scholarly journals Dynamics of phytoplankton productivity and exopolysaccharides (EPS and TEP) pools in the Seine Estuary (France, Normandy) over tidal cycles and over two contrasting seasons

2017 ◽  
Vol 131 ◽  
pp. 162-176 ◽  
Author(s):  
Jérôme Morelle ◽  
Mathilde Schapira ◽  
Pascal Claquin
Keyword(s):  
Seine Estuary ◽  
Phytoplankton Productivity ◽  
Tidal Cycles

Electron Microscopy in the Study of Natural Phytoplankton Assemblages

1985 ◽  
Vol 43 ◽  
pp. 620-623
Author(s):  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Aquatic Environment ◽  
Size Range ◽  
Physical Parameters ◽  
Specific Information ◽  
Phytoplankton Assemblages ◽  
Phytoplankton Productivity ◽  
Ecosystem Effects ◽  
Time Of Year ◽  
Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

scholarly journals Transfer dynamics of macroplastics in estuaries – New insights from the Seine estuary: Part 3. What fate for macroplastics?

2021 ◽  
Vol 169 ◽  
pp. 112513
Author(s):  
R. Tramoy ◽  
J. Gasperi ◽  
L. Colasse ◽  
C. Noûs ◽  
B. Tassin
Keyword(s):  
Seine Estuary

scholarly journals Arctic Ocean stratification set by sea level and freshwater inputs since the last ice age

2021 ◽  
Author(s):  
Jesse R. Farmer ◽  
Daniel M. Sigman ◽  
Julie Granger ◽  
Ona M. Underwood ◽  
François Fripiat ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Surface Waters ◽  
Ice Age ◽  
The Arctic ◽  
Bering Strait ◽  
Central Arctic Ocean ◽  
Phytoplankton Productivity ◽  
Nitrate Consumption ◽  
Western Arctic ◽  
Last Ice Age

AbstractSalinity-driven density stratification of the upper Arctic Ocean isolates sea-ice cover and cold, nutrient-poor surface waters from underlying warmer, nutrient-rich waters. Recently, stratification has strengthened in the western Arctic but has weakened in the eastern Arctic; it is unknown if these trends will continue. Here we present foraminifera-bound nitrogen isotopes from Arctic Ocean sediments since 35,000 years ago to reconstruct past changes in nutrient sources and the degree of nutrient consumption in surface waters, the latter reflecting stratification. During the last ice age and early deglaciation, the Arctic was dominated by Atlantic-sourced nitrate and incomplete nitrate consumption, indicating weaker stratification. Starting at 11,000 years ago in the western Arctic, there is a clear isotopic signal of Pacific-sourced nitrate and complete nitrate consumption associated with the flooding of the Bering Strait. These changes reveal that the strong stratification of the western Arctic relies on low-salinity inflow through the Bering Strait. In the central Arctic, nitrate consumption was complete during the early Holocene, then declined after 5,000 years ago as summer insolation decreased. This sequence suggests that precipitation and riverine freshwater fluxes control the stratification of the central Arctic Ocean. Based on these findings, ongoing warming will cause strong stratification to expand into the central Arctic, slowing the nutrient supply to surface waters and thus limiting future phytoplankton productivity.

scholarly journals Decadal increase in Arctic dimethylsulfide emission

2019 ◽  
Vol 116 (39) ◽  
pp. 19311-19317 ◽  
Author(s):  
Martí Galí ◽  
Emmanuel Devred ◽  
Marcel Babin ◽  
Maurice Levasseur
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Positive Trend ◽  
Aerosol Formation ◽  
Atmospheric Measurements ◽  
Sea Ice Extent ◽  
Phytoplankton Productivity ◽  
Physical Forcing ◽  
Ice Retreat ◽  
Aerosol Cloud Interactions

Dimethylsulfide (DMS), a gas produced by marine microbial food webs, promotes aerosol formation in pristine atmospheres, altering cloud radiative forcing and precipitation. Recent studies suggest that DMS controls aerosol formation in the summertime Arctic atmosphere and call for an assessment of pan-Arctic DMS emission (EDMS) in a context of dramatic ecosystem changes. Using a remote sensing algorithm, we show that summertime EDMS from ice-free waters increased at a mean rate of 13.3 ± 6.7 Gg S decade−1 (∼33% decade−1) north of 70°N between 1998 and 2016. This trend, mostly explained by the reduction in sea-ice extent, is consistent with independent atmospheric measurements showing an increasing trend of methane sulfonic acid, a DMS oxidation product. Extrapolation to an ice-free Arctic summer could imply a 2.4-fold (±1.2) increase in EDMS compared to present emission. However, unexpected regime shifts in Arctic geo- and ecosystems could result in future EDMS departure from the predicted range. Superimposed on the positive trend, EDMS shows substantial interannual changes and nonmonotonic multiyear trends, reflecting the interplay between physical forcing, ice retreat patterns, and phytoplankton productivity. Our results provide key constraints to determine whether increasing marine sulfur emissions, and resulting aerosol–cloud interactions, will moderate or accelerate Arctic warming in the context of sea-ice retreat and increasing low-level cloud cover.

scholarly journals Nutrient dynamics in the Sundarbans mangrove estuarine system of Bangladesh under different weather and tidal cycles

2013 ◽  
Vol 2 (1) ◽  
Author(s):  
Shak Md Bazlur Rahaman ◽  
Lipton Sarder ◽  
Md Sayadur Rahaman ◽  
Alokesh Kumar Ghosh ◽  
Sudhin Kumar Biswas ◽  
...  
Keyword(s):  
Nutrient Dynamics ◽  
Estuarine System ◽  
Tidal Cycles ◽  
Sundarbans Mangrove ◽  
The Sundarbans

scholarly journals Responses of lower trophic-level organisms to typhoon passage on the outer shelf of the East China Sea: an incubation experiment

2013 ◽  
Vol 10 (4) ◽  
pp. 6605-6635 ◽  
Author(s):  
N. Yasuki ◽  
K. Suzuki ◽  
A. Tsuda
Keyword(s):  
Water Column ◽  
East China Sea ◽  
Trophic Level ◽  
Outer Shelf ◽  
East China ◽  
Strong Wind ◽  
The East China Sea ◽  
Phytoplankton Productivity ◽  
China Sea ◽  
Lower Trophic Level

Abstract. Typhoons can induce vertical mixing, upwelling, or both in the water column due to strong wind stress. These events can induce phytoplankton blooms in the oligotrophic ocean after typhoon passage. However, little is known about the responses of lower trophic-level organisms or changes in the community structure following the passage of typhoons, particularly in offshore regions. Therefore, we evaluated community succession on the outer shelf of the East China Sea through on-deck bottle incubation experiments simulating hydrographic conditions after the passage of a typhoon. Under all of the experimental conditions we tested, chlorophyll a concentrations increased more than 9-fold within 6 days, and these algal cells were mainly composed of large diatoms (>10 μm). Ciliates also increased along with the diatom bloom. These results suggest that increases in diatom and ciliate populations may enhance biogenic carbon export in the water column. Typhoons can affect not only phytoplankton productivity, but also the composition of lower trophic-level organisms and biogeochemical processes in oligotrophic offshore regions.

Sign in / Sign up

Export Citation Format

Share Document