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1.
Bela Hieronymus Buck 《Helgoland Marine Research》2007,61(2):87-101
This study summarizes the activities and findings during a 2 year investigation on the grow-out of blue mussels (Mytilus edulis) and the technical requirements to withstand harsh weather conditions at an offshore location. The experimental sites were
two different test areas, each 5 ha in size, 12–15 m in depth, in the vicinity of the offshore lighthouse “Roter Sand” located
15–17 nautical miles northwest of the city of Bremerhaven (Germany). Two versions of submerged longline systems were deployed:
a conventional polypropylene longline in 2002 as well as a steel hawser longline in 2003, both featuring different versions
of buoyancy modes. The spat collectors and grow-out ropes were suspended perpendicular from the horizontal longline for several
months beginning in March of each respective year. The test sites were visited and sampled on a monthly basis using research
vessels. Larval abundances in the surrounding water column reached numbers of up to 1,467 individuals m−3. Post-larval settlement success varied through the entire experimental period, ranging from 29 to 796 individuals of spat
per meter of collector. Settled mussels reached a shell length of up to 28 mm 6 months after settlement. Based on the growth
rates observed for the seed, it is projected that mussels would reach market size (50 mm) in 12–15 months post settlement,
and at the observed densities, each meter of collector rope could yield 10.9 kg of harvestable mussels. The polypropylene
line resisted storm conditions with wind waves of up to 6.4 m and current velocities of 1.52 m s−1 and was retrieved in autumn of 2002. In contrast, the steel hawser-based line did not withstand the harsh weather conditions.
The steel-based line consisted of six twisted strands that were untwisted by the strong currents and turbulences and consequently
the individual strands were torn. Additionally, the line was accidentally cut by a yacht in July 2003. The biological study
revealed that the tested location near “Roter Sand” has the potential to become an offshore seed production site as well as
being exploitable as a grow-out site for mussel production to market size. In light of the technical results, recommendations
for mussel culture strategies using a polypropylene longline system are given. 相似文献
2.
Dynamics of Mya arenaria beds in two bights of the Chupa Inlet (Kandalaksha Bay, White Sea) were studied on a long-term basis. Observations were carried
out at 1– to 3-year intervals from 1979 up to 1999. The studied soft-shell clam beds were characterised by a substantial instability
of age structure. Since 1988, only one year-class has dominated in the beds while other generations have been scarce and recruitment
was not observed. This pattern of Mya bed dynamics was related neither to interannual environmental changes nor to differential reproduction success or predation
effects in the benthic assemblages. Favourable conditions for spat formation in 1988 (low abundance of other M. arenaria generations), as well as for juvenile survival during the following winter, resulted in high abundance of juveniles in both
investigated locations in 1989. The mortality rate (μ) in this 1988 generation varied throughout the period of investigation and was related to age. The mortality level decreased
for the first 2–4 years of the life cycle, then stabilised for the next 3–4 years, and eventually increased in subsequent
years. Overall μ values ranged from 0 to 1.68 year–1. The oldest specimens observed were 17 years old and had a maximum shell length of 79 mm. Significant differences in average
growth rates were observed between molluscs of different locations.
Communicated by H.-D. Franke 相似文献
3.
Atherinomorus aetholepis sp. nov. is described from the holotype and 51 paratypes, 44–72 mm in standard length, collected from Indonesian and Philippine
waters. The species is similar to other congeners in general body appearance, especially A. duodecimalis and A. regina, in having a slender body, a tubercle on the posterior end of the dentary, and a narrow midlateral band, but clearly differing
from them in having a long spatular outgrowth on the posterior margins of most of the predorsal and interdorsal scales. Additionally,
the species differs from A. duodecimalis in having a more slender body [body depth 17–22 (mean 19) % SL vs. 19–25 (mean 22) % SL], more midlateral scales [37–40 (mean
38.4) vs. 35–38 (mean 36.6)], more total vertebrae [38–42 (mean 39.9) vs. 36–40 (mean 38.0)], and fewer lower gill rakers
[18–22 (mean 20.2) vs. 20–25 (mean 22.3)], and from A. regina in having more anal fin soft rays (12–14 vs. 9–10).
