Shell Etching on Clams from Low-Alkalinity Ontario Lakes: A Physical or Chemical Process?

1988 ◽  
Vol 45 (12) ◽  
pp. 2110-2113 ◽  
Author(s):  
Scott G. Hinch ◽  
Roger H. Green
Keyword(s):  
High Water ◽  
Analysis Of Covariance ◽  
Log Analysis ◽  
Elliptio Complanata ◽  
Lake Water Chemistry ◽  
External Shell ◽  
Lake Variation ◽  
Sediment Particles ◽  
Low Exposure ◽  
Water Turbulence

Elliptio complanata (Unionidae: Bivalvia) were sampled from sites of low and high water turbulence in four Ontario lakes that varied in pH (6.0–7.5) and alkalinity (22–243 μeq∙L−1). External shell etching on each clam was quantified using an image analysis digitizer system. Within-lake variation in shell etching was contrasted using a log–log analysis of covariance approach. Clams exposed to higher turbulence regimes (and large sediment particles) were significantly more etched than low-exposure clams (P < 0.05). Approximately 52% of the total shell etching variability resulted from within-lake differences between high- and low-exposure clams. The remaining variation was accounted for by differences among individual clams. Shell etching in these lakes appears to be primarily a physical process probably related to water turbulence. Etching was not related to variation in lake water chemistry and thus is likely not influenced by lake acidification.

scholarly journals Calcifying invertebrates succeed in a naturally CO<sub>2</sub> enriched coastal habitat but are threatened by high levels of future acidification

2010 ◽  
Vol 7 (4) ◽  
pp. 5119-5156 ◽  
Author(s):  
J. Thomsen ◽  
M. A. Gutowska ◽  
J. Saphörster ◽  
A. Heinemann ◽  
K. Trübenbach ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Shell Growth ◽  
Experimental Studies ◽  
Keystone Species ◽  
High Water ◽  
Coastal Habitat ◽  
Kiel Fjord ◽  
Ph Values ◽  
External Shell ◽  
Seawater Pco2

Abstract. CO2 emissions are leading to an acidification of the oceans. Predicting marine community vulnerability towards acidification is difficult, as adaptation processes cannot be accounted for in most experimental studies. Naturally CO2 enriched sites thus can serve as valuable proxies for future changes in community structure. Here we describe a natural analogue site in the Western Baltic Sea. Seawater pCO2 in Kiel Fjord is elevated for large parts of the year due to upwelling of CO2 rich waters. Peak pCO2 values of >230 Pa (>2300 μatm) and pH values of <7.5 are encountered during summer and autumn, average pCO2 values are ~70 Pa (~700 μatm). In contrast to previously described naturally CO2 enriched sites that have suggested a progressive displacement of calcifying auto- and heterotrophic species, the macrobenthic community in Kiel Fjord is dominated by calcifying invertebrates. We show that blue mussels from Kiel Fjord can maintain control rates of somatic and shell growth at a pCO2 of 142 Pa (1400 μatm, pH=7.7). Juvenile mussel recruitment peaks during the summer months, when high water pCO2 values of ~100 Pa (~1000 μatm) prevail. Our findings indicate that calcifying keystone species may be able to cope with surface ocean pH values projected for the end of this century. However, owing to non-linear synergistic effects of future acidification and upwelling of corrosive water, peak seawater pCO2 in Kiel Fjord and many other productive estuarine habitats could increase to values >400 Pa (>4000 μatm). These changes will most likely affect calcification and recruitment, and increase external shell dissolution.

scholarly journals Calcifying invertebrates succeed in a naturally CO<sub>2</sub>-rich coastal habitat but are threatened by high levels of future acidification

2010 ◽  
Vol 7 (11) ◽  
pp. 3879-3891 ◽  
Author(s):  
J. Thomsen ◽  
M. A. Gutowska ◽  
J. Saphörster ◽  
A. Heinemann ◽  
K. Trübenbach ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Shell Growth ◽  
Experimental Studies ◽  
Keystone Species ◽  
High Water ◽  
Coastal Habitat ◽  
Kiel Fjord ◽  
External Shell ◽  
Adaptation Processes ◽  
Seawater Pco2

