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Margaret P. Hughes - One of the best experts on this subject based on the ideXlab platform.
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nano and Microplankton in the northern arabian sea during the southwest monsoon august september 1995 a us jgofs study
Deep-sea Research Part Ii-topical Studies in Oceanography, 1998Co-Authors: David L. Garrison, Marcia M. Gowing, Margaret P. HughesAbstract:As part of the US Joint Global Ocean Flux Studies (JGOFS) Arabian Sea Program, we determined the abundance and biomass of autotrophic and heterotrophic nano- and Microplankton in the upper 100 m at 10 stations in the northern Indian Ocean during the late Southwest Monsoon from 17 August through 15 September 1995. Autotrophic nano- and Microplankton biomass ranged from 0.2 to 68.0 μg C l-1, with most of the biomass in the upper 20–60 m. Phytoplankton assemblages varied markedly in composition along a transect from onshore to about 1500 km offshore. Larger forms, such as diatoms and colonies of the prymnesiophyte Phaeocystis, dominated stations inshore of about 1000 km, whereas picoplankton dominated offshore. Heterotrophic nano- and Microplankton biomass varied from ∼1 to 12 μg C l-1, and nanoflagellates, dinoflagellates, and ciliates reached maximum biomass at different locations and depths. Heterotrophs comprised 18–27% of the biomass over most of the transect. Biomass of all groups of organisms was strongly negatively correlated with depth and positively correlated with each other, suggesting a dynamic food web. Size structure of organisms among stations suggested that larger consumers occurred where phytoplankton cells were large. Sediment trap data indicate high organic carbon and biogenic silica flux at the time of our study. Our findings of abundant diatoms over much of the study area and their apparent transition from healthy-looking cells nearshore to senescent ones offshore suggest that populations could have sunk as a bloom terminated, in addition to being available for mesozooplankton grazers.
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Nano- and Microplankton in the northern Arabian Sea during the Southwest Monsoon, August–September 1995 A US–JGOFS study
Deep Sea Research Part II: Topical Studies in Oceanography, 1998Co-Authors: David L. Garrison, Marcia M. Gowing, Margaret P. HughesAbstract:As part of the US Joint Global Ocean Flux Studies (JGOFS) Arabian Sea Program, we determined the abundance and biomass of autotrophic and heterotrophic nano- and Microplankton in the upper 100 m at 10 stations in the northern Indian Ocean during the late Southwest Monsoon from 17 August through 15 September 1995. Autotrophic nano- and Microplankton biomass ranged from 0.2 to 68.0 μg C l-1, with most of the biomass in the upper 20–60 m. Phytoplankton assemblages varied markedly in composition along a transect from onshore to about 1500 km offshore. Larger forms, such as diatoms and colonies of the prymnesiophyte Phaeocystis, dominated stations inshore of about 1000 km, whereas picoplankton dominated offshore. Heterotrophic nano- and Microplankton biomass varied from ∼1 to 12 μg C l-1, and nanoflagellates, dinoflagellates, and ciliates reached maximum biomass at different locations and depths. Heterotrophs comprised 18–27% of the biomass over most of the transect. Biomass of all groups of organisms was strongly negatively correlated with depth and positively correlated with each other, suggesting a dynamic food web. Size structure of organisms among stations suggested that larger consumers occurred where phytoplankton cells were large. Sediment trap data indicate high organic carbon and biogenic silica flux at the time of our study. Our findings of abundant diatoms over much of the study area and their apparent transition from healthy-looking cells nearshore to senescent ones offshore suggest that populations could have sunk as a bloom terminated, in addition to being available for mesozooplankton grazers.
