Characteristics of tide-water calving at Glaciar San Rafael, Chile

1995 ◽  
Vol 41 (138) ◽  
pp. 273-289 ◽  
Author(s):  
Charles R. Warren ◽  
Neil F. Glasser ◽  
Stephan Harrison ◽  
Vanessa Winchester ◽  
Andrew R. Kerr ◽  
...  
Keyword(s):  
Water Depth ◽  
Environmental Variables ◽  
Empirical Relationship ◽  
Glacier Surface ◽  
Frequency Distributions ◽  
Low Salinity ◽  
The Mean ◽  
Oceanographic Data ◽  
San Rafael ◽  
Tidal Stage

AbstractGlacial calving is a poorly understood process. This study tests the influence of local environmental variables on the magnitude and frequency distributions of calving behaviour at Glaciar San Rafael, Chile. Near the terminus of the glacier, surface speeds average 17 m d −1 in summer and calving is profuse and continual. The size, location and characteristics of over 7000 calving events were recorded during 32d in 1991 and 1992, together with meteorological, bathymetric and oceanographic data. Mean daily calving exceeds 400 events per day and the mean calving flux is more than 2 Mm3d1. Mean annual calving speed and calving flux are about 4500 m a −1 and 2.0 km3 a−1, respectively. This calving speed is higher than that predicted by the established empirical relationship between tide-water calving speed and water depth. This is surprising, given the low salinity of Laguna San Rafael and that fresh-water calving speeds are commonly much lower than those in ride water. Daily patterns of calving frequency and flux correlate poorly or not at all with meteorological variables, but tidal stage may have some control over the timing of large submarine calving events. Submarine calving produced the largest bergs. However, the relatively small total flux recorded from the submerged pars of the ice cliff may imply unusually rapid melt rates.

Characteristics of tide-water calving at Glaciar San Rafael, Chile

1995 ◽  
Vol 41 (138) ◽  
pp. 273-289 ◽  
Author(s):  
Charles R. Warren ◽  
Neil F. Glasser ◽  
Stephan Harrison ◽  
Vanessa Winchester ◽  
Andrew R. Kerr ◽  
...  
Keyword(s):  
Water Depth ◽  
Environmental Variables ◽  
Empirical Relationship ◽  
Glacier Surface ◽  
Frequency Distributions ◽  
Low Salinity ◽  
The Mean ◽  
Oceanographic Data ◽  
San Rafael ◽  
Tidal Stage

AbstractGlacial calving is a poorly understood process. This study tests the influence of local environmental variables on the magnitude and frequency distributions of calving behaviour at Glaciar San Rafael, Chile. Near the terminus of the glacier, surface speeds average 17 m d−1in summer and calving is profuse and continual. The size, location and characteristics of over 7000 calving events were recorded during 32d in 1991 and 1992, together with meteorological, bathymetric and oceanographic data. Mean daily calving exceeds 400 events per day and the mean calving flux is more than 2 Mm3d1. Mean annual calving speed and calving flux are about 4500 m a−1and 2.0 km3a−1, respectively. This calving speed is higher than that predicted by the established empirical relationship between tide-water calving speed and water depth. This is surprising, given the low salinity of Laguna San Rafael and that fresh-water calving speeds are commonly much lower than those in ride water. Daily patterns of calving frequency and flux correlate poorly or not at all with meteorological variables, but tidal stage may have some control over the timing of large submarine calving events. Submarine calving produced the largest bergs. However, the relatively small total flux recorded from the submerged pars of the ice cliff may imply unusually rapid melt rates.

