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1.
The effect of meal size (shrimp Crangon crangon) [0.83–18.82% dry body weight (Dw)] on specific dynamic action (SDA) was assessed in cuttlefish Sepia officinalis (1.03–6.25 g Dw) held at 15 and 20°C. Cuttlefish <2 g significantly expended less energy in feeding and digesting their meal
than cuttlefish >2 g when given the same quantity of food. Handling, eating and digesting a shrimp meal was temperature dependent
with cuttlefish processing and digesting a similar sized shrimp meal faster at 20°C than at 15°C. The proportional increase
in oxygen consumption (2.07 ± 0.02) was not correlated with feeding rate (FR) and was independent of temperature and cuttlefish
size. The SDA peak was not correlated with FRs, and increased as cuttlefish size and temperature increased. The mean SDA coefficient
was 0.87 ± 0.07% of the ingested energy; one of the lowest SDA values recorded amongst vertebrates and invertebrates. Daily
energy requirements (KJ day −1) for S. officinalis were calculated from laboratory estimates of energy losses due to standard ( MO 2
Standard), routine ( MO 2
Routine) and feeding ( MO 2
SDA) oxygen consumption. Laboratory estimates of daily metabolic expenditures were combined with results from previous investigations
to construct an energy budget for 1 and 5 g cuttlefish consuming a meal of 5 and 15% Dw at 20°C and the amount of energy available
for growth was estimated to be between 35 and 80.3% of the ingested energy. 相似文献
2.
Flathead grey mullets Mugil cephalus are commonly found in Mediterranean lagoons, which are regularly subject to high environmental variations. Oxygen is one
of the factors that shows extremely high variation. The objective of this study was to test the effects of acute hypoxia exposure
at two experimental temperatures (i.e. 20 and 30°C) on the stamina (time to fatigue) in M. cephalus swimming at the minimal cost of transport (i.e. optimal swimming speed; U
opt). At each temperature, a relationship was established between swimming speed and oxygen consumption (MO 2). This allowed estimation of U
opt at 45 cm s −1 (~1.12 Body Length s −1). Independent of temperature, stamina at U
opt was significantly reduced in severe hypoxia, i.e. at 15% of air saturation (AS). In these conditions, oxygen supply appears
therefore to be insufficient to maintain swimming, even at the low speed tested here. After the stamina test, MO 2 measured in fish tested at 15% AS was significantly higher than that measured after the test in normoxia. Therefore, we suggest
that in hypoxia, fish used anaerobic metabolism to supplement swimming at U
opt, leading to an oxygen debt. Since flathead grey mullet is a hypoxia-tolerant species, it is possible that hypoxic conditions
less severe than those tested here may reduce stamina at low speed in less tolerant species. In addition, we suggest that
testing stamina at these speeds may be relevant in order to understand the effect of hypoxia on behavioural activities carried
out at low speed, such as food searching. 相似文献
3.
Rates of routine respiration ( R
R, μl O 2 fish −1 h −1) and total ammonia nitrogen excretion ( E
R, μg NH 4–N + NH 3–N fish −1 h −1) were measured on larval and juvenile haddock ( Melanogrammus aeglefinus) to ascertain how energy losses due to metabolism were influenced by temperature ( T), dry body mass ( M
D, mg) and specific growth rate (SGR, % per day). R
R and E
R increased with M
D according to y = a · M
D
b
with b-values of 0.96, 0.98, 1.14, and 0.89, 0.78, 0.74, respectively, at 10, 7, and 4°C, respectively. Multiple regressions explained
98% of the variability in the combined effects of M
D and T on R
R and E
R in larval haddock: R
R = 0.97 · M
D
0.98 · e 0.092 · T
; E
R = 0.06 · M
D
0.79 · e 0.092 · T
. In young juvenile (24–30 mm standard length) haddock, R
R tended to decline ( P = 0.06) and E
R significantly declined ( P = 0.02) with increasing SGR. O:N ratios significantly increased with increasing SGR suggesting that N was spared in relatively
fast-growing individuals. Our results for young larval and juvenile haddock suggest: (1) nearly isometric scaling of R
R with increasing body size, (2) allometric scaling of E
R with increasing body size, (3) Q
10 values of 2.5 for both R
R and E
R, (4) metabolic differences in substrate utilization between relatively fast- and slow-growing individuals, and (5) that rates
of routine energy loss and growth were not positively related. The measurements in this study will provide robust parameter
estimates for individual-based models that are currently being utilized to investigate how variability in climatic forcing
influences the vital rates of early life stages of haddock. Our results also stress that inter-individual differences in rates
of energy loss should not be overlooked as a factor influencing growth variability among individuals. 相似文献
4.
