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1.
Bering Sea snow crabs (Chionoecetes opilio) are a commerciallyimportant crab harvested in the Bering Sea. Optimal managementof this species requires an understanding of the biology ofthis crab that is currently incomplete. Fisheries managers applya continuous growth model in their management of snow crab,which assumes that male crabs increase in size throughout theirlifespan. Male snow crabs undergo a morphometric molt that leadsto a disproportionate increase in chelae size and it is stilldebated whether this molt is associated with a terminal molt.This study was conducted to determine whether adult male C.opilio are anecdysic. Using current knowledge of the hormonalregulation of crustacean growth, snow crab physiology was manipulatedto induce an increase in molting hormones (ecdysteroids). Sincefemale snow crabs are known to undergo a terminal molt afterattaining reproductive maturity, we compared ecdysteroid levelsin eyestalk-ablated terminally molted females, small-clawedmales and large-clawed males. Snow crabs were collected fromthe Bering Sea and maintained in circulating seawater at approximately6°C. Animals were either eyestalk-ablated or left intact.Ecdysteroid levels in hemolymph were quantified using an enzyme-linkedimmunosorbant assay (ELISA). Circulating ecdysteroids were significantlyhigher in small-clawed male crabs when compared to large-clawedmales or terminally molted females. Eyestalk-ablation increasedcirculating ecdysteroids in small-clawed males, but had no significanteffect on circulating ecdysteroids in large-clawed males orin terminally molted females. 相似文献
2.
Winter production of CO2 and N2O from alpine tundra: environmental controls and relationship to inter-system C and N fluxes 总被引:15,自引:0,他引:15
Fluxes of CO2 and N2O were measured from both natural and experimentally augmented snowpacks during the winters of 1993 and 1994 on Niwot Ridge
in the Colorado Front Range. Consistent snow cover insulated the soil surface from extreme air temperatures and allowed heterotrophic
activity to continue through much of the winter. In contrast, soil remained frozen at sites with inconsistent snow cover and
production did not begin until snowmelt. Fluxes were measured when soil temperatures under the snow ranged from –5°C to 0°C,
but there was no significant relationship between flux for either gas and temperature within this range. While early developing
snowpacks resulted in warmer minimum soil temperatures allowing production to continue for most of the winter, the highest
CO2 fluxes were recorded at sites which experienced a hard freeze before a consistent snowpack developed. Consequently, the seasonal
flux of CO2
–C from snow covered soils was related both to the severity of freeze and the duration of snow cover. Over-winter CO2
–C loss ranged from 0.3 g C m−2 season−1 at sites characterized by inconsistent snow cover to 25.7 g C m−2 season−1 at sites that experienced a hard freeze followed by an extended period of snow cover. In contrast to the pattern observed
with C loss, a hard freeze early in the winter did not result in greater N2O–N loss. Both mean daily N2O fluxes and the total over-winter N2O–N loss were related to the length of time soils were covered by a consistent snowpack. Over-winter N2O–N loss ranged from less 0.23 mg N m−2 from the latest developing, short duration snowpacks to 16.90 mg N m−2 from sites with early snow cover. These data suggest that over-winter heterotrophic activity in snow-covered soil has the
potential to mineralize from less than 1% to greater than 25% of the carbon fixed in ANPP, while over-winter N2O fluxes range from less than half to an order of magnitude higher than growing season fluxes. The variability in these fluxes
suggests that small changes in climate which affect the timing of seasonal snow cover may have a large effect on C and N cycling
in these environments.
Received: 5 April 1996 / Accepted: 25 November 1996 相似文献
3.
This study investigated the effect of temperature on the development and overwintering capacity of the pupal parasitoid, Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae), a candidate classical biological control agent against leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae) in Canada. It was estimated that 256.4 day-degrees, above a lower threshold temperature
of 7.3°C, were required for D. pulchellus to complete development, from egg to adult eclosion. Laboratory and field experiments on the immature and mature parasitoids
indicated that D. pulchellus overwinters primarily, if not exclusively, in the adult stage. Only adults were able to survive an entire winter under natural
outdoor conditions in central Europe. Immature parasitoids developing inside their pupal hosts were capable of withstanding
short periods of temperatures as low as −5°C or −10°C, but even much higher temperatures were lethal if sustained for several
weeks. Among adults, females demonstrated greater cold hardiness than males. The LTime50 at −12°C, simulating winter temperatures without snow cover, was 4–5 and 6–7 days for males and females, respectively. The
LTime50 at −4°C, simulating winter temperatures beneath an insulating snow layer, was 1–2 and 2–3 weeks for males and females, respectively,
with maximum survival of eight weeks. It is likely that survival would be even greater in a natural environment where the
parasitoids could select optimal overwintering sites and have the option to feed when temperatures rise enough to permit activity.
