The water masses of the east coast of Tasmania: Seasonal and interannual variability and the influence on phytoplankton biomass and productivity

1987 ◽  
Vol 38 (5) ◽  
pp. 569 ◽  
Author(s):  
G Harris ◽  
C Nilsson ◽  
L Clementson ◽  
D Thomas
Keyword(s):  
Interannual Variability ◽  
Primary Productivity ◽  
Phytoplankton Biomass ◽  
Seasonal Cycle ◽  
East Coast ◽  
Spring Bloom ◽  
Water Masses ◽  
Seasonal And Interannual Variability ◽  
Summer Temperatures

The seasonal and interannual variability of the water masses, nutrients, phytoplankton biomass and primary productivity of the waters off the eastern coast of Tasmania are described. The seasonal and interannual variability in the water masses on the east coast could be explained by the varying influence of tropical and subantarctic waters and the presence of the northern edge of the subtropical convergence north-east from Maria Island. The physical oceanography was dominated by mesoscale events and the influence of the two parent water masses was highly episodic. Subtropical water rarely extended as far south as Tasman Island in summer and subantarctic water never extended as far north as Flinders Island. Data from satellite Advanced Very High Resolution Radiometer (AVHRR) images confirmed the hydrographic data and were used to interpret the seasonal and interannual variability. Interannual variability in maximum summer temperatures at Maria Island was correlated with the southerly extension of subtropical waters and with El Nino/Southern Oscillation events at least until the mid-1970s. There was evidence of a long-term warming at Maria Island and a cyclic fluctuation of 10-15 years in smoothed maximum summer temperatures. The decline in nitrate, and hence the phytoplankton spring bloom, occurred a month earlier inshore than offshore. Long-term data records from the inshore station at Maria Island showed strong interannual changes in the timing of the nitrate decline. The timing of the spring bloom varied from year to year by as much as 4 months. The seasonal cycle of phytoplankton biomass in 1984 and 1985 showed spring (October) and autumnal (April) blooms, with an early summer bloom in December. Low chlorophyll levels in February and March coincided with the influence of subtropical water. The seasonal cycle of phytoplankton biomass was therefore a complex function of seasonal and episodic events. Primary productivity data from the spring of 1984 showed low productivity on the west coast of Tasmania but high productivity on the east coast around Maria Island and the islands in Bass Strait.

The seasonal cycle of phytoplankton biomass and primary productivity in the Ross Sea, Antarctica

2000 ◽  
Vol 47 (15-16) ◽  
pp. 3119-3140 ◽  
Author(s):  
Walker O Smith ◽  
John Marra ◽  
Michael R Hiscock ◽  
Richard T Barber
Keyword(s):  
Primary Productivity ◽  
Phytoplankton Biomass ◽  
Seasonal Cycle ◽  
Ross Sea

scholarly journals Variability of ice conditions of the Bering sea and assessment of the possibility of their modelling

2019 ◽  
Vol 59 (6) ◽  
pp. 920-927
Author(s):  
V. V. Plotnikov ◽  
N. M. Vakulskaya ◽  
V. A. Dubina
Keyword(s):  
Sea Ice ◽  
Interannual Variability ◽  
Bering Sea ◽  
Ice Cover ◽  
Practical Application ◽  
Seasonal And Interannual Variability ◽  
Proposed Model ◽  
Ice Conditions ◽  
The Bering Sea

Various aspects of seasonal and interannual variability of the sea ice cover are estimated on the basis of all available the Bering Sea ice data from 1960 to 2017. The possibility of long-term and superlong-term modeling of the ice cover is investigated. Results of tests are given, and a conclusion about prospects of the proposed model and an opportunity of its practical application is done.

scholarly journals Downward fluxes of sinking particulate matter in the deep Ionian Sea (NESTOR site), eastern Mediterranean: seasonal and interannual variability

2013 ◽  
Vol 10 (11) ◽  
pp. 7235-7254 ◽  
Author(s):  
S. Stavrakakis ◽  
A. Gogou ◽  
E. Krasakopoulou ◽  
A. P. Karageorgis ◽  
H. Kontoyiannis ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Primary Production ◽  
Interannual Variability ◽  
Primary Productivity ◽  
Mass Flux ◽  
Total Mass ◽  
Sediment Traps ◽  
Ionian Sea ◽  
Seasonal And Interannual Variability

Abstract. In order to assess seasonal and interannual variability in the export of particulate matter and its main constituents, sediment traps were deployed at five successive depths from February 2006 to March 2010 in the deepest basin of the Mediterranean (SE Ionian Sea, NESTOR site). The average total mass fluxes were 66, 58, 54, 34, and 52 mg m−2 d−1, at 700, 1200, 2000, 3200, and 4300 m, respectively. The temporal variations of the mass flux showed similar seasonal signal at all sampling depths with higher values in spring–summer and lower in autumn–winter. Changes in the main constituents of the mass flux (organic carbon, carbonates, opal, and lithogenic matter) largely followed the same temporal variability with total mass flux, revealing mechanisms of rapid vertical (top-down) transport from 700 m down to 4300 m depth. Lateral inputs at the deepest trap are probably of importance, attributed to the influence of the deep Adriatic water, characterized by relatively higher turbidity than overlying water masses. Two major processes seem to control the seasonal mass flux variability: (a) primary productivity at the euphotic zone; and (b) episodic dust input events. Primary productivity shows two maxima during late winter/early spring and late spring/summer, as witnessed by the organic carbon, carbonate, and opal fluxes in the mesopelagic and bathypelagic layers, whereas the influence of dust inputs is evidenced by enhanced lithogenic fluxes occurring during spring and summer. The interannual variability generally shows a gradual increase of fluxes during the time frame of the experiment. Both seasonal and interannual variability of mass flux are associated with variations in the intensity and position of the neighboring Pelops anticyclonic gyre, which appears to affect the upwelling of intermediate, nutrient-rich waters and subsequently the surface productivity. Combination of estimated satellite and algorithm-generated primary production data for the Ionian Sea, calculated POC fluxes out of the euphotic layer and POC fluxes measured by sediment traps at the mesopelagic and bathypelagic layers of NESTOR site during our 4 yr experiment, reveal that only a small portion of primary production (0.46%) reaches at 3200 m, corresponding to a mean annual carbon export of 1.12 g C m−2 yr−1.