Abstract. CO2 emissions are leading to an acidification of the oceans. Predicting marine community vulnerability towards acidification is difficult, as adaptation processes cannot be accounted for in most experimental studies. Naturally CO2 enriched sites thus can serve as valuable proxies for future changes in community structure. Here we describe a natural analogue site in the Western Baltic Sea. Seawater pCO2 in Kiel Fjord is elevated for large parts of the year due to upwelling of CO2 rich waters. Peak pCO2 values of >230 Pa (>2300 μatm) and pHNBS values of <7.5 are encountered during summer and autumn, average pCO2 values are ~70 Pa (~700 μatm). In contrast to previously described naturally CO2 enriched sites that have suggested a progressive displacement of calcifying auto- and heterotrophic species, the macrobenthic community in Kiel Fjord is dominated by calcifying invertebrates. We show that blue mussels from Kiel Fjord can maintain control rates of somatic and shell growth at a pCO2 of 142 Pa (1400 μatm, pHNBS = 7.7). Juvenile mussel recruitment peaks during the summer months, when high water pCO2 values of ~100 Pa (~1000 μatm) prevail. Our findings indicate that calcifying keystone species may be able to cope with surface ocean pHNBS values projected for the end of this century when food supply is sufficient. However, owing to non-linear synergistic effects of future acidification and upwelling of corrosive water, peak seawater pCO2 in Kiel Fjord and many other productive estuarine habitats could increase to values >400 Pa (>4000 μatm). These changes will most likely affect calcification and recruitment, and increase external shell dissolution.

Petroleum geology of the Cygnus gas field, UK North Sea: from discovery to development

2017 ◽  
Vol 8 (1) ◽  
pp. 307-318 ◽  
Author(s):  
Ross Catto ◽  
Samantha Taggart ◽  
Gareth Poole
Keyword(s):  
North Sea ◽  
High Water ◽  
Poor Quality ◽  
Log Analysis ◽  
Permian Basin ◽  
Gas Field ◽  
Flow Rates ◽  
Southern North Sea ◽  
Sandstone Formation ◽  
The Uk

AbstractThe Cygnus Field, operated by ENGIE E&P UK Limited, is located in UK Southern North Sea blocks 44/11 and 44/12. The reservoir comprises sandstones of the Permian Leman Sandstone Formation and Carboniferous Ketch Formation.Cygnus was first drilled in 1988 by well 44/12-1, which encountered gas shows in sandstones in the Leman Sandstone Formation whilst targeting a Carboniferous objective. The initial evaluation indicated the presence of poor-quality reservoir with conventional log analysis indicating high water saturations. Further appraisal activity ceased until 2002 when a group led by ENGIE E&P UK Limited were awarded the licence in the 20th round having recognized the missed pay potential. Through appraisal drilling, a second reservoir (the Carboniferous Ketch Formation) was discovered and the Leman Sandstone Formation was proven to be capable of achieving stabilized flow rates greater than 30 MMscf/d.The Cygnus discovery now proves that a northern-sourced Leman Sandstone Formation play fairway exists, establishing an extension of the Rotliegend play to the northern feather edge of the Southern Permian Basin. The Cygnus Field's estimated ultimate recoverable volume is forecast to be 760 Bscf, making it the largest field discovered in the UK Southern North Sea in the last 30 years.

