GROWTH OF COLPOMENIA PEREGRINA (PHAEOPHYCEAE) IN CULTURE: EFFECTS OF SALINITY,TEMPERATURE AND DAYLENGTH1

Increases in size of Colpomenia peregrina (Sauv.) Hamel microthalli were determined at six different combinations of salinity and temperature under laboratory conditions. Microthalli grown at low salinity (15%) did not have a growth rate significantly different from microthalli grown at high salinity (30%). However, more macrothalli were produced in higher salinity media. Fewer macrothalli were produced at lower temperatures. Growth of C. peregrina microthalli was also determined at six different combinations of daylength and temperature. Microthalli under 15:9 h (LD cycle) did not have a growth rate significantly different from microthalli under 9:15 h LD. However, more macrothalli were produced under long day conditions. Of the three different temperatures utilized (5, 13 and 20° C) only 5° C produced significantly different growth rates. Low temperature reduced growth to such an extent that macrothalli of a size that could be recognized in the field took approximately two months to produce in culture. These results may explain the seasonal presence/absence of the delophycean phase of C. peregrina in the field. Zoospore survivorship and macrothallus production of C. peregrina in culture indicated that both PES and an artificial medium were suitable for the laboratory cultivation of this plant.     

Growth and reproduction of Scytosiphon lomentaria (Fucophyceae) in relation to temperature in two populations from Denmark

Two strains of Scytosiphon lomentaria from Denmark have been grown under long-day conditions on a temperature-gradient plate. The material from north-west Jutland (strain No. 46) has a reduced prostrate system (a few-celled lump) whereas the other material from the Sound (strain No. S41) has a well-developed crust. This difference plays a significant role in growth and reproductive patterns. Strain No. 46 rapidly produces a great number of cylindrical macrothalli. Within a four-week experimental period, formation of swarmers from plurilocular sporangia on the macrothalli takes place and results in a maximum dry weight of 32.9 mg at 18.2°C.
Swarmers from the macrothalli of strain S41 always develop into knot-filamentous or crust-shaped thalli. The development of the macrothalli, therefore, takes a longer time than in strain 46 and the maximum dry weight is only 16.5 mg at 16°C even within an experimental period of six weeks. The reproductive pattern is more complex than in strain 46. The crusts produce unilocular sporangia at temperatures between 16°C and 23.8°C, and function, therefore, as the reproductive system during the summer as macrothalli disappear at temperatures above 18°C both in nature and in culture. Formation of plurilocular sporangia on macrothalli starts when they are from 6–9 weeks old at temperatures between 11°C and 18°C.
The temperature range for growth in the two strains also differs: Strain 46 grows from 7.3–24.4°C while strain S41 grows at least from 4–5.1°C to an upper limit of 27.1°C, but lower limit has not been determined precisely in the present experiment. These results indicate that temperature ecotypes exist, even within a limited geographic area.     

Temperature and salinity tolerance of juvenile Rhabdosargus holubi [Steindachner (Teleostei: Sparidae)]

Temperature and salinity tolerances of juvenile Rhabdosargus holubi (Steindachner) were determined experimentally. Results indicated that they are tolerant over a wide range of salinities (0.7–70‰) and temperatures (10–30°C) and that little interaction between temperature and salinity occurs. R. holubi is restricted to the warm temperate waters of southeastern Africa. It is absent from the subtropical Indian Ocean and from temperate Atlantic Ocean waters. The juveniles occur mainly in the inshore waters and estuaries. Evidence from tolerance experiments and salinity and temperature data from southern African estuaries suggested that the distribution of R. holubi is controlled by temperature.     

The effects of temperature and salinity on Tilapia rendalli Boulenger 1896

Temperature and salinity tolerances of Tilapia rendalli were determined experimentally. Results indicate that they are tolerant over a wide range of temperatures (11-37°C), but are incapable of surviving in salinities above 19 ‰ The maximum salinity tolerance is at temperatures between 20–28°C. The osmotic concentration of the blood rises from 255 mosmol/1 in freshwater to 340 mosmol/1 in a salinity of 19‰ T. rendalli is restricted to the warmer waters of the Zambezi river system in central Africa and southwards to the Pongolo river, as well as certain tropical and subtropical brackish water lagoons and lakes. Evidence from these experiments suggest that the distribution of T. rendalli isgoverned by both temperature and salinity.     

