Growth rate of the carrageenophyte Kappaphycus alvarezii (Rhodophyta, Gigartinales) in vitro

Unialgal cultures were established trom a 2.5 g branch ot a brown variant ot Kappaphycus alvarezii (Doty) Doty ex P. Silva, with the main objective to produce branches for monthly outplanting in the sea. Ditterent conditions were tested to optimize production ot branches in the laboratory. The best growth was obtained under culture conditions of 25 ± 2°C, 170–210 μmol photons m² s^?1, 14:10 LD photoperiod and salinity 32–35‰. Three culture media (Provasoli,‘F/2’and von Stosch) were tested. Deleterious ettects were observed in branches incubated continuously in full‐ or halt‐strength Provasoli's enriched seawater medium (PES). Exponential growth rates ot about 3% day^?1 were obtained using PES, pulse‐fed 24 h per week, or other diluted media used continuously (one‐quarter strength ‘F/2’and half‐strength von Stosch). Laboratory‐grown branches with mean weights from 2.97 to 4.25 g were successfully introduced into the sea at Ubatuba, SP, Brazil (23°26.9′S, 45°0.3′W) an area with mean monthly seawater temperature from 20.3 to 28.5°C (extremes: 17.0–31.0°C). Transplantation of branches produced in unialgal culture, as done in the present study, avoids the risk of introduction of unwanted species into new areas.     

GROWTH RESPONSES TO SALINITY VARIATION IN FOUR ARCTIC ICE DIATOMS1,2

During spring, extensive blooms of microalgae grow on the underside of arctic sea ice. The brownish, algal layer penetrates ca. 2 cm into the bottom surface of the ice and the algae are potentially exposed to very high salinities. Four diatom species, Melosira juergensii Ag., Porosira glacialis (Grun.) Jørg., Navicula transitans var. derasa (Grun.) Cleve, and Coscinodiscus lacustris Grun., isolated from, sea ice samples taken from the Beaufort and Chukchi seas near Barrow, Alaska, were grown at 11 salinities ranging from 5 to 70‰ at 5 C under constant illumination. All of the species grew at 5‰ except N. transitans whose lower growth limit was 15‰. Growth was high over a broad range of salinities, but none of the species grew at salinities above 60‰. These diatom species appear to be well suited to tolerate the salinities in the brine pockets near the bottom of annual arctic sea ice where they are found. High brine-cell salinity, however, may limit the upward, penetration of ice algae into the bottom of sea ice.     

Ontogenetic change in the response of the Gulf of California grunion, Leuresthes sardina (Jenkins & Evermann), to a salinity gradient

Larval and juvenile Gulf of California grunion, Leuresthes sardina (Jenkins & Evermann), hatched and reared in the laboratory, were subjected to salinity gradients in a Staaland salinity gradient device to determine their locomotive responses. Newly hatched prolarvae selected salinities in the range 15–24‰, while late postlarvae and juveniles preferred salinities in the range 45–54‰. Early postlarvae exhibited a bimodal preference, indicating that the behavioral change was in progress at that age. These behavioral responses may serve several functions in the physiological and behavioral ecology of the Gulf grunion.     

Growth and Toxigenesis of the Chrysomonad Prymnesium parvum as a Function of Salinity*

SYNOPSIS The euryhaline chrysomonad Prymnesium parvum (Carter) was grown in artificial (ASW) and natural sea water (NSW) media at salinities 1.3-33.3 ‰, and constant illumination. Low salinities (< 10‰) increased the doubling time (DT) and induced higher levels of protein and nucleic acids. DT was lowest for cells in ASW at 25 ‰ and NSW 17.9 ‰. The protein content was more variable. RNA content was lowest for cells at ca. 10 ‰. The DNA content was lowest for cells in 10‰ ASW and 11‰ NSW. Generally, the cells grew faster in NSW but had less protein and RNA than cells in ASW. The highest hemolytic content was in cells grown at 22.8 ‰ ASW or NSW. Glycerol enhanced growth rate and toxin synthesis within 24 hr of addition to the cells. Hemolysis was inhibited by high pH's. A membrane fraction containing ca. 20% of the hemolysin was isolated by density gradient centrifugation.     

