Anoxic marine sediments release significant amount of ammonium, phosphorus, reduced iron and silicate (e.g. Bohlen et al. 2011 & Noffke et al. 2012). Therefore the water layer directly influenced by the sediments, the bottom boundary layer (BBL), contains high concentrations of nutrients and is particular dynamic in terms of N-cycling (e.g. Kalvelage et al. 2013). The nutrient flux from the...
Filaments and the associated submesoscale frontal processes are known to play a crucial role for the offshore and downward transport of biogeochemical tracers in Eastern Boundary Upwelling Regions (EBUS). These fluxes modulate subsurface oxygen concentrations directly but also indirectly through changes in biological production and subsequent remineralisation of organic matter. So far most...
Non-linear internal waves (NLIWs) are a prominent feature on the continental slope and shelfs of all major upwelling regions. They are known to enhance diapycnal mixing and associated nutrient fluxes, thereby fueling biogeochemical cycles. Additionally, they cause elevated near-bottom velocity variability which affects sedimentation rates and benthic distribution of biota. NLIWs are also...
Upwelling of nutrient-rich water fuels high surface productivity and the resultant export of organic matter stimulates strong microbial respiration in the subsurface waters. Combined with poor ventilation, O2-deficient waters called oxygen-minimum-zones (OMZs) develop. Under these low oxygen conditions fixed nitrogen is lost as N2-gas via the anaerobic processes of anammox and...
Global oceans play important role as a sink of atmospheric carbon dioxide (CO2). Dissolved organic carbon (DOC) in the sea waters is an important source of many biogenic volatile organic compounds (BVOCs). Globally, BVOCs are emitted from plants and organism from both terrestrial and oceanic reservoirs. However, spatial and temporal variations in emission and factors controlling production of...
Eastern Boundary Upwelling Ecosystems (EBUS) are well-known “hotspots” for production of greenhouse gases (GHG). Although each year tons of GHG are emitted out of the global ocean, EBUS are focal points with a disproportionally high share of the total efflux of these gases. Given that EBUS are a fundamental component of the socio-economic development of the bordering countries, the associated...
Oxygen (O2) plays a critical role for life on Earth, but over the last 50 years, O2concentrations in the Ocean have decreased massively as a consequence of human activity. These activities include greenhouse gas emissions and nutrient discharge to coastal waters, with major impacts on Ocean biogeochemistry and ecology. This effect is particularly intense in O2depleted tropical Ocean areas,...
The Humboldt Current upwelling ecosystem, particularly the northern component off the coast of Peru is considered a hot spot for the scientific community because of its unique characteristics: it is the upwelling system with the biggest catch productivity despite the fact it is embedded in a shallow and intense oxygen minimum zone (OMZ). It is also an area of intense biogeochemistry activity...
Dissolved oxygen (O$_2$) and nutrient concentrations at the continental margin of the eastern tropical south Pacific (ETSP) exhibit elevated intra-seasonal, seasonal and inter-annual variability. Here, we discuss the impact of remotely forced and locally generated intra-seasonal variability of the eastern boundary circulation at 12°S. Data from a multi-cruise physical and biogeochemical...
Several field studies have demonstrated that shallow waters on the inner-shelf can commonly experience low oxygen conditions, especially in upwelling ecosystems. However, the frequency and intensity of hypoxia events, as well as the physical and biological drivers of such conditions in coastal shallow waters (<30m deep) are still scarcely studied. We used high frequency records obtained...
The Peruvian Upwelling System (PUS) is one of the most important coastal upwelling system in the world ocean because of its intense Oxygen Minimum Zone (OMZ) and high productivity supporting the largest anchovy fishery. Between the 1980s and 2000s, a sea surface cooling, a subsurface deoxygenation and nearshore surface chlorophyll increase were evidenced from satellite and in situ...
St Helena Bay is located in the southern Benguela and is a large, highly productive open bay formed by the Cape Columbine promontory. Here we show oxygen depletion to be a function of local drawdown at seasonal and episodic scales. We investigated plankton community metabolism through estimates of net community production [NCP] and respiration [R] as determined by oxygen fluxes in the water...
Dissolved organic matter (DOM) represents one of the largest active pools of organic carbon in the global carbon cycle. The Humboldt Current Upwelling System off Peru is among the most productive ecosystems in the world ocean, with high rates of primary production and an intense oxygen minimum zone (OMZ). One of the major perturbations of this system is associated to El Niño-Southern...
Methane (CH4) is the most abundant hydrocarbon in the atmosphere and plays an important role in regulating the Earth's radiation balance and atmospheric chemistry in the troposphere. Coastal upwelling regions such as the eastern boundary upwelling systems and the Arabian Sea have been identified as sites of enhanced CH4 concentrations and emissions to the atmosphere. The coastal upwelling area...
N2O is a potent greenhouse gas and a major sink for stratospheric ozone. About a third of atmospheric N2O originates in the ocean, with the Pacific accounting for as much as half of all oceanic N2O emissions. However, little is known about the variability of this flux. Part of the challenge lies in the difficulty of disentangling the multiple, and sometimes simultaneous pathways that produce...
The oxygen budget within the oxygen minimum zone (OMZ) is generally a complex and not yet fully understood interplay between different processes of oxygen supply and consumption. Modelling studies indicate that a deficient circulation is at the core of the problem rather than an admittedly poor quantitative understanding of biogeochemical cycle.
Here we use the new high-resolution nest...
Coastal and shelf regions are particularly vulnerable to deoxygenation due to the highly productive upper ocean ecosystem and to physical transport bringing low oxygen levels from subsurface open ocean waters. Here we use a coupled physical (ROMS-CROCO)-biogeochemical (Oxygen-Phytoplankton-Zooplankton) model of an idealized coastal upwelling system of the Iberian Peninsula forced by upwelling...
Providing critical ocean information to satisfy societies changing socio-economic needs requires a coordinated implementation of multi-disciplinary ocean observing activities. For the past 12 months, building on the Framework for Ocean Observing (FOO), we perform technological readiness level (TRL) assessments for observing the oxycline in highly productive and economically important Eastern...