scholarly journals Long-Term Trends and Impact of SARS-CoV-2 COVID-19 Lockdown on the Primary Productivity of the North Indian Ocean

2021 ◽  
Vol 8 ◽  
Author(s):  
N. Sunanda ◽  
J. Kuttippurath ◽  
R. Peter ◽  
Kunal Chakraborty ◽  
A. Chakraborty
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Primary Productivity ◽  
Virus Disease ◽  
North Indian Ocean ◽  
Chl A ◽  
The North ◽  
Biogeochemical Models ◽  
The Impact

COrona VIrus Disease (COVID) 2019 pandemic forced most countries to go into complete lockdown and India went on complete lockdown from 24th March 2020 to 8th June 2020. To understand the possible implications of lockdown, we analyze the long-term distribution of Net Primary Productivity (NPP) in the North Indian Ocean (NIO) and the factors that influence NPP directly and indirectly, for the period 2003–2019 and 2020 separately. There exists a seasonal cycle in the relationship between Aerosol Optical Depth (AOD), Chlorophyll-a (Chl-a) and NPP in agreement with the seasonal transport of aerosols and dust into these oceanic regions. In Arabian Sea (AS), the highest Chl-a (0.58 mg/m3), NPP (696.57 mg/C/m2/day) and AOD (0.39) are observed in June, July, August, and September (JJAS). Similarly, maximum Chl-a (0.48 mg/m3) and NPP (486.39 mg/C/m2/day) are found in JJAS and AOD (0.27) in March, April, and May (MAM) in Bay of Bengal. The interannual variability of Chl-a and NPP with wind speed and Sea Surface Temperature (SST) is also examined, where the former has a positive and the latter has a negative feedback to NPP. The interannual variability of NPP reveals a decreasing trend in NPP, which is interlinked with the increasing trend in SST and AOD. The analysis of wind, SST, Chl-a, and AOD for the pre-lockdown, lockdown, and post lockdown periods of 2020 is employed to understand the impact of COVID-19 lockdown on NPP. The assessment shows the reduction in AOD, decreased wind speeds, increased SST and reduced NPP during the lockdown period as compared to the pre-lockdown, post-lockdown and climatology. This analysis is expected to help to understand the impact of aerosols on the ocean biogeochemistry, nutrient cycles in the ocean biogeochemical models, and to study the effects of climate change on ocean ecosystems.

scholarly journals Seasonal and Interannual Variability of Satellite-Derived Chlorophyll-a (2003-2019) in Lampung waters and surrounding area

2021 ◽  
Vol 925 (1) ◽  
pp. 012025
Author(s):  
A T Atmojo ◽  
I P Anwar ◽  
I Adil ◽  
A Rohman
Keyword(s):  
Interannual Variability ◽  
Chlorophyll A ◽  
East Coast ◽  
Remote Sensing Data ◽  
Marine Phytoplankton ◽  
Surrounding Area ◽  
Chl A ◽  
Seasonal And Interannual Variability ◽  
Maximum Value ◽  
Phytoplankton Blooming

Abstract In recent years, the phytoplankton blooming phenomenon occurred at Lampung Waters. This event harms living organisms due to its toxicity or caused oxygen depletion. Chlorophyll-a concentration (Chl-a) is the crucial biological parameter for simulating marine phytoplankton biomass. In this study, the monthly average of Chl-a ocean-color remote sensing data from 2003 to 2019 is investigated. The seasonal and interannual variability of Chl-a was analyzed in Lampung waters and its surrounding area. The study area was separated into three regions, namely the East Coast of Lampung waters, Lampung Bay and Sunda Strait area. The spatial pattern showed that the value of Chl-a on the east coast was higher than Lampung Bay and Sunda Strait, with a deal up to 7 mg/mg/m 3. The time series of spatial averages in three areas showed the seasonal and inter-annual variation. The monthly climatology of Chl-a in Lampung Bay more influenced by sea surface temperature. The maximum value occurs in October with Chl-a concentration was 0,87 mg/m 3. Meanwhile, the east coast area and Sunda Strait fit with the monthly rainfall pattern in the Lampung mainland. The maximum value occurs in February with Chl-a abundance were 2,49 mg/m 3 and 0,96 mg/m 3, respectively. The value indicated that the river runoff would be a significant impact on phytoplankton blooming. Otherwise, the interannual variability in three areas showed that the Lampung Bay was more influenced by Indian Ocean Dipole than the East Coast and Sunda Strait. The cross-correlation between Chl-a concentration and Dipole Mode Index in East Coast area, Lampung Bay, and Sunda Straits are -0.2, 0.5, and 0,1, with a significant level of 95%.

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