The salinity preference of members of the genus Macroplea (Coleoptera, Chrysomelidae, Donaciinae), fully aquatic leaf beetles that occur in brackish water

Reed beetles (Donaciinae) of the genus Macroplea Samouelle, 1819 live permanently submerged. Literature indicates that Macroplea mutica occurs in brackish water, whereas Macroplea appendiculata is restricted to freshwater. The salinity preference of these two species was tested in a linear and a circular device that offered a continuous salinity gradient. The distribution of animals in the devices was monitored over at least 3 h in each of the 21 experiments. Both species preferred freshwater (salinity 0) over brackish water (salinity 10). In particular, this holds true for specimens collected in brackish water. Likewise, immediate reactions could be observed when during such experiments the direction of the gradient was reversed. While M. mutica can be regarded as a truly marine insect, this marine environment does not strictly reflect its fundamental niche with respect to salinity preference. This is in line with accumulating evidence that M. mutica can be found in freshwater habitats (and M. appendiculata in brackish water). This indicates that the species’ distribution might be influenced by other factors like host plant preference or dispersal mechanisms. It is discussed if—in spite of similar fundamental niches—differences in salinity tolerance (and hence performance in brackish water) may have contributed to speciation in the genus Macroplea.     

Oxygen diffusion and dark respiration in aquatic macrophytes

Abstract. The supply of oxygen to respiring shoot tissue was investigated for three submerged macrophytes (Potamogeton crispus L., Egeria densa Planch, and Myriophyllum triphyllum Orchard). For all species, the response of oxygen uptake rates to the external O₂ concentration was a rectangular hyperbola over the range 0–5.0 × 10^?3m³ m^?3. However, the response pattern for material with water-infiltrated lacunar airspaces was non-hyperbolic over this range. The change in response was interpreted as an increased substrate (O₂) limitation, resulting from lower radial diffusion rates within the infiltrated material. Neither the uninfiltrated nor the infiltrated responses obeyed the linear and logarithmic formulae of the type observed for submerged macrophytes by earlier authors. These results suggest that the responses observed are affected by factors such as water velocity, internal restrictions to diffusion and the range of oxygen tensions investigated. Therefore, it is unlikely that one response formula can adequately account for the effects of oxygen concentration on submerged macrophyte oxygen uptake. The lacunar airspaces also represent a possible oxygen source for dark respiration. The consumption of oxygen from the airspaces was investigated by displacing the gas from the lacunae and measuring the subsequent increase in the rate of oxygen assimilation from the external liquid. Approximately 30% of the oxygen consumed by E. densa and P. crispus, and more than 40% of that consumed by M. triphyllum, was derived from the lacunar system. This O₂ supply is a consequence of the higher oxygen concentration in the lacunae than in the external medium, due to the low solubility of oxygen in water. Storage of photosynthetically-produced oxygen in the lacunae could not be identified during a light/dark transient, due to rate changes caused by the effects of light on the respiratory metabolism. However, O₂ partial pressure gradients artificially set up between the lacunae and water equilibrated within an hour, suggesting that excess oxygen would be lost to the water within this time.     

Oxygen consumption of active and inactive adult tiger beetles

ABSTRACT. Oxygen consumption (O₂) in six species of adult tiger beetles Cicindela spp. (Coleoptera: Cicindelidae) was correlated with body mass and temperature during rest. In beetles forced to run and/or right themselves continuously for 5–10 min at 25°C, O₂ was approximately 7–12 times as high as in resting individuals; the difference increased with increasing mass. Resting and active VO₂ were similar to previous results for other beetles, although the slope of log O₂ on log mass was lower. Detailed analysis suggests the existence of taxonomic and ecological correlates of resting metabolism. The possible ecological implications and adaptive advantages of these results for adult tiger beetles are discussed.     

温度、盐度对强壮箭虫耗氧率和窒息点的影响

研究了不同温度、盐度下强壮箭虫的耗氧率和窒息点.结果表明:温度和盐度均对强壮箭虫的耗氧率和比耗氧率有显著影响.试验温度在5℃-25℃,强壮箭虫个体耗氧率(IO)和比耗氧率(SO)开始随温度的升高而升高,之后呈明显下降趋势.其回归方程分别为y=0.0058x3 -0.2956x2+4.415x-8.7816(R2=0.99,P＜0.05)和y=0.0011x3 -0.0546x2+0.8161x-1.6232(R2=0.99,P＜0.05),数值分别为6.30～11.71μg·ind-1·h-1和1.22 ～2.16μg· mg-1·h-1,窒息点为4.18～6.87 mg·L-1.盐度10 ～40条件下,IO和SO随盐度的升高逐渐下降,回归方程分别为y=-0.0068x2 -0.1412x+21.702(R2=0.89,P＜0.05)和y=-0.0013x2-0.0261x+4.0114( R2 =0.89,P＜0.05),数值分别为4.98～17.73μg ·ind-1·h-1和0.92～3.56 μg·mg-1 ·h-1,窒息点为4.02～6.24 mg·L-1.对强壮箭虫与其他水生动物的耗氧率和窒息点进行比较得出,强壮箭虫是一种狭氧性浮游动物.     