Effect of salinity and temperature on the growth of yearling Arctic cisco (Coregonus autumnalis) of the Alaskan Beaufort Sea

The growth of 1-year-old Arctic cisco ( Coregonus autumnalis ) was monitored under laboratory conditions for fish acclimated to one of two temperatures (5 and 10° C) and one of five salinities (6, 12, 18,24, 30‰). Fish were maintained for 43 days at rations of 3% wet body weight per day at 5° C and 5% wet body weight per day at 10° C, with rations adjusted for weight gain every 7–12 days. Fish increased 9–11% in length and 55–71% in weight at 5° C, and 23–27% in length and 141–161% in weight at 10° C. Length and weight increased linearly over 43 days. There was a statistically significant effect of temperature on growth but no statistically significant effect of salinity. Higher growth rates at 10° C were partially attributable to significantly greater gross conversion efficiency at the higher temperature. Over the course of the experiment, the condition (weight per unit length) of all fish increased by 3·2 to 63·6% at 5° C and by 5·6 to 46·0% at 10° C. There was no discernible effect of salinity on condition at either temperature. These results demonstrate that, with salinity acclimation and high food ration, 1-year-old Arctic cisco can grow at equivalent rates across salinities ranging from 6 to 30‰. The ecological implications of the results are discussed.     

Does saltwater flushing reduce viability of diapausing eggs in ship ballast sediment?

Flushing of ballast tanks with seawater has been proposed to reduce the risk of invasion associated with residual ballast in 'no ballast on board' ships. The efficacy of this procedure, however, has not been determined. Using diapausing eggs isolated from ballast sediments — as well as from Lake Erie sediment — this study investigated the impact of salinity (0, 8 and 35‰) and temperature (10, 20 and 30 °C) on the cumulative abundance and species richness of hatched zooplankton taxa. The rate and amount of hatching varied dramatically between sediments and across salinity–temperature regimes. Although exposure to saline water inhibited emergence of freshwater taxa during the exposure phase of all trials, mixed results were evident after diapausing eggs were returned to freshwater. The efficacy of salinity as a ballast treatment method was temperature dependent, although the direction of the effect was case-specific. Exposure of eggs to saline water was less effective at 10 and 30 °C than at 20 °C. Although flushing ballast tanks with open ocean water is expected to significantly reduce the number of active invertebrates living in residual ballast water (a potentially larger source of invaders), our results indicate that the most effective treatment conditions for reduction of diapausing egg viability is 8‰ salinity at 20 °C.     

Eco-physiology of Palaemonetes antennarius (Crustacea, Decapoda): the influence of temperature and salinity on cardiac frequency

Abstract.  The effect of different temperatures and salinities on the cardiac frequency of the freshwater shrimp Palaemonetes antennarius is investigated. The results show that both temperature and salinity influence heart rate. Variations in water temperature are associated with changes in heart rate: variations higher than 8°C in 6 h affect not only heart rate, but also shrimp survival. After an initial rapid increase, the heart rate returns to initial values at saline concentrations of 15‰ and 30‰, whereas, at 20‰ salinity, the shrimps show a persistent decrease of heart rate throughout the test. The marked tolerance of variations of temperature and salinity suggests that P.   antennarius is well adapted to waters with large salinity and temperature oscillations. Cardiac frequency can be used as a valid indicator of physiological stress in this species.     

Temperature- and salinity-dependent development of a Nordic strain of Ichthyophthirius multifiliis from rainbow trout

During the twentieth century evidence was presented which suggested the presence of various strains and races of the parasite Ichthyophthirius multifiliis Fouquet. However, ecological profiles of various parasite isolates from different climatic zones are sparse. Such stringent characterizations of parasite development at defined abiotic conditions could provide valuable criteria for the different races; profile comparison from various localities is one way to differentiate these strains. Baseline investigations were therefore performed on the associations between abiotic factors (temperature/salinity) and the development of theronts in tomocysts of I. multifiliis isolated from rainbow trout in a Danish trout farm. It was shown that tomocyst formation and theront development took place between 5 and 30°C. Development rates and sizes of theronts were clearly affected by temperature: theronts escaped tomocysts already after 16–27 h at 25°C and 30°C, whereas this process took 8–9 days at 5°C. Likewise, theront size decreased steadily from a maximum of 57.4 × 28.6 μm at 5°C to 28.6 × 20.0 μm at 30°C. This size variation was only partly associated with the number of theronts that appeared at different temperatures. The lowest number of theronts escaping from one tomocyst was indeed found at 5–7°C (mean 329–413). At 11.6, 17.0 and 21°C, the highest number of theronts appeared (mean 546–642). However, at 25 and 30°C, the number decreased (458 and 424, respectively). Additional studies on the salinity dependent development of the parasite (at 11.6°C) showed that salinities above 5 p.p.t. totally inhibited development. Even at 5 p.p.t. the developmental time significantly increased and the number of theronts produced from one tomocyst decreased.     

