Decadal Patterns of Westerly Winds, Temperatures, Ocean Gyre Circulations and Fish Abundance: A Review

The paper presents a numerical modeling study aimed at a preliminary assessment of the impact of the planned sea outfall of the city of Limassol, Cyprus, on the waters of Akrotiri bay. First the local meteorological and oceanographic conditions as well as the loading characteristics are briefly reviewed. Two-dimensional finite element hydrodynamic and dispersion models are subsequently applied to the study area. The results of the former show an eastbound flow pattern under the prevailing westerly winds, in general agreement with available field observations. The spread of BOD and N under continuous loading is then examined for eastward as well as for westward flow as an indicator for the extent of pollution to be expected. The computed concentrations are generally low and confined to the shallower parts of the bay.

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Conservation of the critically endangered Achondrostoma occidentale (Pisces: Cyprinidae): integrating habitat data in restocking programs to improve population recovery

Gaia Scientia ◽

10.21707/gs.v10.n02a01 ◽

2016 ◽

Vol 10 (2) ◽

pp. 1-9

Author(s):

D. Mameri ◽

C. Sousa Santos ◽

M. F. Magalhães ◽

J. I. Robalo

Keyword(s):

Iberian Peninsula ◽

River Basins ◽

Fish Abundance ◽

Critically Endangered ◽

Ex Situ ◽

Population Recovery ◽

Age Classes ◽

Younger Age ◽

Risk Of Extinction

Cyprinid fauna endemic to the Iberian Peninsula is currently facing several human-caused threats which enhance their risk of extinction. The populations of the critically endangered Achondrostoma occidentale, occurring only in three small and intermittent Portuguese river basins, have been reinforced with fish bred ex-situ in order to minimize their risk of extinction. This study aimed to describe the restocking actions conducted and to identify and characterize the summer refugia that should become targets for restoration and further restocking. The results evidence population increments and a high representativeness of younger age classes in the restocked populations. The importance of annual monitoring of fish abundance to assess how the species is coping with the stochastic and deterministic stressors that may eventually compromise its survival is highlighted.

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Identification and inventory of reef fish abundance in West Simeulue MPA, Aceh, Indonesia

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/674/1/012032 ◽

2021 ◽

Vol 674 (1) ◽

pp. 012032

Author(s):

M Ulfah ◽

R K Isfani ◽

Indra ◽

I N Turnip ◽

R Dirgantara

Keyword(s):

Reef Fish ◽

Fish Abundance

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Assessment of the Impact of Small Hydropower Plants on the Ecological Status Indicators of Water Bodies: A Case Study in Lithuania

Water ◽

10.3390/w13040433 ◽

2021 ◽

Vol 13 (4) ◽

pp. 433

Author(s):

Laima Česonienė ◽

Midona Dapkienė ◽

Petras Punys

Keyword(s):

Water Quality ◽

Benthic Macroinvertebrates ◽

Suspended Solids ◽

Ecological Status ◽

Fish Abundance ◽

Water Bodies ◽

Small Hydropower ◽

Hydropower Plants ◽

Physico Chemical ◽

The Impact

Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices.

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A palaeoenvironmental record of the Southern Hemisphere last glacial maximum from the Mount Cass loess section, North Canterbury, Aotearoa/New Zealand

Quaternary Research ◽

10.1017/qua.2020.95 ◽

2020 ◽

pp. 1-15

Author(s):

Peter C. Almond ◽

Sándor Gulyás ◽

Pál Sümegi ◽

Balázs P. Sümegi ◽

Stephen Covey-Crump ◽

...

