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1.
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 (MO2) 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 MO2 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 LogMO2 and swimming speed data. The estimated LogSMR (±SE) for the pooled data was 2.0937 ± 0.058 or 124 mg O2 kg−1 h−1. The routine metabolic rate (RMR) calculated from seventeen MO2 measurements from all specimens, at all test speeds was (mean ± SE) 344 ± 22 mg O2 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 O2 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
2.
Respiration rates and elemental composition (carbon and nitrogen) were determined for four dominant oncaeid copepods (Triconia borealis, Triconia canadensis, Oncaea grossa and Oncaea parila) from 0–1,000 m depth in the western subarctic Pacific. Across the four species of which dry weight (DW) varied from 2.0
to 32 μg, respiration rates measured at in situ temperature (3°C) increased with DW, ranging from 0.84 to 7.4 nl O2 individual−1 h−1. Carbon (C) and nitrogen (N) composition of the four oncaeid species ranged from 49–57% of DW and 7.0–10.3% of DW, respectively,
and the resultant C:N ratios were 4.8–8.3. The high C contents and C:N ratios were reflected by large accumulation of lipids
in their body. Specific respiration rates (SR, a fraction of body C respired per day) ranged between 0.5 and 1.3% day−1. Respiration rates adjusted to a body size of 1 mg body N (i.e. adjusted metabolic rates, AMR) of the four oncaeid species
[0.6–1.1 μl O2 (mg body N)−0.8 h−1 at 3°C] were significantly lower than those (1.7–5.1) reported in the literature for oithonid and calanoid copepods at the
same temperature. The present results indicate that lower metabolic expenditure due to less active swimming (pseudopelagic
life mode) together with rich energy reserve in the body (as lipids) are the characters of oncaeid copepods inhabiting in
the epi- and mesopelagic zones of this region. 相似文献
3.
Simon Anthony Morley Koh Siang Tan Robert W. Day Stephanie M. Martin Hans-O. Pörtner Lloyd S. Peck 《Marine Biology》2009,156(10):1977-1984
The upper thermal limits for burrowing and survival were compared with micro-habitat temperature for anomalodesmatan clams:
Laternula elliptica (Antarctica, 67°S); Laternula recta, (temperate Australia, 38°S) and Laternula truncata (tropical Singapore, 1°N). Lethal limits (LT50) were higher than burrowing limits (BT50) in L. elliptica (7.5–9.0 and 2.2°C) and L. recta (winter, 32.8–36.8 and 31.1–32.8°C) but the same range for L. truncata (33.0–35.0 and 33.4–34.9°C). L. elliptica and L. truncata had a BT50 0.4 and 2.4–3.9°C, respectively, above their maximum experienced temperature. L. recta, which experience solar heating during midday low tides, had a BT50 0.7–2.4°C below and a range for LT50 that spanned their predicted environmental maximum (33.5°C). L. recta showed no seasonal difference in LT50 or BT50. Our single genus comparisons contrast with macrophysiological studies showing that temperate species cope better with elevated
temperatures.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Holothuroidea represent the dominant benthic megafauna in hadal trenches (~6,000–11,000 m), but little is known about their
behaviour and functional role at such depths. Using a time-lapse camera at 8,074 m in the Peru–Chile Trench (SE Pacific Ocean),
we provide the first in situ observations of locomotory activity for the elasipodid holothurian Elpidia atakama Belyaev in Shirshov Inst Oceanol 92:326–367, (1971). Time-lapse sequences reveal ‘run and mill’ behaviour whereby bouts of feeding activity are interspersed by periods of locomotion.
Over the total observation period (20 h 25 min), we observed a mean (±SD) locomotion speed of 7.0 ± 5.7 BL h−1, but this increased to 10.9 ± 7.2 BL h−1 during active relocation and reduced to 4.8 ± 2.9 BL h−1 during feeding. These observations show E. atakama translocates and processes sediment at rates comparable to shallower species despite extreme hydrostatic pressure and remoteness
from surface-derived food. 相似文献
5.