Tolerance, behaviour and oxygen consumption in the sand goby, Pomatoschistus minutus (Pallas), exposed to hypoxia

Behavioural and metabolic reactions of Pomatoschistus minutus (Pallas) exposed to various degrees of hypoxia were studied. At 15°C and 20‰ mortality was 50% at 15.2% oxygen saturation. Avoidance and oxygen saturation showed a linear inverse relationship. At levels lower than 60% saturation increased activity occurred; avoidance was significant at 30% saturation. Active, routine and standard MO₂ correlated linearly with weight at 6 and 15°C (salinity = 19‰). During hypoxia at 15°C routine MO₂ rose significantly at 60–50% and 40–30% saturation expressed either as MO₂ during longer periods at night or MO₂ at shorter intervals during the day. Standard MO₂ was unaffected by hypoxia at 15°C. Haemoglobin concentration was significantly increased when P. minutus was acclimatized to 35% saturation.     

Euryhaline adaptations in the fat sleeper, Dormitator maculatus

Salinity tolerances and plasma osmotic concentrations were determined in the fat sleeper, Dormitator maculatus , a common species in estuarine and coastal fresh waters along the Atlantic and Caribbean coasts of North, Central and South America. Analyses followed sequential laboratory acclimations to a series of ambient salinities at a constant temperature of 20 ± 1° C and photoperiod of 12L: 12D. These fish tolerated a range of ambient salinities from fresh water through a salinity of 75‰. Plasma osmotic concentrations were regulated at an essentially constant level in the salinity range from fresh water through a salinity of 50‰, beyond which plasma concentrations trended upward with increased ambient salinity. We conclude that D. maculatus , while truly euryhaline, docs not show the extreme euryhalme capabilities of several teleost fishes that are 'full-time' estuarine inhabitants.     

Salinity tolerance of freshwater acclimated, small-sized Arctic charr, Salvelinus alpinus from northern Labrador

Arctic charr, Salvelinus alpinus , less than 150 mm in size were frequently captured at sea in northern Labrador in areas where salinities of 30‰ or higher had been recorded. These captures were inconsistent with many earlier reports for other areas that indicated Arctic charr less than 150 mm in size were not found at sea. A series of salinity challenge tests was carried out in the field, using wild Ikarut River charr, and in the laboratory, using cultured Fraser River charr, to understand more about the potential fate of these small fish. The results of challenge tests with small Arctic charr (< 120 mm) indicated that at intermediate salinities (10–20‰), these fish can readily survive. In laboratory tests with salinities at 30‰, survival was size dependent and would suggest that in natural situations, small charr would require periodic access to fresh or brackish water to stay alive. The influence of water temperature on salinity tolerance may be important when fish are exposed to temperatures that are below 0° C.     

CULTURE STUDIES ON REPRODUCTION OF SPERMATOCHNUS PARADOXUS (PHAEOPHYCEAE,CHORDARIALES)1

The life history of Spermatochnus paradoxus (Roth) Kütz. isolated from the Mediterranean Sea was studied in culture. Meiospores develop to a microscopic stage (microthallus) which at 20°C perpetuates asexually by plurilocular sporangia and formation of new microthalli. At 9°C microthalli act as homothallic gametophytes. Fusion of isogametes results in a diploid microthallus which, after differentiation of an apical cell, leads back to Spermatochnus plants. In addition, gametes develop without fusion to form haploid macrothalli, the further fate of which has not been determined. Chromosome numbers alternate between n = 20 ± 2 in the microthalli and 2n = 41 ± 4 in macrothalli.     

