scholarly journals Spatial variation in seabird density at a shallow sea tidal mixing front in the Irish Sea

1997 ◽  
Vol 54 (4) ◽  
pp. 552-565 ◽  
Author(s):  
G Begg
Keyword(s):  
Spatial Variation ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Shallow Sea ◽  
Tidal Mixing Front ◽  
The Irish Sea

Biological studies in the vicinity of a shallow-sea tidal mixing front. I. Physical and chemical background

1985 ◽  
Vol 310 (1146) ◽  
pp. 407-433 ◽  
Keyword(s):  
Ammonium Nitrogen ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Total Biomass ◽  
Shallow Sea ◽  
High Biological Activity ◽  
Biological Studies ◽  
Chemical Background ◽  
Tidal Mixing Front ◽  
Physical And Chemical

A study has been made of the distribution and activities of bacteria and zooplankton as they varied seasonally in 1980 and 1981 in the vicinity of a shallow-sea tidal mixing front in the western Irish Sea (approximate position 53° 20' N, 5° 45' W to 53° 50' N, 5° 0' W ). This paper presents the physical and chemical background to these studies as shown by the variations in temperature and salinity and concentrations of chlorophyll a , phaeopigments, cellular adenosine triphosphate (ATP), nitrate, nitrite and ammonium nitrogen, in sections normal to the front. Observations at drogue stations were made to establish the extent of diurnal variations in these properties but these appeared to be small relative to other variations. As the front developed, higher chlorophyll a concentrations appeared in the surface stratified water, in contrast to the bottom stratified water and mixed water, with highest concentrations at the surface at the stratified side of the front and in subsurface patches in the vicinity of the pycnocline. As the phytoplankton populations increased nitrate became depleted in the surface stratified water but nitrite and ammonium nitrogen concentrations remained at about the same levels. Cellular ATP concentration did not appear to be a useful measure of total biomass but indicated high biological activity in the surface stratified water.

Biological studies in the vicinity of a shallow-sea tidal mixing front IV. Seasonal and spatial distribution of urea and its uptake by phytoplankton

1985 ◽  
Vol 310 (1146) ◽  
pp. 471-500 ◽  
Keyword(s):  
Strong Relationship ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Shallow Sea ◽  
High Productivity ◽  
Biological Studies ◽  
Urea Uptake ◽  
Uptake Rates ◽  
Tidal Mixing Front ◽  
Significant Patterns

On six cruises in 1980 the vertical and horizontal distributions of urea concentration and uptake rates were determined in the vicinity of a shallow-sea tidal mixing front in the western Irish Sea. Urea concentrations, while patchy, were similar throughout the year and showed no significant patterns of distribution and no relation to stratification of the water column. Urea uptake rates, on the other land, showed a consistent and strong relationship to stratification, both vertically and horizontally, fastest rates being found in the less dense water on the stratified side of the front and above the pycnocline. Large differences between waters above and below the pycnocline were found during months of strong stratification. Similar differences occurred between the stratified and mixed surface waters on each side of the front. From relatively low urea uptake rates in March, when stratification was weak, extremely high rates were observed in June and thereafter decreased attaining another minimum at the end of September when stratification was weakening. Urea uptake indices (uptake per unit of chlorophyll a ) were also highest in the surface stratified waters and followed a similar vertical, horizontal and seasonal distribution pattern as that of urea uptake rates. The seemingly unchanging urea concentrations throughout the year and its extremely fast uptake by micro-organisms indicate a rapid flux of this nitrogenous com pound in the surface of the stratified waters. The possible routes of urea regeneration are discussed. Budget calculation indicate that urea was an important source of nitrogen for phytoplankton in the surface stratified waters when oxidized forms of nitrogen such as nitrate were depleted and that the rapid flux of reduced nitrogen in the form of urea may be a major factor in sustaining high productivity associated with the frontal system.

