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.

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 Latitudinal variations of zooplankton community structure and productivity in the Barents sea (summer 2013)

2018 ◽  
Vol 64 (3) ◽  
pp. 294-310
Author(s):  
V. G. Dvoretsky ◽  
A. G. Dvoretsky
Keyword(s):  
Community Structure ◽  
Barents Sea ◽  
Sea Water ◽  
Dry Mass ◽  
Atlantic Water ◽  
Zooplankton Biomass ◽  
Total Zooplankton ◽  
Daily Production ◽  
The Barents Sea ◽  
Zooplankton Succession

The Barents Sea is regarded as one of the world’s most unique regions with its high summer productivity. However, there were a few studies dealing with estimation of daily secondary production in the Barents Sea. The aim of the present study was to conduct an investigation of the pelagic mesozooplankton assemblage in the Barents Sea, to calculate daily production levels of mesozooplankton and to analyze the relationship between the community structure and environmental drivers.Structure of zooplankton communities was investigated within the main water masses of the Barents Sea in the summer 2013 (June–July). Calanus finmarchicus presented as copepodites IV–V dominated in terms of the total zooplankton abundance and biomass in Murmansk Coastal Water and Atlantic Water. Spring phase of zooplankton succession cycle was found in Arctic Water where Copepoda nauplii were the most abundant and Calanus glacialis dominated by zooplankton biomass. Zooplankton of the Barents Sea Water had features of spring and summer phases of zooplankton succession cycle. Spatial variations in the zooplankton distribution were associated with hydrological conditions and phytoplankton density. Maximum of the mean zooplankton biomass was registered in Atlantic Water (30,7 mg dry mass/m3) while the minimum was found in Barents Sea Water (5,4 mg dry mass/m3). Calculated daily production of zooplankton ranged from 0,01 to 1,57 mg dry mass/m3per day. Total zooplankton stock for the study area of 281 000 km2was estimated to be > 740 000 t of dry mass. The obtained values of zooplankton biomass and stock were considerably lower than in previous years, which are probably connected with higher predator pressure — grazing of zooplankton by capelin and other predators as well as with possible climatic influence.

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.

scholarly journals Zooplankton abundance trends on Georges Bank, 1977–2004

2007 ◽  
Vol 64 (5) ◽  
pp. 909-919 ◽  
Author(s):  
Joseph Kane
Keyword(s):  
Calanus Finmarchicus ◽  
Zooplankton Abundance ◽  
Georges Bank ◽  
Total Zooplankton ◽  
Key Factors ◽  
The Past ◽  
Abundance Trends ◽  
Temora Longicornis ◽  
Northeast Us ◽  
Centropages Typicus

Abstract Kane, J. 2007. Zooplankton abundance trends on Georges Bank, 1977–2004. – ICES Journal of Marine Science, 64: 909–919. Interannual trends in Georges Bank zooplankton abundance are described and related to variations in environmental variables for the period 1977–2004. Total zooplankton counts increased to above average levels in 1989 and stayed over or close to average through 2004. This analysis identified a group of taxa including Centropages typicus, Metridia lucens, and Temora longicornis that had similar interannual patterns of abundance. All these taxa increased sharply in the early 1990s and remained high through 2001. Some taxa declined sharply in 2002, others have continued elevated through 2004. Total zooplankton counts in the past two years were also boosted by a substantial increase in the abundance of the copepod Calanus finmarchicus. Evidence is presented that these changes may be related to variations in Scotian Shelf inflow, which freshened water on the Northeast US continental shelf, perhaps increasing both primary production and the influx of zooplankton into the region. There was a positive correlation between the biomass of pelagic predators and the abundance of several zooplankton taxa, suggesting that bottom-up processes and advective supply are the key factors that regulate the Georges Bank foodweb.

scholarly journals Distribution and feeding of dominant zooplankton species under autumn coccolithophorid development in the eastern part of the Barents sea

2019 ◽  
Vol 59 (5) ◽  
pp. 734-745
Author(s):  
V. M. Sergeeva ◽  
A. V. Drits ◽  
M. V. Flint
Keyword(s):  
Spatial Distribution ◽  
Barents Sea ◽  
Feeding Activity ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
Grazing Impact ◽  
The Barents Sea ◽  
Diel Vertical Migrations ◽  
Upper Mixed Layer