Sprat, Sprattus sprattus L., is a small schooling clupeid forming large stocks in several ecosystems. Despite its high trophodynamic impact, little
is known about its energy consumption rates. As a central component of a bioenergetic budget, metabolic rates of sprat from
3.11 to 9.71 g wet weight (WW) were measured at nine different temperatures (T) ranging from 9 to 21°C using a computer-controlled
intermittent-flow respirometer. Routine metabolism ( R
R) was related to T (°C) and WW (g) by R
R = 0.074 WW 1.077 e 0.080 T. Standard metabolic rates ( R
S) as calculated from the 10% percentiles of the repeated measurements were on average 12% lower and still influenced by continuous
swimming activity: R
S = 0.069 WW 1.073 e 0.078 T. We interpret the deviation of the scaling exponent b from typically found exponents of b ~ 0.8 as a consequence of permanently elevated activity level. The high permanent swimming activities also indicated that
the concept of standard metabolism may not be meaningful in schooling planktivorous fish. These results suggest that generally
in bioenergetic models for clupeid schooling fish the activity multipliers should be chosen very conservatively. 相似文献
5.
Laboratory measurements of oxygen consumption were made on Penaeus monodon (Fabricius) from protozoea to adult stage at temperatures between 15° and 35°C. The logarithmic relationship between weight-specific respiration rate ( WRt) and temperature ( T) for two size groups, Protozoea 1 (PZ1) to Postlarva 1 (PL1) and PL to adult, are given as; WRt=10 0.431+0.0146 (T) (ml O 2 g -1 h -1) and WRt=10 -0.948+0.0338 (T) (ml O 2 g -1 h -1), respectively. Additionally, equations relating metabolic rate, temperature and size for the two size groups are; PZ1-PL1: log M=0.431+0.0146 T+(1.25 (log TL)+0.579), and PL1-adult: log M=-0.948+0.0338 T+(2.60(log CL)-0.683), where M=oxygen consumption in ml O 2 individual -1h -1, T=temperature in °C, TL=total length in cm, and CL=carapace length in cm. Activation energies of 6 186.75 J for PZ1-PL1 and 14 066.62 J for PL-adults point to different metabolic pathways or to differences in the ratio between the metabolic pathways used. 相似文献
6.
The shortfin mako shark, Isurus oxyrinchus, is a highly streamlined epipelagic predator that has several anatomical and physiological specializations hypothesized to
increase aerobic swimming performance. A large swim-tunnel respirometer was used to measure oxygen consumption (MO 2) in juvenile mako sharks (swimming under controlled temperature and flow conditions) to test the hypothesis that the mako
shark has an elevated maintenance metabolism when compared to other sharks of similar size swimming at the same water temperature.
Specimen collections were conducted off the coast of southern California, USA (32.94°N and 117.37°W) in 2001-2002 at sea-surface
temperatures of 16.0–21.0°C. Swimming MO 2 and tail beat frequency (TBF) were measured for nine mako sharks [77–107 cm in total length (TL) and 4.4 to 9.5 kg body mass]
at speeds from 28 to 54 cm s −1 (0.27–0.65 TL s −1) and water temperatures of 16.5–19.5°C. Standard metabolic rate (SMR) was estimated from the extrapolation to 0-velocity
of the linear regression through the LogMO 2 and swimming speed data. The estimated LogSMR (±SE) for the pooled data was 2.0937 ± 0.058 or 124 mg O 2 kg −1 h −1. The routine metabolic rate (RMR) calculated from seventeen MO 2 measurements from all specimens, at all test speeds was (mean ± SE) 344 ± 22 mg O 2 kg −1h −1 at 0.44 ± 0.03 TL s −1. The maximum metabolic rate (MMR) measured for any one shark in this study was 541 mg O 2 kg −1h −1 at 54 cm s −1 (0.65 TL s −1). The mean (±SE) TBF for 39 observations of steady swimming at all test speeds was 1.00 ± 0.01 Hz, which agrees with field
observations of 1.03 ± 0.03 Hz in four undisturbed free-swimming mako sharks observed during the same time period. These findings
suggest that the estimate of SMR for juvenile makos is comparable to that recorded for other similar-sized, ram-ventilating
shark species (when corrected for differences in experimental temperature). However, the mako RMR and MMR are apparently among
the highest measured for any shark species. 相似文献
7.