T. Kikuchi - One of the best experts on this subject based on the ideXlab platform.
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short term changes in a Microplankton community in the chukchi sea during autumn consequences of a strong wind event
Biogeosciences, 2016Co-Authors: N. Yokoi, K. Matsuno, M. Ichinomiya, A. Yamaguchi, S. Nishino, J. Onodera, J. Inoue, T. KikuchiAbstract:Abstract. Recent studies indicate an increase in atmospheric turbulence in the Chukchi Sea due to the recent drastic sea-ice reduction during summer months. The importance of the effects of this atmospheric turbulence on the marine ecosystem in this region, however, is not fully understood. To evaluate the effects of atmospheric turbulence on the marine ecosystem, high-frequency sampling (daily) from five layers of the Microplankton community between 0 and 30 m at a fixed station in the Chukchi Sea from 10 through 25 September 2013 was conducted. During the study period, a strong wind event (SWE) was observed on 18 and 19 September. The abundance of Microplankton was 2.6 to 17.6 cells mL−1, with a maximum abundance being reported at 20 m on 22 September, while diatoms were the most dominant taxa throughout the study period. The abundance of diatoms, dinoflagellates and ciliates ranged between 1.6 and 14.1, 0.5 and 2.4 and 0.1 and 2.8 cells mL−1, respectively. Diatoms belonging to 7 genera consisting of 35 species (Cylindrotheca closterium and Leptocylindrus danicus were dominant), dinoflagellates belonging to 7 genera consisting of 25 species (Prorocentrum balticum and Gymnodinium spp. were dominant) and ciliates belonging to 7 genera consisting of 8 species (Strobilidium spp. and Strombidium spp. were dominant) were identified. Within the Microplankton species, there were 11 species with abundances that increased after the SWE, while there was no species with an abundance that decreased following the SWE. It is conjectured that atmospheric turbulences, such as that of an SWE, may supply sufficient nutrients to the surface layer that subsequently enhance the small bloom under the weak stratification of the Chukchi Sea Shelf during the autumn months. After the bloom, the dominant diatom community then shifts from centric-dominated to one where centric/pennate are more equal in abundance.
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Short-term changes in a Microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event
2015Co-Authors: N. Yokoi, K. Matsuno, M. Ichinomiya, A. Yamaguchi, S. Nishino, J. Onodera, J. Inoue, T. KikuchiAbstract:Abstract. An increase in atmospheric turbulence in the Chukchi Sea due to the recent drastic sea-ice reduction during summer months has been reported. The importance of the effects of this atmospheric turbulence on the marine ecosystem in this region, however, is not fully understood. To evaluate the effects of atmospheric turbulence on the marine ecosystem, high-frequency sampling (daily) from five layers of the Microplankton community between 0 and 30 m at a fixed station in the Chukchi Sea from 10 through 25 September 2013 was conducted. During the study period, a strong wind event (SWE) was observed on 18 and 19 September. The abundance of Microplankton was 2.6 to 17.6 cells mL−1, with a maximum abundance reported at 20 m on 22 September, while diatoms were the most dominant taxa throughout the study period. The abundances of diatoms, dinoflagellates and ciliates ranged between 1.6 and 14.1, 0.5 and 2.4 cells mL−1 and 0.1 and 2.8 cells mL−1, respectively. Diatoms belonging to seven genera consisting of 35 species (Cylindrotheca closterium and Leptocylindrus danicus were dominant), dinoflagellates belonging to seven genera consisting of 25 species (Prorocentrum balticum and Gymnodinium spp. were dominant) and ciliates belonging to seven genera consisting of eight species (Strobilidium spp. and Strombidium spp. were dominant) were identified. Within the Microplankton species, there were 11 species whose abundance increased after the SWE, while there was no species whose abundance decreased following the SWE. It is conjectured that atmospheric turbulences, such as that of an SWE, may supply sufficient nutrients to the surface layer that then enhance the small bloom under the weak stratification of the Chukchi Sea shelf during the autumn months. After the bloom, the dominant diatom community then shifts from a centric diatom to a pennate diatom, thus suggesting that an SWE accelerates the seasonal succession of the Microplankton community from summer to winter.
David L. Garrison - One of the best experts on this subject based on the ideXlab platform.