Combined effects of physicochemical variables (pH and salinity) on sperm motility: characterization of sperm motility in European sea bass Dicentrarchus labrax

Gamete activation in fish is an important step in terms of artificial fertilization of oocytes, cryopreservation studies and other experimental manipulations. Salinity and pH differences in activation media affect to sperm motility and fertilizing ability. These experiments were therefore designed to investigate the combined effects of pH (range 5.0–9.0) and salinity (20, 30, 37, and 45‰) of activation media on sperm motility of European sea bass Dicentrarchus labrax. The best results were obtained at salinity 37‰ and a pH of 9.0. Our results also demonstrated that non-progressive motility at salinity 45‰ was observed in the range of 5.0–9.0 pH. In conclusion, spermatozoa can be motile at a wide range of pH and salinity values although the percent of motile spermatozoa and motility duration are negatively affected by low pH values.     

Temperature and salinity effects on the respiratory metabolism of the first zoeal stage of Macrobrachium holthuisi Genofre & Lobão (decapoda: Palaemonidae)

Oxygen consumption rates of stage I Macrobrachium holthuisi Genofre & Lobão zoeae were measured in 24 different temperature and salinity combinations using Cartesian diver microrespirometers. Metabolic rates varied little with salinity at 15°C while at 20°C a marked elevation occurred in 0 and 35‰ At 25°C, a slight elevation occurred in 0‰; rates remained constant, however, in the other salinities. At 30°C, respiratory rates were similar to those recorded at 25°C except for decreases at 0 and 28‰ salinity. Q₁₀ values in the different salinities were usually highest between 15 and 20°C. Statistical analyses showed that while both temperature, salinity and their interaction significantly influenced larval respiratory rates, temperature had the more pronouced effect. Larval metabolism is salinity independent over the salinity range encountered in the larval biotope (7–21‰) at temperatures of 15–30°C.     

Metabolic and osmoregulatory changes in response to reduced salinities in the red grouper, Epinephelus akaara (Temminck & Schlegel), and the black sea bream, Mylio macrocephalus (Basilewsky)

Red groupers (Epinephelus akaara Temminck & Schlegel) and black sea breams (Mylio macrocephalus Basilewsky) were transferred from 30‰ into 3, 7, 12, 20, and 30‰ salinity. Fish were sampled at 0, 6, 24, 96, 168 and 336h after transfer. Serum osmolality, glucose, protein, Na⁺, K⁺, Ca²⁺, liver glycogen, liver protein, muscle water and haematocrit were determined. In general, transient disturbances in these variables were observed after transfer. For both species, no tissue hydration was observed upon acclimation to different salinities, whereas a progressive increase in haematocrit value was found as salinity decreased. Liver glycogen of both species, however, was higher in hypo-osmotic salinities. Serum Na⁺ of the red groupers declined upon acclimation to 7‰ salinity but the opposite was found for the black sea breams. The results indicate that both species are extremely euryhaline, and physiological stress is unlikely to occur within the salinity regime of 7 to 30‰ Comparatively, the black sea bream appears to be a more efficient osmoregulator.     

Hydromineral regulation in the saline water corixid Trichocorixa reticulata (Hemiptera: Corixidae)

The aquatic corixid Trichocorixa reticulata (Guerin-Meneville) inhabits coastal marshes, brackish water ponds and salt ponds of high salinity, suggesting the presence of well developed mechanisms for hydromineral regulation.Groups of corixids acclimated in salinities ranging from fresh water to just above 300% sea water (100‰) were analyzed for total body water content, haemolymph ionic and osmotic levels, and haemolymph free amino acids.Results indicate an excellent ability to maintain haemolymph Na⁺, Cl^?, Mg²⁺ and K⁺ hyperosmotic to the medium at low salinities and hyposmotic at high salinities. Calcium appears to conform closely to changes in external medium, becoming hyposmotic at very high salinities (80‰).Total haemolymph osmotic pressure was well regulated, the freezing point depression varying from 0.75°C in distilled water to 1.15°C in salinities of 100‰. Total body water was maintained at approx. 75% of the total animal wet weight at all salinities tested.Free amino acids were maintained between 40–60 mM in all tests and did not appear to change with salinity.     