Based on these results, D. pulchellus is expected to survive winters in the targeted release areas of Ontario and Quebec. 相似文献
4.
Sten Ivar Siikavuopio Ragnhild Dragøy Whitaker Bjørn Steinar Sæther Philip James Bjørn Ronald Olsen Tina Thesslund 《Marine Biology Research》2017,13(7):744-750
This study investigates the effects of temperature on the survival, food intake, oxygen consumption and growth during long-term live holding of captive male snow crab (Chionoecetes opilio) (average?=?0.7?kg). The crabs were held at three different temperatures, 3, 6 and 9°C. The trials were done using groups of snow crabs held in nine land-based holding tanks (three replicates per temperature treatment). The results showed that temperature had a significant effect on survival. The survival rate at 3°C (61%) was significantly higher than at 6°C (33%) and at 9°C (28%). Specific oxygen consumption rates of unfed crab at 6°C were significantly higher than at 9°C and 3°C. In summary, the current study shows that the Barents Sea snow crab have a narrow temperature range in which they thrive compared with the Barents Sea red king crab (Paralithodes camtschaticus). Barents Sea snow crab has similar metabolic and physiological attributes to other major snow crab populations. In conditions when ambient temperatures are approximately 6°C, it may prove beneficial for animal welfare and also be financially advantageous to reduce ambient water temperatures in live snow crab holding facilities on boat or on land. 相似文献
5.
In winter of 2009/2010, Aphanizomenon flos-aquae bloomed in the ice and snow covered oligo-mesotrophic Lake Stechlin, Germany. The photosynthesis of the natural population was measured at eight temperatures in the range of 2–35°C, at nine different irradiance levels in the range of 0–1,320 μmol m−2 s−1 PAR at each applied temperature. The photoadaptation parameter (I k) and the maximum photosynthetic rate (P max) correlated positively with the temperature between 2 and 30°C, and there was a remarkable drop in both parameters at 35°C. The low I k at low temperatures enabled the active photosynthesis of overwintering populations at low irradiance levels under ice and snow cover. The optimum of the photosynthesis was above 20°C at irradiances above 150 μmol m−2 s−1. At lower irradiance levels (7.5–30 μmol m−2 s−1), the photosynthesis was the most intensive in the temperature range of 2–5°C. The interaction between light and temperature allowed the proliferation of A. flos-aquae in Lake Stechlin resulting in winter water bloom in this oligo-mesotrophic lake. The applied 2°C is the lowest experimental temperature ever in the photosynthesis/growth studies of A. flos-aquae, and the results of the P–I and P–T measurements provide novel information about the tolerance and physiological plasticity of this species. 相似文献
6.
We describe endorhizal fungi associated with Equisetum species collected from Ellesmere Island (82°N), Axel Heiberg Island (80°N), and from sites in Yukon Territory and the Prairie
Provinces (51–67°N). Fungal colonization was assessed using a multiple quantitation microintersect method for lactofuchsin-stained
roots examined with wide-field and confocal epifluorescence microscopy. Equisetum roots host abundant and diverse endorhizal fungal associates. For 85 specimens from 14 sites, total colonization averaged
30 ± 3%, range 0–97%. Colonization rates for wide aseptate hyphae characteristic of arbuscular mycorrhizae (5 ± 1%) was significantly
less than for fine endophytes (20 ± 3%) or septate endophytes (17 ± 2%). Equisetum spp. are abundant in tundra and an important understory plant in boreal forests, where they are particularly common on burned
or disturbed sites. Endorhizal fungi associated with Equisetum may have broad ecological relevance. 相似文献
7.