As part of the evaluation of fluxes between the water column and a rich benthic community of the Dover Strait (Eastern English
Channel), laboratory measurements of oxygen consumption were carried out on a common ophiurid, Ophiothrix fragilis (Abildgaard), from February 1993 to February 1995. The mean O2-consumption rate was evaluated at 0.31 mg O2 g−1 h−1 (ash-free dry weight). Simultaneous measurements of O2 consumption and CO2 production using the pH-alkalinity method revealed an average respiratory quotient of 0.69 proved suitable for converting
oxygen demand to carbon flux. A seasonal trend in respiration data was demonstrated by sinusoidal curves fitted to O2-uptake and CO2-release data as a function of time. The influence on respiration rate of two seasonal parameters (temperature and food availability)
is discussed; linear regression indicated a highly significant relationship between O2 consumption (or CO2 production) and temperature; both O2-consumption and CO2-production rates decreased with starvation. The average O:N ratio was estimated at 8.46, close to the theoretical value when
proteins constitute the catabolic substrate. The annual carbon respired by the O. fragilis community examined and the estimated annual primary production by phytoplankton indicate that the respiration of the O. fragilis community could supply 35% of phytoplankton carbon requirements.
Received: 1 August 1996 / Accepted: 4 September 1996 相似文献
6.
Effect of temperature fluctuations and food supply on the growth and metabolism of juvenile sea scallops (Placopecten magellanicus) 总被引:1,自引:0,他引:1
On the eastern shore of Nova Scotia late summer atmospheric systems cause upwelling of shelf water; the associated temperature
variations of 10 °C with a 6 to 8 d period are comparable in magnitude to the seasonal variation. A laboratory study was undertaken
to assess the effects of these temperature fluctuations on sea scallop (Placopecten magellanicus) growth and metabolism. In a factorial design, scallops were subjected to constant (10 °C) or a variable (6 to 15 °C) 8 d
temperature cycle, and either a low (seston in filtered seawater) or high (seston supplemented with cultured phytoplankton)
food diet. During the 48 d experiment scallop mortality was low and growth positive in all treatments. Shell and total tissue
growth rate did not differ between temperature treatments, but growth in the high food treatments was 40 to 50% higher than
in the low food treatments. However, soft tissue (excluding adductor) growth did show a temperature treatment effect; growth
rates were significantly higher in the fluctuating temperature treatment, due in part to greater gonad development. Weight-standardized
rates of scallop oxygen consumption (V
sO2 , μmol O2 g−1 h−1) were 20 to 25% higher in high food than in low food treatments, consistent with the expected increase in respiration due
to the higher growth rates. Scallop metabolism did not acclimate to the fluctuating temperature cycle; V
sO2 and ammonium excretion (V
sNH+
4, μmol O2 g−1 h−1) remained dependent on ambient temperature throughout the experiment. V
sNH+
4 Q10 (2.77) was higher than V
sO2 Q10 (2.01) which was reflected in a decrease in the O:N ratio at 15 °C, indicating a shift toward increased protein catabolism
and a stressed state. At 10 °C, V
sO2 and V
sNH+
4 in the variable temperature treatments were 15 to 18% lower than in the constant temperature treatments, a difference that
was not detected in growth measurements. Results demonstrate that the metabolism of Placopecten magellanicus, unlike some bivalve species, is tightly coupled to fluctuations in ambient temperature. Although an absence of compensatory
acclimation had a minimal effect on growth in this study, if high temperatures were combined with low food conditions a reduction
in scallop production could result.
Received: 23 June 1998 / Accepted: 8 February 1999 相似文献
7.
