Slope turbulence, internal waves and phytoplankton growth at the Celtic Sea shelf-break

1981 ◽  
Vol 302 (1472) ◽  
pp. 663-682 ◽  
Keyword(s):  
Internal Waves ◽  
Surface Waters ◽  
Cold Water ◽  
Interdisciplinary Studies ◽  
Shelf Break ◽  
Phytoplankton Growth ◽  
Atmospheric Conditions ◽  
Celtic Sea ◽  
Break Region ◽  
Made In

The edge of the Celtic Sea shelf is characterized during the summer by a band of cold water ( ca . 100 km broad), which is generally conspicuous in high resolution infrared images from satellites, particularly under high pressure atmospheric conditions with clear skies. Preliminary studies of mixing in this region were made in 1972, 1973 and 1974 and were followed by more detailed interdisciplinary studies in 1976, 1979 and 1980 relating phytoplankton growth to the ways in which turbulence in the environment controls the availability of nutrients and light energy. The results have shown the cooler water to be about 1-2 °C colder than the adjacent surface waters of the Celtic Sea and Atlantic Ocean. This cold band also exhibits higher than background surface values of inorganic nitrate and chlorophyll a . Although these values are generally low compared with the values that have been observed near the neighbouring shelf tidal fronts, the increased surface values along the shelf break in summer appear to be significant. The observed increases of chlorophyll a are thought to be related to physical processes associated with the slopes, ridges and canyons where enhanced mixing, particularly due to internal waves or upwelling, results in nutrient renewal and subsequent phytoplankton growth along the shelf-break region of the Celtic Sea.

Baroclinic eddies bordering the celtic sea in late summer

1979 ◽  
Vol 59 (3) ◽  
pp. 689-703 ◽  
Author(s):  
R. D. Pingree
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Large Scale ◽  
Late Summer ◽  
Shelf Break ◽  
Sea Surface ◽  
Growth Time ◽  
Infra Red ◽  
Celtic Sea ◽  
Break Region

Infra-red images of sea surface temperature indicate that shelf sea frontal regions around the British Isles are characterized by cyclonic eddies with typical wavelengths between 20 and 40 km and growth time scales in the order of a day. A similar analysis for the shelf-break region of the Celtic Sea based on the interpretation of structures observed in infra-red sattllite images and a survey at sea shows that this region is also characterized by eddies. These eddies are usually associated with a general lowering of sea surface temperature that occurs over the shelf-break region in late summer. In this paper, observed eddy scales are compared with estimates based on theory originally developed for large-scale (3000 km wavelength) atmospheric eddies and the role of eddies in cross-frontal exchange is examined in more detail.

scholarly journals Human thermoregulatory responses during serial cold-water immersions

1998 ◽  
Vol 85 (1) ◽  
pp. 204-209 ◽  
Author(s):  
John W. Castellani ◽  
Andrew J. Young ◽  
Michael N. Sawka ◽  
Kent B. Pandolf
Keyword(s):  
Body Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Alternative Explanation ◽  
Cold Water ◽  
Metabolic Heat Production ◽  
Normal Body Temperature ◽  
Repeat Trial ◽  
Metabolic Heat ◽  
Made In

This study examined whether serial cold-water immersions over a 10-h period would lead to fatigue of shivering and vasoconstriction. Eight men were immersed (2 h) in 20°C water three times (0700, 1100, and 1500) in 1 day (Repeat). This trial was compared with single immersions (Control) conducted at the same times of day. Before Repeat exposures at 1100 and 1500, rewarming was employed to standardize initial rectal temperature. The following observations were made in the Repeat relative to the Control trial: 1) rectal temperature was lower and heat debt was higher ( P < 0.05) at 1100; 2) metabolic heat production was lower ( P < 0.05) at 1100 and 1500; 3) subjects perceived the Repeat trial as warmer at 1100. These data suggest that repeated cold exposures may impair the ability to maintain normal body temperature because of a blunting of metabolic heat production, perhaps reflecting a fatigue mechanism. An alternative explanation is that shivering habituation develops rapidly during serially repeated cold exposures.

scholarly journals Sources and Species of Cryptosporidium Oocysts in the Wachusett Reservoir Watershed

2002 ◽  
Vol 68 (2) ◽  
pp. 569-575 ◽  
Author(s):  
Kristen L. Jellison ◽  
Harold F. Hemond ◽  
David B. Schauer
Keyword(s):  
Public Health ◽  
Surface Waters ◽  
Management Practices ◽  
Immunofluorescence Microscopy ◽  
Cold Water ◽  
Environmental Data ◽  
The Public ◽  
Specificity And Sensitivity ◽  
Cryptosporidium Oocysts ◽  
Reservoir Watershed

ABSTRACT Understanding the behavior of Cryptosporidium oocysts in the environment is critical to developing improved watershed management practices for protection of the public from waterborne cryptosporidiosis. Analytical methods of improved specificity and sensitivity are essential to this task. We developed a nested PCR-restriction fragment length polymorphism assay that allows detection of a single oocyst in environmental samples and differentiates the human pathogen Cryptosporidium parvum from other Cryptosporidium species. We tested our method on surface water and animal fecal samples from the Wachusett Reservoir watershed in central Massachusetts. We also directly compared results from our method with those from the immunofluorescence microscopy assay recommended in the Information Collection Rule. Our results suggest that immunofluorescence microscopy may not be a reliable indicator of public health risk for waterborne cryptosporidiosis. Molecular and environmental data identify both wildlife and dairy farms as sources of oocysts in the watershed, implicate times of cold water temperatures as high-risk periods for oocyst contamination of surface waters, and suggest that not all oocysts in the environment pose a threat to public health.