Sand shrimp, Crangon septemspinosa Say, are important to the trophic dynamics of coastal systems in the northwestern Atlantic. To evaluate predatory impacts of sand shrimp, daily energy requirements (J ind. –1 day –1) were calculated for this species from laboratory estimates of energy losses due to routine ( RR), active ( RA), and feeding ( RSDA) oxygen consumption rates (J ind. –1 h –1), coupled with measurements of diel motile activity. Shrimp used in this study were collected biweekly from the Niantic River, Connecticut (41°33N; 72°19W) during late spring and summer of 2000 and 2001. The rates of shrimp energy loss due to RR and RA increased exponentially with increasing temperature, with the magnitude of increase greater between 6°C and 10°C ( Q10=3.01) than between 10°C and 14°C ( Q10=2.85). Rates of RR doubled with a twofold increase in shrimp mass, and RSDA was 0.130 J h –1+ RR, irrespective of shrimp body size. Shrimp motile activity was significantly greater during dark periods relative to light periods, indicating nocturnal behavior. Nocturnal activity also increased significantly at higher temperatures, and at 20°C shifted from a unimodal to a bimodal pattern. Laboratory estimates of daily metabolic expenditures (1.7–307.4 J ind. –1 day –1 for 0.05 and 1.5 g wet weight shrimp, respectively, between 0°C and 20°C) were combined with results from previous investigations to construct a bioenergetic model and make inferences regarding the trophic positioning of C. septemspinosa. Bioenergetic model estimates indicated that juvenile and adult shrimp could meet daily energy demands via opportunistic omnivory, selectively preying upon items of high energy content (e.g. invertebrate and fish tissue) and compensating for limited prey availability by ingesting readily accessible lower energy food (e.g. detritus and plant material).Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by J.P. Grassle, New Brunswick 相似文献
8.
The vertical distribution, diel gut pigment content and oxygen consumption of Calanus euxinus were studied in April and September 1995 in the Black Sea. Gut pigment content of C. euxinus females was associated with diel vertical migration of the individuals, and it varied with depth and time. Highest gut pigment content was observed during the nighttime, when females were in the chlorophyll a (chl a) rich surface waters, but significant feeding also occurred in the deep layer. Gut pigment content throughout the water column varied from 0.8 to 22.0 ng pigment female –1 in April and from 0.2 to 21 ng pigment female –1 in September 1995. From the diel vertical migration pattern, it was estimated that female C. euxinus spend 7.5 h day –1 in April and 10.5 h day –1 in September in the chl a rich surface waters. Daily consumption by female C. euxinus in chl a rich surface waters was estimated by taking into account the feeding duration and gut pigment concentrations. Daily carbon rations of female C. euxinus, derived from herbivorous feeding in the euphotic zone, ranged from 6% to 11% of their body carbon weight in April and from 15% to 35% in September. Oxygen consumption rates of female and copepodite stage V (CV) C. euxinus were measured at different temperatures and at different oxygen concentrations. Oxygen consumption rates at oxygen-saturated concentration ranged from an average of 0.67 g O 2 mg –1 dry weight (DW) h –1 at 5°C to 2.1 g O 2 mg –1 DW h –1 at 23°C for females, and ranged from 0.48 g O 2 mg –1 DW h –1 at 5°C to 1.5 g O 2 mg –1 DW h –1 at 23°C for CVs. The rate of oxygen consumption at 16°C varied from 0.62 g O 2 mg –1 DW h –1 at 0.65 mg O 2 l –1 to 1.57 g O 2 mg –1 DW h –1 at 4.35 mg O 2 l –1 for CVs, and from 0.74 g O 2 mg –1 DW h –1 at 0.57 mg O 2 l –1 to 2.24 g O 2 mg –1 DW h –1 at 4.37 mg O 2 l –1 for females. From the oxygen consumption rates, daily requirements for the routine metabolism of females were estimated, and our results indicate that the herbivorous daily ration was sufficient to meet the routine metabolic requirements of female C. euxinus in April and September in the Black Sea.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
9.