Spatial and seasonal variations of subtidal free-living nematode assemblages in the northern Beibu Gulf, South China Sea

2011 ◽  
Vol 92 (2) ◽  
pp. 255-264 ◽  
Author(s):  
S.J. Fu ◽  
L.Z. Cai ◽  
J. Yang ◽  
X.P. Zhou ◽  
X. Peng ◽  
...  
Keyword(s):  
Organic Matter ◽  
South China Sea ◽  
Water Depth ◽  
Environmental Variables ◽  
Beibu Gulf ◽  
Free Living ◽  
Deposit Feeders ◽  
Free Living Nematode ◽  
Offshore Station ◽  
The Mean

This study determined the spatial and seasonal density, number of genera, genera composition, maturity index and trophic structure of free-living nematode assemblages in the subtidal waters of the northern Beibu Gulf, South China Sea, and explored whether these five biotic characteristics were related to various environmental variables. Based on the data derived from samples collected seasonally at nine stations, the mean densities of nematodes decreased from alongshore to offshore station in the northern Beibu Gulf. However, the number of nematode genera increased from alongshore to offshore station. Non-parametric multidimensional scaling analysis showed no clear seasonal changes for nematode assemblages in most sampling stations. Higher densities of the generaElzaliaandTricomawere found in offshore sampling stations, and a higher density of the genusCheironchuswas found in alongshore sampling stations. The mean percentage of each feeding type compared to the total numbers was highest in epigrowth feeders (2A), second highest in non-selective deposit feeders (1B), third highest in predators (2B), and lowest in selective deposit feeders (1A). There were significant negative correlations between nematode density and water depth and temperature; significant positive correlations between the number of nematode genera and water depth and salinity; and significant negative correlation between the maturity index of the nematode assemblage and organic matter. BIOENV analysis indicated that water depth, salinity, pH, median sediment particle size and organic matter were the most correlated combination of environmental variables affecting the nematode assemblages.

scholarly journals Growth and population biology of the sand-bubbler crab Scopimera crabricauda Alcock 1900 (Brachyura: Dotillidae) from the Persian Gulf, Iran

2021 ◽  
Vol 82 (1) ◽  
Author(s):  
Sana Sharifian ◽  
Vahid Malekzadeh ◽  
Ehsan Kamrani ◽  
Mohsen Safaie
Keyword(s):  
Persian Gulf ◽  
Population Biology ◽  
Slow Growth ◽  
Carapace Width ◽  
Population Data ◽  
Natural Mortality ◽  
Frequency Distributions ◽  
Iranian Coast ◽  
The Mean ◽  
The Persian Gulf

Abstract Background Dotillid crabs are introduced as one common dwellers of sandy shores. We studied the ecology and growth of the sand bubbler crab Scopimera crabricauda Alcock, 1900, in the Persian Gulf, Iran. Crabs were sampled monthly by excavating nine quadrats at three intertidal levels during spring low tides from January 2016 to January 2017. Results Population data show unimodal size-frequency distributions in both sexes. The Von Bertalanffy function was calculated at CWt = 8.76 [1 − exp (− 0.56 (t + 0.39))], CWt = 7.90 [1 − exp (− 0.59 (t + 0.40))] and CWt = 9.35 [1 − exp (− 0.57 (t + 0.41))] for males, females, and both sexes, respectively. The life span appeared to be 5.35, 5.07, and 5.26 years for males, females, and both sexes, respectively. The cohorts were identified as two age continuous groups, with the mean model carapace width 5.39 and 7.11 mm for both sexes. The natural mortality (M) coefficients stood at 1.72 for males, 1.83 for females, and 1.76 years−1 for both sexes, respectively. The overall sex ratio (1:0.4) was significantly different from the expected 1:1 proportion with male-biased. Recruitment occurred with the highest number of annual pulse once a year during the summer. Conclusions The results, which show slow growth, emphasize the necessity of proper management for the survival of the stock of S. crabricauda on the Iranian coast of the Persian Gulf.

