Spatial links of phytoplankton abundance and community structure between shelf and slope waters off Oregon, USA

Abstract Coastal upwelling is known for inducing nearshore primary production, which can be advected to the offshore environment through offshore Ekman transport. However, this nearshore−offshore phytoplankton link has been less characterized at the community level. This study focuses on two shelf and slope sites off Oregon during years of 2013−2017 to examine the shelf−slope covariations in diatom and dinoflagellate abundance and community structure at seasonal and annual timescales. In general, the temporal changes of diatom and dinoflagellate abundance were coherent between shelf and slope. However, some differences were also noticeable. For example, diatom and dinoflagellate bloom magnitudes were higher in 2017 and 2014 on the shelf, but were higher in 2014−2016 at the slope. Diatom abundance had a stronger shelf−slope correlation than dinoflagellate correlation particularly in spring. The community structure was significantly correlated between shelf and slope during the annual upwelling period and in spring season. Ekman transport and nutrients played a significant role in shaping the diatom abundance and community structure temporal patterns at the slope. This shelf−slope correlation study infers that the benefits of nearshore upwelling blooms to the offshore food chains are season dependent and under high interannual variability.

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Nematode Community Structure Along a Mediterranean Shelf-slope Gradient

Marine Ecology ◽

10.1111/j.1439-0485.1995.tb00405.x ◽

1995 ◽

Vol 16 (3) ◽

pp. 189-206 ◽

Cited By ~ 21

Author(s):

K. Soetaert ◽

M. Vincx ◽

C. Heip

Keyword(s):

Community Structure ◽

Nematode Community ◽

Slope Gradient ◽

Shelf Slope

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SEASONAL PATTERN OF WIND INDUCED UPWELLING OVER JAVA-BALI SEA WATERS AND SURROUNDING AREA

International Journal of Remote Sensing and Earth Sciences (IJReSES) ◽

10.30536/j.ijreses.2008.v5.a1228 ◽

2010 ◽

Vol 5 (1) ◽

Author(s):

Siswanto ◽

Suratno

Keyword(s):

Wind Stress ◽

Coastal Upwelling ◽

Sea Water ◽

Mixed Layer Depth ◽

Surface Wind ◽

Ekman Transport ◽

Monsoon Circulation ◽

Wide Field ◽

Surrounding Area ◽

Noaa Avhrr

The influence of monsoonal wind to coastal upwelling mechanism which is generated by Ekman transport was studied here by analyzing wind stress curl (WSC) distribution over Java-Bali Sea waters and its surrounding area. Surface wind data were used as input data to calculate curl of wind stress in barotropic model. Confirmation with Corioli effect in the Southern Hemisphere, it could be known that negative curl value has relation with vertical motion of sea water as resulted by Ekman transport. Result of analysis showed that negative curl near coast over Java Sea which is stretching to Lombok Sea occurred in December to April when westerly wind of the North West Monsoon actives. It can be guidance and related with season of coastal upwelling in the region. Reversal condition, the occurrance of coastal upwelling in the south coast of JAva island related with the negative value of WSC that occurs since easterlies wind take place in May to August as a part of South East Monsoon episode. Generally, upwelling occurrance in the field of study is a response to the Monsoon circulation. This study with related data such as sea surface temperature, chlorophyll concetration and mixed layer depth that derived from satellite imaging data National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA-AVHRR), Aqua/Modis and sea viewing Wide Field-of-view Sensor(Sea WiFS) shows as magnificent confirmation pattern. So applying WSC to recoqnize upwelling zone is alternatively way as climatic approach to maps potential fertilizing of sea water in maritime-continent Indonesia. Key words: coastal upwelling, Ekman transport, Java-Bali Sea, Monsoon circulation, upwelling.

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Community structure and environmental factors affecting diatom abundance and diversity in a Mediterranean climate river system

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.152366 ◽

2021 ◽

pp. 152366

Author(s):

Tatenda Dalu ◽

Ross N. Cuthbert ◽

Olaf L.F. Weyl ◽

Ryan J. Wasserman

Keyword(s):

Community Structure ◽

Environmental Factors ◽

Mediterranean Climate ◽

River System ◽

Factors Affecting ◽

Diatom Abundance ◽

Abundance And Diversity

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The Connectivity of Nutrient Ratios on The Abundance of Phytoplankton Population In Jakarta Bay

E3S Web of Conferences ◽

10.1051/e3sconf/202014702012 ◽

2020 ◽

Vol 147 ◽

pp. 02012 ◽

Cited By ~ 1

Author(s):

Tumpak Sidabutar ◽

Endang S. Srimariana

Keyword(s):

Community Structure ◽

Strong Correlation ◽

Rainy Season ◽

Mesh Size ◽

Nutrient Ratios ◽

Phytoplankton Abundance ◽

Phytoplankton Population ◽

Very High

The frequency of algal bloom’s event has been increased in Jakarta Bay, recently. Most of the bloom events were tend to be reoccurred after the rainy season. The research was conducted from 2008 until 2015 to study the linkage of nutrients and the ratios on the growth of the phytoplankton population. Collecting samples were conducted using a canonical plankton net of 20 µm mesh size, 125 cm length and 30 cm diameter of the opening mouth. The results of the study showed that the concentration of phosphate in the waters ranged from 0.01-12.5 µg/l (average 4.58 µg/l) and nitrate ranged from 0.01-15.89 µg/l (average 0.72 µg/l). The N/P ratio during the study ranging from 0.2 up to 45.4. High ratios of nutrients were mostly recorded in 2010 where the overall abundance of phytoplankton is very high. There is a strong correlation of N/P ratio with the community structure or composition of the phytoplankton population. The variability of phytoplankton abundance appears to be related to nutrient ratios of nitrate and phosphate.