Hematite (Fe2O3) chemical reduction into FeO and Fe3O4 by releasing O2 at high temperatures is considered one of the generally accepted mechanisms for processing waste minerals and clay into lightweight
aggregate construction materials. In many case studies, this mechanism has not been strictly confirmed. To verify whether
hematite can effectively release O2 at 1,000–1,260°C, a material containing hematite, simulating waste sediments from a Taiwanese reservoir, was shaped into
pellets and fired into lightweight aggregates at high temperatures for 20 min and studied with various techniques. As revealed
by the X-ray absorption near-edge structure technique, almost all the hematite remained as Fe(III) in the pellets when fired
at 1,000–1,260°C, implying a negligible release of O2 leading to the creation of pores. This finding shows that the generally accepted mechanism for lightweight aggregate formation
associated with hematite decomposition into FeO, Fe3O4, and O2 is invalid. Furthermore, Fe(III)-containing composites were formed in the fired pellets. Although firing at 1,000°C can trigger
the decomposition of the components K2CO3, Na2CO3, and CaCO3 with a release of CO2, the sintering reaction was seemingly too weak to encapsulate the gases effectively. For pellets fired at 1,050–1,150°C,
pores grew in size because the sintering reaction sufficed to generate a glassy phase that could better encapsulate gases. 相似文献
8.
Reproductive biology in two species of deep-sea squids 总被引:2,自引:0,他引:2
Deep-sea squids, Moroteuthis ingens and Gonatus antarcticus, were collected in the slope waters off the Falkland Islands and their reproductive systems preserved and investigated onshore.
Changes in oocyte length-frequencies at maturation and spawning, and their fecundity were studied. These squids, as well as
many other species, are characterised by a synchronous oocyte growth and ovulation. Oviducts are not used for ripe egg accumulation
and consequently the universal scale of Lipinski (1979) cannot be applied to assign female maturity. M. ingens spawns near the bottom; its fecundity is 168–297 thousand eggs. Maximum egg size is 1.8–2.7 mm. G. antarcticus spawns midwater; its fecundity is 10–25 thousand eggs. Egg size is 3.2–3.3 mm. In M. ingens spawning takes place in the austral autumn and winter, in G. antarcticus—in austral winter. Our data and the literature data show that the so-called “synchronous ovulation” probably occurs in all
deepwater squids. This pattern is very rare among fish, but is quite common among benthic octopods that brood their egg masses. 相似文献
9.
Kate F. Lankin Myron A. Peck Lawrence J. Buckley David A. Bengtson 《Marine Biology》2008,155(5):461-472
Rates of routine respiration (R
R, μl O2 fish−1 h−1) and total ammonia nitrogen excretion (E
R, μg NH4–N + NH3–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 · e0.092 · T
; E
R = 0.06 · M
D
0.79 · e0.092 · 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
10.
The effect of ration size, temperature and body weight on specific dynamic action of the common cuttlefish Sepia officinalis 总被引:1,自引:0,他引: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 (MO2
Standard), routine (MO2
Routine) and feeding (MO2
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
11.
Rates of progression and transmission of black band disease (BBD) on the staghorn coral, Acropora muricata, were compared between months for seasonal in situ studies and between temperature treatments in experimental aquaria manipulations
at Lizard Island on the Great Barrier Reef (GBR). In situ field experiments demonstrated that BBD progressed along branches
approximately twice as fast (1.7–2.4 times) during the austral summer month of January (0.99 ± 0.04 cm/day) than in the cooler
months of July (0.58 ± 0.04 cm/day) and May (0.41 ± 0.07 cm/day). Transmission of BBD between colonies was also accelerated
in warmer months, with signs of infection becoming visible 1.2 days earlier in January compared to May. The greater seawater
temperatures by ∼2 to 3°C and light intensities by up to 650 μE/m2/s in January, suggest that rates of progression and transmission of BBD are linked to one or both of these parameters. Manipulative
experiments in summer provide corroborative evidence that elevated temperatures increase rates of BBD progression, with the
disease progressing 1.3 times more rapidly in the 32°C elevated temperature treatment than in the 30°C ambient treatment (1.17 ± 0.06 cm/day
versus 0.92 ± 0.07 cm/day; F
2,6 = 7.66, P = 0.022). In contrast, although a trend for greatest BBD progression was measured in elevated temperature treatments of 29°C
(0.46 ± 0.07 cm/day) and 31°C (0.52 ± 0.06 cm/day) in winter, these rates did not differ significantly (F
3,7 = 1.72, P = 0.249) from those measured for the ambient 27°C treatment (0.37 ± 0.06 cm/day) or the field controls (0.41 ± 0.09 cm/day).