Reference points for the length-based indicator Lmax5% for use in the assessment of data-limited stocks

2019 ◽  
Vol 76 (7) ◽  
pp. 2125-2139 ◽  
Author(s):  
Tanja Miethe ◽  
Yves Reecht ◽  
Helen Dobby
Keyword(s):  
Life Histories ◽  
Stock Assessment ◽  
Reference Points ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Simulation Tools ◽  
Spawning Potential Ratio ◽  
The Mean ◽  
Commercial Sources ◽  
Length Frequency Data

Abstract In the absence of abundance indices from scientific surveys or commercial sources, reliable length frequency data from sampled commercial catches can be used to provide an indirect assessment of fishing mortality. Length-based indicators are simple metrics which describe length frequency distributions. The length-based indicator Lmax5%, the mean length of the largest 5% of individuals in the catch, combined with appropriately selected reference points, can be used to evaluate the presence of very large individuals in the catch and hence determine exploitation level. Using analytical per-recruit models, we derive reference points consistent with a spawning potential ratio of 40%. The reference points depend on the life history parameters for natural mortality, maturity, and growth (M, Lmat, L∞, k, CVL∞). Using available simulation tools, we investigate the sensitivity of the reference points to errors in these parameters and explore the usefulness of particular reference points for management purposes for stocks with different life histories. The proposed reference points are robust to uncertainty in length at first capture, Lc, and take into account the maturation schedule of a species. For those stocks with high M/k ratios (>1), Lmax5%, combined with the appropriate reference point, can be used to provide a data-limited stock assessment.

Implications of body condition and seasonality on morphological and functional parameters of testes of Myotis nigricans (Chiroptera: Vespertilionidae)

2018 ◽  
Vol 30 (7) ◽  
pp. 1029
Author(s):  
Marcelo Ferreira ◽  
Aline Soldati ◽  
Sirlene S. S. Rodrigues ◽  
Laércio dos Anjos Benjamin
Keyword(s):  
Light Microscopy ◽  
Body Condition ◽  
Environmental Variables ◽  
Reproductive Strategies ◽  
Leydig Cells ◽  
Dry Season ◽  
The Body ◽  
Reproductive Capacity ◽  
Seminiferous Tubules ◽  
The Mean

The insectivorous bat Myotis nigricans is widely distributed throughout the Neotropics, including Brazil, and has a reproductive biology that is affected by climate and food availability. To evaluate the reproductive capacity of this species, morphofunctional parameters of the testes were correlated with environmental variables and the body condition of individuals captured. After bats had been killed, their testes were removed, fixed in Karnovsky’s fluid for 24 h and embedded in resin for evaluation by light microscopy. The mean annual tubulosomatic index (0.58%) and the percentage of seminiferous tubules in the testes (88.96%) were the highest ever recorded for the Order Chiroptera. The percentage of Leydig cells and volume of the cytoplasm of Leydig cells were higher in the rainy than dry season (80.62 ± 3.19% and 573.57 ± 166.95 μm, respectively; mean ± s.d.). Conversely, the percentage of nuclei of the Leydig cells in the dry season (26.17 ± 3.70%; mean ± s.d.) and the total number of Leydig cells (6.38 ± 1.84 × 109; mean ± s.d.) were higher in the dry season. The results of the present study could help in future conservation of these bats because they provide a better understanding of the bats’ reproductive strategies and how the species can adapt to changes.

scholarly journals Evaluating the Sensitivity and Efficacy of Fungicides with Different Modes of Action Against Botryosphaeria dothidea

Plant Disease ◽  
2018 ◽  
Vol 102 (9) ◽  
pp. 1785-1793 ◽  
Author(s):  
Yingying Song ◽  
Lili Li ◽  
Chao Li ◽  
Zengbin Lu ◽  
Xingyuan Men ◽  
...  
Keyword(s):  
Field Trials ◽  
Apple Fruit ◽  
Effective Concentration ◽  
Botryosphaeria Dothidea ◽  
Control Efficacy ◽  
Frequency Distributions ◽  
Considerable Potential ◽  
Ring Rot ◽  
Fungal Plant Pathogen ◽  
The Mean