Seabird Observations at a Tidal Mixing Front in the Irish Sea

1998 ◽  
Vol 47 (2) ◽  
pp. 153-164 ◽  
Author(s):  
R. Durazo ◽  
N.M. Harrison ◽  
A.E. Hill
Keyword(s):  
Tidal Mixing ◽  
Irish Sea ◽  
Tidal Mixing Front ◽  
The Irish Sea

Biological studies in the vicinity of a shallow-sea tidal mixing front III. Seasonal and spatial distribution of heterotrophic uptake of glucose

1985 ◽  
Vol 310 (1146) ◽  
pp. 445-469 ◽  
Keyword(s):  
Spatial Distribution ◽  
Water Masses ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Glucose Turnover ◽  
Turnover Rates ◽  
Shallow Sea ◽  
Biological Studies ◽  
Tidal Mixing Front ◽  
Mixed Water

Heterotrophic incorporation and respiration of 14C-labelled glucose (tracer approach) and natural concentrations of glucose were measured, as part of a multidisciplinary research projection five cruises in the western Irish Sea from M arch to September 1980. The investigations were carried out along a transect across a shallow-sea tidal mixing front and its adjacent stratified and vertically mixed water masses. The spatial distribution pattern in relation to hydrographical conditions, diurna changes observed at drogue stations, and seasonal developments are described. High turnover rates of [14C]glucose were strongly associated with stratification, both spatially as well as seasonally, starting with low rates early in spring at the beginning of stratification, increasing to maxim um rates in July after the phytoplankton bloom, and subsequent y declining in autumn when stratification weakened. Turnover rates were consistently and significantly higher in the waters above the pycnocline than below it or in the vertically mixed water masses to the east of the front. No distinct diurnal rhythm s were recognized. The mixed water column, in particular, was totally uniform in heterotrophic uptake of glucose whereas the surface of the stratified water showed greater variability. A fairly constant proportion of, on average, 32 % of the glucose carbon was respired. Natural glucose concentration ranged from less than 30 to 322 nM, mean 116 nM. No particular pattern in its distribution could be detected in the different water masses despite considerable changes in use of glucose. Turnover rates of glucose were unrelated to numbers of bacterial cells or their biomass. Glucose uptake per bacterial cell (uptake index) was estimated and showed pronounced seasonal increase during sum m er in the surface stratified water mass, especially, in the vicinity of the front. The importance of the surface waters of the stratified water body and the frontal zone in respect to carbon flux and potential bacterial biomass production is discussed.

Biological studies in the vicinity of a shallow-sea tidal mixing front VII. The frontal ecosystems

1985 ◽  
Vol 310 (1146) ◽  
pp. 555-571 ◽  
Keyword(s):  
Nitrogen Cycling ◽  
Dynamic Equilibrium ◽  
Standing Stock ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Heterotrophic Activity ◽  
Plume Front ◽  
Biological Studies ◽  
Tidal Mixing Front ◽  
Standing Stocks

Three, possibly four, ecosystems forming seasonally are associated with the tidal mixing front in the western Irish Sea. They are distinguished not only by the presence or absence of particular species but by their relative intensities of heterotrophic activity and degree of organization as shown in the number of statistically significant correlations between the variables pertaining to them. The mam body of surface stratified water, at first dominated by an expanding population of phototrophs, attains during the summer a state of dynamic equilibrium in which the standing stock of phytoplankton remains at about the same level, its primary productivity being balanced by high levels of heterotrophic activity and cycling of nitrogen. The bottom stratified water, besides having minimal photosynthetic activity, shows low zooplankton stocks, low heterotrophic activity and the lowest level of organization. Mixed water has lower standing stocks, less heterotrophic activity, lower rates of nitrogen cycling, and is a less highly organized system than the surface stratified water. The stratified water in a band about 10 km wide adjacent to the front does not show conspicuously higher total standing stocks of phytoplank ton, bacteria and zooplankton in the water column down to the pycnocline, than the rest of the stratified water. Animals migrating into it do not provide an appreciable extra source of nutrients for the phytoplankton. It does, however, show much higher heterotrophic activity and rates of nitrogen cycling than the rest of the stratified water. This is tentatively attributed to increased photosynthesis, consequent on the redistribution of phytoplankton by frontal eddies, being taken up in increased heterotrophic activity rather than in growth of the phytoplankton itself. A similar situation appears to exist at the plume front in Liverpool Bay but here there is the additional factor of collection at the front of particulate organic matter derived from river inflow.