The density, distribution and population structure of Opusia indica were studied through transects method. Two transects were delimited in a mangrove area of Korangi creek (24°79′ N/67°20′
E). On each transect, three 0.25 m2 quadrats were sampled at three tidal levels on a monthly basis during low tide. A total of 1919 crabs were obtained, of which
775 were males, 945 were non-ovigerous females and 199 were ovigerous females. Density of crabs varied between 198 m−2 to 798 m−2. The density and size distribution showed significant difference from low tide level to high tide level and were positively
correlated with the percent moisture, percent organic matter and sediment structure. Based on carapace width (CW) males were
significantly larger than the females indicating sexual dimorphism. The monthly size frequency distribution of crabs showed
recruitment of juvenile crabs (< than 4 mm) nearly throughout the year except in few months. The monthly sex ratio deviated
from 1:1 throughout the year, with female bias (χ
2 = 31.633, P = 0.001 and df =11). Breeding was seasonal with peaks in SW monsoon. Size at sexual maturity based on smallest ovigerous
female was CW = 4.0 mm. The average number of eggs per female were 2066 ± 479 (n = 25). Positive linear relationship was observed between the size of the female crabs and the egg numbers (r
2 = 0.554). 相似文献
8.
Hydromedion sparsutum is a locally abundant herbivorous beetle on the sub-Antarctic island of South Georgia, often living in close association
with the tussock grass Parodiochloa flabellata. Over a 4-day period in mid-summer when the air temperature varied from 0 to 20°C, the temperature in the leaf litter 5–10 cm
deep at the base of tussock plants (the microhabitat of H. sparsutum) was consistently within the range of 5–7.5°C. Experiments were carried out to assess the ability of H. sparsutum larvae collected from this thermally stable environment to acclimate when maintained at lower (0°C) and higher (15°C) temperatures.
The mean supercooling points (freezing temperature) of larvae collected in January and acclimated at 0°C for 3 and 6 weeks
and 15°C for 3 weeks were all within the range of −2.6 to −4.6°C. Larvae in all treatment groups were freeze tolerant. Acclimation
at 0°C significantly increased survival in a 15-min exposure at −8°C (from 27 to 96%) and −10°C (from 0 to 63%) compared with
the field-fresh and 15°C-treated larvae. Similarly, survival of 0°C-acclimated larvae in a 72-h exposure at −6°C increased
from 20 to 83%. Extending the acclimation period at 0°C to 6 weeks did not produce any further increase in cold tolerance.
The concentrations of glucose and trehalose in larval body fluids increased significantly with low temperature acclimation.
Larvae maintained at 15°C for 3 weeks (none survived for 6 weeks) were less able to survive 1-h exposures between 30 and 35°C
than the 0°C-treated samples. Whilst vegetation and snow cover are an effective buffer against low winter temperatures in
many polar insects, the inability of H. sparsutum larvae to acclimate or survive at 15°C suggests that protection against high summer temperatures is equally important for
this species.
Accepted: 2 August 1999 相似文献
9.
Simulated climate change impacts on fluxes of carbon in Norway spruce ecosystems along a climatic transect in Sweden 总被引:2,自引:0,他引:2
Per-Erik Jansson Magnus Svensson Dan Berggren Kleja David Gustafsson 《Biogeochemistry》2008,89(1):81-94
A simulation study based on recent regional climate scenarios for Sweden investigated possible changes in carbon (C) dynamics
and net ecosystem exchange (NEE) of Swedish Norway spruce forest ecosystems. Four sites, representative of well-drained soils
in four regions, were included. Stand development was simulated for a 100-year rotation period using a coupled model describing
abiotic and biotic processes in the soil-plant-atmosphere system. Two IPCC climate change scenarios, corresponding to a mean
annual temperature increase of about 2°C (A2) or 3°C (B2) from the reference period 1961–1990 to a new period 2061–2090, were
considered. Annual maximum snow depth decreased with the increase in air temperature, whereas maximum soil frost depth and
mean annual soil temperature showed only small changes, especially for the sites in northern Sweden. Simulations suggested
that in the warmer climate, gross primary production (GPP) increased by 24–32% in northern Sweden and by 32–43% in the south.
