Short-term changes in the mesozooplankton community and copepod gut pigment in the Chukchi Sea in autumn: reflections of a strong wind event

Abstract. To evaluate the effect of atmospheric turbulence on a marine ecosystem, high-frequency samplings (two to four times per day) of a mesozooplankton community and the gut pigment of dominant copepods were performed at a fixed station in the Chukchi Sea from 10 to 25 September 2013. During the study period, a strong wind event (SWE) was observed on 18 September. After the SWE, the biomass of chlorophyll a (Chl a) increased, especially for micro-size (> 10 μm) fractions. The zooplankton abundance ranged from 23 610 to 56 809 ind. m−2 and exhibited no clear changes as a result of the SWE. In terms of abundance, calanoid copepods constituted the dominant taxa (mean: 57 %), followed by barnacle larvae (31 %). Within the calanoid copepods, small-sized Pseudocalanus spp. (65 %) and large-sized C. glacialis (30 %) dominated. In the population structure of C. glacialis, copepodid stage 5 (C5) dominated, and the mean copepodid stage did not vary with the SWE. The dominance of accumulated lipids in C5 and C6 females with immature gonads indicated that they were preparing for seasonal diapause. The gut pigment of C. glacialis C5 was higher at night and was correlated with ambient Chl a (Chl a, and a significant increase was observed after the SWE (2.6 vs. 4.5 ng pigment ind.−1). The grazing impact by C. glacialis C5 was estimated to be 4.14 mg C m−2 day−1, which corresponded to 0.5−4.6 % of the biomass of the micro-size phytoplankton. Compared with the metabolic food requirement, C. glacialis feeding on phytoplankton accounted for 12.6 % of their total food requirement. These facts suggest that C. glacialis could not maintain their population by feeding solely on phytoplankton and that other food sources (i.e., microzooplankton) must be important in autumn. As observed by the increase in gut pigment, the temporal phytoplankton bloom, which is enhanced by the atmospheric turbulence (SWE) in autumn, may have a positive effect on copepod nutrition.

Download Full-text

Short-term changes of the mesozooplankton community and copepod gut pigment in the Chukchi Sea in autumn

Biogeosciences Discussions ◽

10.5194/bgd-12-3879-2015 ◽

2015 ◽

Vol 12 (5) ◽

pp. 3879-3904

Author(s):

K. Matsuno ◽

A. Yamaguchi ◽

S. Nishino ◽

J. Inoue ◽

T. Kikuchi

Keyword(s):

Atmospheric Turbulence ◽

Chukchi Sea ◽

Marine Ecosystem ◽

Standing Stock ◽

Calanoid Copepods ◽

Mesozooplankton Community ◽

Chl A ◽

Food Requirement ◽

Copepodid Stage ◽

Gut Pigment

Abstract. In the Chukchi Sea, due to the recent drastic reduction of sea-ice during the summer, an increasing formation of atmospheric turbulence has been reported. However, the importance and effects of atmospheric turbulence on the marine ecosystem are not fully understood in this region. To evaluate the effect of atmospheric turbulence on the marine ecosystem, high-frequent sampling (two to four times per day) on the mesozooplankton community and the gut pigment of dominant copepods were made at a fixed station in the Chukchi Sea from 10 to 25 September 2013. During the study period, a strong wind event (SWE) was observed on 18 September. After the SWE, the standing stock of chlorophyll a (chl a) was increased, especially for micro-size (> 10 μm) fractions. Zooplankton abundance ranged 23 610–56 809 ind. m−2 and exhibited no clear changes with SWE. In terms of abundance, calanoid copepods constituted the most dominated taxa (mean: 57%), followed by barnacle larvae (31%). Within the calanoid copepods, small-sized Pseudocalanus spp. (65%) and large-sized Calanus glacialis (30%) dominated. In the population structure of C. glacialis, copepodid stage 5 (C5) dominated, and the mean copepodid stage did not vary with SWE. The dominance of accumulated lipids in C5 and C6 females with immature gonads indicated that they were preparing for seasonal diapause. The gut pigment of C. glacialis C5 was higher at night and was correlated with ambient chl a, and a significant increase was observed after SWE (2.6 vs. 4.5 ng pigment ind.−1). Assuming C : Chl a ratio, the grazing impact by C. glacialis C5 was estimated to be 4.14 mg C m−2 day−1, which corresponded to 0.5–4.6% of the standing stock of micro-size phytoplankton. Compared with the metabolic food requirement, their feeding on phytoplankton accounted for 12.6% of their total food requirement. These facts suggest that C. glacialis could not maintain their population on solely phytoplankton food, and other food sources (i.e., microzooplankton) are important in autumn. As observed for the increase in gut pigment, temporal phytoplankton bloom, which is enhanced by the atmospheric turbulence (SWE) in autumn, may have a positive effect on copepod nutrition. However, because of the relatively long generation length of copepods, a smaller effect was detected for their abundance, population structure, lipid accumulation and gonad maturation within the short-term period (16 days).