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Mesopelagic Microplankton of the Arabian Sea
2003Co-Authors: Marcia M. Gowing, David L. Garrison, Karen F. Wishner, Celia GelfmanAbstract:Abstract The Arabian Sea is notable for its dramatic monsoonal effects on euphotic zone biogeochemical processes and the large spatial extent of its mesopelagic oxygen minimum zone. As part of the US Joint Global Ocean Flux Study Arabian Sea project, we sampled Microplankton (organisms 20–200 μm including diatoms, dinoflagellates, ciliates, sarcodines and nauplii) at five depths from 250 to 1000 or 1100 m at six stations during four seasonal cruises in 1995. Abundances of groups of organisms at discrete depths averaged 1–2 l −1 seasonally. Mean seasonal integrated biomass of the assemblage was 29 mg C m −2 during the late Northeast Monsoon, 37 mg C m −2 during the Spring Intermonsoon, 47 mg C m −2 during the late Southwest Monsoon and 49 mg C m −2 during the early Northeast Monsoon. Overall, protozoans dominated the mesopelagic Microplankton assemblage. Integrated biomass peaked during the late SW Monsoon at two stations as expected if Microplankton responded to surface productivity and mesopelagic organic carbon fluxes. At three stations, Microplankton biomass peaked during the early NE Monsoon; this may reflect a continuing response to SW Monsoon productivity signals by these larger, slow-growing organisms. Protozooplankton abundance did not appear to be negatively affected by low ( 2 l −1 ) oxygen, whereas naupliar abundance and biomass were higher where oxygen concentration was higher. Total Microplankton biomass was highest where oxygen concentrations and also mesozooplankton biomass were lowest, suggesting that predation also played a role in Microplankton distributions. Calculations based on allometric relationships indicated that the mesopelagic heterotrophic Microplankton assemblage could, on average, respire 9–38% of the particulate carbon flux that entered the system at 100 m and possibly 18–76% of the flux remaining at 250 m. Microplankton may therefore be significant carbon cyclers in the ocean's vast “twilight zone”.
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nano and Microplankton in the northern arabian sea during the southwest monsoon august september 1995 a us jgofs study
Deep-sea Research Part Ii-topical Studies in Oceanography, 1998Co-Authors: David L. Garrison, Marcia M. Gowing, Margaret P. HughesAbstract:As part of the US Joint Global Ocean Flux Studies (JGOFS) Arabian Sea Program, we determined the abundance and biomass of autotrophic and heterotrophic nano- and Microplankton in the upper 100 m at 10 stations in the northern Indian Ocean during the late Southwest Monsoon from 17 August through 15 September 1995. Autotrophic nano- and Microplankton biomass ranged from 0.2 to 68.0 μg C l-1, with most of the biomass in the upper 20–60 m. Phytoplankton assemblages varied markedly in composition along a transect from onshore to about 1500 km offshore. Larger forms, such as diatoms and colonies of the prymnesiophyte Phaeocystis, dominated stations inshore of about 1000 km, whereas picoplankton dominated offshore. Heterotrophic nano- and Microplankton biomass varied from ∼1 to 12 μg C l-1, and nanoflagellates, dinoflagellates, and ciliates reached maximum biomass at different locations and depths. Heterotrophs comprised 18–27% of the biomass over most of the transect. Biomass of all groups of organisms was strongly negatively correlated with depth and positively correlated with each other, suggesting a dynamic food web. Size structure of organisms among stations suggested that larger consumers occurred where phytoplankton cells were large. Sediment trap data indicate high organic carbon and biogenic silica flux at the time of our study. Our findings of abundant diatoms over much of the study area and their apparent transition from healthy-looking cells nearshore to senescent ones offshore suggest that populations could have sunk as a bloom terminated, in addition to being available for mesozooplankton grazers.
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Nano- and Microplankton in the northern Arabian Sea during the Southwest Monsoon, August–September 1995 A US–JGOFS study
Deep Sea Research Part II: Topical Studies in Oceanography, 1998Co-Authors: David L. Garrison, Marcia M. Gowing, Margaret P. HughesAbstract:As part of the US Joint Global Ocean Flux Studies (JGOFS) Arabian Sea Program, we determined the abundance and biomass of autotrophic and heterotrophic nano- and Microplankton in the upper 100 m at 10 stations in the northern Indian Ocean during the late Southwest Monsoon from 17 August through 15 September 1995. Autotrophic nano- and Microplankton biomass ranged from 0.2 to 68.0 μg C l-1, with most of the biomass in the upper 20–60 m. Phytoplankton assemblages varied markedly in composition along a transect from onshore to about 1500 km offshore. Larger forms, such as diatoms and colonies of the prymnesiophyte Phaeocystis, dominated stations inshore of about 1000 km, whereas picoplankton dominated offshore. Heterotrophic nano- and Microplankton biomass varied from ∼1 to 12 μg C l-1, and nanoflagellates, dinoflagellates, and ciliates reached maximum biomass at different locations and depths. Heterotrophs comprised 18–27% of the biomass over most of the transect. Biomass of all groups of organisms was strongly negatively correlated with depth and positively correlated with each other, suggesting a dynamic food web. Size structure of organisms among stations suggested that larger consumers occurred where phytoplankton cells were large. Sediment trap data indicate high organic carbon and biogenic silica flux at the time of our study. Our findings of abundant diatoms over much of the study area and their apparent transition from healthy-looking cells nearshore to senescent ones offshore suggest that populations could have sunk as a bloom terminated, in addition to being available for mesozooplankton grazers.