In the north, the increase was related to the combined effect of air and soil temperature extending the growing season, whereas
in the south it was mainly governed by increased N availability due to increased soil temperature. NEE increased by about
20% (A2) or 25% (B2) at all sites, more or less solely due to increased accumulation of C in the tree biomass (including harvest
residues), since changes in soil C were small compared with the current climate. Both light use efficiency and water use efficiency
were improved in the future climate scenarios, despite increases in atmospheric CO2 not being considered. 相似文献
10.
Summary Plants of European chestnut (Castanea sativa) have been consistently recovered from cryopreserved in vitro-grown shoot apices by using the vitrification procedure. Factors found to influence the success of cryopreservation include
the source of the shoot tips (terminal buds or axillary buds), their size, the duration of exposure to the cryoprotectant
solution, and the composition of the post-cryostorage recovery medium. The most efficient protocol for shoot regrowth employed
0.5–1.0 mm shoot tips isolated from 1 cm-long terminal buds that had been excised from 3–5-wk shoot cultures and cold hardened
at 4°C for 2 wk. The isolated shoot tips were precultured for 2d at 4°C on solidified Gresshoff and Doy medium (GD) supplemented
with 0.2M sucrose, and were then treated for 20 min at room temperature with a loading solution (2M glycerol+0.4M sucrose) and for 120 min at 0°C with a modified PVS2 solution before rapid immersion in liquid nitrogen (LN). After 1 d in
LN, rapid rewarming and unloading in 1.2M sucrose solution for 20 min, the shoot tips were plated on recovery medium consisting of GD supplemented with 2.2 μM benzyladenine, 2.9 μM 3-indoleacetic acid, and 0.9 μM zeatin. This protocol achieved 38–54% shoot recovery rates among five chestnut clones (three of juvenile origin and two of
mature origin), and in all cases plant regeneration was also obtained. 相似文献
11.
E. B. Lopatina V. E. Kipyatkov S. V. Balashov D. A. Dubovikoff I. V. Sokolova 《Entomological Review》2012,92(2):135-145
The data are obtained on development time at six constant temperatures (12, 14, 16, 18, 20, 22°C) and thermal requirements
for preimaginal development in a ground beetle Amara communis from Arkhangelsk (64°34′N) and St. Petersburg (59°53′N). The larval and pupal development times were found to be significantly
shorter in the Arkhangelsk than in the St. Petersburg population under all temperatures. As a result, total preimaginal development
appeared to be shorter by 6.2–6.6% in the Arkhangelsk population. The regression lines of the larval, pupal and total (egg-to-adult)
development rate on temperature for the Arkhangelsk population run above and steeper than the respective lines for the St.
Petersburg population. Both populations share the similar values of the thermal thresholds (7.2–8.2°C). This explains faster
preimaginal development in the northern population under all temperatures above the threshold. Thus, the slope of the regression
lines increases, i.e., the sum of degree-days decreases, whereas the thermal threshold for development exhibited no distinctive
changes from south to north in this species. Adults from Arkhangelsk reared in the experiments appeared heavier on the average
in comparison with those from St. Petersburg, especially at 18–22°C. Temperature did not significantly affect adult weight,
except the fact that the beetles were slightly heavier at 20 and 22°C. Consequently, the well-known “temperature-size rule”
is violated in this species. Relative growth rate in larvae of A. communis increased considerably with temperature rise from 14 to 22°C. It was significantly higher in the beetles from Arkhangelsk
at 18–22°C. There were no differences in larval growth rate between the two populations at 14 and 16°C. 相似文献
12.
Mats of coenocytic “snow molds” are commonly observed covering the soil and litter of alpine and subalpine areas immediately
following snow melt. Here, we describe the phylogenetic placement, growth rates, and metabolic potential of cold-adapted fungi
from under-snow mats in the subalpine forests of Colorado. SSU rDNA sequencing revealed that these fungi belong to the zygomycete
orders Mucorales and Mortierellales. All of the isolates could grow at temperatures observed under the snow at our sites (0°C
and −2°C) but were unable to grow at temperatures above 25°C and were unable to grow anaerobically. Growth rates for these
fungi were very high at −2°C, approximately an order of magnitude faster than previously studied cold-tolerant fungi from
Antarctic soils. Given the rapid aerobic growth of these fungi at low temperatures, we propose that they are uniquely adapted
to take advantage of the flush of nutrient that occurs at the soil–snow interface beneath late winter snow packs. In addition,
extracellular enzyme production was relatively high for the Mucorales, but quite low for the Mortierellales, perhaps indicating
some niche separation between these fungi beneath the late winter snow pack. 相似文献
13.
