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531.
Alonso R Bermejo V Sanz J Valls B Elvira S Gimeno BS 《Environmental pollution (Barking, Essex : 1987)》2007,146(3):692-698
Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O3 sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g(s) values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O3 critical levels for semi-natural Mediterranean species. 相似文献
532.
Frati L Santoni S Nicolardi V Gaggi C Brunialti G Guttova A Gaudino S Pati A Pirintsos SA Loppi S 《Environmental pollution (Barking, Essex : 1987)》2007,146(2):311-316
Effects of high ammonia emissions and nitrogen deposition were investigated on lichens around a pig stockfarm (ca. 7,000 animals) in central Italy. Four sites were selected along a transect at 200, 400, 1000 and 2500 m from the stockfarm, the diversity of epiphytic lichens was measured and transplanted thalli of Xanthoria parietina and Flavoparmelia caperata exposed, together with passive NH3 (diffusion tubes) samplers. Ammonia dramatically decreased from the centre of the stockfarm to the sampled sites, where it was correlated with bark pH. Total lichen diversity was not associated with either NH3 concentrations or bark pH, but the diversity of strictly nitrophytic species was highly correlated with both parameters. Physconia grisea was the best indicator species for NH3 pollution. Total N accumulated in X. parietina and F. caperata was correlated with NH3 concentrations. 相似文献
533.
The effects of variable food supply on growth rate and feeding behaviour in two coexisting intertidal gastropods were examined
through field and laboratory experiments involving mark and recapture procedures, growth experiments under controlled food
supply and video observations of feeding. All cohorts of both Japeuthria species grew most in summer, with the highest growth rate being achieved by the youngest cohort of both sexes. In contrast,
almost all cohorts (except the youngest one) showed zero to negative growth in winter. The growth rates of Japeuthria species clearly varied depending on feeding frequencies and the initial size of individuals. Females of both species had
a significantly higher growth rate than males, though the difference became less marked with decreasing food supply. The total
time spent on feeding and the length of the first feeding bout generally increased as the duration of the interval between
meals was increased across treatments. From both the field growth experiment and the observations of feeding behaviour it
is clear that J. ferrea had a higher frequency of feeding than J. cingulata in the field; 1- to 3-d intervals of feeding frequency in the former and 3- to 6-d intervals in the latter. Most notably,
the two species showed a reversal in growth rates with changing conditions of food supply. When food was relatively abundant
J. ferrea achieved better growth than J. cingulata, but J. cingulata grew better than J. ferrea under low food supply. In view of the fact that J. ferrea seems to be competitively superior to J. cingulata under normal levels, the present observation that J. cingulata can perform better than J. ferrea when food availability is low gives an important advantage to the latter in terms of its coexistence with the former.
Received: 9 March 1999 / Accepted: 8 October 1999 相似文献
534.
Strontium (Sr) and calcium (Ca) contents in the otoliths of yellow and silver European eels [Anguilla anguilla (L.)] collected from coastal waters of the Baltic Sea and a freshwater lake in Sweden were examined by wavelength dispersive
X-ray spectrometry with an electron microprobe. The mean Sr/Ca ratios from elver check to otolith edge were significantly
higher for the eels from coastal waters (5.39 ± 1.09‰) than for those from the lake (0.71 ± 0.89‰). The evidence indicates
that European eels in the Baltic Sea do not necessarily migrate into freshwater streams during the growth phase.
Received: 30 September 1999 / Accepted: 6 April 2000 相似文献
535.
Effects of dissolved ammonium addition and host feeding with Artemia salina on photoacclimation of the hermatypic coral Stylophora pistillata 总被引:6,自引:0,他引:6
E. Titlyanov K. Bil' I. Fomina T. Titlyanova V. Leletkin N. Eden A. Malkin Z. Dubinsky 《Marine Biology》2000,137(3):463-472
Effects of nutrient treatments on photoacclimation of the hermatypic coral Stylophora pistillata (Esper) were studied. Studies on photoacclimation of colonies from different light regimes in the field were evaluated and
used to design laboratory experiments. Coral colonies were collected in the Gulf of Eilat (Israel) from January to March 1993.