The impact of a realistic warming scenario on the metabolic physiology of early cephalopod (squid Loligo vulgaris and cuttlefish Sepia officinalis) life stages was investigated. During exposure to the warming conditions (19 °C for the western coast of Portugal in 2100), the increase in oxygen consumption rates throughout embryogenesis was much steeper in squid (28-fold increase) than in cuttlefish (11-fold increase). The elevated catabolic activity–accelerated oxygen depletion within egg capsules, which exacerbated metabolic suppression toward the end of embryogenesis. Squid late-stage embryos appear to be more impacted by warming via metabolic suppression than cuttlefish embryos. At all temperature scenarios, the transition from encapsulated embryos to planktonic paralarvae implied metabolic increments higher than 100 %. Contrary to the nektobenthic strategy of cuttlefish newborns, the planktonic squid paralarvae rely predominantly on pulsed jet locomotion that dramatically increases their energy requirements. In the future, hatchlings will require more food per unit body size and, thus, feeding intake success will be crucial, especially for squid with high metabolic rates and low levels of metabolic reserves. 相似文献
10.
Metabolic changes and toxic effects in Crangon crangon (collected during summer 1989 near Helsingør, Denmark and at Kulhuse in the Isefjord) were observed during exposure to different arsenate concentrations. Survival, respiration, and concentrations of hemolymph glucose, muscle glycogen andadenine nucleotides were measured. C. crangon was very tolerant of arsenate; survival was only affected at arsenate concentrations >25 ppm. Small individuals (0.2 to 0.29 g wet weight) were less tolerant than medium-sized and large individuals (0.5 to 0.59 g and 0.8 to 0.89 g wet weight), e.g. at 50 ppm the LT 50 for small individuals was 180 h compared to 343 h and 360 h in middle-sized and large individuals. The relation between size and toxicity is probably due to the change in surface/volume ratio. Under clean conditions the respiration of C. crangon showed a clear relation between routine MO 2 (O 2 in mlg -1 h -1) and wet weight (r 2=0.89; P<0.001). During shortterm exposure to arsenate (10 and 50 ppm), the respiratory rates (MO 2) seemed to decrease in a size-dependent manner. The concentrations of blood glucose and muscle glycogen did not change in response to arsenate exposure. The concentrations of adenylate phosphates were high and constant throughout the experiments. C. crangon had maximal adenylate energy charge (AEC) values of ca. 0.8. No decrease in AEC due to the exposure to arsenate was observed. 相似文献
11.
The scaling of metabolic rates with body mass is one of the best known and most studied characteristics of aquatic animals.
Herein, we studied how size is related to oxygen consumption, ammonia excretion, and ingestion rates in tropical ( Octopus maya) and cold-water ( Enteroctopus megalocyathus) cephalopod species in an attempt to understand how size affects their metabolism. We also looked at how cephalopod metabolisms
are modulated by temperature by constructing the relationship between metabolism and temperature for some benthic octopod
species. Finally, we estimated the energy balance for O. maya and E. megalocyathus in order to validate the use of this information for aquaculture or fisheries management. In both species, oxygen consumption
and ammonia excretion increased allometrically with increasing body weight (BW) expressed as Y = aBW
b
. For oxygen consumption, b was 0.71 and 0.69 for E. megalocyathus and O. maya, respectively, and for ammonia excretion it was 0.37 and 0.43. Both species had low O/N ratios, indicating an apparent dependence
on protein energy. The mean ingestion rates for E. megalocyathus (3.1 ± 0.2% its BW day −1) and O. maya (2.9 ± 0.5% its BW day −1) indicate that voracity, which is characteristic of cephalopods, could be independent of species. The scope for growth ( P = I − ( H + U + R) estimated for E. megalocyathus was 28% higher than that observed in O. maya (320 vs. 249 kJ day −1 kg −1). Thus, cold-water cephalopod species could be more efficient than tropical species. The protein and respiratory metabolisms
of O. maya, E. megalocyathus, and other octopod species are directly dependent on temperature. Our results offer complementary evidence that, as Clarke
( 2004) stated, the metabolic response ( R and U) cannot be determined mechanistically by temperature, as previously proposed (Gillooly et al. 2002). 相似文献
12.