Download Full-text

Short-term changes in a microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event

Biogeosciences Discussions ◽

10.5194/bgd-12-8789-2015 ◽

2015 ◽

Vol 12 (11) ◽

pp. 8789-8817 ◽

Cited By ~ 3

Author(s):

N. Yokoi ◽

K. Matsuno ◽

M. Ichinomiya ◽

A. Yamaguchi ◽

S. Nishino ◽

...

Keyword(s):

Atmospheric Turbulence ◽

Chukchi Sea ◽

Marine Ecosystem ◽

Seasonal Succession ◽

Centric Diatom ◽

Strong Wind ◽

Cylindrotheca Closterium ◽

Wind Event ◽

Weak Stratification ◽

High Frequency Sampling

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.

Download Full-text

Short-term changes in a microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event

Biogeosciences ◽

10.5194/bg-13-913-2016 ◽

2016 ◽

Vol 13 (4) ◽

pp. 913-923 ◽

Cited By ~ 8

Author(s):

Naoya Yokoi ◽

Kohei Matsuno ◽

Mutsuo Ichinomiya ◽

Atsushi Yamaguchi ◽

Shigeto Nishino ◽

...

Keyword(s):

Atmospheric Turbulence ◽

High Frequency ◽

Chukchi Sea ◽

Marine Ecosystem ◽

Strong Wind ◽

Short Term ◽

Cylindrotheca Closterium ◽

Wind Event ◽

Weak Stratification ◽

High Frequency Sampling

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.

Download Full-text

A Case Study of Strong Wind Event over Yeongdong Region on March 18-20, 2020

Journal of the Korean earth science society ◽

10.5467/jkess.2021.42.5.479 ◽

2021 ◽

Vol 42 (5) ◽

pp. 479-495

Author(s):

Bo-Yeong Ahn ◽

Yoo-Jun Kim ◽

Baek-Jo Kim ◽

Yong-Hee Lee

Keyword(s):

Strong Wind ◽

Wind Event

Download Full-text

A numerical simulation of a strong wind event in January 2013 at King Sejong station, Antarctica

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.3496 ◽

2019 ◽

Vol 145 (720) ◽

pp. 1267-1280

Author(s):

Hataek Kwon ◽

Sang‐Jong Park ◽

Solji Lee ◽

Baek‐Min Kim ◽

Taejin Choi ◽

...

Keyword(s):

Numerical Simulation ◽

Strong Wind ◽

Wind Event

Download Full-text

Case Study of a Barrier Wind Corner Jet off the Coast of the Prince Olav Mountains, Antarctica

Monthly Weather Review ◽

10.1175/mwr-d-11-00261.1 ◽

2012 ◽

Vol 140 (7) ◽

pp. 2044-2063 ◽

Cited By ~ 25

Author(s):

Melissa A. Nigro ◽

John J. Cassano ◽

Matthew A. Lazzara ◽

Linda M. Keller

Keyword(s):

Strong Wind ◽

Ice Shelf ◽

Maximum Wind ◽

Ross Ice Shelf ◽

Wind Speeds ◽

Wind Event ◽

Transantarctic Mountains ◽

Upper Level ◽

Forcing Mechanisms

Abstract The Ross Ice Shelf airstream (RAS) is a barrier parallel flow along the base of the Transantarctic Mountains. Previous research has hypothesized that a combination of katabatic flow, barrier winds, and mesoscale and synoptic-scale cyclones drive the RAS. Within the RAS, an area of maximum wind speed is located to the northwest of the protruding Prince Olav Mountains. In this region, the Sabrina automatic weather station (AWS) observed a September 2009 high wind event with wind speeds in excess of 20 m s−1 for nearly 35 h. The following case study uses in situ AWS observations and output from the Antarctic Mesoscale Prediction System to demonstrate that the strong wind speeds during this event were caused by a combination of various forcing mechanisms, including katabatic winds, barrier winds, a surface mesocyclone over the Ross Ice Shelf, an upper-level ridge over the southern tip of the Ross Ice Shelf, and topographic influences from the Prince Olav Mountains. These forcing mechanisms induced a barrier wind corner jet to the northwest of the Prince Olav Mountains, explaining the maximum wind speeds observed in this region. The RAS wind speeds were strong enough to induce two additional barrier wind corner jets to the northwest of the Prince Olav Mountains, resulting in a triple barrier wind corner jet along the base of the Transantarctic Mountains.