S. D. Kashenko 《Russian Journal of Marine Biology》2009,35(5):422-430
The combined effects of temperatures of 14, 17, 20, 22, and 25°C and salinities of 36–12‰ on embryos and larvae of the sand
dollar Scaphechinus mirabilis was studied. Embryonic development is the most sensitive stage in the early ontogenesis of S. mirabilis. It is completed at a temperature of 14–20°C in a salinity range of 36–24‰ and at temperature of 22°C to 26‰. The fertilization
proceeds in wider ranges of temperature and salinity. Among the swimming larvae, blastulae showed the greatest resistance
to variations of these environmental factors. All the larvae survived at a temperature of 14–22°C and a salinity of 36–20‰,
and more than 70% of them at 18‰. The pluteus I is the most vulnerable stage; probably this is related to the formation of
the larval skeleton and transition to phytoplankton feeding. The survival of larvae at the age of 20 days was 100% at 14–22°
C and a salinity of 36–24‰, most of them survived at 14–20°C and a salinity 18‰. The temperature 25 ° C is the most damaging
for early development of S. mirabilis. The duration of development of that species lasts 28.5–29 days at 20°C and a salinity of 32.2–32.6‰. At 20 and 22°C, the
larvae settled and completed metamorphosis more quickly if sand from the parental habitat was present. The larvae did not
settle during the experiment (14 days) at 14 ° C and in the absence of sand. 相似文献
14.
Salt marshes and shallow-water macroalgal beds are known to provide nursery habitat for many species of fish and invertebrates.
The role of these habitats as refuge from predation is well established, but the degree to which indigenous primary production
within the nursery provides food for growth and development of estuarine species remains unresolved. In this study, we tested
the hypothesis that juvenile blue crabs depend on indigenous primary production, directly or indirectly, during their entire
stay within the nursery. To test this hypothesis, we conducted isotopic studies and stomach content analyses of juveniles
from habitats near the mouth of Delaware Bay and from an adjacent lagoonal estuary (ca. 39.5° N, 75.1° W). Primary producers,
marsh detritus, various life-history stages of blue crabs and potential prey species were sampled in the main estuary and
in an adjacent marsh during the summer and early fall of two consecutive years. Newly settled juveniles (<15 mm carapace width)
from the marsh were about 1.8‰ lighter in carbon (−17.2‰) relative to larger juveniles from the marsh (15–30 mm carapace width)
and appeared to have retained a carbon isotopic signature indicative of the phytoplankton-based food web associated with larval
stages. However, the signature of juveniles changed as a function of size. Large juveniles and crabs >60 mm were enriched
in δ13C (−14.7 ± 0.1‰) compared to small crabs, suggesting a gradual shift in diet from a planktonic to a detritus-based food web
with increasing size. As with crabs from Delaware Bay, the δ13C signature of juvenile crabs sampled from macroalgal beds in the lagoonal estuary (Rehoboth Bay) changed as a function of
size. Also, δ13C ratios of crabs varied among the various species of macroalgae. The δ15N composition of primary producers in the marsh and main estuary also was reflected in the δ15N values of crabs and other benthic consumers in the respective habitats. Results of stomach-content analysis in this study
were consistent with isotope data. Observed changes in prey preferences were related to changes in size of juvenile crabs
and also differed among habitats. Gut content analyses of the three size classes of juveniles in macroalgal beds from Rehoboth
Bay indicated that the crabs depend heavily on various amphipod species that occur on the seaweeds. These amphipods graze
directly on the macroalgae and are among the most abundant invertebrates in the macroalgal beds. This implies a direct trophic
relationship between the juvenile crabs and the macroalgae. In summary, our study provides strong evidence that the value
of nursery areas such as salt marshes and macroalgal beds goes beyond that of providing refuge from predation, and that species
using these nurseries (e.g. juvenile blue crabs) are ultimately dependent on primary production originating in benthic plants
indigenous to the nursery. 相似文献
15.