Growth, age and somatic production of the benthic predator Adelomelon brasiliana were studied at the southern limit of its distribution on the South American Atlantic shelf. Stable oxygen isotope ratios confirmed annual formation of internal shell growth marks. Modal shell length of the population was 140 mm, while modal shell-free wet mass was 255 g. A logistics growth function (SL =186.28 mm, K=0.185, t0=4.601) fitted 131 pairs of size-at-age data (25 shells) best. A. brasiliana is a very long-lived species, reaching up to 20 years of age. The maximum individual somatic production of 46 g shell-free wet mass year –1 is attained at 145 mm shell length, which corresponds to about 12 years of age.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
13.
Marine organisms are exposed to increasingly acidic oceans, as a result of equilibration of surface ocean water with rising
atmospheric CO 2 concentrations. In this study, we examined the physiological response of Mytilus edulis from the Baltic Sea, grown for 2 months at 4 seawater pCO 2 levels (39, 113, 243 and 405 Pa/385, 1,120, 2,400 and 4,000 μatm). Shell and somatic growth, calcification, oxygen consumption
and
\text NH4 + {\text{NH}}_{4}^{ + } excretion rates were measured in order to test the hypothesis whether exposure to elevated seawater pCO 2 is causally related to metabolic depression. During the experimental period, mussel shell mass and shell-free dry mass (SFDM)
increased at least by a factor of two and three, respectively. However, shell length and shell mass growth decreased linearly
with increasing pCO 2 by 6–20 and 10–34%, while SFDM growth was not significantly affected by hypercapnia. We observed a parabolic change in routine
metabolic rates with increasing pCO 2 and the highest rates (+60%) at 243 Pa.
\text NH4 + {\text{NH}}_{4}^{ + } excretion rose linearly with increasing pCO 2. Decreased O:N ratios at the highest seawater pCO 2 indicate enhanced protein metabolism which may contribute to intracellular pH regulation. We suggest that reduced shell growth
under severe acidification is not caused by (global) metabolic depression but is potentially due to synergistic effects of
increased cellular energy demand and nitrogen loss. 相似文献
14.
Oxygen consumption and tail beat frequency were measured on saithe ( Pollachius virens) and whiting ( Merlangius merlangus) during steady swimming. Oxygen consumption increased exponentially with swimming speed, and the relationship was described by a power function. The extrapolated standard metabolic rates (SMR) were similar for saithe and whiting, whereas the active metabolic rate (AMR) was twice as high for saithe. The higher AMR resulted in a higher scope for activity in accordance with the higher critical swimming speed ( U
crit) achieved by saithe. The optimum swimming speed ( U
opt) was 1.4 BL s −1 for saithe and 1.0 BL s −1 for whiting with a corresponding cost of transport (COT) of 0.14 and 0.15 J N −1 m −1. Tail beat frequency correlated strongly with swimming speed as well as with oxygen consumption. In contrast to swimming speed and oxygen consumption, measurement of tail beat frequency on individual free-ranging fish is relatively uncomplicated. Tail beat frequency may therefore serve as a predictor of swimming speed and oxygen consumption of saithe and whiting in the field. 相似文献
15.