Effects of salinity on larval and early juvenile growth of an extremely euryhaline crab species,Armases miersii (Decapoda: Grapsidae)

The neotropical crab Armases miersii (Rathbun, 1897) breeds in supratidal rock pools, where great salinity variations occur. In laboratory experiments, all larval stages and the first juveniles were reared at six different salinities (5–55 PSU, intervals of 10 PSU). In five series of experiments, exposure to these conditions began either from hatching (Zoea I) or from the onset of successively later stages (Zoea II, III, Megalopa, Crab I). Growth was measured in terms of dry weight, carbon, nitrogen and hydrogen content. At osmotically extreme conditions (5 and 55 PSU, resp.), all stages showed minimum biomass accumulation; this was consistent with maximum mortality and longest duration of development (data presented in a separate paper). Successively later exposure to these salinities tended to reduce these effects. Lowest mortality and shortest time of development occurred generally at 15–25 PSU, indicating an optimum at moderately reduced salinities. This response pattern, however, was not congruent with that observed in growth. Biomass accumulation was initially maximum within a wide range of salinities (15–45 PSU), but in the Zoea II and III stages, this range tended to narrow and to shift towards higher salinities (35–45 PSU). These trends reversed in the Megalopa and Crab I, where maximum growth occurred again in a wider range and at lower salinities (15–35 PSU). The reduction of zoeal growth in moderately dilute media (15–25 PSU), which were optimal for survival and development, is interpreted as an energetic cost of hyper-osmoregulation, which begins already at hatching. Five PSU caused hypo-osmotic stress, exceeding in the long term the larval capacity for hyper-regulation. Poor zoeal survival and growth at 55 PSU are interpreted as effects of hyper-osmotic stress. In the Megalopa and Crab I, reduced growth at salinities 35 PSU may reflect the energetic costs of hypo-osmoreguation beginning in these stages. Our data suggest that the physiological adaptations of larval and early juvenile A. miersii allowing for survival and development in a physically harsh and unpredictable habitat imply a trade-off with reduced growth, due to energetic costs of osmoregulation.     

Effect of salinity on growth,biochemical composition,and lipid productivity of Nannochloropsis oculata CS 179

Effect of salinity (15, 25, 35, 45, and 55‰) on growth, biochemical composition, and lipid productivity of Nannochloropsis oculata CS 179 was investigated under controlled cultivation in a 19‐day study. The results demonstrate that the dry biomass of N. oculata was the highest at a salinity of 25‰ among the treatments in the first 10‐day cultivation (P<0.05). During days 14–19 (stage III), the dry biomass productivity was the highest at a salinity of 35‰ (P<0.05). The algae had the highest chlorophyll a content (26.47 mg g^?1) at 25‰ in stage I, and it decreased continuously at stage III. Protein content (as% of dry biomass) of algae reached the highest value of 42.25 ± 2.10% at 15‰, and the lipid content was the highest of 32.11 ± 1.30% of dry biomass at 25‰. However, the lipid productivity of these algae was the highest at 35‰ (64.71 mg L^?1 d^?1; P<0.001). C16 series content was the highest among the total fatty acid methyl esters (FAME), and eicosapentaenoic acid C20:5n‐3 (EPA) content was high at the low salinity. Fatty acid profiles of N. oculata varied significantly under different salinities.     

Distribution ofVibrio cholerae in two Florida estuaries

The distribution ofVibrio cholerae was examined in 2 Florida estuaries, Apalachicola and Tampa Bay.Vibrio cholerae serotype non-01 was the most abundant serotype, being isolated from 45% of the oyster samples, 30% of the sediments, 50% of the waters, and 75% of the blue crabs.Vibrio cholerae serotype 01 was isolated from only one oyster sample. Strong linear correlations betweenV. cholerae and temperature, salinity, or the other physical/chemical parameters measured,Escherichia coli, or fecal coliforms were not observed, but a range of temperatures and salinities appeared relevant to the distribution of the organism. The organism was present in the highest concentrations when salinities were 10‰–25‰ and temperatures were 20?C–35?C.In vitro growth curves of 95V. cholerae environmental isolates further supported that 10‰–25‰ was an ideal salinity range for the organisms. The results suggest thatV. cholerae is a widely distributed organism in the nutrient-rich warm waters of the Gulf Coast estuaries.     