Morphological variation of Elliptio complanata (Bivalvia: Unionidae) in differing sediments of soft-water lakes exposed to acidic deposition

1989 ◽  
Vol 67 (8) ◽  
pp. 1895-1899 ◽  
Author(s):  
Scott G. Hinch ◽  
Laura J. Kelly ◽  
Roger H. Green
Keyword(s):  
Water Chemistry ◽  
Acidic Deposition ◽  
Principal Component ◽  
Environmental Water ◽  
Shell Morphology ◽  
Environmental Data ◽  
Sediment Type ◽  
Elliptio Complanata ◽  
Lake Water Chemistry ◽  
South Central

Clam shell morphology was related to lake water chemistry and sediment properties for Elliptio complanata from 40 south central Ontario lakes. Principal component analyses described the major trends in the environmental data. Relationships between shell morphology and the environmental trends were ascertained through a canonical correlation analysis. Thicker shells were related to increasing alkalinity, conductivity, and pH, suggesting that shell formation is favoured in well-buffered habitats that are not affected by acidic deposition. We also determined that narrow shells were related to coarse sediment in deeper water. This pattern of variation in shell morphology may be adaptive because streamlined shells would better enable clams to maintain their position in turbulent habitats. The water chemistry and sediment property correlates with shell morphology were independent of each other. Any attempt to use unionid shells as long-term indicators of changes in environmental water chemistry must be preceded by a consideration of other habitat variables such as water turbulence, sediment type, and depth.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

The ultrastructure of the abdominal musculature of an orchestid amphipod

1990 ◽  
Vol 48 (3) ◽  
pp. 464-465
Author(s):  
Martin A. Levin ◽  
Lisa L. Cale ◽  
Valerie Lynch-Holm
Keyword(s):  
Intertidal Zone ◽  
High Water ◽  
Abdominal Muscles ◽  
Abdominal Musculature ◽  
Dorsal Muscle ◽  
High Water Mark ◽  
Thoracic Legs ◽  
Orchestia Cavimana

Orchestia is a genus of amphipod in the crustacean class Malacostraca. The order Amphipoda contains over 6000 species commonly called side swimmers, scuds and beach fleas(1). Most are marine bottom-dwellers utilizing their thoracic legs and posterior abdominal uropods for walking, crawling and swimming. However, some, like those in the genera Orchestia and Hyale are semiterrestrial. These amphipods, commonly referred to as “beach fleas,' “beach hoppers” or “sand fleas” can hop vigorously for great distances (up to 50 times their length) by extending their abdomens and telsons against the sand(2).In our study, the ultrastructure of the dorsal muscle cord of Orchestia grillus was examined. Vogel(3) described the abdominal muscles of Orchestia cavimana as consisting of two groups of muscles: a strong, complex, dorsal muscle cord used mainly for hopping and a group of weaker, ventral, longitudinal and oblique muscles.The specimens were collected in clumps of decaying seaweed and other detritus from the intertidal zone near the high water mark at Avery Point Beach, Connecticut.

Effects of a 6-Week Straw Phonation in Water Exercise Program on the Aging Voice

2020 ◽  
Vol 63 (4) ◽  
pp. 1018-1032
Author(s):  
Chia-Hsin Wu ◽  
Roger W. Chan
Keyword(s):  
Acoustic Analysis ◽  
Vocal Tract ◽  
Exercise Program ◽  
Analysis Of Covariance ◽  
Elderly Subjects ◽  
Control Group ◽  
Perceptual Evaluation ◽  
Positive Effects ◽  
Aging Voice ◽  
Before And After

Purpose Semi-occluded vocal tract (SOVT) exercises with tubes or straws have been widely used for a variety of voice disorders. Yet, the effects of longer periods of SOVT exercises (lasting for weeks) on the aging voice are not well understood. This study investigated the effects of a 6-week straw phonation in water (SPW) exercise program. Method Thirty-seven elderly subjects with self-perceived voice problems were assigned into two groups: (a) SPW exercises with six weekly sessions and home practice (experimental group) and (b) vocal hygiene education (control group). Before and after intervention (2 weeks after the completion of the exercise program), acoustic analysis, auditory–perceptual evaluation, and self-assessment of vocal impairment were conducted. Results Analysis of covariance revealed significant differences between the two groups in smoothed cepstral peak prominence measures, harmonics-to-noise ratio, the auditory–perceptual parameter of breathiness, and Voice Handicap Index-10 scores postintervention. No significant differences between the two groups were found for other measures. Conclusions Our results supported the positive effects of SOVT exercises for the aging voice, with a 6-week SPW exercise program being a clinical option. Future studies should involve long-term follow-up and additional outcome measures to better understand the efficacy of SOVT exercises, particularly SPW exercises, for the aging voice.

