Biological studies in the vicinity of a shallow-sea tidal mixing front V. Composition, abundance and distribution of zooplankton in the Western Irish sea, April 1980 to November 1981

1985 ◽  
Vol 310 (1146) ◽  
pp. 501-519 ◽  
Keyword(s):  
Abundant Species ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
Tidal Mixing ◽  
Frontal Region ◽  
Irish Sea ◽  
Total Zooplankton ◽  
Biological Studies ◽  
Standing Stocks ◽  
Abundance And Distribution

There has been no change in the overall species composition of the western Irish Sea zooplankton during the last 80 years. Although Pseudocalanus elongatus and Acartia clausi were always the most abundant species encountered in the survey area, Calanus finmarchicus has been the main contributor to the total zooplankton biomass. The marked decline in numbers of this copepod in 1981 was almost totally responsible for the large decrease in zooplankton biomass observed during that year. The highest zooplankton standing stocks were found to occur above the thermocline in the stratified region between April and June. In the mixed isothermal region zooplankton standing stocks were much lower with a maximum at least one month later than on the stratified side of the front. The frontal region was found to have little influence on the distribution of the total zooplankton. On the isolated occasions when higher zooplankton concentrations were observed within the frontal region they were always found to be associated with localized high densities of surface chlorophyll and due to increased copepod production rather than mechanical aggregation.

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. 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.

scholarly journals Interannual dynamics of zooplankton in the Kola Section of the Barents Sea during the recent warming period

2019 ◽  
Vol 76 (Supplement_1) ◽  
pp. i10-i23
Author(s):  
Irina P Prokopchuk ◽  
Alexander G Trofimov
Keyword(s):  
Barents Sea ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Zooplankton Abundance ◽  
Total Zooplankton ◽  
The Barents Sea ◽  
Warming Period ◽  
Total Zooplankton Biomass

Abstract Our research focused on the analysis of interannual variability of zooplankton in the Kola Section (the Barents Sea) in the period of current warming in the Arctic basing on previously unpublished data. The zooplankton community was investigated based on the analysis of 240 plankton samples, collected in late May–early June 2009–2017. A total of 74 zooplankton taxa of nine phyla were identified in the plankton samples, but copepods were the most diverse and numerous taxonomic group. The biodiversity index varied considerably from year to year, but a stable tendency for the index to increase since the beginning of the period studied was observed. Copepods dominated in terms of abundance and biomass, comprising on average 73–96% of the total zooplankton abundance and 81–96% of the total zooplankton biomass. Calanus finmarchicus was the main zooplankton species utterly dominated by abundance and biomass (on average 92 and 97% respectively). Considerable differences in zooplankton abundance and biomass at different stations of the section were observed. Although the investigations were carried out during a warming period, interannual differences in zooplankton abundance and biomass were observed. Zooplankton biomasses were higher in the years with higher temperatures and stronger water inflow.

scholarly journals Zooplankton productivity in the coastal area of the southern Barents Sea in spring

2020 ◽  
Vol 5 (4) ◽  
pp. 3-14
Author(s):  
V. G. Dvoretsky ◽  
A. G. Dvoretsky
Keyword(s):  
Coastal Water ◽  
Barents Sea ◽  
Dry Mass ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
Zooplankton Abundance ◽  
Total Zooplankton ◽  
Dominant Group ◽  
Hydrological Conditions ◽  
Oithona Similis

The results of the analysis of zooplankton assemblage state of the southern Barents Sea are presented. Zooplankton samples were collected during the cruise of the RV “Dalnie Zelentsy” in May 2016. Hydrological conditions were typical for Murmansk coastal water this season. A total of 47 zooplankton taxa were identified. Taxa number varied between stations, ranging 18–29, with copepods being a dominant group in zooplankton. The most frequent ones were Calanus finmarchicus, Metridia longa, Metridia lucens, Microcalanus spp., Oithona atlantica, Oithona similis, Pseudocalanus spp., copepod nauplii and ova, as well as cladoceran Evadne nordmanni, larvae of Echinodermata and Polychaeta, chaetognath Parasagitta elegans, and early stages of the euphausiids of the genus Thysanoessa. In populations of common copepod species Pseudocalanus spp. and Oithona similis, early age stages dominated, which indicated their continued reproduction. Total zooplankton abundance ranged from 748 to 6576 ind.·m−3, averaging 3012. Total zooplankton biomass varied from 17 to 157 mg of dry mass per m³, with a mean value of 83. The data obtained were comparable to those registered in Murmansk coastal water in July 2008 and were higher than those in August 2007. The authors suggest that it might be related to the differences in sampling seasons and hydrological conditions. Daily zooplankton production was estimated to be 0.49–4.04 mg of dry mass per m³, averaging (2.17 ± 0.17). These estimates were about twice as high as mean values, registered in Murmansk coastal water during summer period. This seems to be due to higher phytoplankton concentrations in spring. Total zooplankton stock for water area studied (25.8 thousand km²) was estimated to be 425,000 thousand tons of dry mass. Cluster analysis revealed four groups of stations that differ in relative abundance of Calanus finmarchicus, Copepoda nauplii, Oithona similis, larvae of Echinodermata, and appendicularian Fritillaria borealis. Spatial variation of zooplankton abundance was closely related to station location (latitude, longitude, and sampling depth), as well as bottom layer temperature and mean salinity at the station.