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Seasonal variability of the Ekman transport and pumping in the upwelling system off central-northern Chile (∼  30° S) based on a high-resolution atmospheric regional model (WRF)

Ocean Science ◽

10.5194/os-12-1049-2016 ◽

2016 ◽

Vol 12 (5) ◽

pp. 1049-1065 ◽

Cited By ~ 17

Author(s):

Luis Bravo ◽

Marcel Ramos ◽

Orlando Astudillo ◽

Boris Dewitte ◽

Katerina Goubanova

Keyword(s):

High Resolution ◽

Wind Stress ◽

Seasonal Variability ◽

Coastal Upwelling ◽

Ekman Transport ◽

Northern Chile ◽

Ekman Pumping ◽

Relative Contribution ◽

Alongshore Wind Stress ◽

Alongshore Wind

Abstract. Two physical mechanisms can contribute to coastal upwelling in eastern boundary current systems: offshore Ekman transport due to the predominant alongshore wind stress and Ekman pumping due to the cyclonic wind stress curl, mainly caused by the abrupt decrease in wind stress (drop-off) in a cross-shore band of 100 km. This wind drop-off is thought to be an ubiquitous feature in coastal upwelling systems and to regulate the relative contribution of both mechanisms. It has been poorly studied along the central-northern Chile region because of the lack in wind measurements along the shoreline and of the relatively low resolution of the available atmospheric reanalysis. Here, the seasonal variability in Ekman transport, Ekman pumping and their relative contribution to total upwelling along the central-northern Chile region (∼  30° S) is evaluated from a high-resolution atmospheric model simulation. As a first step, the simulation is validated from satellite observations, which indicates a realistic representation of the spatial and temporal variability of the wind along the coast by the model. The model outputs are then used to document the fine-scale structures in the wind stress and wind curl in relation to the topographic features along the coast (headlands and embayments). Both wind stress and wind curl had a clear seasonal variability with annual and semiannual components. Alongshore wind stress maximum peak occurred in spring, second increase was in fall and minimum in winter. When a threshold of −3  ×  10−5 s−1 for the across-shore gradient of alongshore wind was considered to define the region from which the winds decrease toward the coast, the wind drop-off length scale varied between 8 and 45 km. The relative contribution of the coastal divergence and Ekman pumping to the vertical transport along the coast, considering the estimated wind drop-off length, indicated meridional alternation between both mechanisms, modulated by orography and the intricate coastline. Roughly, coastal divergence predominated in areas with low orography and headlands. Ekman pumping was higher in regions with high orography and the presence of embayments along the coast. In the study region, the vertical transport induced by coastal divergence and Ekman pumping represented 60 and 40 % of the total upwelling transport, respectively. The potential role of Ekman pumping on the spatial structure of sea surface temperature is also discussed.

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The El Nino-Southern Oscillation in south-eastern Australian waters

Marine and Freshwater Research ◽

10.1071/mf9910263 ◽

1991 ◽

Vol 42 (3) ◽

pp. 263 ◽

Cited By ~ 10

Author(s):

WW Hsieh ◽

BV Hamon

Keyword(s):

Sea Level ◽

Coastal Upwelling ◽

Southern Oscillation ◽

Geostrophic Wind ◽

Air Pressure ◽

Ekman Transport ◽

Hydrographic Data ◽

South Eastern ◽

Eastern Australia ◽

South Eastern Australia

Using four decades of hydrographic data collected off the coast near Sydney, New South Wales, and sea-level data at Sydney, we studied the interannual variability in south-eastern Australian shelf waters. The first two empirical orthogonal function (EOF) modes of the band-pass-filtered 50-m-depth hydrographic data (temperature, T; salinity, S; nitrate, N; inorganic phosphate, P; and oxygen, O) and the sea level (SL) and adjusted sea level (ASL) data accounted respectively for 51 and 27% of the total variance. Both modes were significantly correlated with the Southern Oscillation Index (SOI). The first mode, with T, S, O and ASL varying in opposition to N and P, represented the internal or baroclinic response, associated with vertical displacements of the isopycnals. The second mode, with large in-phase fluctuations in SL and ASL but small changes in the hydrographic variables, represented mainly the external or barotropic response during the El Niiio-Southern Oscillation (ENSO). Three-year composites centred around seven ENSO warm episodes revealed that T, S, O and ASL were generally low and N, P, SL and SO1 were high in the year before each ENSO warm episode, but the former group rose while the latter group dropped in the year of the warm episode. The changes in the hydrographic variables at 50 m depth were consistent with relatively shallow isopycnals in the year before the ENSO warm episode, followed by a deepening of the isopycnals during the warm episode. Estimates of this downward displacement of isopycnals, as determined from T, N, P and O, were in the range 7-10 m. The geostrophic wind arising from the pressure fluctuations during ENSO is proposed as a probable cause for the vertical displacement of the isopycnals. In the year before the warm episode, the low air pressure over Australia would produce a clockwise geostrophic wind around south-eastern Australia, generating offshore Ekman transport and coastal upwelling. During the warm episode, air pressure over Australia rises, the geostrophic wind reverses, and downward movement of the isopycnals would occur off south-eastern Australia.

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