Inter-annual variability in the timing of stratification and the spring bloom in the North-western North Sea

Sharples, Jonathan; Ross, Oliver N.; Scott, Beth E.; Greenstreet, Simon P. R.; Fraser, H. M.

doi:10.1016/j.csr.2006.01.011

Cited by 133 publications

(127 citation statements)

References 35 publications

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“…Although under this scenario, the upper sea should become more stratified, the outcome of warming on stratification is uncertain, because of the trade-off between events producing water column stabilization and destabilization events (4). Furthermore, this outcome may vary regionally, and long-term time series of direct observations are lacking (37). Our results provide evidence that enhanced stratification of coastal waters due to global warming is occurring in the northwestern Mediterranean.…”

Section: Resultsmentioning

confidence: 66%

Global warming-enhanced stratification and mass mortality events in the Mediterranean

Coma

Ribes²,

Serrano³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

346

272

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Summer conditions in the Mediterranean Sea are characterized by high temperatures and low food availability. This leads to ''summer dormancy'' in many benthic suspension feeders due to energetic constraints. Analysis of the most recent 33-year temperature time series demonstrated enhanced stratification due to global warming, which produced a Ϸ40% lengthening of summer conditions. Many biological processes are expected to be affected by this trend, culminating in such events as mass mortality of invertebrates. Climatic anomalies concomitant with the occurrence of these events represent prolonged exposure to warmer summer conditions coupled with reduced food resources. Simulation of the effects of these conditions on a model organism demonstrated a biomass loss of >35%. Losses of this magnitude result in mortality similar to that noted in field observations during mass mortality events. These results indicate that temperature anomalies are the underlying cause of the events, with energetic constraints serving as the main triggering mechanism.climatic anomalies ͉ summer lengthening ͉ energetic constraints ͉ benthic suspension feeders ͉ extreme events I n a rapidly warming world, marine and terrestrial biodiversity and ecosystems are responding through shifts in distribution and changes in abundance, phenology, structure, and functioning (1-3). Furthermore, global environmental change is expected to lead to a higher frequency and shorter return time of extreme events (4). An example of this is the occurrence of mass mortality events, which are affecting an increasing number of marine species and ecosystems worldwide (5, 6). These events have been well documented in coral reef ecosystems, where they have produced dramatic phase shifts in community structure (7-9). In recent years, the coralligenous community, one of the most diverse in the Mediterranean Sea (Ϸ1,666 species; ref. 10), where suspension feeders are dominant, has been strongly affected by several mass mortality events [supporting information (SI) Table S1]. Engineer species, including gorgonians and sponges, have been the most affected taxa down to depths of 45 m (11-13). The impact of these events on populations is similar to that observed in the 1980s and 1990s in the Caribbean Sea (14, 15). But despite the wide extent of these effects on Caribbean populations, identification of the causes has not always been possible; however, some were associated with temperature increases (15), and others were associated with diseases (14). Understanding mass mortality events is becoming increasingly important, given the escalating presence of anthropogenic stressors that affect marine ecosystems (5, 6, 16).The causes of mass mortality events in the Mediterranean remain unknown, and our ability to predict the effects of these events depends on characterizing them and elucidating trends exhibited by potentially causative factors. Current hypotheses about the causes of these events in the Mediterranean focus on their relationship with the occurrence of distinctive cl...