Electronic supplementary material to this article is available at and accessible to authorized users.
Received: October 22, 2001 / Revised: March 14, 2002 / Accepted: March 26, 2002
An erratum to this article is available at . 相似文献
4.
Victor D. Hosfeld Steffan Puwal Keith Jankowski Bradley J. Roth 《Journal of biological physics》2007,33(2):145-153
Traditionally, cardiac defibrillation requires a strong electric shock. Many unwanted side effects of this shock could be
eliminated if defibrillation were performed using weak stimuli applied to several locations throughout the heart. Such multi-site
pacing algorithms have been shown to defibrillate both experimentally (Pak et al., Am J Physiol 285:H2704–H2711, 2003) and
theoretically (Puwal and Roth, J Biol Systems 14:101–112, 2006). Gauthier et al. (Chaos, 12:952–961, 2002) proposed a method
to pace the heart using an algorithm based on nonlinear dynamics feedback applied through a single electrode. Our study applies
a related but simpler algorithm, which essentially configures each electrode as a demand pacemaker, to simulate the multi-site
pacing of fibrillating cardiac tissue. We use the numerical model developed by Fenton et al. (Chaos, 12:852–892, 2002) as
the reaction term in a reaction–diffusion equation that we solve over a two-dimensional sheet of tissue. The defibrillation
rate after pacing for 3 s is about 30%, which is significantly higher than the spontaneous defibrillation rate and is higher
than observed in previous experimental and theoretical studies. Tuning the algorithm period can increase this rate to 45%.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Miguel Jiménez-Valdés Héctor Godínez-Alvarez Javier Caballero Rafael Lira 《Economic botany》2010,64(2):149-160
Population Dynamics of
Agave marmorata
Roezl. under Two Contrasting Management Systems in Central Mexico. This paper evaluates the impacts of traditional management on the population dynamics of Agave marmorata, a multipurpose, useful species that is dominant in the Zapotitlán Salinas Valley, Puebla, Mexico. During 2002–2003 and 2003–2004,
we constructed matrix models for two populations—one unmanaged, the other subject to plant extraction and cutting of flowering
stalks. We also conducted prospective (elasticity) and retrospective (life table response experiments) analyses. Overall,
the unmanaged population had higher finite rates of increase (λ) than the managed one. This variation in λ was the result
of a decrease in the individual growth and fecundity in the managed population. Survival and growth were the demographic processes
with the highest contribution to λ in the unmanaged population, while survival was the most important in the managed one.
Our results suggest that management and plant extraction practices could be having negative effects on the population dynamics
of this plant species. Recommendations are provided in order to promote positive effects on its vital rates and regeneration
capacity. 相似文献
6.
Despite the dwindling populations and an urgent need for conservation of unionid freshwater mussels in Japan, there are gaps
in our understating of their fundamental ecology. This study examined size-dependent annual growth rates, elucidated size-specific
intra-annual growth patterns, and estimated age and longevity of P. japanensis individuals for two locally isolated populations in agricultural drainage channels. Annual growth rates of P. japanensis were strongly size-dependent, with growth rates being exponentially decelerated with increasing shell length. Irrespective
of sizes, individuals ceased to grow in winter when water temperature fell below 10°C. Intra-annual growth patterns were weakly
explained by the changes in water temperature and differed among size classes; juveniles (<25 mm) maximized growth rate in
May whereas the growth rates were the highest in June or July for larger individuals. Only adult individuals exhibited growth
cessation in the July–August period, suggesting that energy investment was directed towards reproductive activities. Adults
also showed negative growth rates (shrinkage of individuals) in winter, suggesting possible dissolution of shell margins.
Age estimation based on two 1-year periods suggests that large numbers of P. japanensis individuals were >10 years old, and the oldest individuals were >20 years old for both study populations. Our findings suggest
that anthropogenic activities conducted in spring may have strong influences on juveniles and population dynamics of P. japanensis and underscore the need for accurately determining age and longevity of remaining populations of unionid mussels. 相似文献
7.
