نتایج جستجو برای: upwelling
تعداد نتایج: 4540 فیلتر نتایج به سال:
The variation of paralarval abundance in a region subjected to wind-driven upwelling (Ria of Vigo, northwestern Spain) was studied. Research cruises were undertaken during the favourable upwelling season (May to October) in 2000 and 2001. Each cruise included biological and hydrographic sampling and consisted of five stations in waters located to the east and west of the Cies Islands. A total o...
Dispersal and recruitment are central processes that shape the geographic and temporal distributions of populations of marine organisms. However, significant variability in factors such as reproductive output, larval transport, survival, and settlement success can alter the genetic identity of recruits from year to year. We designed a temporal and spatial sampling protocol to test for genetic h...
Until recently, studies of the fate of primary production in coastal upwelling systems have focused mainly on export through sinking of particulate organic matter (POM). In week-long deck incubations conducted during the upwelling season off Oregon, a large accumulation of carbonrich (C:N ≥ 16) dissolved organic matter (DOM) occurred following nitrate depletion by diatom blooms. The response of...
Although previous studies have described opposing states in upwelling regions, i.e., the rise of cold nutrient-rich waters and prevalence of surface warm nutrient-poor waters, few have addressed the transition from one state to the other. This study aimed to describe the microbial and viral structure during this transition and was able to obtain the taxonomic and metabolic compositions as well ...
31 32 Abstract The short-term, meso-scale variability of the mesozooplankton community present in the coastal upwelling system of the Ría de Vigo (NW Spain) has been analysed. Three well-defined communities were identified: coastal, frontal and oceanic, according to their holoplankton-meroplankton ratio, richness, and total abundance. These communities changed from summer to autumn due to a shi...
In spring/summer 2015, a toxic bloom by the diatom Pseudo-nitzschia (PN) occurred along the west coast of the United States which led to closures of the harvest of razor clams and Dungeness crabs. Twice monthly observations of temperature, salinity, nutrients, chlorophyll and phytoplankton species composition allowed us to track oceanographic conditions preceding and during the development of t...
[1] An idealized, two‐dimensional numerical modeling study is presented to investigate the effects of variable shelf slope and stratification on surface mixed layer (SML) nutrient supply during upwelling. As reported previously, the physical flow regime is governed by a topographic Burger number. Gradual shelf slope and weak stratification concentrate onshore transport in the bottom boundary la...
The nutrient cycles of coastal upwelling zones are studied with simple mass balance models of Ekman transport, longshore transport, surface productivity, and dissolved phosphorous. The models are constrained with data from the Peru, northwest Africa, and Oregon upwelling systems. The onshore-offshore mass balance model agrees with published Ekman transport, surface productivity, and nutrient da...
The California Current System is an eastern boundary upwelling system (EBUS) with high biological production along the coast. Oligotrophic offshore waters create cross-shore gradients of biological and physical properties, which are affected by intense mesoscale eddy activity. The influence of eddies on ecosystem dynamics in EBUS is still in debate. To elucidate the mechanisms that influence th...
The California Current of the Last Glacial Maximum at 42oN: Reconstruction based on multiple proxies
Multiple paleoceanographic proxies in a zonal transect across the California Current near 42øN record modern and last glacial maximum (LGM) thermal and nutrient gradients. The offshore thermal gradient, derived from foraminiferal slx•ies assemblages and oxygen isotope data, was similar at the LGM to that at present (warmer offshore), but average temperatures were 3.3 ø +1.5øC colder. Observed g...
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