The lower rates of BBD progression in the 31°C winter treatment (0.52 ± 0.06 cm/day) than in the 30°C (0.92 ± 0.07 cm/day)
summer treatment, may have been a response to 28-fold decreased light irradiance in the former, suggesting that high irradiance
in combination with elevated temperatures may promote progression of BBD. Results from this study indicate that the impact
of elevated temperature on BBD progression is complex with a combination of environmental factors including temperature and
light playing key roles in progression and transmission of the disease. 相似文献
12.
Oxygen transport by the hemocyanin of the protobranch mollusc Solemya reidi Bernard was studied in native hemolymph samples. Clams were collected from two different reducing environments, beneath log
booms in Alberni Inlet, British Columbia, Canada, and from the sewage effulent in Santa Monica Bay, California, USA. The hemocyanin
concentration in a pooled hemolymph sample (n = 10 individuals) was 33.5 mg ml−1. The mean hemolymph pH of five Alberni clams maintained for 3 wk in mud was 7.96 ± 0.06. No significant variation in hemocyanin
oxygen-affinity or cooperativity was found for hemocyanin in whole hemolymph samples from these five individually studied
clams. There was a significant difference only at 15 °C in the oxygen affinity of hemocyanin in pooled whole-hemolymph samples
from S. reidi collected from Alberni Inlet compared with clams collected from Santa Monica Bay. Little effect of temperature on hemocyanin
oxygen-affinity was found for temperatures below 20 °C; above 20 °C, the oxygen affinity was reduced for clams from both sites.
Temperature and pH had no apparent affect on hemocyanin cooperativity. Moderate Bohr shifts were found at all temperatures
examined. The presence of physiologically relevant concentrations of thiosulphate in hemocyanin samples resulted in a decrease
in hemocyanin oxygen-affinity, opposite to the effect on hemocyanin found for the hydrothermal vent crab Byth-ograea thermydron, but thiosulphate had no effect on hemocyanin cooperativity.
Received: 2 September 1997 / Accepted: 6 February 1998 相似文献
13.
Role of Rh promoter on increasing stability of Au/Al2O3 catalyst for CO oxidation at low temperature
Xiaohong Wang Guanzhong Lu Yun Guo Zhigang Zhang Yanglong Guo 《Environmental Chemistry Letters》2011,9(2):185-189
The Au/Al2O3 and Au–Rh/Al2O3 catalysts were prepared by deposition–precipitation. The promotional effect of Rh on the performance of the Au/Al2O3 catalyst for CO oxidation was studied. The results indicate that using Au/Al2O3 catalyst, CO can be completely oxidized at 0°C or much lower temperature but the catalyst deactivated very fast. Rh can improve
the stability of Au/Al2O3 catalyst more than 10 times, which gives an important hint to develop high stable catalyst for CO oxidation at low temperature. 相似文献
14.
Short-term effects of temperature and irradiance on oxygenic photosynthesis and O2 consumption in a hypersaline cyanobacterial mat were investigated with O2 microsensors in a laboratory. The effect of temperature on O2 fluxes across the mat–water interface was studied in the dark and at a saturating high surface irradiance (2162 μmol photons
m−2 s−1) in the temperature range from 15 to 45 °C. Areal rates of dark O2 consumption increased almost linearly with temperature. The apparent activation energy of 18 kJ mol−1 and the corresponding Q
10 value (25 to 35 °C) of 1.3 indicated a relative low temperature dependence of dark O2 consumption due to mass transfer limitations imposed by the diffusive boundary layer at all temperatures. Areal rates of
net photosynthesis increased with temperature up to 40 °C and exhibited a Q
10 value (20 to 30 °C) of 2.8. Both O2 dynamics and rates of gross photosynthesis at the mat surface increased with temperature up to 40 °C, with the most pronounced
increase of gross photosynthesis at the mat surface between 25 and 35 °C (Q
10 of 3.1). In another mat sample, measurements at increasing surface irradiances (0 to 2319 μmol photons m−2 s−1) were performed at 25, 33 (the in situ temperature) and 40 °C. At all temperatures, areal rates of gross photosynthesis saturated
with no significant reduction due to photoinhibition at high irradiances. The initial slope and the onset of saturation (E
k = 148 to 185 μmol photons m−2 s−1) estimated from P versus E
d curves showed no clear trend with temperature, while maximal photosynthesis increased with temperature. Gross photosynthesis
was stimulated by temperature at each irradiance except at the lowest irradiance of 54 μmol photons m−2 s−1, where oxygenic gross photosynthesis and also the thickness of the photic zone was significantly reduced at 40 °C. The compensation
irradiance increased with temperature, from 32 μmol photons m−2 s−1 at 25 °C to 77 μmol photons m−2 s−1 at 40 °C, due to increased rates of O2 consumption relative to gross photosynthesis. Areal rates of O2 consumption in the illuminated mat were higher than dark O2 consumption at corresponding temperatures, due to an increasing O2 consumption in the photic zone with increasing irradiance. Both light and temperature enhanced the internal O2 cycling within hypersaline cyanobacterial mats.