Download Full-text

Atmospheric forcing of sea ice anomalies in the Ross Sea Polynya region

10.5194/tc-2016-89 ◽

2016 ◽

Cited By ~ 1

Author(s):

Ethan R. Dale ◽

Adrian J. McDonald ◽

Jack H.J. Coggins ◽

Wolfgang Rack

Keyword(s):

Wind Speed ◽

Sea Ice ◽

Ross Sea ◽

Strong Wind ◽

Sea Ice Concentration ◽

Sea Ice Extent ◽

Wind Speeds ◽

Wind Event ◽

Wind Events ◽

Ice Production

Abstract. Despite warming trends in global temperatures, sea ice extent in the Southern Hemisphere has shown an increasing trend over recent decades. Wind-driven sea ice export from coastal polynyas is an important source of sea ice production. Areas of major polynyas in the Ross Sea, the region with largest increase in sea ice extent, have been suggested to produce a vast amount of the sea ice in the region. We investigate the impacts of strong wind events on the Ross Sea Polynyas and its sea ice concentration and possible consequences on sea ice production. We utilise Bootstrap sea ice concentration (SIC) measurements derived from satellite based, Special Sensor Microwave Imager (SSM/I) brightness temperatures. We compared these with surface winds and temperatures from automatic weather stations (AWS) of the University of Wisconsin-Madison Antarctic Meteorology Program. Our analysis focusses on the austral winter period defined as 1st April to 1st November in this study. Daily data were used to classified into characteristic regimes based on the percentiles of wind speed. For each regime, a composite of SIC anomaly was formed for the Ross Sea region. We found that persistent weak winds near the edge of the Ross Ice Shelf are generally associated with positive SIC anomalies in the Ross Sea Polynya (RSP). Conversely we found negative SIC anomalies in this area during persistent strong winds. By analysing sea ice motion vectors derived from SSM/I and SSMIS brightness temperatures, we find significant sea ice motion anomalies throughout the Ross Sea during strong wind events. These anomalies persist for several days after the strong wind event. Strong, negative correlations are found between SIC and AWS wind speed within the RSP indicating that strong winds cause significant advection of sea ice in the region. We were able to recreate these correlations using co-located ERA-Interim wind speeds. However when only days of a certain percentile based wind speed classification were used, the cross correlation functions produced by ERA-Interim wind speeds differed significantly from those produced using AWS wind speeds. The rapid decrease in SIC during a strong wind event is followed by a more gradual recovery in SIC. This increase occurs on a more gradual time scale than the average persistence of a strong wind event and the resulting sea ice motion anomalies, highlighting the production of new sea ice through thermodynamic processes. In the vicinity of Ross Island, ERA-Interim underestimates wind speeds by a factor of 1.7, which results in a significant misrepresentation of the impact of winds on polynya processes.

Download Full-text

Eulerian and Lagrangian Comparison of Wind Jets in the Tokar Gap Region

Fluids ◽

10.3390/fluids5040193 ◽

2020 ◽

Vol 5 (4) ◽

pp. 193

Author(s):

Larry J. Pratt ◽

E. Jason Albright ◽

Irina Rypina ◽

Houshuo Jiang

Keyword(s):

Red Sea ◽

Wrf Model ◽

High Elevation ◽

Dust Storms ◽

Weather Research And Forecasting ◽

Strong Wind ◽

Wind Event ◽

Bernoulli Function ◽

Horizontal Momentum ◽

Supercritical Flows

The Lagrangian and Eulerian structure and dynamics of a strong wind event in the Tokar Gap region are described using a Weather Research and Forecasting (WRF) model hindcast for 2008. Winds in the Tokar Gap reach 25 m s−1 and remain coherent as a jet far out over the Red Sea, whereas equally strong wind jets occurring in neighboring gaps are attenuated abruptly by jump-like hydraulic transitions that occur just offshore of the Sudan coast. The transition is made possible by the supercritical nature of the jets, which are fed by air that spills down from passes at relatively high elevation. By contrast, the spilling flow in the ravine-like Tokar Gap does not become substantially supercritical and therefore does not undergo a jump, and also carries more total horizontal momentum. The Tokar Wind Jet carries some air parcels across the Red Sea and into Saudi Arabia, whereas air parcel trajectories in the neighboring jets ascend as they cross through the jumps, then veer sharply to the southeast and do not cross the Red Sea. The mountain parameter Nh/U is estimated to lie in the range of 1.0–4.0 for the general region, a result roughly consistent with a gap jet having a long extension, and supercritical flows spilling down from higher elevation passes. The strong event is marked by the formation of a feature with a vertical cellular structure in the upstream entrance region of the Tokar Gap, a feature absent from the more moderate events that occur throughout the summer. The cell contains descending air parcels that are fed into the Tokar Gap and one of the neighboring gaps. An analysis of the Bernoulli function along air parcel trajectories reveals an approximate balance between the loss of potential energy and gain of internal energy and pressure, with surprisingly little contribution from kinetic energy, along the path of the descending flow. The winds in all gaps attain the critical wind speed nominally required to loft dust into the atmosphere, though only the Tokar Gap has a broad, silty delta region capable of supplying particulate matter for dust storms.