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Section: Resultsmentioning

confidence: 66%

Global warming-enhanced stratification and mass mortality events in the Mediterranean

Coma

Ribes²,

Serrano³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

346

272

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“…salinity and nutrients) that are not strongly constrained by atmospheric feedback. In contrast temperature and seasonal stratification can be adequately modelled with 1-D models (Sharples et al, 2006) and 3-D models of limited area and boundary condition information (Young and Holt, 2007;Meyer et al, 2011). Hence, such models can be usefully employed in climate change downscaling studies to investigate changes in atmospheric and riverine forcing (e.g.…”

Section: Introductionmentioning

confidence: 99%

Oceanic controls on the primary production of the northwest European continental shelf: model experiments under recent past conditions and a potential future scenario

et al. 2012

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Abstract. In this paper we clearly demonstrate that changes in oceanic nutrients are a first order factor in determining changes in the primary production of the northwest European continental shelf on time scales of 5-10 yr. We present a series of coupled hydrodynamic ecosystem modelling simulations, using the POLCOMS-ERSEM system. These are forced by both reanalysis data and a single example of a coupled ocean-atmosphere general circulation model (OA-GCM) representative of possible conditions in 2080-2100 under an SRES A1B emissions scenario, along with the corresponding present day control. The OA-GCM forced simulations show a substantial reduction in surface nutrients in the open-ocean regions of the model domain, comparing future and present day time-slices. This arises from a large increase in oceanic stratification. Tracer transport experiments identify a substantial fraction of on-shelf water originates from the open-ocean region to the south of the domain, where this increase is largest, and indeed the on-shelf nutrient and primary production are reduced as this water is transported on-shelf. This relationship is confirmed quantitatively by comparing changes in winter nitrate with total annual nitrate uptake. The reduction in primary production by the reduced nutrient transport is mitigated by on-shelf processes relating to temperature, stratification (length of growing season) and recycling. Regions less exposed to ocean-shelf exchange in this model (Celtic Sea, Irish Sea, English Channel, and Southern North Sea) show a modest increase in primary production (of 5-10 %) compared with a decrease of 0-20 % in the outer shelf, Central and Northern North Sea. These findings are backed up by a boundary condition perturbation experiment and a simple mixing model.

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“…The details of this model will not be discussed further but can be found in Ref. [14]. In this context, its main function is to convert meteorological data into temperatureedepth profiles corresponding to each depth in the temperature field.…”

Section: Boundary Conditions For the Pipeline Thermal Modelmentioning

confidence: 99%

“…The nozzle velocity required for optimum hydraulic efficiency and a constant angular velocity is calculated using equation (14). The nozzle area required to obtain this nozzle velocity is a function of the system flow rate, and can be obtained from equation (15).…”

Section: Mechanical System Modelmentioning

confidence: 99%

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Steady-state analysis of a conceptual offshore wind turbine driven electricity and thermocline energy extraction plant

Buhagiar

Sant

2014

Renewable Energy

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a b s t r a c tA system for using offshore wind energy to generate electricity and simultaneously extract thermal energy is proposed. This concept is based on an offshore wind turbine driven hydraulic pump supplying deep seawater under high pressure to a land based plant consisting of a hydroelectric power generation unit and heat exchanger. A steady-state system model is developed using empirical formulae. The mathematical model comprises the fundamental system sub-models that are categorised as the rotor, hydraulic pump, pipeline, hydroelectric turbine and heat exchanger. A means for modelling the seawater temperature field across a two-dimensional bathymetry is also discussed. These mathematical models are integrated into a computational tool and a brief parametric static analysis is undertaken. The results illustrate the effect of pipeline diameter, rotational speed of the grid connected hydroelectric turbine, and the turbine distance from shore on the overall performance of the system. Through adequate parameter selection, the total rate of energy output for such a system, consisting of both electricity and thermal energy, is shown to increase by as much as 84%, when compared to a conventional wind turbine having an identical rotor diameter but which supplies only electrical energy.

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Inter-annual variability in the timing of stratification and the spring bloom in the North-western North Sea

Cited by 133 publications

References 35 publications

Global warming-enhanced stratification and mass mortality events in the Mediterranean

Global warming-enhanced stratification and mass mortality events in the Mediterranean

Oceanic controls on the primary production of the northwest European continental shelf: model experiments under recent past conditions and a potential future scenario

Steady-state analysis of a conceptual offshore wind turbine driven electricity and thermocline energy extraction plant

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