Decline in skeletal growth of the coral Porites?lutea from the Andaman Sea, South Thailand between 1984 and 2005 总被引:1,自引:1,他引:0
Of the few studies that have examined in situ coral growth responses to recent climate change, none have done so in equatorial
waters subject to relatively high sea temperatures (annual mean >27°C). This study compared the growth rate of Porites lutea from eight sites at Phuket, South Thailand between two time periods (December 1984–November 1986 and December 2003–November
2005). There was a significant decrease in coral calcification (23.5%) and linear extension rates (19.4–23.4%) between the
two sampling periods at a number of sites, while skeletal bulk density remained unchanged. Over the last 46 years, sea temperatures
(SST) in the area have risen at a rate of 0.161°C per decade (current seasonal temperature range 28–30°C) and regression analysis
of coral growth data is consistent with a link between rising temperature and reduced linear extension in the order of 46–56%
for every 1°C rise in SST. The apparent sensitivity of linear extension in P. lutea to increased SST suggests that corals in this part of the Andaman Sea may already be subjected to temperatures beyond their
thermal optimum for skeletal growth.
Communicated by Environment Editor Prof. Rob van Woesik 相似文献
16.
Nitrogenous excretion in two snails, Littorina saxatilis (high intertidal) and L. obtusata (low intertidal) was studied in relation to temperature acclimation (at 4° and 21°C), including total N excretion rates,
the fraction of urea in N excretion, corresponding O:N ratios and the partitioning of deaminated protein between catabolic
and anabolic processes at 4°, 11° and 21°C. Aggregate N excretion rates in both species showed no significant compensatory
adjustments following acclimation. Total weight specific N excretion rates at 21°C were higher in standard 3 mg L. saxatilis (739 ng N mg−1 h−1) than standard 5 mg L. obtusata (257 ng N mg−1 h−1) for snails acclimated to 21°C. Comparisons of Q10 values of total weight specific N excretion to Q10 values for weight specific oxygen consumption ({xxV}O2) between 4° to 11 °C and 11° to 21°C indicated that, while total rates of catabolic metabolism ({xxV}O2) and protein deamination in L. obtusata were essentially parallel, the relationship between N excretion and {xxV}O2 in L. saxatilis revealed the partitioning of a larger share of deaminated protein carbon into anabolism at 4° and 21°C than at 11°C. Urea
N accounted for a larger share of aggregate N excreted in L. saxatilis than in L. obtusata, but in both species urea N is a greater proportion of total N excreted when acclimated at 4°C (urea N: ammonia N ratio range:
1 to 2.15) than in snails acclimated to 21°C (urea N: ammonia N ratio range: 0.46 to 1.39). Molar O:N ratios indicate that
the proportion of metabolism supported by protein catabolism is greater in L. saxatilis (O:N range: 2.5–8.4) than in L. obtusata (O:N range: 7.3–13.0). In both species, regardless of acclimation temperature, the O:N ratios are generally lowest (high
protein catabolism) at 4°C and highest at 21°C. 相似文献
17.
Based on materials from plankton surveys carried out in 2004–2009, the period of occurrence, density, and distribution of
larvae of three commercial species of crabs in the Peter the Great bay and adjacent areas of Sea of Japan were studied. The
larvae of the horsehair crab Erimacrus isenbeckii (Brandt, 1848) occurred in the plankton from mid-March to early June, within the range of water temperature from −1 to 10.8°C.
The larvae of the helmet crab Telmessus cheiragonus (Tilesius, 1812) appeared in the plankton in mid-April and occurred to the end of June within the temperature range from
2.8 to 13.0°C. The larvae of the snow crab Chionoecetes opilio (O. Fabricius, 1788) appeared in the plankton in mid-April as well, but some individuals sporadically occurred until early
August. All the species of crabs produced one generation of larvae for their reproduction season. The terms of larval stay
in plankton depended on water temperature and the duration of the pelagic period increased in colder years. In that area,
the larvae of C. opilio were the most abundant (up to 41 ind./m3) and the zoea density of horsehair and helmet crabs was significantly lower (no more than 2 ind./m3). The larvae of C. opilio occurred over the entire area of the Peter the Great bay; the greatest aggregations of their early stages were observed in
its southwestern open part. The maximum density of E. isenbeckii zoea was recorded in the south of the Amursky bay and in the Posyet bay. Individual larvae of T. cheiragonus occurred in the Posyet bay and in the southern part of the Amursky and Ussuriisky bays. The late-stage larvae of all crab
species were concentrated in areas of the coastal circulation. 相似文献
18.