Download Full-text

A Field Study of Rough Shore-Fast Sea Ice

Journal of Glaciology ◽

10.3189/s0022143000005980 ◽

1984 ◽

Vol 30 (105) ◽

pp. 230-234

Author(s):

Thomas O’D ◽

S.J. Hanley

Keyword(s):

Temperature Gradient ◽

Sea Ice ◽

Large Deviations ◽

Field Study ◽

Chukchi Sea ◽

Ice Cover ◽

Strong Wind ◽

Cover Thickness

AbstractDuring December 1973 the initial smooth ice cover on the Chukchi Sea near Barrow, Alaska, broke away from the shore during a period of strong wind and was replaced by a cover of broken, rafted ice which remained for the rest of the winter. Cores pulled from this cover were examined visually, and the salinity and density of sections of the cores were measured. Temperatures at several depths in the ice were recorded continuously, and these are presented near the date when the temperature gradient changed sign. Despite large deviations probably due to the irregularity of the ice cover, thickness and salinity followed the patterns seen by other observers.

Download Full-text

Abundance and Structure of the Zooplankton Community During a Post-eruptive Process: The Case of the Submarine Volcano Tagoro (El Hierro; Canary Islands), 2013-2018

Frontiers in Marine Science ◽

10.3389/fmars.2021.692885 ◽

2021 ◽

Vol 8 ◽

Author(s):

María Luz Fernández de Puelles ◽

Magdalena Gazá ◽

Miguel Cabanellas-Reboredo ◽

Alba González-Vega ◽

Inma Herrera ◽

...

Keyword(s):

Mixing Layer ◽

Zooplankton Community ◽

Adaptive Strategy ◽

Species Number ◽

Zooplankton Abundance ◽

Calanoid Copepods ◽

Submarine Volcano ◽

Volcanic Emissions ◽

Mesozooplankton Community ◽

El Hierro

The mesozooplankton community was analyzed over a 6-year period (2013-2018) during the post-eruptive stage of the submarine volcano Tagoro, located south of the island of El Hierro (Canary Archipelago, Spain). Nine cruises from March 2013 to March 2018 were carried out in two different seasons, spring (March-April) and autumn (October). A high-resolution study was carried out across the main cones of Tagoro volcano, as well as a large number of reference stations surrounding El Hierro (unaffected by the volcano). The zooplankton community at the reference stations showed a high similarity with more than 85% of the variation in abundance and composition attributable to seasonal differences. Moreover, our data showed an increase in zooplankton abundance in waters affected by the volcano with a higher presence of non-calanoid copepods and a decline in the diversity of the copepod community, indicating that volcanic inputs have a significant effect on these organisms. Fourteen different zooplankton groups were found but copepods were dominant (79%) with 59 genera and 170 species identified. Despite the high species number, less than 30 presented a larger abundance than 1%. Oncaea and Clausocalanus were the most abundant genera followed by Oithona and Paracalanus (60%). Nine species dominated (>2%): O. media, O. plumifera, and O. setigera among the non-calanoids and M. clausi, P. nanus, P. parvus, C. furcatus, C. arcuicornis, and N. minor among the calanoids. After the initial low abundance of the copepods as a consequence of the eruption, an increase was observed in the last years of the study, where besides the small Paracalanus and Clausocalanus, the Cyclopoids seem to have a good adaptive strategy to the new water conditions. The increase in zooplankton abundance and the decline in the copepod diversity in the area affected by the volcano indicate that important changes in the composition of the zooplankton community have occurred. The effect of the volcanic emissions on the different copepods was more evident in spring when the water was cooler and the mixing layer was deeper. Further and longer research is recommended to monitor the zooplankton community in the natural laboratory of the Tagoro submarine volcano.

Download Full-text