Upwelling Research Papers

Page 1. BULLETIN OF MARINE SCIENCE, 69(1): 151169, 2001 151 CORAL BLEACHING AND MORTALITY ASSOCIATED WITH THE 199798 EL NIÑO IN AN UPWELLING ENVIRONMENT IN THE EASTERN PACIFIC (GULF OF PAPAGAYO, COSTA RICA) ...

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- by Carlos Jimenez
- •
- 3
  Coral Reef, Upwelling, El Nino

The upwelling system off the southern Caribbean coast is probably the main source of the nutrients that support biological productivity in the oligotrophic Caribbean Sea. Subtropical underwater (SUW) that forms the sub-surface salinity... more

The upwelling system off the southern Caribbean coast is probably the main source of the nutrients that support biological productivity in the oligotrophic Caribbean Sea. Subtropical underwater (SUW) that forms the sub-surface salinity maximum in the Caribbean Sea is the main source of upwelled waters in this system. Profiles of salinity and temperature with depth derived from four oceanographic cruises and Argo floats showed that upwelled waters have a salinity that is ~0.11 g kg À 1 lower than the SUW in the central Caribbean Sea and a seasonal variation of approximately 0.09 g kg À 1 that reflects the rainy/dry seasons. In addition, the SUW is ~50 m shallower on the continental shelf slope (~100 m) compared to the depth of the SUW in the central Caribbean Sea. The origin of these modified SUW was analyzed using the Mercator numerical model, which reproduces the main vertical characteristics of the subsurface salinity maximum. The modeled data showed that SUW upwelling off of the La Guajira Peninsula and Venezuela arrive into the system via an intense Caribbean Coastal Undercurrent (CaCU, mean speed ~0.28 m s À 1). This current is formed in front of the Nicaragua platform from the divergence of subsurface water flow at the salinity maximum depth. The lower salinity observed in the upwelled waters may be the result of intense vertical mixing processes that could occur when the SUW are transported by the CaCU below the Panama-Colombia Gyre (PCG) region before reaching the upwelling zones. The mixing processes-involving double diffusion and mechanical turbulence driven by vertical shear of horizontal currents-were analyzed using the Turner Angle and the Thorpe scale, respectively. Below a depth of 200 m, double diffusion by salt fingers (diffusivities > 5 x 10 À 5 m 2 s À 1) was the main process of salt diffusion, generating a downward salt flux of >2 x 10 À 2 g kg À 1 m d À 1 between the SUW and the North Atlantic Central Waters (NACW). Above a depth of 100 m, mechanical turbulent diffusion generates a salt flux towards the surface ranging 0.5-4 x 10 À 2 g kg À 1 m d À 1 , where double diffusion by salt finger is not possible. The diluted SUW is subsequently transported by the CaCU, connecting-at the subsurface level-the PCG region with the upwelling zones off of Colombia and Venezuela. As well as modifying the salt content of the coastal SUW, these mixing processes may also alter the nutrient content of upwelling waters, the ecosystem effects of which are still unknown.

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- by Marco Correa and +1
  Marco Correa-Ramirez
- •
- Upwelling

Upwelling occurs on several coasts of the world, but it has mostly been studied on eastern ocean boundaries. We investigated upwelling on a western ocean boundary for which limited information exists. Using daily in-situ data on sea... more

Using the long-term wind time series, coastal upwelling was investigated in the northern Persian Gulf. The shoreline was divided into 34 segments from NW to SE and the daily Ekman transport components were computed. Based on the Ekman... more

ABSTRACT Earth’s most extreme extinction event near the end of the Late Permian decimated more than 90% of all extant marine species. Widespread and intensive oceanic anoxia almost certainly contributed to the catastrophe, though the... more