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.

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.

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.

scholarly journals Influence of net-cage fish farming on zooplankton biomass in the Itá reservoir, SC, Brazil

2012 ◽  
Vol 23 (4) ◽  
pp. 357-367 ◽  
Author(s):  
Bruna Roque Loureiro ◽  
Christina Wyss Castelo Branco ◽  
Evoy Zaniboni Filho
Keyword(s):  
Fish Farming ◽  
Dry Weight ◽  
Control Area ◽  
Zooplankton Biomass ◽  
Total Density ◽  
Total Zooplankton ◽  
Net Cage ◽  
Uruguay River ◽  
Cage Fish ◽  
Total Zooplankton Biomass

OBJECTIVES: This study aimed to verify the influence of net-cage fish farming on zooplankton biomass in the Itá reservoir (Uruguay River, Brazil). METHODS: Samples were collected monthly from October/2009 to May/2010 at the surface and at the bottom in two sampling stations, the net-cage area and in a control area using a Van Dorn bottle and a plankton net (68 µm). RESULTS: The Cladocera and Copepoda biomass was estimated by dry weight using a micro-analytical balance, and the Rotifera biomass by Biovolume. Total zooplankton biomass varied between 6.47 and 131.56 mgDW.m-3 Calanoida copepod presented the highest value of biomass (127.56 mgDW.m-3) and rotifers, despite having an important contribution to total density, showed a maximum biomass of 2.01 mgDW.m-3. Zooplankton biomass at the net-cage area surface was higher when compared with the control area during the months of October to January. However, the zooplankton biomass was similar at the bottom of the two areas throughout the studied period. From February until May, zooplankton biomass decreased in both sampling stations, a fact probably associated with the flushing of the reservoir, followed by an increase in water transparency and a decrease in chlorophyll-a concentration in the following months (February to May). CONCLUSIONS: The influence of fish farming on zooplankton biomass was detected at the surface of the net-cage area only from October to January. From February to May this influence was not found, probably by the influence of the flushing of the reservoir.

scholarly journals Contribution of Calanus species to the mesozooplankton biomass in the Barents Sea

2017 ◽  
Vol 75 (7) ◽  
pp. 2342-2354 ◽  
Author(s):  
Johanna Myrseth Aarflot ◽  
Hein Rune Skjoldal ◽  
Padmini Dalpadado ◽  
Mette Skern-Mauritzen
Keyword(s):  
Barents Sea ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Arctic Water ◽  
Mesozooplankton Biomass ◽  
The Barents Sea ◽  
Main Driver ◽  
Calanus Species

Abstract Copepods from the genus Calanus are crucial prey for fish, seabirds and mammals in the Nordic and Barents Sea ecosystems. The objective of this study is to determine the contribution of Calanus species to the mesozooplankton biomass in the Barents Sea. We analyse an extensive dataset of Calanus finmarchicus, Calanus glacialis, and Calanus hyperboreus, collected at various research surveys over a 30-year period. Our results show that the Calanus species are a main driver of variation in the mesozooplankton biomass in the Barents Sea, and constitutes around 80% of the total. The proportion of Calanus decreases at low zooplankton biomass, possibly due to a combination of advective processes (low C. finmarchicus in winter) and size selective foraging. Though the Calanus species co-occur in most regions, C. glacialis dominates in the Arctic water masses, while C. finmarchicus dominates in Atlantic waters. The larger C. hyperboreus has considerably lower biomass in the Barents Sea than the other Calanus species. Stages CIV and CV have the largest contribution to Calanus species biomass, whereas stages CI-CIII have an overall low impact on the biomass. In the western area of the Barents Sea, we observe indications of an ongoing borealization of the zooplankton community, with a decreasing proportion of the Arctic C. glacialis over the past 20 years. Atlantic C. finmarchicus have increased during the same period.

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