Metabolic demand and growth of juveniles of Centropomus parallelus as function of salinity

The effect of salinity and time of exposure on metabolism and growth of juveniles of fat snook, Centropomus parallelus, were investigated. Food conversion efficiency (FCE), specific growth rate (SGR), oxygen consumption, ammonia excretion rate and O:N (oxygen/nitrogen) ratio were assessed on groups of fat-snook (mean weight 2 g) acclimated for 15- and 30-day periods, to 5‰, 20‰ and 30‰ salinities. For 15-day period, differences between FCEs as well as SGRs at different salinities were not significant. For 30-day period, however, these differences were significant between 5‰ and the other salinities, with the highest and lowest values at 5‰ and 30‰, respectively, for both parameters. Salinity and acclimation period exerted significant influence on the oxygen consumption, ammonia excretion and the O:N ratio of juveniles of C. parallelus. The lowest and highest oxygen consumption was at 20‰ for 15- and 30-day period, respectively. Differences in oxygen consumption between fishes maintained at 5‰ and at 30‰ were not significant, at each period, while between those maintained at 5‰ and 20‰, and at 20‰ and 30‰ differences were significant. Ammonia excretion rates were significantly different between all salinities, at each period, and between periods at each salinity, except at 30‰. The highest and lowest rates were found at 5‰ and 30‰, respectively. The highest O:N ratio for 15-day period was at 30‰ with no difference between those at 5‰ and 20‰. For 30-day period, differences of O:N ratio were significant between salinities. The effect of acclimation period on the O:N was significant only at 20‰. Although C. parallelus is a fish species adapted to face a wide variation of environmental salinity, results show that juvenile fishes kept at different salinities, in laboratory, found better condition to efficiently channel the energy of food into growth at 5‰ for both acclimation periods.     

Short- and long-term effects of a dietary yeast beta-glucan (Macrogard) and alginic acid (Ergosan) preparation on immune response in sea bass (Dicentrarchus labrax)

The present study investigated the immunomodulatory activity of Ergosan, an algal extract containing alginic acid, and Macrogard, a yeast extract containing beta-glucans, on innate and specific immunity in sea bass (Dicentrarchus labrax). Four cycles of experimental feeding using normal fish feed formulation (control group) supplemented with Ergosan (0.5%) or Macrogard (0.1%) were performed at 60-day intervals (15 days of treatment+45 days of suspension). Serum complement, lysozyme, total proteins and heat shock protein (HSP) concentrations were measured at 15, 30 and 45 days from the end of the first 15-day feeding cycle (short term) and 45 days after the end of each feeding cycle over a 35-week period (long term). The percentage of B- and T-lymphocytes in peripheral blood leucocytes and gut were measured over long-term trial. Significant elevation (P < 0.05) in serum complement activity occurred in sea bass fed with alginic acid and glucans, at 15 days from the end of first cycle of treatment. Significant elevation (P < 0.05) in serum lysozyme, gill and liver HSP concentration were observed in the same experimental groups at 30 days from the end of treatment, whereas a significant increase (P < 0.05) of complement activity was only observed in fish that received an Ergosan diet. At 45 days from the end of treatment, complement, lysozyme and HSP concentration did not differ among groups. Over the long-term period, no significant differences were observed in innate and specific immune parameters, survival, growth performances and conversion index in treated and control fish. A dramatic decrease of both innate and acquired immune parameters was observed during the winter season in all groups, followed by a partial recovery when water temperature increased. Reduction in complement and lysozyme activities was significatively correlated (p < 0.01) to water temperature variation. The results suggested the potential of alginic acid and beta-glucans to activate some innate immune responses in sea bass, and particularly under conditions of immunodepression related to environmental stress.     