Studies of zooplankton spatial distribution and feeding were conducted in the eastern part of the Barents Sea in early October 2014. The study period was characterized by positive anomalies of the water temperature in the upper mixed layer and by the dominance of coccolithophorids in phytoplankton. The scale of spatial variability of zooplankton biomass (6.143.3 mg DW m-3) over the 30,000 km2 investigated area was comparable to the range of interannual variation of zooplankton biomass in the Barents Sea. Calanus finmarchicus and Metridia longa dominated in the zooplankton community. The spatial distribution of C. finmarchicus was correlated with the depth: at the stations, where the depth exceeded 250 m, the biomass was threefold higher than that at the shallower stations. Both species performed diel vertical migrations ascending to the upper 50 m layer during night and actively consuming there coccolithophorids and tintinnids Acanthostomella norvegica. Taking into account the contribution of tintinnids, the amount of assimilated organic carbon in C. finmarchicus CV, CIV and M. longa CV, CIV was 2.6, 8.3 and 3.5, 4.9% of body carbon content, respectively, and compensated therefore the metabolic costs. Grazing impact on the autotrophic phytoplankton by the populations of C. finmarchicus and M. longa did not exceed 5% of its biomass and was preconditioned by the abundance and the feeding activity of migrating copepods.

Planktivory by the predacious cladoceran Bythotrephes longimanus: effects on zooplankton size structure and abundance

1999 ◽  
Vol 56 (10) ◽  
pp. 1865-1872 ◽  
Author(s):  
Eva Wahlström ◽  
Erika Westman
Keyword(s):  
Size Structure ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Zooplankton Abundance ◽  
Large Species ◽  
Bythotrephes Longimanus ◽  
Total Zooplankton ◽  
Natural Systems ◽  
Phytoplankton Communities ◽  
Zooplankton Communities

In order to study density-dependent effects of invertebrate planktivory, four different densities of Bythotrephes longimanus were inoculated into mesocosm enclosures with a mixed zooplankton community. Changes in size structure and abundance of zooplankton and phytoplankton communities were recorded over a period of 3 weeks. High densities of Bythotrephes were able to reduce total zooplankton abundance, which was mainly due to a decrease in the density of the relatively large species Holopedium gibberum. The density of the smaller species Bosmina longirostris was also reduced with increasing densities of Bythotrephes, whereas rotifer abundance remained largely unaffected. The mean size of Holopedium increased with increasing densities of Bythotrephes. Despite the decrease in total zooplankton biomass in high-Bythotrephes treatments, no effect of Bythotrephes density on primary producers was observed. Our experiment shows that predacious cladocerans may reduce macrozooplankton biomass, large as well as small species. Predation from invertebrate planktivores results in a zooplankton community consisting of larger individuals. Comparing our experimental densities with densities of Bythotrephes found in natural systems suggests that invertebrate planktivores may influence size structure and abundance of zooplankton communities even in lakes with planktivorous fish.

scholarly journals Zooplankton Distribution and Community Structure in the Pacific and Atlantic Sectors of the Southern Ocean during Austral Summer 2017–18: A Pilot Study Conducted from Ukrainian Long-Liners

2020 ◽  
Vol 8 (7) ◽  
pp. 488
Author(s):  
Evgeny A. Pakhomov ◽  
Leonid K. Pshenichnov ◽  
Anatoly Krot ◽  
Valery Paramonov ◽  
Ilia Slypko ◽  
...  
Keyword(s):  
Pilot Study ◽  
Southern Ocean ◽  
Ross Sea ◽  
Austral Summer ◽  
Water Layer ◽  
Zooplankton Biomass ◽  
Zooplankton Abundance ◽  
Total Biomass ◽  
Total Zooplankton ◽  
Zooplankton Dynamics

Preliminary results of the pilot study of the zooplankton in the region between the Ross and Scotia Seas from November 2017 to April 2018 are presented. In total, 53 zooplankton samples were collected in the top 100 m water layer using vertical tows of a 0.1 m2 Juday net from four Ukrainian longliners operating during the Antarctic toothfish fishery. Total zooplankton abundance ranged from 3 to 2836 ind m−3 with a global mean of 360 ± 550 (±1 SD) ind m−3. The highest abundances were recorded at the northeastern Ross Sea. At those stations, small copepods (mainly Oithona spp., Oncaea spp., Ctenocalanus spp. and copepod nauplii) numerically dominated the samples. Total biomass ranged from 0.3 to 85 mg DW m−3 with a mean of 10.9 ± 14.5 mg DW m−3. The highest biomasses were recorded at the eastern Ross Sea, where pelagic tunicates Salpa thompsoni, siphonophores and ctenophora Callianira sp. accounted for >90% of total zooplankton biomass. At other stations, zooplankton biomass generally ranged from 5 to 20 mg DW m−3 with no clear pattern in distribution. The community composition was driven by the sampling latitude and/or season rather than longitudinally. This pilot study emphasized the unique opportunity to investigate zooplankton dynamics in the regions traditionally not sampled during the oceanographic surveys. It also created unprecedented opportunities to increase the seasonal and geographical zooplankton sampling coverage using ships of opportunity at a fraction of a dedicated oceanographic survey costs. The potential of such surveys are enormous in both providing invaluable information, contributing to existing long-term databases and enhancing an international collaboration in the Southern Ocean, particularly in light of recent modeling initiatives of the whole Antarctic system undertaken by the Commission for the Conservation of Antarctic Marine Living Resources.