N. Yokoi - One of the best experts on this subject based on the ideXlab platform.
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short term changes in a Microplankton community in the chukchi sea during autumn consequences of a strong wind event
Biogeosciences, 2016Co-Authors: N. Yokoi, K. Matsuno, M. Ichinomiya, A. Yamaguchi, S. Nishino, J. Onodera, J. Inoue, T. KikuchiAbstract:Abstract. Recent studies indicate an increase in atmospheric turbulence in the Chukchi Sea due to the recent drastic sea-ice reduction during summer months. The importance of the effects of this atmospheric turbulence on the marine ecosystem in this region, however, is not fully understood. To evaluate the effects of atmospheric turbulence on the marine ecosystem, high-frequency sampling (daily) from five layers of the Microplankton community between 0 and 30 m at a fixed station in the Chukchi Sea from 10 through 25 September 2013 was conducted. During the study period, a strong wind event (SWE) was observed on 18 and 19 September. The abundance of Microplankton was 2.6 to 17.6 cells mL−1, with a maximum abundance being reported at 20 m on 22 September, while diatoms were the most dominant taxa throughout the study period. The abundance of diatoms, dinoflagellates and ciliates ranged between 1.6 and 14.1, 0.5 and 2.4 and 0.1 and 2.8 cells mL−1, respectively. Diatoms belonging to 7 genera consisting of 35 species (Cylindrotheca closterium and Leptocylindrus danicus were dominant), dinoflagellates belonging to 7 genera consisting of 25 species (Prorocentrum balticum and Gymnodinium spp. were dominant) and ciliates belonging to 7 genera consisting of 8 species (Strobilidium spp. and Strombidium spp. were dominant) were identified. Within the Microplankton species, there were 11 species with abundances that increased after the SWE, while there was no species with an abundance that decreased following the SWE. It is conjectured that atmospheric turbulences, such as that of an SWE, may supply sufficient nutrients to the surface layer that subsequently enhance the small bloom under the weak stratification of the Chukchi Sea Shelf during the autumn months. After the bloom, the dominant diatom community then shifts from centric-dominated to one where centric/pennate are more equal in abundance.
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Short-term changes in a Microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event
2015Co-Authors: N. Yokoi, K. Matsuno, M. Ichinomiya, A. Yamaguchi, S. Nishino, J. Onodera, J. Inoue, T. KikuchiAbstract:Abstract. An increase in atmospheric turbulence in the Chukchi Sea due to the recent drastic sea-ice reduction during summer months has been reported. The importance of the effects of this atmospheric turbulence on the marine ecosystem in this region, however, is not fully understood. To evaluate the effects of atmospheric turbulence on the marine ecosystem, high-frequency sampling (daily) from five layers of the Microplankton community between 0 and 30 m at a fixed station in the Chukchi Sea from 10 through 25 September 2013 was conducted. During the study period, a strong wind event (SWE) was observed on 18 and 19 September. The abundance of Microplankton was 2.6 to 17.6 cells mL−1, with a maximum abundance reported at 20 m on 22 September, while diatoms were the most dominant taxa throughout the study period. The abundances of diatoms, dinoflagellates and ciliates ranged between 1.6 and 14.1, 0.5 and 2.4 cells mL−1 and 0.1 and 2.8 cells mL−1, respectively. Diatoms belonging to seven genera consisting of 35 species (Cylindrotheca closterium and Leptocylindrus danicus were dominant), dinoflagellates belonging to seven genera consisting of 25 species (Prorocentrum balticum and Gymnodinium spp. were dominant) and ciliates belonging to seven genera consisting of eight species (Strobilidium spp. and Strombidium spp. were dominant) were identified. Within the Microplankton species, there were 11 species whose abundance increased after the SWE, while there was no species whose abundance decreased following the SWE. It is conjectured that atmospheric turbulences, such as that of an SWE, may supply sufficient nutrients to the surface layer that then enhance the small bloom under the weak stratification of the Chukchi Sea shelf during the autumn months. After the bloom, the dominant diatom community then shifts from a centric diatom to a pennate diatom, thus suggesting that an SWE accelerates the seasonal succession of the Microplankton community from summer to winter.