ABSTRACT Earth’s most extreme extinction event near the end of the Late Permian decimated more than 90% of all extant marine species. Widespread and intensive oceanic anoxia almost certainly contributed to the catastrophe, though the driving mechanisms that sustained such conditions are still debated. Of particular interest is whether water column anoxia was a consequence of a ‘stagnant ocean’, or if it was controlled by increases in nutrient supply, primary productivity, and subsequent heterotrophic respiration. Testing these competing hypotheses requires deconvolving sedimentary/bottom water redox conditions from changes in surface water productivity in marine sediments. We address this issue by studying marine shales from East Greenland and the mid-Norwegian shelf and combining sedimentary redox proxies with cadmium-isotopic analyses. Sedimentary nitrogen-isotopic data, pyrite framboid analyses, and organic and inorganic shale geochemistry reveal sulfidic conditions with vigorous upwelling, and increasingly anoxic conditions with a strengthening upwelling in the Greenland and Norwegian sections, respectively. Detailed analysis of sedimentary metal budgets illustratesthat Cd is primarily associated with organic carbon and records primary geochemical signatures, thus enabling reconstruction of surface water nutrient utilization. Cadmium-isotopic analyses of the authigenic shale fraction released by inverse aqua regia digestion yield an average δ114/110Cd of +0.15 ± 0.01‰ (2 SE, n =12; rel. NIST SRM 3108), indicative of incomplete surface water nutrient utilization up-section. The constant degree of nutrient utilization combined with strong upwelling requires increasing primary productivity – and not oceanic stagnation – to balance the larger nutrient fluxes to both study sites during the development of the Late Permian water column anoxia. Overall, our data illustrate that if bottom water redox and upwelling can be adequately constrained, Cd-isotopic analyses of organic-rich sediments can be used to provide valuable information on nutrient utilization and therefore past productivity.

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Corals of the eastern tropical Pacific live in a marginal and oceanographically dynamic environment. Along the Pacific coast of Panamá, stronger seasonal upwelling in the Gulf of Panamá in the east transitions to weaker upwelling in the... more

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Sixteen years of sea surface temperature (SST, 1994-2009) were used to characterize the southern Caribbean upwelling system. This system extends from 61-75.51W and 10-12.51N, with 21 upwelling foci clustered in seven groups differentiated... more

Five oceanographic cruises were made between November 2005 and June 2006, sampling a cross-shelf transect off the South Brazilian Bight (SBB; 26146 0 S) to follow the seasonal development of the South Atlantic Central Water (SACW)... more

Wind-driven coastal hypoxia represents an environmental stressor that has the potential to drive redistribution of gilled marine organisms, and thereby indirectly affect the foraging characteristics of air-breathing upper trophic-level... more

... When examined by light microscopy, these proto-kerogen concentrates appear almost exclusively composed of amorphous organic matter (AOM) associated with pyrite. ... Three types of AOM can be distinguished, based on differences in... more

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The California Current System is described in its regional setting using two modern datasets. Argo provides a broadscale view of the entire eastern North Pacific Ocean for the period 2004–2010, and the High Resolution XBT Network includes... more

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- by Marina Baldi
- •
- 3
  Upwelling, Linear theory, Shallow Water

ABSTRACT The reproductive biology of the seabream Diplodus argenteus, a dominant coastal fishery species, was investigated over two consecutive seasons (2001–2002) at Cabo Frio, Brazil, a low-latitude upwelling system. The sex ratio was... more

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- by Nelson Silva
- •
- 11
  Geochemistry, Oceanography, Salinity, Ph

... for conservation and management lenin oviedo 1,2 , mari&amp;amp;amp;amp;#x27;a alejandra esteves 1 , romina acevedo 2 , noemi silva 2 , ... Baumgarther MF (1997) The distribution of Risso&amp;amp;amp;amp;#x27; dolphin (Grampus... more

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The appearance of submesoscale structures in the Gulf of Finland was investigated using model simulations for series of coastal upwelling events in July–September 2006. We applied the Princeton Ocean Model. The horizontal step of the... more

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