Rates of oxygen consumption were measured for embryos, larvae and juveniles of the seastar Mediaster aequalis for 76 days post-fertilization. The rate increased from 0.65 nmol O 2 ind –1 h –1 at 6 h after fertilization to 2.8 nmol O 2 ind –1 h –1 at day 35. Larvae became competent to metamorphose around day 35 post-fertilization and began to decrease their metabolic rate after this time. Metamorphosed juveniles consumed 0.74 nmol O 2 ind –1 h –1. Eggs contained 138.6 µg lipid ind –1 and 12.1 µg protein ind –1. Lipid levels decreased in concentration throughout development while protein levels increased slightly. The lipid levels decreased by 88.5 µg from eggs to day 76 larvae, accounting for 3.5 J of energy. Total oxygen consumption to this point was 3.74 µmol O 2 ind –1, accounting for 1.84 J. The energetic demand up to day 76 was met completely through the use of lipid reserves. Metamorphosed juveniles expended 0.5 J more than larvae at the same age. Tubes of the polychaete Phyllochaetopterus prolifica were able to induce metamorphosis in M. aequalis larvae and a non-polar extract of these tubes also triggered metamorphosis. Larvae that are delayed to metamorphose can sustain their metabolic rate with lipid reserves for a limited, yet undetermined, period.Communicated by P.W. Sammarco, Chauvin 相似文献
16.
On the roofs of subtidal crevices, the giant cuttlefish ( Sepia apama) of southern Australia lays clutches of lemon-shaped eggs which hatch after 3 to 5 mo. Diffusion of oxygen through the capsule
and chorion membrane to the perivitelline fluid and embryo was modelled using the equation V˙
O2 = G
O2( P
O2out− P
O2in), where V˙
O2 = rate of oxygen consumption, G
O2 = oxygen conductance of the capsule, and P
O2 values = oxygen partial pressures across the capsule. During development, V˙
O2 rose exponentially as the embryo grew, reaching 5.5 μl h −1 at hatching. Throughout development, the capsule dimensions enlarged by absorption of water into the perivitelline space,
increasing G
O2 by a combination of increasing surface area, and decreasing thickness of the capsule. These processes maintained P
O2in high enough to allow unrestricted V˙
O2 until shortly before hatching. Diffusion limitation of respiration in hatching-stage embryos was demonstrated by (1) increased
embryonic V˙
O2 when P
O2out was experimentally raised, (2) greater V˙
O2 of resting individuals immediately after hatching, and (3) reduced V˙
O2 of hatchlings at experimental P
O2 levels higher than P
O2in before hatching. Thus, low P
O2in may be the stimulus to hatch. Potential problems of diffusive gas-exchange are mitigated by the relatively low incubation
temperature (12 °C), which may be a factor limiting the distribution of the species to cool, southern waters.
Received: 14 August 1999 / Accepted: 24 January 2000 相似文献
17.
To explore the effect of traffic emissions on air quality within street canyon, the wind flow and pollutant dispersion distribution in urban street canyons of different H/W, building gap and wind direction are studied and discussed by 3D computational fluid dynamics simulations. The largest PM2.5 concentrations are 46.4, 37.5, 28.4 µg/m3 when x = ? 88, ? 19.3, ? 19.3 m in 1.5 m above the ground level and the ratio of H/W is 1:1, 1:2 and 2:1, respectively. The flow around the top of the building and clearance flow between the buildings in street canyon influence by different H/W, which affected the diffusion of fine particulate matters. The largest PM2.5 concentrations are 88.1, 31.6 and 33.7 µg/m3 when x = 148.0, ? 92.3 and ? 186.7 m above the ground level of 1.5 m height and the building gap of 0, 20 and 40%, respectively. The air flows are cut by the clearance in the street canyons, and present the segmental characteristics. The largest PM2.5 concentrations are 10.6, 11.2 and 16.0 µg/m3 when x = 165.3 m, x = 58.0 and 1.5 m above the ground level of 1.5 m height and wind direction of the parallel to the street, perpendicular to the street and southwest, respectively. Modelled PM2.5 concentrations are basic agreement with measured PM2.5 concentrations for southwest wind direction. These results can help analyze the difussion of PM2.5 concentration in street canyons and urban planning. 相似文献
18.