Influence of salinity and cadmium on capsule strength in Pacific herring eggs

Eggs of Pacific herring (Clupea pallasi) were incubated at 5°C in salinities of 5, 20, and 35‰, and in cadmium concentrations of 0.05, 0.1, 1, 5, and 10 ppm (20‰ S). Bursting pressures of eggs in the eight groups were measured throughout incubation. In general, bursting pressures rose to a primary maximum after fertilization, declined, rose to a secondary maximum, then declined again toward hatching. Rate of attainment of the primary maximum was related to salinity of the incubation medium. Bursting pressures at the primary and secondary maxima reached final values of about 1300 and 700 g, respectively, in incubation salinities at and above 20‰. Corresponding egg volumes were greatest in low salinities (5‰) and near minimum values in salinities of 20‰ or greater (35‰). Cadmium in the incubation medium delayed attainment of primary maximum bursting pressures and primary and secondary maxima were reduced to 200–350 g at Cd concentrations near 1 ppm. Egg volumes also decreased with increased Cd concentration. It appears that Ca⁺⁺/Cd⁺⁺ ratios, depending on salinity and Cd levels in the incubation medium, influence the properties of both the jelly coat and the capsule of herring eggs. Changes in the properties of these layers could make the eggs more susceptible to mechanical damage, particularly at combinations of higher (?1 ppm) Cd concentration and lower (?20 ‰) salinities.     

Changes in plasma osmolality and Na+/K+ ATPase activity of juvenile obscure puffer Takifugu obscurus following salinity challenge

The osmoregulatory capabilities of 6-month-old juvenile obscure puffer Takifugu obscurus, transferred directly from fresh water to different salinities (0‰, freshwater control; 10‰; 20‰ and 30‰), were studied over an 8-day period. After transfer, plasma osmolality of the fish at 30‰ was significantly higher than those at all other salinities throughout the experiment. The Na⁺/K⁺ ATPase activity in the gills of the fish treated with various salinities increased significantly, peaking at 48 h, then decreased gradually to the control level at 192 h. Similar fluctuation trends of the Na⁺/K⁺ ATPase activity were observed in the kidneys. Modified Gaussian model provided accurate fits for the time-course changes in the Na⁺/K⁺ ATPase activities after abrupt salinity challenge. The results demonstrated that obscure puffer has strong capacity to tolerate abrupt salinity changes and can osmoregulate well over a wide range of salinities even in juvenile stage.     

盐度对脊尾白虾亲虾抱卵及其子代生长发育的影响

选用室内人工培育的性腺已发育到Ⅱ期的脊尾白虾亲虾,经逐级淡化后,盐度稳定在2、5、10、15、20、25、30,研究了盐度对雌虾抱卵、胚胎发育及子代生长发育的影响.结果表明： 在试验盐度范围内脊尾白虾性腺均可发育成熟,但在盐度2时无法完成抱卵,最适抱卵盐度为10~20;在抱卵盐度范围内,胚胎均可正常发育,盐度对胚胎发育速率影响显著,15、20、25盐度下的孵化时间显著低于其他盐度组;盐度对脊尾白虾幼体后的变态和存活无显著影响,但对仔虾的个体干质量影响显著,15和20盐度下仔虾的干质量显著高于其他盐度组;盐度对20日龄脊尾白虾的生长影响显著,其特定生长率随着盐度升高而逐渐增大,在盐度20时达到最大,之后开始降低;鳃Na⁺-K⁺ ATPase的mRNA相对表达量在高盐或低盐时均较高,表达量最低时的理论盐度为17.5,可能为脊尾白虾的等渗点.研究表明,脊尾白虾亲虾可在较广盐度范围内繁殖,20日龄脊尾白虾在其理论等渗点附近具有较快的生长速度.
     

Energetics of the muricid gastropod Thais (Nucella) lapillus (L.)