温度、盐度和体长对西藏拟溞耗氧率的影响

在实验室内研究了盐度(S=5、10、15、20和25)、温度(T=3、8、14、20和22℃)和体长(L=0.83、1.25、1.49、1.87和2.42mm)对西藏拟耗氧率的影响。结果表明,在试验盐度内该的个体耗氧率(IO)和比耗氧率(SO)均随盐度(S)升高而升高,其回归方程分别为IO=0.0014S 0.0126和SO=0.115S0.5612,数值范围为0.02～0.045μg/(indh)和0.31～0.67μg/(mg·h)。个体耗氧率和比耗氧率在温度试验中有同样的趋势,回归方程分别为IO=0.0049e0.1574T和SO=0.0678e0.1605T,数值分别为0.0076～0.13μg/(ind·h)和0.10～1.71μg/(mg·h)。体长试验中个体耗氧率随体长增大而增大,而比耗氧率则降低,回归方程分别为:IO=0.0545L2.5962和SO=-0.2059L 0.7908,数值范围为0.036～0.68μg/(ind·h)和0.38～0.63μg/(mg·h)。讨论了盐度、温度和体长对西藏拟耗氧率的影响。     

Oxygen consumption of flying locusts

ABSTRACT. Desert locusts ( Schistocerca gregaria Forskal.) were flown into an airstream from a wind tunnel while tethered to a balance. Rate of oxygen consumption and lift were recorded. The mean rate of oxygen consumption of male locusts in level flight at airspeeds between 2.5 and 3m/s was found to be 12.6ml/g/h.     

Oxygen consumption rates of tilapia in fresh water, sea water, and hypersaline sea water

Whole animal oxygen consumption rates and plasma constituents were determined in the tilapia O. mossambicus , acclimated for 1 month in fresh water, sea water, and 1·6 × sea water. Oxygen consumption rates for the three water salinities were: 177·2 ± 16·86, 78·6 ± 2·32, and 195·4 ± 15·39 mg O₂ kg⁻¹ h⁻¹ (means ± 1 s.e.), respectively. Plasma prolactin (tPRL₁₈₈) concentration was significantly lower in 1·6 × sea water compared to fresh and sea water. There were no significant differences among mean plasma cortisol concentration and lysozyme activity. Ventilation was significantly higher in fish in sea water compared to the fish in fresh and 1·6 × sea water. The lowest oxygen consumption rates were found in fish acclimated to sea water. That salinity is probably closest to the brackish waters from which they were captured in the wild, and this agreement likely reflects the selection for optimal morphological and physiological characteristics to live in that environment.     

Effects of salinity and weight on routine metabolism in the juvenile croaker, Micropogonias furnieri (Desmarest 1823)

Juvenile croakers from a brackish water bay showed minimal oxygen consumption rates at salinities between 17–19.     

Oxygen transport and consumption by suspended cells in microgravity: a multiphase analysis

A rotating bioreactor for the cell/tissue culture should be operated to obtain sufficient nutrient transfer and avoid damage to the culture materials. Thus, the objective of the present study is to determine the appropriate suspension conditions for the bead/cell distribution and evaluate oxygen transport in the rotating wall vessel (RWV) bioreactor. A numerical analysis of the RWV bioreactor is conducted by incorporating the Eulerian-Eulerian multiphase and oxygen transport equations. The bead size and rotating speed are the control variables in the calculations. The present results show that the rotating speed for appropriate suspensions needs to be increased as the size of the bead/cell increases: 10 rpm for 200 microm; 12 rpm for 300 microm; 14 rpm for 400 microm; 18 rpm for 600 microm. As the rotating speed and the bead size increase from 10 rpm/200 microm to 18 rpm/600 microm, the mean oxygen concentration in the 80% midzone of the vessel is increased by approximately 85% after 1-h rotation due to the high convective flow for 18 rpm/600 microm case as compared to 10 rpm/200 microm case. The present results may serve as criteria to set the operating parameters for a RWV bioreactor, such as the size of beads and the rotating speed, according to the growth of cell aggregates. In addition, it might provide a design parameter for an advanced suspension bioreactor for 3-D engineered cell and tissue cultures.     