Received: 30 November 1999 / Accepted: 11 April 2000 相似文献
15.
The purpose of the research was to study the behavior of lignin degradation under different conditions (T 110–190°C, pO2 0.5–1.5 MPa, pH 5, 9 and 12) and to develop a predictive model. Temperature increase improved lignin removal from 75% at
110°C to 100% at 190°C (experimental). Increasing the pH enhanced the lignin removal efficiency from 30 to 97% (experimental).
The developed model predicted the lignin degradation and changes in COD, BOD and TOC. The model agreed well with the experimental
data (R
2 = 0.93 at pH 5 and 12). 相似文献
16.
In this paper we describe a cryopreservation protocol followed by the culture of Symbiodinium sp. isolated from the Caribbean gorgonian Pseudopterogorgia elisabethae as a potential renewable source of the dinoflagellate symbiont. Four different freezing protocols were designed: a controlled
cooling device designed to cool at 1°C/min, a three-step protocol (−20°C for 2 h, −70°C for 2 h, liquid nitrogen-LN2), a two-step protocol (−70°C for 2 h, LN2), and a one-step protocol (LN2). All cells were stored in LN2 after cryopreservation. The cryoprotective agents (CPA) used were ethanol (EtOH) and methanol (MeOH) at 10 and 20%, and seawater
(FSW) was used as a control. Viability measurements using cell counts showed that all cryopreservation protocols were relatively
successful, and no trends were observed regarding freezing protocol or CPA used. After 19 weeks in culture the viability of
samples which had high biomass was determined by the fluorescent assay CellTiter Blue™. The most viable cultures were those
cryopreserved by a two-step protocol using 20% MeOH or 20% EtOH as a CPA. A genetic examination of the DNA of these samples
using Symbiodinium-specific PCR primers confirmed that the composition of the culture had not changed. For the first time, we report that Symbiodinium sp. isolated from a gorgonian can be cryopreserved and subsequently cultured successfully.
Lory Z. Santiago-Vázquez and Nealie C. Newberger contributed equally to this publication. 相似文献
17.
I. Sötje F. Neues M. Epple W. Ludwig A. Rack M. Gordon R. Boese H. Tiemann 《Marine Biology》2011,158(5):1149-1161
The rhopalia and statocysts of Periphylla periphylla (Péron and Lesueur in Ann Mus Hist Nat Marseille 14:316–366,1809) and Chironex fleckeri Southcott (Aust J Mar Freshw Res 7(2):254–280 1956) were examined histologically and showed several homologous characteristics. Differences in sensory area distribution could
be connected to a slightly different functionality of equilibrium sensing. In P. periphylla, the statoliths (crystals) grow independently of each other; whereas in C. fleckeri, one large crystal covers the smaller ones. The structures of both statoliths were examined in detail with single-crystal
diffraction, microtomography and diffraction contrast tomography. The single compact statolith of C. fleckeri consisted of bassanite as was previously known only for other rhopaliophoran medusae. An origin area with several small oligocrystals
was located in the centre of the cubozoan statolith. The origin areas and the accretion of statoliths are similar in both
species. Our results lead to the assumption that the single bassanite statolith of C. fleckeri (Cnidaria, Cubozoa) is a progression of the scyphozoan multiplex statolith. It is therefore suggested that the Cubozoa are
derived from a scyphozoan ancestor and are a highly developed taxa within the Rhopaliophora. 相似文献
18.