Multivariate analysis of the physiological energetics of Thais (Nucella) lapillus (L.) was used to predict combinations of salinity and temperature at which scope for growth and reproduction will be positive. The scope for growth correlated positively with change in energy content at 15 and 20°C. The results suggest that energetic constraints set limits to capacity adaptation at ≈ 22‰ salinity, in agreement with field observations of the species distribution limit within estuaries. The zone of resistance adaptation is limited to salinities 15‰, probably because of an inefficiency in volume regulation at lower salinities. Growth of these dogwhelks is suppressed at minimum winter (5°C) and maximum summer (20°C) temperature, largely due to suppression of feeding. Constraints imposed by physiological energetics are important for an understanding of the ecology of this species, and may explain some features of seasonal change in behaviour, e.g. aggregations for purposes of egg-laying in the winter.     

AUTECOLOGICAL STUDIES ON THE MARINE DIATOM RHIZOSOLENIA FRAGILISSIMA BERGON. I. THE INFLUENCE OF LIGHT,TEMPERATURE, AND SALINITY1

The influence of 113 combinations of temperature (9, 12, 18, 25, 30 C), salinity (5–35 ‰ at 5 ‰ intervals), and light (4 levels) on the mean daily cell division rate (K) of the Narragansett Bay clone of Rhizosolenia fragilissima was examined following appropriate preconditioning. Growth did not occur below 9 C, but was excellent (K =～1.2) under certain combinations of light and salinity at 12, 18, and 25 C. The optimal salinity of 20–25 ‰ was temperature independent. Growth was not measurable at 5 ‰, although survival occurred. At 20 ‰ and 1200 ft-c, K increased approximately 1.8-fold from 0.65 to ～1.2 between 9 and 18–25 C. The optimal light intensity was generally 600 ft-c, although several light-temperature-salinity trends were found. At 10 ‰ at all temperatures, the mean daily division rate decreased with increasing light above 600 ft-c, a response found at all salinities at 12 C, but not at other temperatures. Between 15 and 25 ‰, at 18 and 25 C, mean growth was independent of light intensity; at 30–35 ‰ a direct relationship with light may be present with maximum growth occurring at 1200–1800 ft-c. The in situ and in vitro responses of Rhiz. fragilissima to salinity and the optimum and upper temperature levels are in general agreement. However, growth failure below 9 C in vitro is at odds with reports that natural populations occur even at ?1.11 C. The questions of to what extent this discrepancy reflects the occurrence of thermal clones, different taxa, and/or experimental artifacts are briefly discussed. It is suggested that naturally occurring populations found below 9 C might be designated as Rhiz. fragilissima f. faeröensis, and that Rhiz. fragilissima f. bergonii be used for populations growing at higher temperatures, until this matter is resolved. Observations on auxospore formation are presented.     

Growth,body composition and digestive enzyme responses of Caspian Kutum,Rutilus frisii (Kamenskii, 1901), juveniles fed different levels of carbohydrates

The study evaluated the effects of dietary carbohydrate levels on growth performance and digestive enzyme activities in juveniles Caspian Kutum, Rutilus frisii (Kamenskii, 1901). Fish with an initial average weight of 0.8 ± 0.2 g (means ± SD) were fed five isonitrogenous and isoenergic formulated diets with different carbohydrate levels of 15%, 20%, 25%, 30% and 35% in triplicate groups for 10 weeks (fifteen 45‐L aquaria with 30 fish per tank and water temperature of 21.5–23.5°C). Based on the results, growth performance of Caspian Kutum was significantly improved by increasing carbohydrate levels from 15% to 35% (p < .05). A result of body composition analysis showed that the protein content was elevated with increasing carbohydrate levels (p < .05). Digestive enzyme activities were significantly influenced by dietary carbohydrate levels (p < .05). Trypsin, chymotrypsin, lipase and amylase specific activities increased significantly with rising carbohydrate levels from 15% to 35%. Alkaline phosphatase and N amino peptidase activities increased with carbohydrate levels increasing from 15% to 25%, but decreased with a further rise in the carbohydrate level from 25% to 35%. The results indicate that increasing carbohydrate levels from 15% to 35% have positive effects on growth parameters. However, carbohydrate amounts at levels higher than 35% and their effects on growth performance and digestive enzymes are not obvious, hence, more widespread studies on this nutrient are recommended.