Colonisation of Heliconia caribaea by aquatic invertebrates: resource and microsite characteristics

Abstract.  1. Colonisation of ephemeral aquatic habitats via oviposition by invertebrates may be influenced by a variety of factors, such as the quality of aquatic habitat and the characteristics of the surrounding terrestrial environment. The water-holding bracts of Heliconia caribaea , a subtropical herb that produces ephemeral aquatic habitats, are colonised by a variety of aquatic invertebrates. To date, no experiments have been conducted to identify the cues that affect colonisation patterns via oviposition selection in Heliconia .
2. Artificial bracts were used to assess the influence of two types of resources found in bracts (plant produced carbohydrates and terrestrial snail faeces) on oviposition site-selection by invertebrate taxa via a replicated factorial design at four locations in the Luquillo Experimental Forest of Puerto Rico, U.S.A. Eleven microsite characteristics thought to affect oviposition were measured for each experimental container.
3. Most taxa responded in a minor way to microsite characteristics, whereas site selection by the most numerically dominant groups (e.g. Syrphidae) were influenced principally by resources within artificial bracts. Overall, the greatest response by particular taxa was to the presence of snail faeces. At the community level, total abundance, richness, and evenness of invertebrates increased with increasing biomass of faeces. Variation in sugar produced a more complex response.
4. In general, the terrestrial matrix surrounding these aquatic habitats was only a secondary determinant of population and community attributes; the principal factor affecting site selection was the quality of the aquatic habitat.     

Effects of temperature, salinity, and fish size on growth and consumption of juvenile bluefish

Consumption and growth rates of juvenile bluefish Pomatomus saltatrix increased with increasing temperature and decreased with increasing fish size in short-term (7 days) experiments. Salinity had no effect on growth or consumption rate in a short-term experiment. In a long-term (90 days) mesocosm experiment, consumption and growth rates declined with increasing body size. Predictive equations developed from short-term experiments did not adequately predict observed consumption rates in the mesocosm experiment. However, growth in the mesocosm experiment was similar to field growth. Also, mesocosm consumption rates and consumption rates calculated using field growth and mesocosm growth efficiencies were similar to published independent field estimates of consumption rate. Our results indicate that experiments to determine the effects of temperature and the allometry of body size on growth and consumption rates should be conducted over long time periods simulating field conditions. Juvenile bluefish have rapid growth and their individual cumulative consumption is large. This result suggests that bluefish may have a large effect on their prey populations. This effect has yet to be quantified.     

Oxygen and salinity characteristics of predator–prey distributional overlaps shown by predatory Baltic cod during spawning

In the distributional overlap volume of Baltic cod Gadus morhua and its prey, studied in the Bornholm Basin in the southern Baltic Sea, only a fraction of the sprat Sprattus sprattus population vertically overlapped with the Baltic cod population. Sprat occurred in the intermediate water, in the halocline and in the bottom water, while herring Clupea harengus and Baltic cod occurred exclusively in the halocline and in the bottom water. Only parts of the sprat population were hence accessible for Baltic cod, and only a fraction of the sprat had access to the Baltic cod eggs below the halocline. Baltic cod–clupeid overlap volumes appeared to be determined by salinity stratification and oxygenation of the bottom water. Hydrography time series were used to estimate average habitat volumes and overlap from July to September in 1958–1999. In the 1999 survey spawning Baltic cod had greater ratios of empty stomachs and lower average rations than non-spawning Baltic cod. The average ration for Baltic cod caught within 11· 4 m from the bottom (demersal) did not differ from the average ration of Baltic cod caught in shallower waters (pelagic), because spawning and non-spawning Baltic cod in both strata were caught at equal rates. The diet of the Baltic cod caught demersally contained more benthic invertebrates, especially Saduria entomon, but Baltic cod caught pelagically also had fresh benthic food in their stomachs, indicating vertical migration of individual fish.     