Exterior branches of colonies from different depths (1 to 40 m) displayed different trends in production characteristics at
reduced and very low levels of illumination. From 24 ± 3% to 12 ± 2% of incident surface photosynthetic active radiation (PARo), zooxanthella population density and chlorophyll a+c per 106 zooxanthellae increased, a trend seen in the range of light levels optimal for coral growth (90 to 30% PARo). The P
max of CO2 per 106 zooxanthellae decreased, while P
max of CO2 per 103 polyps increased, indicating an increase in zooxanthella population density at low light levels. Proliferous zooxanthella
frequency (PZF, a measure of zooxanthella division) declined significantly at light levels <18 ± 3% PARo. At the lowest levels of illumination (<5% PARo), zooxanthella population density decreased, as did the PZF; chl a+c per 106 zooxanthellae was unchanged. In 28-d experiments, exterior coral branches from the upper surfaces of colonies from 3 m depth
(65 ± 4% PARo) were incubated in aquaria under bright (80 to 90% PARo), reduced (20 to 30% PARo), and extremely low (2 to 4% PARo) light intensities. At each light intensity, the corals were maintained in three feeding treatments: sea water (SW); ammonium
enriched SW (SW + N); SW with Artemia salina nauplii (SW + A). An increase in P
max of CO2 per 103 polyps was found in corals acclimated to reduced light (20 to 30% PARo) in nutrient-enriched SW, while in SW, where the increase in zooxanthella population density was smaller, it did not occur.
Nutrient enrichments (SW + N at 2 to 4% PARo and SW + A at 20 to 30% PARo) increased zooxanthella population density, but had no effect on chl a+c per 106 zooxanthellae. Acclimation for 14 d to reduced (10 to 20% PARo) and extremely low (1 to 3% PARo) light intensities shifted 14C photoassimilation into glycerol and other compounds (probably glycerides), rather than sugars. Both ammonium addition and
feeding with Artemia salina nauplii resulted in an increase in photosynthetic assimilation of 14C into amino acids. We conclude that acclimation to reduced light consists of two processes: an increase in photosynthetic
pigments and in zooxanthella population density. Both processes require nitrogen, the increase in zooxanthella population
density needing more; this adaptation is therefore limited in nitrogen-poor sea water.
Received: 19 June 1998 / Accepted: 13 June 2000 相似文献
536.
Relatively few insects have invaded the marine environment, and only five species of sea skaters, Halobates Eschscholtz (Hemiptera: Gerridae), have successfully colonized the surface of the open ocean. All five species occur in the
Pacific Ocean, H. germanus White also occurs in the Indian Ocean, whereas H. micans Esch- scholtz is the only species found in the Atlantic Ocean. We sequenced a 780 bp long region of the mitochondrial cytochrome
oxidase subunit I gene (COI) for a total of 66 specimens of the five oceanic Halobates species. Our purpose was to investigate the genetic variation within species and estimate the amount of gene flow between
populations. We defined 27 haplotypes for H. micans and found that haplotype lineages from each of the major oceans occupied by this species are significantly different, having
sequences containing five to seven unique base substitutions. We conclude that gene flow between populations of H. micans inhabiting the Atlantic, Pacific, and Indian Ocean is limited and hypothesize that these populations have been separated
for 1 to 3 million years. Similarly, there may be limited gene flow between H. germanus populations found in the Pacific and Indian Ocean and between H. sericeus populations inhabiting the northern and southern parts of the Pacific Ocean. Finally, we discuss our findings in relation
to recent hypotheses about the influence of oceanic diffusion on the distribution and population structure of oceanic Halobates spp.
Received: 29 July 1999 / Accepted: 23 November 1999 相似文献
537.
Modulation of the free amino acid pool and protein content in populations of the brine shrimp Artemia spp. 总被引:3,自引:0,他引:3
S. Helland G. V. Triantaphyllidis H. J. Fyhn M. S. Evjen P. Lavens P. Sorgeloos 《Marine Biology》2000,137(5-6):1005-1016
Free amino acid (FAA) and protein content were measured in various developmental stages of Artemia franciscana, from cysts to Instar III metanauplii. In addition, decapsulated cysts of 15 Artemia populations from different localities were compared with respect to their FAA and protein content. Furthermore, the content
and composition of the FAA pool were modulated by hatching the cysts at various salinities, and by enriching the nauplii with
algae or a lipid-enrichment emulsion. The FAA content increased threefold from cysts to nauplii, and Instar III metanauplii
contained nearly 50% taurine of total FAA. Cysts of A. franciscana were found to contain one-third the amount of FAA compared to the other Artemia species investigated. The content and pool composition of FAA was successfully modulated in 11 of 13 populations, where by
the content of FAA was significantly increased when hatched at high salinity. Finally, enrichment elevated the content of
FAA and changed the pool composition, thereby showing a dietary effect. Algal enrichment also increased the protein content.
Received: 27 September 1999 / Accepted: 17 July 2000 相似文献
538.