Botryosphaeria dothidea, the causal agent of apple ring rot, is an important fungal plant pathogen that can cause serious reductions in crop yield, and fungicides still play a crucial role in management. In the present study, the sensitivity of B. dothidea to fludioxonil, fluazinam, and pyrisoxazole was assessed in 162 isolates. Moreover, the protective and curative activity of the three fungicides on detached apple fruit as well as the control efficacy in the field were determined. The results showed that the mean 50% effective concentration (EC50) values (± standard deviation) were 0.01 ± 0.008, 0.04 ± 0.03, and 0.02 ± 0.01 μg ml−1, with individual EC50 values of 0.002 to 0.05, 0.003 to 0.19, and 0.005 to 0.26 μg ml−1 for fludioxonil, fluazinam, and pyrisoxazole, respectively. In addition, the frequency distributions of EC50 values were both unimodal curves. However, significant correlations (P < 0.05) were found between fludioxonil and iprodione, between fluazinam and iprodione, as well as between pyrisoxazole and difenoconazole. In field trials conducted during 2016 and 2017, the control efficacy ranged from 75.91 to 87.41% when fludioxonil was applied at 100 to 150 mg active ingredient (a.i.) kg−1, 81.90 to 85.13% when fluazinam was applied at 400 mg a.i. kg−1, and 77.43 to 80.97% when pyrisoxazole was applied at 400 mg a.i. kg−1. The control efficacy of the fungicides in storage was higher than 60%, with the exception of fluazinam. These results demonstrated that fludioxonil, fluazinam, and pyrisoxazole have considerable potential to control apple ring rot.

Collagen and elastin fibers in human pulmonary alveolar walls

1988 ◽  
Vol 64 (4) ◽  
pp. 1659-1675 ◽  
Author(s):  
S. S. Sobin ◽  
Y. C. Fung ◽  
H. M. Tremer
Keyword(s):  
Transpulmonary Pressure ◽  
Collagen Fibers ◽  
Capillary Blood ◽  
Fiber Bundles ◽  
Cube Root ◽  
Inflation Pressure ◽  
Frequency Distributions ◽  
Normal Distributions ◽  
Statistical Frequency ◽  
The Mean

The morphology and morphometric data of collagen and elastin fibers in the pulmonary alveolar walls are presented. Specimens were obtained from postmortem lungs quick-frozen at specified transpulmonary pressures. Collagen was stained by silver, and elastin was stained by orcein. Photomicrographs were composed by computer. Young lungs typically show small collagen fibers that radiate from the "posts," whereas larger fiber bundles traverse the septum irrespective of capillary blood vessels. In older lungs, rings of collagen around the posts appear enlarged. Elastin bundles do not show obvious variation in pattern with age and inflation pressure. Statistical frequency distributions of the fiber width and curvature are both skewed, but the square root of the width and the cube root of the curvature have approximate normal distributions. Typically, for young lungs at transpulmonary pressure of 4 cmH2O, the mean of (width)1/2 (in micron1/2) for collagen fibers is 0.952 +/- 0.242 (SD), that of (curvature)1/3 (in micron-1/3) is 0.349 +/- 0.094. The corresponding values for elastin are 0.986 +/- 0.255 and 0.395 +/- 0.094.

scholarly journals Characterization of Canadian High Arctic glacier surface albedo from MODIS C6 data, 2001–2016