温度、盐度及交互作用对僧帽牡蛎(Saccostrea cucullata)呼吸排泄的影响

采用实验生态学方法研究了温度(13、18、23、28、31、34℃)和盐度(18、23、28、33)对僧帽牡蛎(Saccostrea cueullata)耗氧率和排氨率的影响,并分析了二者交互作用对呼吸排泄的影响。结果表明,不同温度条件下,僧帽牡蛎的耗氧率变化范围为0.43-3.15mg g~(-1)h~(-1),排氨率的变化范围为72.62-1245.77μg g~(-1)h~(-1),方差分析显示,温度和盐度对僧帽牡蛎耗氧率(F=60.440,P0.01)和排氨率(F=61.083,P0.01)的影响均极显著;二者的交互作用对僧帽牡蛎耗氧率(F=4.907,P0.01)和排氨率(F=11.412,P0.01)影响也极显著,耗氧率(Y)、排氨率(Y)与温度(T)和盐度(S)之间的二元线性回归方程为y=a+bT+cS+dT×S。在一定温度范围内(13-31℃)僧帽牡蛎单位体重耗氧率(Y)与温度(T)呈正相关符合指数方程Y=ae~(bT),其中a的取值范围为0.1378-0.2117,b的取值范围为0.0757-0.0912;单位体重排氨率也与温度呈正相关,符合上述指数方程,其中a的取值范围为20.364-30.634,b的取值范围为0.1004-0.1341。不同温度和盐度条件下,僧帽牡蛎呼吸排泄的氧氮比在2.20-7.78之间,平均值为3.81。     

Chemical mobility and bioavailabity of sediment-bound heavy metals influenced by salinity

The transfer of metals from contaminated sediments to algal cell walls (Scenedesmus quadricauda) and organisms from various trophic levels (euryhaline osmoconform hydroid Cordylophora caspia and algae Brachiomonas submarina) was studied with a multichamber device. The system consists of a central chamber which contained the mud suspension and six external chambers containing the different biological indicators. The solids in the central and external chambers are separated by 0.45 m-diameter membranes which allow diffusion of the mobilized, dissolved metal compounds. Experiments were performed with dredged sediments at various salinities (0.5, 1.0, 1.5, and 2.0 percent, respectively) and the kinetic of re-adsorption was obtained by taking samples after different time intervals. High enrichment of Cd was found in the living alga Brachiomonas submarina, but on the other side only a weak influence of salinity on re-adsorption could be observed. Model experiments with ionic Cd showed a clear dependency on Cd-sorption on the algae, Cd-concentration in solution, and salinity. These results indicate that the transfer of metals mainly depends on the specific surface properties of the substrates and on the specific chemical form of the dissolved mobilized metal.     

Oxygen consumption by eggs and larvae of striped mullet, Mugil cephalus, in relation to development, salinity and temperature

Oxygen consumption rates during embryonic and the first 38 days of larval development of the striped mullet were measured at 24° C by differential respirometry. Measurements were obtained at the blastula, gastrula and four embryonic stages, and at the yolk-sac, preflexion, flexion and post-flexion larval stages.
Oxygen uptake rates of eggs increased linearly from 0.024 μl O₂ per egg h^-1 (0·323 μl O₂ mg^-1 dry wt h^-1) by blastulae to 0·177 μlO₂ per egg h^-1 (2·516 μlO₂mg ¹dry wth^-1) by embryos prior to hatching. Respiration rates did not vary significantly among four salinities (20,25, 30, 35%₀).
Larval oxygen consumption increased in a curvilinear manner from 0·243 μl O₂ per larva h^-1 shortly after hatching to 18·880 μl O₂ per larva h^-1 on day 38. Oxygen consumption varied in direct proportion to dry weight. Mass-specific oxygen consumption rates of preflexion, flexion, and postflexion larvae did not change with age (10·838 μl O₂ mg ¹dry wt h^-1).
Larval oxygen consumption rates did not vary significantly among salinities 10–35%. Acute temperature increases elicited significant increases in oxygen consumption, these being relatively greater in yolk-sac larvae ( Q₁₀ = 2·75) than in postflexion larvae ( Q₁₀ = 1·40).     

Effect of salinity on oxygen consumption in fishes: a review

The effect of salinity on resting oxygen uptake was measured in the perch Perca fluviatilis and available information on oxygen uptake in teleost species at a variety of salinities was reviewed. Trans‐epithelial ion transport against a concentration gradient requires energy and exposure to salinities osmotically different from the body fluids therefore imposes an energetic demand that is expected to be lowest in brackish water compared to fresh and sea water. Across species, there is no clear trend between oxygen uptake and salinity, and estimates of cost of osmotic and ionic regulation vary from a few per cent to >30% of standard metabolism.     