Satoshi Suzuki Kazushige Furuya Tadashi Kawai Ichiro Takeuchi 《Journal of applied phycology》2008,20(5):833-844
Recent studies on global climate change report that increase in seawater temperature leads to coastal ecosystem change, including
coral bleaching in the tropic. In order to assess the effect of increased seawater temperature on a temperate coastal ecosystem,
we studied the inter-annual variation in productivity of Laminaria japonica using long-term oceanographic observations for the Uwa Sea, southern Japan. The annual productivity estimates for L. japonica were 2.7 ± 2.5 (mean ± SD) kg wet wt. m−1 (length of rope) (2003/2004), 1.0 ± 0.6 kg wet wt. m−1 (2004/2005) and 12.1 ± 12.5 kg wet wt. m−1 (2005/2006). Our previous study using the same methodology at the same locality reported that the productivity was estimated
for the 2001/2002 (33.3 ± 15.2 kg wet wt. m−1) and 2002/2003 (34.0 ± 8.7 kg wet wt. m−1) seasons. Productivity in 2003/2004 and 2004/2005 was significantly lower than in years 2001/2002, 2002/2003 and 2005/2006.
A comparison of oceanographic conditions among the 5 years revealed the presence of threshold seawater temperature effects.
When the average seawater temperature during the first 45 days of each experiment exceeded 15.5°C, productivity was reduced
to about 10 % of that in cooler years. Moreover the analysis of growth and erosion rates indicates that when the seawater
temperature was over 17.5°C, erosion rate exceeded growth rate. Thus, an increase of seawater temperature of just 1°C during
winter drastically reduces the productivity of L. japonica in the Uwa Sea. 相似文献
8.
Jens Abildgaard Poul Erik Hansen Marlon N. Manalo Andy LiWang 《Journal of biomolecular NMR》2009,44(3):119-126
Quantum mechanical calculations are presented that predict that one-bond deuterium isotope effects on the 15N chemical shift of backbone amides of proteins, 1Δ15N(D), are sensitive to backbone conformation and hydrogen bonding. A quantitative empirical model for 1Δ15N(D) including the backbone dihedral angles, Φ and Ψ, and the hydrogen bonding geometry is presented for glycine and amino
acid residues with aliphatic side chains. The effect of hydrogen bonding is rationalized in part as an electric-field effect
on the first derivative of the nuclear shielding with respect to N–H bond length. Another contributing factor is the effect
of increased anharmonicity of the N–H stretching vibrational state upon hydrogen bonding, which results in an altered N–H/N–D
equilibrium bond length ratio. The N–H stretching anharmonicity contribution falls off with the cosine of the N–H···O bond
angle. For residues with uncharged side chains a very good prediction of isotope effects can be made. Thus, for proteins with
known secondary structures, 1Δ15N(D) can provide insights into hydrogen bonding geometries.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
A new acropomatid fish, Acropoma
argentistigma, is described on the basis of six specimens (59.0–107.5 mm in standard length) from the Andaman Sea, off southern Thailand
(Phuket Island). The new species is distinguished from all other congeners by the combination of the following characters:
a short U-shaped luminous gland, 16–18 gill rakers, anus situated about midway along depressed pelvic fin, proximal radial
of first anal fin pterygiophore with a trough, a single row of well-developed conical teeth on the lower jaw, and head length
40.0–41.1% of standard length.
Received: April 17, 2001 / Revised: April 15, 2002 / Accepted: May 7, 2002 相似文献
10.
N. I. Selin 《Russian Journal of Marine Biology》2000,26(3):204-208
Linear growth rates and age-related changes in shell form are analyzed in the bivalveScapharca broughtoni from several areas of Peter the Great Bay, Sea of Japan. Mollusks grow fast during the first 4 to 5 years of life; at the
age of 10–12 years, the annual growth increment in shell size does not usually exceed 1–3 mm. Irrespective of habitat, the
shell valve convexity ofS. broughtoni increases with age, but the most significant changes in shell form occur during the first year of life. The peculiarities
of growth and age-related changes in shell form ofS. broughtoni are discussed from the standpoint of the functional morphology of burrowing bivalve mollusks, which, at the postlarval stage,
change from an attached to a free-living mode of life. 相似文献
11.