The accumulation of lipofuscin, which is an indictor of physiological age, in the brain of juvenile European lobster (Homarus gammarus L.) was monitored for 22 mo in three experimental temperature regimes that simulated seasonal variation in temperature in
the geographic range of this species. Metabolic rate responses to changes in temperature were estimated by measuring the activity
of the electron transport system (ETS) in muscle tissue and in vivo rates of oxygen consumption. Lipofuscin accumulation oscillated
with simulated seasonal changes in temperature and was described by seasonalised von Bertalanffy growth functions. The incremental
accumulation in lipofuscin between sampling dates was linearly related to the number of degree days that accumulated between
dates, irrespective of the amplitude of temperature fluctuation that had occurred. ETS activity increased with acclimation
temperature and was modelled using a polynomial function. This indicated a lower temperature sensitivity in the temperature
mid-range (12 to 16 °C), although the Q10 for this mid-range was 2.1. ETS activity in lobsters acclimated to 8 and 18 °C and assayed at 13 °C was similar, indicating
no compensation for changes in environmental temperature. Oxygen consumption rate was significantly higher at 14 °C than at
10.5 °C and had a Q10 of 3.6, again suggesting no compensation to temperature change. The absence of metabolic compensation in response to temperature
change in H. gammarus is consistent with the predictability of changes in temperature and food availability in the sub-littoral environment of
this species. As lipofuscin accumulates according to metabolic rate, and metabolic rate in H. gammarus is directly correlated with temperature, geographic differences and long-term temporal trends in temperature will need to
be considered when converting physiological age indices, obtained from lipofuscin estimates, to a chronological scale.
Received: 27 April 2000 / Accepted: 21 July 2000 相似文献
539.
The endemic New Zealand echinoid, Evechinus chloroticus (Valenciennes), was sampled approximately monthly from September 1990 to October 1994 at three sites in Tory Channel, Marlborough
Sounds, New Zealand. These channel sites (outer, mid and inner) were up to 20 km from the open ocean and differed in their
shore type, exposure to wave action and macrophyte abundance. E. chloroticus showed an annual reproductive cycle at each site, with gametogenesis commencing in the late austral winter and spawning in
summer. Maximum gonad indices (reproductive potential) varied spatially, with the outer site generally having higher maximum
gonad indices than the inner site, and temporally, with maximum gonad indices occurring earlier in 3 of the 4 seasons at the
outer site than the inner site. The mid and inner sites showed much greater variation in maximum gonad indices (range 15.83
to 26.99% and 11.87 to 20.90%, respectively) than the outer site (range 19.31 to 22.95%). Reproductive output (weight of gametes
released per gram echinoid) also varied, with the different sites showing significantly different outputs in the different
years. A regression of maximum reproductive potential against reproductive output was significant ( p < 0.001), and had a positive slope with an r
2 of 0.79. While, the initiation of gametogenesis was relatively synchronous between sites and years, and is possibly cued
by increasing daylength, it progressed at different rates among populations. Spawning did show spatial and temporal variability,
occurring near the time of highest sea-surface temperatures (∼15 °C). The observed variations in reproductive cycle may be
related to small-scale variability in diet and environmental conditions. Furthermore, asynchronous spawning, variable spawning
duration, and variable reproductive output are likely to strongly influence annual recruitment variability in E. chloroticus, with different larval subpopulations contributing unequally in different years. The ecological consequences of this, both
for the ability of E. chloroticus to propagate itself in space and time and for the management of the developing E. chloroticus fishery in New Zealand, are discussed.
Received: 9 December 1998 / Accepted: 13 June 2000 相似文献
540.
Cadmium accumulation in the female shore crab Carcinus maenas during the moult cycle and ovarian maturation 总被引:2,自引:0,他引:2
The influence of moulting and ovarian maturation on cadmium accumulation in the tissues of female shore crabs Carcinus maenas exposed to 1 mg Cd l−1 in the water was investigated. Cadmium accumulation in all tissues examined was markedly increased in crabs in the postmoult
stages (A and B) compared to crabs in all other moult stages. During the moult cycle, average cadmium accumulation in the
midgut gland ranged from 29 μg Cd g−1 dw at premoult stage (D2) to 589 μg Cd g−1 dw at postmoult stage (A). Average cadmium concentrations in the haemolymph ranged from 0.56 μg Cd ml−1 at intermoult stage (C4) to 4.6 μg Cd ml−1 at postmoult stage (A), while the gills accumulated from 103 μg Cd g−1 dw in intermoult stage (C3) to 352 μg Cd g−1 dw in postmoult stage (A). Cadmium concentration in gills and haemolymph was also significantly higher in crabs in late premoult
stage (D3) compared to C4-crabs, while midgut gland cadmium concentration remained elevated in C1- and C3- intermoult stages relative to C4. During ovarian maturation the cadmium accumulation in midgut gland, gills, ovaries and haemolymph decreased. Average cadmium
concentration in the midgut gland decreased from 63 μg g−1 dw in ovarian Stage I to 19 μg g−1 dw in ovarian Stage VI. The same pattern was observed for gills, haemolymph and ovaries. The present study demonstrates that
cadmium accumulation in the female shore crab strongly depends on the physiological status of the animal. A possible association
between physiological calcium requirements and cadmium accumulation during moulting is discussed.
Received: 20 January 2000 / Accepted: 20 July 2000 相似文献