Movement rate, oxygen consumption, and respiratory tree ammonium concentration were measured in situ in the holothurians Pearsonothuria graeffei and Holothuria edulis in the Agan-an Marine Reserve, Sibulan, Philippines (9°20′30″N, 123°18′31″E). Measurements were made both day and night for
both species during April–July 2005. P. graeffei had significantly higher movement rate during the day than at night (1.14 and 0.27 m h−1, respectively; three-way ANOVA, P < 0.05) while H. edulis had higher movement rate at night compared to the day (0.83 and 0.07 m h−1, respectively), spending the daylight hours sheltering under coral. More than 80% of H. edulis had movement rate of zero during the day. Oxygen consumption of P. graeffei was significantly higher during the day than at night (1.61 and 0.83 μmol O2 g−1 h−1, respectively; two-way ANCOVA, P < 0.05), but the reduction at night was not as pronounced as the reduction in movement. H. edulis had a 75% reduction in oxygen consumption during the day compared to night (0.51 and 1.96 μmol O2 g−1 h−1, respectively), matching this species’ reduced movement rates during the day. Ammonium concentration in water withdrawn from
the respiratory trees of P. graeffei during the day (12.0 μM) was three times higher than in respiratory tree water sampled at night (4.3 μM) and 15 times higher
than ambient seawater (0.8 μM; three-way ANOVA, P < 0.05). Ammonium concentration in the respiratory tree water of H. edulis was six times higher at night (14.6 μM) than during the day (2.2 μM) and 16 times higher than that of ambient seawater (0.9 μM).
Even though H. edulis and P. graeffei are found within the same coral reef environment, they may affect different substrates and reef organisms due to their different
habitats and distinct but opposite diel cycles. 相似文献
19.
The population of species Corophium urdaibaiense has been studied for a year in the Urdaibai estuary (NE Spain). The new species is characterised by its preference for muddy
sand sediments (15% of mud) and the long body size (with a maximum length of 10.24 mm). The maximum abundance occurs in November
(11,600 ind m−2); it almost disappears at the end of spring. The juveniles represent 79% of the population and the recruitment is concentrated
within the October–December period. The breeding period begins in May, when the temperature is above 15°C, and it ceases in
November, when the temperature is below 15°C. Bivoltinism is probable, taking into account the latitude (43°), temperature
range (12–25°C) and breeding period (May and August–October), but the data are not sufficiently consistent to confirm the
hypothesis. The production ranges from 2.93 to 5.85 g m−2 year−1, considering one and two generations per year, respectively. Some aspects concerning the food availability, predation and
intraspecific competition could have an influence on the dynamics of the population and are discussed. 相似文献
20.
In 1977, Phidiana hiltoni (O’Donoghue in J. Entomol Zool (Pomona College, Claremont, California) 19:77–119, 1927) began spreading northward from Monterey, California. By 1992, it had reached Duxbury Reef (37° 53′ 23″ N, 122° 41′ 59″ W),
100 km to the north, where other nudibranchs subsequently appeared to decline. The role of P. hiltoni in this decline was investigated through diet analysis, feeding trials, and comparison of historical and recent abundance
data. In the wild, P. hiltoni preyed largely on hydroids, but also showed evidence of predation on nudibranchs. In the laboratory, P. hiltoni attacked most of the dendronotid and aeolid nudibranchs presented to it, ingesting small individuals whole. The pooled abundance
of nudibranchs vulnerable to attack by P. hiltoni declined an average of two-thirds at Duxbury Reef since its arrival, compared to (1) no change in the non-vulnerable species
and (2) no change in either group at two other sites where P. hiltoni was one to two orders of magnitude less abundant. Phidiana
hiltoni therefore appears to have caused this decline, likely through a combination of direct predation and competition for prey.
A brief larval period, combined with cyclonic re-circulation in the lee of Point Reyes, may be driving self-recruitment of
P. hiltoni at Duxbury Reef, as well as hindering further northward spread. 相似文献