Effects of salinity fluctuation on routine metabolism of juvenile spot, Leiostomus xanthums

We subjected juvenile spot, Leiostomus xanthurus , to eight different salinity fluctuation schedules to evaluate the effects of magnitude, rate, mean, and direction of salinity changes on their routine metabolism. Routine respiration stabilized within 3 h after all salinity changes and no fish died. Very rapid rates of change and changes at low mean salinity elicited short-term stress responses in 40–70 mm spot. Spot adapted more rapidly to increasing salinity changes than to decreasing changes, but the acclimation state of the fish apparently did not affect their salinity tolerance. Our results also indicated that spot undergo size-dependent changes in sensitivity to salinity fluctuation which correspond to seasonal shifts in distribution.     

Effects of low salinity on juvenile pink shrimp Farfantepenaeus paulensis (Perez-Farfante 1967, Crustacea)

It is of paramount importance to study salinity tolerance of commercially important crustaceans, such as the pink shrimp Farfantepenaeus paulensis to determine possible mortality causes in the wild and in aquaculture in oligohaline waters. The aim of this study was to determine the lethal salinity concentration (LC50) for juvenile pink shrimp F. paulensis and measure its oxygen consumption and ammonia excretion at different salinity levels. Shrimp of two length classes (49.4?±?4.3 and 78.5?±?5.5?mm) were placed in 10-L containers and exposed to salinity levels of 35, 30, 25, 20, 15, 10 and 5. The experiments were tripled, with seven shrimp in each container. The average lethal concentration (LC50s) for an exposure of 24?h was 13.33 (11.26–15.78) and 10.26 (8.60–12.64), respectively, for the two classes of juveniles. For an exposure of 48?h, LC50s were 12.71 (10.68–15.12) for the larger animals and 9.20 (7.34–11.52) for the smaller ones. There was an inverse relationship between salinity and rates of oxygen consumption and ammonia excretion. The average reduction in specific oxygen consumption in salinities 20, 25 and 30 showed a decrease in metabolic rate of 63, 80 and 82%, respectively, in relation to salinity level 0. The same occurred for the averages of ammonia excretion at salinity levels of 15, 20, 25, 30 and 35, which represented low metabolic rates of 57, 61, 70, 71 and 74% respectably in relation to salinity level 0.     

Early development of milkfish: effects of salinity on embryonic and larval metabolism, yolk absorption and growth

During embryogenesis of Chanos chanos , more than half of the yolk was consumed and the majority of it was converted into larval tissue. Salinity affected both yolk absorption and embryonic and larval growth. Larvae hatched in 20% had larger yolk reserves but were smaller and grew more slowly than larvae in 35 and 50%. Larvae hatched in 35 and 50% had equal amounts of yolk but those from 35% were larger. Oxygen consumption rates increased during development (from 0.06 ± 0.01 μl O₂ egg^–1 h^–1 by blastulae to 0.37 ± 0-01 μl O₂ egg^–1 h^–1 by prehatch embryos and 0–43 ± 0–03 μl O₂ larva ^–1 h ^–1 by newly-hatched larvae) and were significantly affected by salinity. Eggs and yolk-sac larvae incubated in 35% consumed more oxygen than those in the low and high salinities. Salinity affected both the rate and pattern of yolk utilization but salinity-related differences in metabolism, yolk absorption, and growth were not related directly to the osmotic gradient. Low salinity retarded yolk absorption while high salinity reduced yolk utilization efficiencies. Differences in oxygen consumption rates were probably related to variations in the relative amounts of metabolically active embryonic and larval tissue and/or higher activity levels rather than differential osmoregulatory costs. 35% is probably the most suitable salinity for incubation and larval rearing of milkfish.     

Effects of leaf type on the consumption rates of aquatic detritivores

Silver maple (Acer saccharinum) and cottonwood (Populus deltoides) leaves were incubated in cages excluding (controls) or containing (experimental) detritivores for periods of up to 123 days. Experimental cages contained either the cranefly larvae Tipula abdominalis, the amphipod Gammarus pseudolimnaeus or the caddisfly Pycnopsyche guttifer. Differences in daily consumption between leaf types and among species were compared.In control cages 20–23% of initial leaf weight was lost by leaching and 8–10% by microbial processes. T. abdominalis and P. guttifer consumed more silver maple than cottonwood during feeding intervals; no significant differences were observed for G. pseudolimnaeus. Invertebrate consumption of cottonwood leaves significantly increased with time; no significant differences in consumption of silver maple leaves with time were observed. Potential factors influencing the observed feeding pattern between leaf species are discussed.