Biological studies in the vicinity of a shallow-sea tidal mixing front II. The distribution of bacteria

1985 ◽  
Vol 310 (1146) ◽  
pp. 435-444 ◽  
Keyword(s):  
Thermal Stratification ◽  
Staining Method ◽  
Late Summer ◽  
Early Spring ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Biological Studies ◽  
Sampling Regime ◽  
Tidal Mixing Front ◽  
Nested Analysis

The work described in this paper was carried out in the summers of 1980 and 1981 in the western Irish sea. The purpose was to ascertain the effects of the annual thermal stratification which occurs in the region on the distribution of bacteria. The sampling regime involved a line of ten stations on a transect normal to a tidal mixing front, sampled at four depths in 1980 and six depths in 1981. Estimation of bacterial numbers was carried out by using a modified acridine orange epifluorescent staining method. The data was statistically analysed by using a nested analysis of variance technique which showed a stable and relatively uniform winter—early spring distribution with low overall counts which became more patchy as the spring progressed and the counts increased. In late summer the distribution became more uniform again within the mixed and stratified water masses but with significantly higher counts in the stratified water.

scholarly journals Small-scale spatio-temporal variability in ichthyoplankton and zooplankton distribution in relation to a tidal-mixing front in the Irish Sea

2005 ◽  
Vol 62 (6) ◽  
pp. 1021-1036 ◽  
Author(s):  
O. Lee ◽  
R.D.M. Nash ◽  
B.S. Danilowicz
Keyword(s):  
Temporal Dynamics ◽  
Fish Larvae ◽  
Sampling Period ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Small Scale ◽  
Surface Salinity ◽  
Average Value ◽  
Tidal Mixing Front ◽  
Spatio Temporal

Abstract This study examines the spatio-temporal dynamics of fish larvae and their prey at a tidal-mixing front in the central Irish Sea. The distribution of ichthyoplankton and zooplankton was analysed in relation to environmental variables (depth, surface temperature, surface salinity, and water column stratification) using Redundancy Analysis (RDA). Significant interannual variability in the formation and position of the tidal-mixing front coincided with large differences in the species abundances of both ichthyoplankton and zooplankton. During the summer, ichthyoplankton and zooplankton communities were structured by a combination of depth and hydrography, and the variability in species composition was directly related to the average value of the stratification parameter. Several ichthyoplankton species were consistently associated with frontal waters, while fewer species were concentrated in mixed water masses throughout the sampling period. The distribution of individual zooplankton species was also examined, and water mass affinities were shown to vary with developmental stage.

The Phytoplankton Production Cycle in Belfast Lough

1988 ◽  
Vol 68 (4) ◽  
pp. 555-564 ◽  
Author(s):  
James G. Parker ◽  
R. S. Rosell ◽  
K. C. MacOscar
Keyword(s):  
Phytoplankton Growth ◽  
Early Years ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Phytoplankton Production ◽  
Production Cycle ◽  
Nutrient Inputs ◽  
Treated Effluent ◽  
The Irish Sea ◽  
Belfast Lough

Spring and autumn phytoplankton blooms are characteristic of those temperate marine waters where thermal stratification occurs during the summer months (e.g. Raymont, 1976). However, in well-mixed coastal waters the phytoplankton production cycle may consist of a single peak of growth during the summer (Boalch, Harbour & Butler, 1978; Wafar, Le Carre & Birrien, 1983). In a recent paper, Brander & Dickson (1984) considered evidence from the Irish Sea continuous plankton recorder which reflects the phytoplankton growth cycle largely in the well-mixed areas of the sea. These data suggested a single late peak of production, in contrast to the bimodal blooms which are known to develop in the stratified areas of the Irish Sea (Burrows & Sharpies, 1973; Slinn, 1974). The purpose of the present work was to establish the production cycle for Belfast Lough, which lies adjacent to the North Channel, an area of strong tidal mixing which forms the northerly exit for water from the Irish Sea (Lee & Ramster, 1981; Howarth, 1984). There have been no previous measurements of primary production in Belfast Lough. There was considerable interest in this topic in the early years of this century when the Royal Commission on Sewage Treatment (1908) heard evidence that nutrient inputs from sewers into the lough resulted in excessive growth of the green alga Ulva, which caused a nuisance as it decayed around the shores. Although there have been no recent reports of this phenomenon, several sewage works continue to discharge partially treated effluent to the lough. An aim of this work was therefore to assess the role of anthropogenic nutrient inputs upon phytoplankton growth.

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