scholarly journals Winter decrease of zooplankton abundance and biomass in subalpine oligotrophic Lake Atnsjøen (SE Norway)

2019 ◽  
Vol 78 (3) ◽  
Author(s):  
Thomas C. Jensen
Keyword(s):  
Water Temperature ◽  
Phytoplankton Biomass ◽  
Phytoplankton Bloom ◽  
Zooplankton Biomass ◽  
Zooplankton Abundance ◽  
Total Biomass ◽  
Total Zooplankton ◽  
Additional Food ◽  
Lake Ecosystems ◽  
Lake Atnsjøen

Despite the rapidly changing winter conditions in temperate ecosystems, little attention has been devoted to the effects of these changes on lake ecology. Few studies on the seasonal changes in abundance and biomass of the major groups of the metazooplankton community (i.e. rotifers, cladocerans and copepods) in northern oligotrophic lakes include data from the ice-covered winter months. This study reports monthly variation in zooplankton abundance and biomass from June 2010 to October 2011, including winter, in an oligotrophic, subalpine lake in southeastern Norway (Lake Atnsjøen). Changes in rotifer, cladoceran, copepod, and total zooplankton abundances and biomass were related to seasonal variation in water temperature and phytoplankton biomass by means of ordination analysis. The zooplankton abundance and biomass were much lower in winter than during the open water season. However, an under-ice phytoplankton bloom occurred during the final winter months, when snow cover and ice thickness were reduced and (presumably) light penetration increased, leading to an increase in abundance of copepod nauplii. Winter zooplankton abundance was dominated by copepods and rotifers, while winter zooplankton biomass was dominated by copepods and cladocerans. Both phytoplankton and zooplankton had two biomass peaks in 2010 and one peak in 2011. Rotifers dominated zooplankton abundance with a peak in August and total zooplankton abundance followed a similar pattern. In contrast, cladocerans dominated zooplankton biomass with a peak in July and total zooplankton biomass also peaked at this time. Rotifer and total zooplankton abundance and rotifer biomass were most closely correlated to water temperature. However, cladoceran biomass and total biomass were most closely correlated with phytoplankton biomass, but also appeared to be dependent on other carbon sources. Estimates of non-phytoplankton particulate organic carbon indicated that this part of the carbon pool could be an additional food source for zooplankton particularly in early and mid-winter. The longer growing season in 2011 than in 2010, owing to earlier ice-off in 2011, may have contributed to higher phytoplankton and zooplankton biomass in 2011. With climate warming, this is an expected change in temperate lake ecosystems.

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.

scholarly journals Features of winter zooplankton assemblage in the Central Trough of the Barents Sea

2018 ◽  
Vol 18 (1) ◽  
pp. 28-36 ◽  
Author(s):  
Vladimir Dvoretskiy ◽  
Alexander Dvoretskiy
Keyword(s):  
Barents Sea ◽  
Cold Water ◽  
Sea Water ◽  
Zooplankton Community ◽  
Trophic Levels ◽  
Zooplankton Abundance ◽  
Total Zooplankton ◽  
Transfer Energy ◽  
Commercial Fish ◽  
The Barents Sea

The Barents Sea is a highly productive shelf region. Zooplankton assemblages are a key component of the carbon cycle in Arctic marine ecosystems; they transfer energy from lower trophic levels to higher levels, including larval and young commercial fish. The winter state of the zooplankton community in the Central Through and their slopes (Barents Sea) was investigated in late November 2010. Vertical structure of water layer was characterised by pycnocline located below 80 m. The upper strata were occupied by transformed Atlantic Water, while winter Barents Sea Water with negative temperatures was in the bottom strata. Total zooplankton abundance varied from 162 to 1214 individuals/m3. Biomass ranged from 88 to 799 mg wet mass/m3. Copepods dominated in terms of total zooplankton abundance (average 99%) and biomass (92%). Maximum densities of Calanusfinmarchicus and Calanusglacialis were registered in the frontal zone separating warm and cold water masses. Abundances of Metridialonga and O.similis were highest in cold waters. Three groups of stations differing in terms of the common copepod composition were delineated with cluster analysis. The age structure of Calanusfinmarchicus and Metridialonga was characterised by a prevalence of copepodites IV–V. Total zooplankton abundance and biomass were correlated to water temperature and salinity, suggesting that hydrological conditions were the key driver of spatial variations of the zooplankton communities. High biomass of large copepods suggests potential significance of the investigated region for feeding of young and adult fish.

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