Pedro Francisco Quintana-Ascencio Idoia Caballero José Miguel Olano Adrián Escudero Maria José Albert 《Population Ecology》2009,51(2):317-328
Habitat heterogeneity may influence plant demography because conditions for survival, growth, and reproduction vary within
a species’ range. We assessed the role of microhabitat spatial structure on the demography of Helianthemum squamatum, a shrubby gypsum specialist endemic to the Iberian Peninsula. We evaluated the demographic effect of microhabitat spatial
variation using an approach that combined cellular automata with matrix population models, and included environmental and
demographic stochasticty. We collected data on seed bank (2003–2005), seedling emergence (2003–2006), and adult survivorship
(2004–2007) for H. squamatum in two independent blocks with different grazing intensity in Belinchón (Cuenca, Spain). We built spatial scenarios for each
block based on field data of cover and spatial pattern of four microhabitats: lichenic crust, litter, H. squamatum, and shrub. Seedling survivorship was affected by year, block, and microhabitat, with individuals emerging under conspecifics
having the highest survival rate and on litter the lowest in both blocks, whereas the effect of crust and other shrubs differed
across blocks. Our models indicated population increase in the block with low grazing, but population decline in the block
with intense grazing. We hypothesize that higher pressure of livestock grazing and trampling leads to a shift in relative
microhabitat suitability for crust and shrub. This potential effect of grazing on spatial demographic variation opens interesting
questions for future research. We emphasize the importance of considering microhabitat spatial structure when evaluating management
and conservation strategies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Maren Huck Marcelo Rotundo Eduardo Fernandez-Duque 《International journal of primatology》2011,32(5):1133-1152
Life history predicts that in sexually dimorphic species in which males are the larger sex, males should reach sexual maturity
later than females (or vice versa if females are the larger sex). The corresponding prediction that in sexually monomorphic
species maturational rates will differ little between the sexes has rarely been tested. We report here sex differences in
growth and development to adulthood for 70 female and 69 male wild owl monkeys (Aotus azarai). In addition, using evidence from natal dispersal and first reproduction (mean: 74 mo) for 7 individuals of known age, we
assigned ages to categories: infant, 0–6 mo; juvenile, 6.1–24 mo; subadult, 24.1–48 mo; adult >48 mo. We compared von Bertalanffy
growth curves and growth rates derived from linear piecewise regressions for juvenile and subadult females and males. Growth
rates did not differ between the sexes, although juvenile females were slightly longer than males. Females reached maximum
maxillary canine height at ca. 2 yr, about a year earlier than males, and females’ maxillary canines were shorter than males’. Thus apart from canine eruption
and possibly crown–rump length, the development of Azara’s owl monkeys conforms to the prediction by life history that in
monomorphic species the sexes should develop at similar paces. 相似文献
13.
A total of 45 juvenile [30.0–57.4 mm total length (TL)] slime flounder Microstomus achne were collected in the coastal area of southern Hokkaido from April to July in 2001 and April to June in 2002. Their diets
were analyzed. Slime flounder juveniles of 30.0–39.9 mm TL fed predominantly on small crustaceans (gammarid amphipods, harpacticoids
and cumaceans) and those of 40.0–57.4 mm TL on gammarid amphipods, cumaceans and polychaetes. The major prey items changed
with growth from small crustaceans (e.g., harpacticoids) to polychaetes, although gammarid amphipods were the major prey items
throughout the juvenile period (30.0–57.4 mm TL). 相似文献
14.
Statolith shape and microstructure were studied in 151 specimens of the common arctic squid Gonatus fabricii (7.3–322 mm pen length) collected in the southern Norwegian Sea. Statolith development and growth both comprised two main
periods, which corresponded with the epipelagic and meso-bathypelagic ontogenetic periods of G. fabricii. During the epipelagic period (pen length range from 3 to 50–60 mm), statoliths quickly developed from the droplet-like form
in early paralarvae to the pre-definite stage in juveniles (30–50 mm pen length). Paralarval and juvenile statoliths grew
with high growth rates, and their microstructure contained narrow first-order growth increments. Three main growth zones (Z1,
Z2, Z3) developed during this period, being well distinguished from each other by specific patterns of microstructure and
separated from each other by distinct checks. During the meso-bathypelagic period (from 50–60 to 322 mm pen length), statoliths
hardly changed their shape and grew very slowly. Only one growth zone (Z4) was formed within the statolith microstructure,
characterized by disappearance of the first growth increments and formation of specific second-order bands. Each second-order
band consisted of approximately seven first-order increments. If the assumption “one increment-one day” is true for G. fabricii, the squid would then be a slow-growing animal with a life span for both sexes not exceeding 2 years.