Francisco G. Figueiras - One of the best experts on this subject based on the ideXlab platform.
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A spring poleward current and its influence on Microplankton assemblages and harmful dinoflagellates on the western Iberian coast
Harmful Algae, 2007Co-Authors: B. G. Crespo, Francisco G. FigueirasAbstract:Abstract Along-shore currents can propagate harmful algal blooms (HABs) over long distances in many coastal areas of the ocean. Harmful dinoflagellate blooms on the west coast of Iberia frequently occur when the Iberian poleward current (IPC) establishes on the continental slope. This has led to the suggestion that HABs could be transported northward by the IPC. To examine this possibility, the Microplankton composition along the west coast of Iberia was studied in May 1993 coinciding with the presence of the IPC. The Microplankton of the IPC was almost exclusively composed of small flagellates, with the notable absence of the harmful species usually associated with coastal waters. The primary influence of the IPC was to confine coastal Microplankton populations to the shelf, where a downwelling convergence prevented their export from the coastal environment. Microplankton assemblages on the shelf revealed a north–south gradient related to different stages of succession. Earlier stages of succession in which diatoms were prominent were found on the northern shelf, whereas dinoflagellates were more abundant in the south. The toxic species Gymnodinium catenatum , which was only present in the southern shelf, did not show a northward transport associated with the IPC. It is suggested that the northward spreading of HABs along the west coast of Iberia must be related to the interaction between the IPC, which accumulates coastal populations on the shelf, and the latitudinal progress of Microplankton succession that determines species composition. Thus, during the course of the season, HABs are likely to be observed in the south prior to their development in the north.
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The Microplankton succession in the Ría de Vigo revisited: species assemblages and the role of weather-induced, hydrodynamic variability
Journal of Marine Systems, 2004Co-Authors: E. Nogueira, Francisco G. FigueirasAbstract:Abstract We have analysed meteorological, hydrographic, and Microplankton species abundance data, collected every 3–4 days during 1987 in the Ria de Vigo (NW Iberian Peninsula), to investigate the effect of environmental variability on the structure of the Microplankton community. Three Microplankton assemblages were distinguished, composed chiefly of: small- to medium-sized centric and pennate diatoms (i.e., C- and/or R-species, r-strategists), small-sized organisms from different taxonomic groups (i.e., C- or S-species, r-strategists), and medium- to large-sized dinoflagellates (i.e., S-species, K-strategists). Community changes were related to different scales of meteorological and hydrographic variability. At the seasonal scale, the succession from r-strategists towards K-strategists, or from C- and/or R-species towards S-species, was related with the annual cycle of mixing/stratification and high/low flushing. Within this seasonal pattern, a series of short-term ‘successions’ were identified, the onset of which co-occurred with hydrodynamic changes induced by meteorological disturbances. These results support the conclusions articulated in a previous paper on Microplankton community structure during 1991 concerning: (1) the relative persistence of characteristic Microplankton assemblages and their ecological interpretation in terms of adaptive strategies, and (2) the key role of weather-induced, hydrodynamic variability, especially at short-term scales, in shaping the structure of the community. The contrasting meteorology in 1987 and 1991 would explain interannual differences of community structure, such as the larger proportion of diatoms in 1991 than in 1987 due to increased intensity and duration of the upwelling seasonal cycle that year. At the species level, the early phase of the seasonal succession was characterised by the coexistence (i.e., single-species biomass, Bi≤40% of total biomass) or alternating dominance (Bi>40% BT) among (C–R) species, while the late part was characterised by the alternating dominance among species with different adaptive strategies. For instance, in September–October, the short-term succession started with the dominance of the (C–R) species Leptocylindrus danicus (∼80% of BT, during 3 weeks), followed by the (S–R) species Ceratium fusus+Ceratium furca (∼70% of BT, 1 week), and finished with the dominance of small microheterotrophs (∼70% of BT, 2 weeks).