A temperature-dependent growth model is presented for nauplii and copepodites of the estuarine calanoid copepod Acartia tonsa from southern Europe (Portugal). Development was followed from egg to adult in the laboratory at four temperatures (10, 15, 18 and 22°C) and under saturating food conditions (>1,000 μg C l −1). Development times versus incubation temperature were fitted to a Belehradek’s function, showing that development times decreased with increasing incubation temperature: at 10°C, A. tonsa need 40.3 days to reach adult stage, decreasing to 8.9 days when reared at 22°C. ANCOVA (homogeneity of slopes) showed that temperature ( P<0.001) and growth phase ( P<0.01) had a significant effect on the growth rate. Over the range of temperatures tested in this study, highest weight-specific growth rates were found during naupliar development (NI–NVI) and varied from 0.185 day −1 (10°C) to 0.880 day −1 (22°C) with a Q
10 equal to 3.66. During copepodite growth (CI–CV), the weight-specific growth rates ranged from 0.125 day −1 (10°C) to 0.488 day −1 (22°C) with a Q
10 equal to 3.12. The weight-specific growth rates ( g) followed temperature ( T) by a linear relationship and described as ln g=−2.962+0.130 T ( r
2=0.99, P<0.001) for naupliar stages and ln g=−3.134+0.114 T ( r
2=0.97, P<0.001) for copepodite stages. By comparing in situ growth rates (juvenile growth and fecundity) for A. tonsa taken from the literature with the temperature-dependent growth model defined here we suggest that the adult females of A. tonsa are more frequently food limited than juveniles. 相似文献
19.
Changes in seawater carbonate chemistry that accompany ongoing ocean acidification have been found to affect calcification
processes in many marine invertebrates. In contrast to the response of most invertebrates, calcification rates increase in
the cephalopod Sepia officinalis during long-term exposure to elevated seawater pCO 2. The present trial investigated structural changes in the cuttlebones of S. officinalis calcified during 6 weeks of exposure to 615 Pa CO 2. Cuttlebone mass increased sevenfold over the course of the growth trail, reaching a mean value of 0.71 ± 0.15 g. Depending
on cuttlefish size (mantle lengths 44–56 mm), cuttlebones of CO 2-incubated individuals accreted 22–55% more CaCO 3 compared to controls at 64 Pa CO 2. However, the height of the CO 2-exposed cuttlebones was reduced. A decrease in spacing of the cuttlebone lamellae, from 384 ± 26 to 195 ± 38 μm, accounted
for the height reduction The greater CaCO 3 content of the CO 2-incubated cuttlebones can be attributed to an increase in thickness of the lamellar and pillar walls. Particularly, pillar
thickness increased from 2.6 ± 0.6 to 4.9 ± 2.2 μm. Interestingly, the incorporation of non-acid-soluble organic matrix (chitin)
in the cuttlebones of CO 2-exposed individuals was reduced by 30% on average. The apparent robustness of calcification processes in S. officinalis, and other powerful ion regulators such as decapod cructaceans, during exposure to elevated pCO 2 is predicated to be closely connected to the increased extracellular [HCO 3
−] maintained by these organisms to compensate extracellular pH. The potential negative impact of increased calcification in
the cuttlebone of S. officinalis is discussed with regard to its function as a lightweight and highly porous buoyancy regulation device. Further studies working
with lower seawater pCO 2 values are necessary to evaluate if the observed phenomenon is of ecological relevance. 相似文献
20.
Adult Sepia officinalis L. were caught in June 1984, in the coastal waters of Wimereux (France). Deposition of the eggs took place in the seawater aquaria of the Station Marine. The oxygen consumption of S. officinalis was measured during embryonic and juvenile development. Aerobic metabolism occurs as soon as the early embryonic Stage 21. Oxygen diffuses through the initially thick egg shell; the oxygen level in the perivitelline liquid reaches a maximal value just before hatching (116.7±6.9 mm Hg). Hatchings display only a slight increase in oxygen consumption compared to embryos in the last stage of development. Respiration experiments with 40 d old juveniles showed that oxygen consumption increases with temperature, but is not affected by photoperiod. Experiments under increasing hypoxia revealed that S. officinalis juveniles are good regulators and maintain a constant oxygen consumption in the range of 4 to 7 mg O 2l -1. Juveniles successfully recover from an hypoxic stress of 2 mg O 2l -1 maintained for 1 h. This suggests that the respiratory pigments (pre-hemocyanins) of 40 d-old juveniles have a high oxygen affinity and/or that these juveniles have the ability to adapt to anaerobic conditions. 相似文献
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