Accepted: 25 May 1999 相似文献
15.
The predation potential of the indigenous leech Glossiphonia weberi on the snail Pomacea bridgesii, introduced in India, was evaluated in the laboratory. Snails used belonged to the size-classes ≤‰3.0, 3.1–5.0, 5.1–7.0 and
7.1–9.0 mm in shell height, using them both separately and together (mixed) in combinations. In each experiment lasting 24 h
a single leech belonging to the size-classes 2.0–3.9, 4.0–5.9, 6.0–7.9, 8.0–9.9 and 10.0–11.9 mm in length was used. Except
the 4.0–5.9 mm size-class, leeches were able to capture and kill P. bridgesii irrespective of latter’s size; the predation, however, was confined to snails ≤3.0 mm. The rate of predation varied with
the size of the predator and the prey, and a leech was able to kill a maximum of three snails per day. In India, in nature
G. weberi feeds mostly on the pulmonate snail, Lymnaea (Radix) luteola. Experimental studies, however, revealed that G. weberi prefers the snails P. bridgesii and L. (R) luteola at the same rate from amongst the many other either less or not-preferred native operculate and non-operculate snails. 相似文献
16.
Zulima González-Parrado Carmen Reyes Fuertes-Rodríguez Ana M. Vega-Maray Rosa M. Valencia-Barrera F. Javier Rodríguez-Rajo Delia Fernández-González 《Aerobiologia》2006,22(1):47-53
Winter-flowering trees such as the alder (Alnus glutinosa (L.) Gaertner) can survive periods of adverse climatic conditions, entering a period of dormancy in the early fall. The end
of dormancy and the start of the pollen season require a period of low temperatures followed by another of warm temperatures.
These requirements were studied from 1995 to 2002, in order to develop a model to predict the onset of the alder pollen season
in Ponferrada (Spain). Chilling accumulation took place from late October to late December or early January. The best result
was obtained with a threshold temperature of 6.5 °C and an average of 848 chilling hours (CH). Heat requirements were calculated
at maximum temperature, an average 143 growth degree days (GDD) were needed, with a threshold temperature of 0 °C. In order
to validate models, predicted values were compared with real values for 2002–2003, 2003–2004 and 2004–2005, years not used
in developing the models. Predictions for the pollen-season start-date differed only slightly from observed dates: in 2002–2003
predicted and observed dates were the same, in 2003–2004 there was a difference of 7 days and in 2004–2005 a difference of
3 days. 相似文献
17.
A marine fungus was isolated from the black tiger prawn Penaeus monodon at Nha Trang, Vietnam, on March 20, 2001 and named isolate NJM 0131. The fungus was identified as Haliphthoros milfordensis from the characteristics of asexual reproduction, and its physiological characteristics were investigated. Although the optimum
temperature for growth of the isolate was 25°–30°C, the fungus grew at a wide range of temperatures (15°–40°C). H. milfordensis grew well in 50%–100% seawater, but poorly in PYG agar containing 1.0%–5.0% NaCl and KCl. The fungus grew at a wide range
of pH (4.0–11.0) with the optimum pH value of 7.0–9.0. The isolate also showed pathogenicity to swimming crab larvae (Portunus trituberculatus) by artificial infection, but mortality was not high. This is the first report of disease in the black tiger prawn P. monodon in Vietnam caused by H. milfordensis.
Received: July 22, 2002 / Accepted: January 21, 2003
Correspondence to:K. Hatai 相似文献
18.