Exploring Particular Facets of Cognitive Emotion Regulation and Their Relationships With Nonsuicidal Self-Injury Among Adolescents

Crisis ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 280-286 ◽  
Author(s):  
Nir Madjar ◽  
Nicole Segal ◽  
Gilad Eger ◽  
Gal Shoval
Keyword(s):  
Emotion Regulation ◽  
High School Students ◽  
Analysis Of Covariance ◽  
Depression Symptoms ◽  
Emotion Regulation Strategies ◽  
Cognitive Emotion Regulation ◽  
School Students ◽  
Self Injury ◽  
Regulation Strategies ◽  
Nonsuicidal Self Injury

Abstract. Background: Nonsuicidal self-injury (NSSI) has been found to be associated with poor emotion regulation. Aims: The goal of this study was to examine the association of multidimensional cognitive emotion regulation strategies with NSSI among adolescents and compare the different patterns of NSSI. Method: A sample of 594 high-school students (54.4% boys; mean age = 14.96 years), from five regional schools across Israel, were assessed for five facets of cognitive emotion regulation strategies (acceptance, refocus on planning, positive refocusing, putting into perspective, and positive reappraisal) and NSSI behaviors using validated scales. Participants were allocated into three groups: repetitive NSSI (more than six occasions of NSSI; 7.1%), occasional NSSI (at least one incident but less than six; 8.3%), and no NSSI (84.6%). Results: Analysis of covariance, controlling for gender and depression symptoms, revealed that students with NSSI reported higher levels of acceptance, but lower levels of refocus on planning and putting into perspective. Limitations: The study used a cross-sectional design, which was a limitation. Conclusion: These findings demonstrate that particular cognitive emotion regulation strategies differ substantially in their relationship with NSSI. Adolescents who focus on planning and putting stressful situations into perspective may have increased resilience, whereas adolescents who are accepting of negative events that have happened may be more prone to maladaptive coping behaviors.

Influence of General and Crystallized Intelligence on Vocabulary Test Performance

2002 ◽  
Vol 18 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Eva Ullstadius ◽  
Jan-Eric Gustafsson ◽  
Berit Carlstedt
Keyword(s):  
Hierarchical Model ◽  
Test Performance ◽  
Verbal Ability ◽  
Testing Procedure ◽  
Intellectual Ability ◽  
Analysis Of Covariance ◽  
Categorical Variables ◽  
Vocabulary Test ◽  
Crystallized Intelligence ◽  
General Ability

Summary: Vocabulary tests, part of most test batteries of general intellectual ability, measure both verbal and general ability. Newly developed techniques for confirmatory factor analysis of dichotomous variables make it possible to analyze the influence of different abilities on the performance on each item. In the testing procedure of the Computerized Swedish Enlistment test battery, eight different subtests of a new vocabulary test were given randomly to subsamples of a representative sample of 18-year-old male conscripts (N = 9001). Three central dimensions of a hierarchical model of intellectual abilities, general (G), verbal (Gc'), and spatial ability (Gv') were estimated under different assumptions of the nature of the data. In addition to an ordinary analysis of covariance matrices, assuming linearity of relations, the item variables were treated as categorical variables in the Mplus program. All eight subtests fit the hierarchical model, and the items were found to load about equally on G and Gc'. The results also indicate that if nonlinearity is not taken into account, the G loadings for the easy items are underestimated. These items, moreover, appear to be better measures of G than the difficult ones. The practical utility of the outcome for item selection and the theoretical implications for the question of the origin of verbal ability are discussed.

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