THE EFFECT OF TEMPERATURE ON EGGS AND IMMATURE STAGES OF CULEX ANNULIROSTRIS SKUSE (DIPTERA: CULICIDAE)

Abstract
No immature stages of Culex annulirostris were found during field sampling in 1979–1980 when the average water temperature was < 17 °C; they reappeared when the average water temperature was 19 °C and reached the peak density (mean 107 immatures/cylinder) at 26.5 °C.
The effect of 6 temperatures (15–40°C) on egg hatching, development and survival of the immature stages of Cx annulirostris in the laboratory showed that at 15 and 40°C, eggs failed to hatch and larvae died in the first instars. The optimum temperatures for egg hatching and the survival of immature stages were 25 and 30°C. At these temperatures, 85 and 82% respectively of egg rafts hatched, the mean number of larvae per raft was 258 ± 9.8 and 260 ± 11.4 with immature survival of 83.5 and 79.0% respectively. Mean time to hatch at 20–35°C ranged from 1.2 d (35°C) to 2.9 d (20 °C). Developmental times from first instar to adult ranged from 7.1 d (35 °C) to 25.2 d (20 °C). The threshold for development of the immatures was 15.6 ± 2.5°C and the thermal constant was 142.9 ± 26.5 day—degrees (incubation temperatures 20–35°C). At less suitable temperatures of 20 and 35 °C, hatching (57.5 and 45%), number larvae per raft (mean 139.8 ± 9.8 and 102.6 ± 14.2) and survival were low.     

RELATION OF TEMPERATURE TO DEVELOPMENT OF THE MACROTHALLUS OF DESMOTRICHUM UNDULATUM1,2

Desmotrichum undulatum (J. Agardh) Reinke (Phaeophyta) was found in the winter months in the littoral zone of a tidal marsh in Virginia. When field collections were maintained in culture media at 21 C, most cells of the thallus developed into plurilocular sporangia. Released zoospores developed into microthalli from which clonal cultures were established. At 21 C microthalli produced sporangia which released zoospores, subsequently developing into more microthalli. However, microthalli at 6 C formed filaments which subsequently developed into thalloid plants. When the thalloid plants of Desmotrichum formed in culture were subjected to 21 C, plurilocular sporangia were formed. These results support the proposition that the seasonal periodicity of Desmotrichum is due to a temperature-regulated phenomenon in the development of macrothalli.     

Survival of Vibrio cholerae 01 in common foodstuffs during storage at different temperatures

Survival of Vibrio cholerae El Tor serotype Inaba was examined in pasteurized milk, freshwater fish, raw beef and raw chicken at a variety of temperatures. Both food type and incubation temperature affected survival. At the lowest temperatures, V. cholerae remained viable in meats for up to 90 d at—5°C and 300 d at —25°C. In milk, however, it was not detectable after 34 d at —5°C and 150 d at —25°C. At 7°C it survived 32 d, on average, in milk and only 18–20 d in the other foods. At room temperatures survival periods were shorter, never exceeding 10 d, and it was not detected after 2 d incubation at 35°C in chicken and fish.     

A systematic survey for thermophilic fermentative bacteria and archaea in high temperature petroleum reservoirs

Abstract: Production waters from 36 high temperature petroleum reservoirs were examined for the presence of thermophilic, fermentative microorganisms. The direct supplementation of production waters with glucose and either yeast extract, peptone, tryptone or casamino acid resulted in the isolation of thermophilic, fermentative microorganisms from 47% of the petroleum reservoirs examined. Three distinctive morphological groups were isolated from the production waters of petroleum reservoirs with depths ranging from 396–3048 metres, temperatures ranging from 21–130°C, salinities ranging from 2.8–128 gl⁻¹ and pHs ranging from 6.0–8.5. Group 1 were pleomorphic rod-shaped bacteria, Group 2 were sheathed rod-shaped bacteria, and Group 3 were coccoid archaea. Partial characterisation of strains from one seawater-flooded petroleum reservoir and three non-waterflooded petroleum reservoirs tentatively identified some strains in Group 1 as members of the genera Thermoanaerobacter and Thermoanaerobacterium , Group 2 as members of the Thermotogales order, and Group 3 as members of the genus Thermococcus . Production water salinity determined the type of microorganisms that were isolated. Group 1 organisms were found primarily in petroleum reservoirs with salinities less than 30 g/l, while Group 2 and 3 organisms were found to dominate in more saline reservoirs. The successful isolation of thermophilic, fermentative microorganisms from petroleum reservoirs decreased significantly with increasing salinity and temperature. These findings support the existence of a deep biosphere where fermentative microorganisms are widespread.     