Numerical simulations of the interaction of internal waves with a shelf break

2006 ◽  
Vol 18 (7) ◽  
pp. 076603 ◽  
Author(s):  
S. K. Venayagamoorthy ◽  
O. B. Fringer
Keyword(s):  
Numerical Simulations ◽  
Internal Waves ◽  
Shelf Break

scholarly journals Integration of cooking and vacuum cooling of carrots in a same vessel

2012 ◽  
Vol 32 (1) ◽  
pp. 187-195 ◽  
Author(s):  
Luiz Gustavo Gonçalves Rodrigues ◽  
Darlene Cavalheiro ◽  
Franciny Campos Schmidt ◽  
João Borges Laurindo
Keyword(s):  
Cold Water ◽  
Textural Properties ◽  
Boiling Water ◽  
Integrated Process ◽  
Atmospheric Conditions ◽  
Final Temperature ◽  
Single Vessel ◽  
Vacuum Cooling ◽  
Feasible Alternative ◽  
Integrated Processes

Cooked vegetables are commonly used in the preparation of ready-to-eat foods. The integration of cooking and cooling of carrots and vacuum cooling in a single vessel is described in this paper. The combination of different methods of cooking and vacuum cooling was investigated. Integrated processes of cooking and vacuum cooling in a same vessel enabled obtaining cooked and cooled carrots at the final temperature of 10 ºC, which is adequate for preparing ready-to-eat foods safely. When cooking and cooling steps were performed with the samples immersed in boiling water, the effective weight loss was approximately 3.6%. When the cooking step was performed with the samples in boiling water or steamed, and the vacuum cooling was applied after draining the boiling water, water loss ranged between 15 and 20%, which caused changes in the product texture. This problem can be solved with rehydration using a small amount of sterile cold water. The instrumental textural properties of carrots samples rehydrated at both vacuum and atmospheric conditions were very similar. Therefore, the integrated process of cooking and vacuum cooling of carrots in a single vessel is a feasible alternative for processing such kind of foods.

Temporal and spatial patterns of spawning in jack mackerel, Trachurus declivis (Pisces:Carangidae), during 1988-91 in eastern Tasmanian waters

1995 ◽  
Vol 46 (5) ◽  
pp. 831 ◽  
Author(s):  
A Jordan ◽  
G Pullen ◽  
J Marshall ◽  
H Williams
Keyword(s):  
Thermal Structure ◽  
Shelf Break ◽  
Eastern Coast ◽  
Jack Mackerel ◽  
Spatial And Temporal Patterns ◽  
Cold Event ◽  
Temporal And Spatial ◽  
High Concentrations ◽  
Break Region ◽  
Eggs And Larvae

Ichthyoplankton surveys conducted during the summer and autumn of 1988-89, 1989-90 and 1990-91 along the eastern coast of Tasmania were used to examine the spatial and temporal patterns of eggs and larvae of jack mackerel, Trachurus declivis. Results indicate that the species spawns along the entire eastern coast during summer. Trachurus declivis eggs were most abundant at shelf-break stations, indicating that spawning is concentrated in this region, although high concentrations of eggs were present on the inner shelf in 1988-89, which can be attributed to rapid onshore transport in that year. Larvae were evenly dispersed over the shelf, with the distribution of larval ages showing no indication of inshore recruitment. Considerable interannual differences in sea surface temperatures and vertical thermal structure were apparent, with the warmer waters and strong thermal stratification in the summer of 1988-89 resulting from the influx of subtropical East Australian Current (EAC) water onto the shelf, which corresponded with a major La Nina 'cold event' at that time. It is suggested that the distribution of spawning is unaffected by the interannual variations in oceanography as the mature population spawns in deeper water in the shelf-break region that is unaffected by the warming in surface waters.

scholarly journals Seasonal and spatial comparisons of phytoplankton growth and mortality rates due to microzooplankton grazing in the northern South China Sea

2012 ◽  
Vol 9 (11) ◽  
pp. 16005-16032
Author(s):  
B. Chen ◽  
L. Zheng ◽  
B. Huang ◽  
S. Song ◽  
H. Liu
Keyword(s):  
South China Sea ◽  
Mixed Layer ◽  
South China ◽  
Surface Waters ◽  
Northern South China Sea ◽  
Phytoplankton Growth ◽  
China Sea ◽  
Grazing Effect ◽  
Basin Surface ◽  
Microzooplankton Grazing

Abstract. We conducted a comprehensive investigation on the microzooplankton herbivory effect on phytoplankton in the northern South China Sea (SCS) using the seawater dilution technique at surface and deep chlorophyll maximum (DCM) layers in two cruises (July–August of 2009 and January of 2010). We compared vertical (surface vs. DCM), spatial (onshore vs. offshore), and seasonal (summer vs. winter) differences of phytoplankton growth (μ0) and microzooplankton grazing rates (m). During summer, both μ0 and m were significantly higher at the surface than at the layer of DCM, which was below the mixed layer. During winter, surface μ0 was significantly higher than at DCM, while m was not significantly different between the two layers, both of which were contained within the mixed layer. Surface μ0 was, on average, significantly higher in summer than in winter; while average surface m was not different between the two seasons. There were no significant cross-shelf trends of μ0 in summer or winter surface waters. In surface waters, μ0 was not correlated with ambient nitrate concentrations and the effect of nutrient enrichment on phytoplankton growth was not pronounced. There was a decreasing trend of m from shelf to basin surface waters in summer, but not in winter. Microzooplankton grazing effect on phytoplankton (m/μ0) did not increase with distance offshore, suggesting that the importance of microzooplankton as grazers of phytoplankton may not decrease in onshore waters. On average, microzooplankton grazed 73% and 65% of the daily primary production in summer and winter, respectively.

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