimental white spot syndrome virus challenge of juvenile Litopenaeus vannamei (Boone) at different salinitiesAQUACULTURE RESEARCH, Issue 15 2008I S Carbajal-Sánchez Abstract In recent years, the shrimp industry has turned to inland freshwater culture as one method to avoid problems such as the introduction of possible vectors of viral pathogens into seawater ponds. Our experiments evaluated susceptibility to white spot syndrome virus (WSSV) in Litopenaeus vannamei held under different salinity regimens. Juvenile L. vannamei that were conditioned at salinities of 35, 25, 15, 5 and 2 g L,1 were challenged with WSSV. In order to assess the severity of white spot disease, histological analysis and nested polymerase chain reaction (PCR) tests were carried out on the challenged shrimp every 4 h after 48 h post challenge. The results indicated that significantly more severe infections resulted at 15, than at other salinities. Mortality could not be compared due to the sampling design and because severe WSSV infections occurred in all test groups such that few shrimp remained alive in each challenged group at the end of the test. Despite this, the results suggest that salinity may affect the course and outcome of WSSV infections. [source] Influence of salinity, diurnal rhythm and daylength on feeding in Laternula marilina ReeveAQUACULTURE RESEARCH, Issue 2 2005Shuhong Zhuang Abstract A nature-simulating culture system was used to explore the influence of salinity, the diurnal cycle and daylength on ingestion rate (IR) and assimilation efficiency (AE) of Laternula marilina. The clams used in the experiments were grouped into three sizes: large, medium and small according to shell length and dry fresh weight. The clams in all size groups demonstrated a common response pattern in IR and AE under salinities ranging from 18 to 34 g L,1. The clams achieved the greatest IR within the salinity range 27,30 g L,1. There was a marked reduction in IR outside this range. Of the salinities tested 18 g L,1 was the harshest stress to the feeding of L. marilina. Between the salinities of 24 and 34 g L,1, the AE of the clam responded in an inverse way to that of IR, suggesting that L. marilina is able to compensate for the loss of IR by an increase in AE. Although the differences between clam size groups were not statistically different, those between different salinities were except those between 27 and 34 g L,1 (IR) and 23 and 34 g L,1 (AE). All sizes of clam showed a two-phase diurnal feeding pattern, a high ingestion phase from 00:00 to 08:00 hours and a low ingestion phase from 12:00 to 20:00 hours. The response of feeding (as measured by IR) to daylength comprised high and constant feeding at daylengths from 0 to 16 h and declining and unstable feeding as daylength increased from 16 to 24 h. All sizes of clams demonstrated an inverse adaptation to AE compared with IR, indicating that the clam is able to achieve a stable feeding physiology by compensating for daylength-induced variations in IR by changing AE. [source] Laboratory-based reproduction success of ruffe, Gymnocephalus cernuus (L.), in brackish water is determined by maternal propertiesECOLOGY OF FRESHWATER FISH, Issue 2 2006A. Albert Abstract,, Body length, age, egg size, embryo salinity tolerance and length at hatching of the freshwater (salinity <0.1 ppt, Lake Peipsi) and brackish-water (salinity 2,6 ppt, Pärnu and Matsalu Bay) ruffe, Gymnocephalus cernuus (L.), were examined to reveal their reproductive success in moderate salinity. Eggs of females originating from brackish water were significantly larger than eggs of freshwater females. No correlation between egg size and female size and age was found in brackish-water populations. In the freshwater population there was a small negative correlation between egg size and female size, but no correlation with female age. Fertilisation by sperm of males of different origin (brackish water or freshwater) produced no significant differences at any critical developmental stage (fertilisation, gastrulation, hatching) in the development of eggs from brackish-water or freshwater females at 3.3, 5.5, 7.7 and 9.9 ppt salinity. Survival rates in different salinity depended only on female origin; embryonic salinity tolerance was higher in ruffe inhabiting brackish water. Obviously, embryo salinity tolerance in ruffe is determined by egg qualities. [source] | |||||||||||||