Keyword(s):

New Zealand ◽

Southern Hemisphere ◽

Last Glacial Maximum ◽

Climatic Variability ◽

Glacial Maximum ◽

Pollen Record ◽

Good Correspondence ◽

Last Glacial ◽

Event Stratigraphy ◽

Westerly Winds

Abstract Calcareous loess in North Canterbury, eastern South Island, New Zealand (NZ), preserves subfossil bird bone, terrestrial gastropods, and eggshell, whose abundances and radiocarbon ages allowed us to reconstruct aspects of palaeoenvironment at high resolution through 25 to 21 cal ka BP. This interval includes millennial-scale climatic variability during the extended last glacial maximum (30–18 ka) of Australasia. Our loess palaeoclimatic record shows good correspondence with stadial and interstadial climate events of the NZ Climate Event Stratigraphy, which were defined from a pollen record on the western side of South Island. An interstade from 25.4 to 24 cal ka BP was warm but also relatively humid on eastern South Island, and loess grain size may indicate reduced vigour of the Southern Hemisphere westerly winds. The subsequent stade (24–22.6 cal ka BP) was drier, colder, and probably windier. The next interstade remained relatively dry on eastern South Island, and westerly winds remained vigorous. The 25.4–24 ka interstade is synchronous with Heinrich stade 2, which may have driven a southward migration of the subtropical front, leading to warming and wetting of northern and central South Island and retreat of Southern Alps glaciers at ca. 26.5 ka.

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The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

Journal of Climate ◽

10.1175/jcli-d-19-0364.1 ◽

2020 ◽

Vol 33 (6) ◽

pp. 2111-2130

Author(s):

Woo Geun Cheon ◽

Jong-Seong Kug

Keyword(s):

Ocean Circulation ◽

North Atlantic ◽

North Pacific ◽

Global Ocean ◽

The North ◽

Westerly Winds ◽

The North Atlantic ◽

Global Ocean Circulation ◽

The Antarctic ◽

The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

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The Variability of the Indian–East Asian Summer Monsoon Interface in Relation to the Spring Seesaw Mode between the Indian Ocean and the Central-Western Pacific

Journal of Climate ◽

10.1175/jcli-d-15-0839.1 ◽

2016 ◽

Vol 29 (13) ◽

pp. 5027-5040 ◽

Cited By ~ 7

Author(s):

Jie Cao ◽

Shu Gui ◽

Qin Su ◽

Yali Yang

Keyword(s):

Indian Ocean ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

General Circulation ◽

Asian Summer Monsoon ◽

East Asian ◽

Western Pacific ◽

Observational Analysis ◽

Westerly Winds ◽

Asian Summer

Abstract The interannual zonal movement of the interface between the Indian summer monsoon and the East Asian summer monsoon (IIE), associated with the spring sea surface temperature (SST) seesaw mode (SSTSM) over the tropical Indian Ocean (TIO) and the tropical central-western Pacific (TCWP), is studied for the period 1979–2008. The observational analysis is based on Twentieth Century Reanalysis data (version 2) of atmospheric circulations, Extended Reconstructed SST data (version 3), and the Climate Prediction Center Merged Analysis of Precipitation. The results indicate that the IIE’s zonal movement is significantly and persistently correlated with the TIO–TCWP SSTSM, from spring to summer. The results of two case studies resemble those obtained by regression analysis. Experiments using an atmospheric general circulation model (ECHAM6) substantiate the key physical processes revealed in the observational analysis. When warmer (colder) SSTs appear in the TIO and colder (warmer) SSTs occur in the TCWP, the positive (negative) SSTSM forces anomalous easterly (westerly) winds over the Bay of Bengal (BOB), South China Sea (SCS), and western North Pacific (WNP). The anomalous easterly (westerly) winds further result in a weakened (strengthened) southwest summer monsoon over the BOB and a strengthened (weakened) southeast summer monsoon over the SCS and WNP. This causes the IIE to shift farther eastward (westward) than normal.

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Barotropic variability in the presence of an ocean gyre

Journal of Marine Research ◽

10.1357/002224090784984588 ◽

1990 ◽

Vol 48 (1) ◽

pp. 37-53 ◽

Cited By ~ 2

Author(s):

Richard J. Greatbatch ◽

Jin Li

Keyword(s):

Ocean Gyre

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