The dynamics of aseasonal lowland dipterocarp forest in Borneo is influenced by perturbation from droughts. These events might
be increasing in frequency and intensity in the future. This paper describes drought-affected dynamics between 1986 and 2001
in Sabah, Malaysia, and considers how it is possible, reliably and accurately, to measure both coarse- and fine-scale responses
of the forest. Some fundamental concerns about methodology and data analysis emerge. In two plots forming 8 ha, mortality,
recruitment, and stem growth rates of trees ≥10 cm gbh (girth at breast height) were measured in a ‘pre-drought’ period (1986–1996), and in a period (1996–2001) including the 1997–1998
ENSO-drought. For 2.56 ha of subplots, mortality and growth rates of small trees (10–<50 cm gbh) were found also for two sub-periods (1996–1999, 1999–2001). A total of c. 19 K trees were recorded. Mortality rate increased by 25% while both recruitment and relative growth rates increased by
12% for all trees at the coarse scale. For small trees, at the fine scale, mortality increased by 6% and 9% from pre-drought
to drought and on to ‘post-drought’ sub-periods. Relative growth rates correspondingly decreased by 38% and increased by 98%.
Tree size and topography interacted in a complex manner with between-plot differences. The forest appears to have been sustained
by off-setting elevated tree mortality by highly resilient stem growth. This last is seen as the key integrating tree variable
which links the external driver (drought causing water stress) and population dynamics recorded as mortality and recruitment.
Suitably sound measurements of stem girth, leading to valid growth rates, are needed to understand and model tree dynamic
responses to perturbations. The proportion of sound data, however, is in part determined by the drought itself.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Mario Arias Zabala Mónica Angarita Juan M. Restrepo Luis A. Caicedo Margarita Perea 《In vitro cellular & developmental biology. Plant》2010,46(3):233-238
Thevetia peruviana is a small tree that produces several compounds with pharmaceutical application, among which peruvoside could be highlighted.
However, these compounds are produced in low concentration in the plant, making it important to develop strategies such as
plant cell culture and elicitation to obtain higher quantities of the desired product. In this work, cell suspension cultures
of T. peruviana were established in four different culture media: Murashige–Skoog (MS), half Murashige–Skoog (half MS), Schenk–Hildebrandt
(SH), and Gamborg (B5) to study their effect on cell growth. Cell growth kinetics were studied in SH medium, and the extracellular
peruvoside production during the culture time was determined. The best culture medium for the establishment of cell suspension
cultures was MS with a growth index of 3.17 ± 0.2 g g−1 inoculum. The cell growth kinetics showed the four characteristic growth phases of a cell culture (lag, exponential, stationary,
and death), and during none of these phases was it possible to observe peruvoside production. The elicitor effect of methyl-jasmonate
(MeJ) was studied in cell suspension cultures established in SH medium. The effect of MeJ concentration and the time in which
it should be applied were determined. The best results were obtained at a concentration of 100 mg l−1 of MeJ applied at the beginning of the culture, which induced a peruvoside production of 8.93 mg l−1 medium. The current results are the first report of an in vitro peruvoside production system. 相似文献
20.
The movement of butterflies within habitat patches is usually assumed to be random, although few studies have shown this unambiguously.
In the case of the highly specialized genus Maculinea, two contradictory hypotheses exist to explain the movement and distribution of imagos within patches: (1) due to the high
spatial variance of survival rates among caterpillars, the “risk-spreading” hypothesis predicts that females will tend to
make linear flight paths in order to maximize their net displacement and scatter the eggs as widely as possible; and (2) recent
mark–release–recapture (MRR) data suggest that within-habitat displacement of some Maculinea species is constrained and that adults may establish home ranges. We tested both hypothesis by analysing the movement pattern
of individuals. We also investigated whether egg laying is time constrained, which would enhance the trade-off between flying
and egg laying. Thirty females of Maculinea rebeli (Lepidoptera: Lycaenidae) were tracked within a single population in Central Hungary. Their egg-laying behaviour and individual
patterns of movement were recorded, and the latter were compared with random walk model predictions. The population was also
sampled by MRR to estimate survival rates, and four non-mated, freshly eclosed females were dissected to assess their potential
egg load. Net squared displacement of females was significantly lower than predicted by the random walk model and declined
continuously after the 15th move. The ratio of net displacement and cumulative move length decreased with the number of moves,
supporting the hypothesis that Maculinea butterflies establish home ranges. We found that low survival and a low rate of egg laying prevented females from laying
their potential number of eggs within their lifespan. Time limitation increased the cost of movement, providing another possible
explanation for the restricted movement of females.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献