2017 ◽  
Author(s):  
Colleen A. Mortimer ◽  
Martin Sharp
Keyword(s):  
Large Scale ◽  
Surface Albedo ◽  
Temporal Trends ◽  
Principal Component ◽  
High Arctic ◽  
Shortwave Radiation ◽  
Glacier Surface ◽  
Annual Variations ◽  
The Mean ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. Inter-annual variations and longer-term trends in the annual mass balance of glaciers in Canada's Queen Elizabeth Islands (QEI) are largely attributable to changes in summer melt. The largest source of melt energy in the QEI in summer is net shortwave radiation, which is modulated by changes in glacier surface albedo. We used measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors to investigate large scale spatial patterns and temporal trends and variability in the summer surface albedo of QEI glaciers and their relationship to observed changes in glacier surface temperature from 2001 to 2016. Mean summer black-sky shortwave broadband albedo (BSA) decreased at a rate of 0.029 ± 0.025 decade-1 over that period. Larger reductions in BSA occurred in July (−0.050 ± 0.031 decade-1). No change in BSA was observed in either June or August. Most of the decrease in BSA, which was greatest at lower elevations around the margins of the ice masses, occurred between 2007 and 2012 when mean summer BSA was anomalously low. The First Principal Component of the 16-year record of mean summer BSA was well correlated with the mean summer North Atlantic Oscillation Index, except in 2006, 2010, and 2016. During this 16-year period, the mean summer LST increased by 0.046 ± 0.036 °C yr-1 and the BSA record was negatively correlated (−0.64, p 

The use of frequency distributions in an attempt to detect host mortality induced by infections of diplostomatid metacercariae

Parasitology ◽  
1984 ◽  
Vol 89 (2) ◽  
pp. 209-220 ◽  
Author(s):  
C. R. Kennedy
Keyword(s):  
Small Sample Size ◽  
Parasite Burden ◽  
Fish Host ◽  
Small Sample ◽  
Host Age ◽  
Parasite Abundance ◽  
Frequency Distributions ◽  
Host Mortality ◽  
The Mean ◽  
Over Dispersion

SummaryFollowing recent suggestions that a peaked host age–parasite abundance curve, concomitant with a decline in the degree of dispersion of parasites in the older age classes of hosts, can provide evidence of parasite-induced host mortality, the changes in mean abundance and over-dispersion of metacercarial stages of Diplostomum spathaceum, D. gasterostei, Tylodelphys clavata and T. podicipina in relation to fish age were studied in a field locality. The mean parasite burden of D. spathaceum, D. gasterostei and T. clavata increased with host age and the maximum mean burden was found in the oldest hosts. The variance to mean ratio also increased in D. gasterostei, but decreased in the oldest hosts in D. spathaceum and T. clavata. It is concluded that this decrease could be due to parasite-induced host mortality but could equally be due to death of parasites within the host or to changes in infection rate or could be a reflection of the small sample size of the oldest fish. The mean burden of T. podicipina declined gradually with host age, but the variance to mean ratio remained constant and it is concluded that this could be explained by death of the parasites within the host. None of these data or data from other localities provided clear and unambiguous evidence of host mortality induced by heavy infections of any of the four species, although they are consistent with such mortality and do not refute such a possibility. It is concluded that it may be just as difficult to detect and unequivocally demonstrate parasite-induced host mortality in metacercarial digenean–fish host systems as in any other parasite–host systems.

The common origin of family and non-family asteroids: Implications for meteorites and NEAs

2018 ◽  
Vol 14 (S345) ◽  
pp. 281-282
Author(s):  
Stanley F. Dermott ◽  
Dan Li ◽  
Apostolos A. Christou
Keyword(s):  
Hierarchical Clustering ◽  
Common Origin ◽  
Clustering Method ◽  
Main Belt ◽  
Frequency Distributions ◽  
Size Frequency ◽  
The Family ◽  
The Common ◽  
The Mean ◽  
Asteroid Families

AbstractThe observed size-frequency distributions (SFDs) of the five major asteroid families in the Inner Main Belt (IMB), defined by Nesvorný (2015) using the Hierarchical Clustering Method (Zappala et al. 1990), are distinctly different and deviate significantly from the linear log-log relation described by Dohnanyi (1969). The existence of these differences in the SFDs, and the fact that the precursor bodies of the major families have distinctly different eccentricities and inclinations, provides an explanation for the observations that the mean sizes of both the family and the non-family asteroids are correlated with their mean proper eccentricities and anti-correlated with their mean proper inclinations. We deduce from this, and from the fact that the SFDs of the family and the non-family asteroids are almost identical, that the family and most of the non-family asteroids in the IMB have a common origin (Dermott et al. 2018).

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