Bruce Vondracek Wayne A. Wurtsbaugh Joseph J. Cech 《Environmental Biology of Fishes》1988,21(1):45-57
The allocation of energy to growth and reproduction, in relation to temperature and food availability, was investigated in
laboratory experiments with the mosquitofish,Gambusia affinis. At constant temperature of 20, 25 and 30°C and ad libitum feeding, specific growth rates increased with increasing temperature
at 1.7, 3.1 and 3.4% dry mass day−1, respectively. Growth rates in a cycling temperature regime (20–30°C,
) were faster than in a 25°C constant temperature. As temperature increased from 20 to 30°C, mean age at first reproduction
decreased from 191 to 56 days and brood size and mass of offspring increased significantly. Interbrood interval was also temperature
dependent; estimates at 25 and 30°C for females >1000 mg were 22.6 and 18.6 days, respectively. Interbrood interval could
not be calculated at 20°C. Although fitness was highest at 30°C, females at 25°C invested a greater proportion of surplus
energy (growth and reproduction) to reproduction (38%) than at 20 (17%) or 30°C (36%) during the 32-week study. Fish at cooler
temperatures began reproduction at a smaller size.
Where rations were controlled at low, medium, and ad libitum levels, somatic and gonadal growth increased with increasing
temperatures and food availability. The proportion of energy invested in reproduction was highest at 25°C for each comparable
ration level. Calculated energy budgets indicated that over the 10-week study, 17–22% of the food energy was invested in growth,
0–7% in reproduction, and 75–83% in respiration and excretory losses, depending on feeding and temperature conditions. 相似文献
19.
Andrew Rogerson 《Hydrobiologia》1981,85(2):117-128
The consumption, production and respiration of Amoeba proteus were measured in the laboratory for cells cultured over a range of Tetrahymena pyriformis concentrations (125–4 000 cells/0.5 ml) at 10, 15 and 20 °C. Differences were attributed to both temperature and prey availability.
A series of generation energy budgets were constructed for amoebae grown under the above conditions. The biological efficiencies
linking the parameters of the budget equation were calculated. Assimilation efficiencies ranged from 22–59% regardless of
temperature. Net production efficiencies were high at 15 and 20 °C (65–82%) but low at 10 °C (11–49%). Gross production efficiencies
were also higher at 15 and 20 °C (16–47%) than at 10 °C (4–29%). The ecological implications of this investigation are discussed. 相似文献
20.
Weathers WW Gerhart KL Hodum PJ 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(8):561-572
We measured resting metabolic rates at air temperatures between ca. −5 and 30 °C in snow petrels (Pagodroma nivea), cape petrels (Daption capense), Antarctic petrels (Thalassoica antarctica), and Antarctic fulmars (Fulmarus glacialoides). We measured seven age classes for each species: adults, and nestlings that were 3, 8, 15, 28, 35, and 42 days old. Basal
metabolic rate (BMR) and thermal conductance (C) of adults averaged, respectively, 140% and 100% of values predicted allometrically
for nonpasserine birds. Minimum metabolic rates of unfasted nestlings aged 15–42 days averaged, respectively, 97% and 98%
of predicted adult BMR in Antarctic petrels and snow petrels, versus 119% and 126% of predicted in Antarctic fulmars and cape
petrels. Nestlings of the southerly breeding snow petrel and Antarctic petrel were relatively well insulated compared with
nestlings of other high-latitude seabirds. Adult lower critical temperature (Tlc) was inversely related to body mass and averaged 9 °C lower than predicted allometrically. As nestlings grew, their Tlc decreased with increasing body mass from ca. 14 to 22 °C (depending upon species) at 3 days of age, to −4 to 8 °C when nestlings
attained peak mass. Nestling Tlc subsequently increased as body mass decreased during pre-fledging weight recession. Nestling Tlc was close to mean air temperature from the end of brooding until fledging in the three surface nesting species.
Accepted: 12 July 2000 相似文献