Relation of water odour, salinity and temperature to ascent of glass-eels, Anguilla anguilla (L.): a laboratory study

The ascent of Anguilla anguilla (L.) which shows a variable pattern, has prompted much research that is not related to environmental conditions in a simple manner. Physico-chemical parameters of the water can be used by glass-eels as orienting cues during upstream migration. Temperature, salinity and odour linked with marine and river waters are three of the most important cues. Laboratory experiments were carried out by testing the responses of groups of 20 glass-eels, acclimated to either salt or fresh water at 11° C, towards water flows differing in temperature (8, 11 and 14° C), salinity (fresh water and 33‰ salt water) and odour (natural surface, marine or odourless tap water). Preferences were tested varying any one or two of the three factors at a time, or presenting the three factors simultaneously, in all possible combinations. The three factors tested singly reveal that thermal and salinity preferences recorded using odorous waters were analogous to those already observed with odourless water. Freshwater flows are preferred to salt-water. Temperatures below the acclimation temperature are preferred to higher temperatures. Natural odorous waters are preferred to odourless water at the same salinity. Data from 2900 choices recorded in 163 tests demonstrate that salinity is the most important factor guiding flow choice. Preference for fresh water is affected more by temperature than by odour. The latter, in turn, influences more thermal than salinity choices. Odour attractiveness mainly acts by reinforcing preferred stimuli or offsetting unpleasant ones. Preference differences were found between glasseels acclimated to fresh and salt water. Preference for fresh water strongly affects the choices of the former group, blunting the effects of thermal and odorous stimuli. Salt-water reared glass-eels, less conditioned by salinity, seem to be more sensitive to thermal and odorous attractions.     

Plant mitochondria electron partitioning is independent of short-term temperature changes

We tested the hypotheses that relative activity of the less efficient alternative oxidase (AOX) path changes with diurnal temperature changes, and thus changes carbon use efficiency with temperature. The activities of the alternative and cytochrome oxidase (COX) paths in plant tissues of three species were determined by measuring ¹⁸O/¹⁶O discrimination and total respiration from 17 to 36 °C. A new, more accurate method for calculating oxygen uptake rate from the mass spectrometry data was developed. Total carbon use efficiency was calculated from the ratio of respiratory heat and CO₂ rates measured from 10 to 35 °C. Oxygen isotope discrimination (22.9 ± 0.4‰) and AOX participation were invariant with temperature in leaf tissue of Cucurbita pepo , Nicotiana sativa and Vicia faba , thus falsifying the first part of the hypothesis. Stress responses of respiration at the temperature extremes limited the range for which carbon use efficiency could be accurately measured to 15–30 °C in N. sativa , to 10–25 °C in C. pepo and to 20–30 °C in V. faba . Carbon-use efficiency was invariant at these temperatures in these species, demonstrating that changes in other pathways that would vary carbon-use efficiency were also invariant with temperature.     

Phenotypic plasticity in the growth of the self-fertilizing hermaphroditic fish Rivulus marmoratus

Temperature, salinity, food ration and interactions among them had significant effects on overall growth of hatchlings of the self-fertilizing hermaphrodite Rivulus marmoratus . Low temperature (19° C) suppressed growth. At 26° C, the treatment groups at 12 and 40‰ salinity had higher final wet masses than the group at 1‰. When provided with high food ration, individuals whose parents were provided with low food had a significantly higher specific growth rate in the first month than those whose parents were provided with high food ration. This effect was also found in the final wet masses. It appears that genetic variation in this species occurs only between strains, yet within a strain there is considerable scope for phenotypic plasticity. The combination of a fixed genotype and plastic expression, along with a suite of specialized physiological characteristics, may explain how a self-fertilizing hermaphrodite can thrive in such an abiotically stressful and variable habitat as an estuary.     

Partial purification and characterization of phospholipase C from Yersinia enterocolitica

About 34% of the strains of Yersinia enterocolitica isolated from raw milk were found to produce lecithinase. A selected strain produced phospholipase C at 22°C and 37°C; production was optimum at 37°C in the stationary phase (14–16 h). A decrease in phospholipase C activity at various storage temperatures (—5°C, 4°C, 37°C) was also observed, although the enzyme was active over a wide range of temperature (5–65°C) and pH (3mD5–7mD5). The phospholipase C was partially purified by ammonium sulphate precipitation and Sephadex column chromatography, and characterized.