scholarly journals Surface transport of DOC acts as a trophic link among Mediterranean sub-basins

Author(s):  
Chiara Santinelli ◽  
Roberto Iacono ◽  
Ernesto Napolitano ◽  
Maurizio Ribera d'Alcalá

Abstract. Characterizing carbon cycling and redistribution in the ocean is an important issue for Mankind, because it may affect key ecosystem services, e.g., support to climate system and food provision. In this paper, using an integrated approach, we explore the impact of the surface circulation on carbon dynamics in the Western Mediterranean Sea, where strong inter-basin differences in primary production do exist. Detailed information on the surface circulation, derived from high-resolution model simulations, is combined with the analysis of accurate, repeated dissolved organic carbon (DOC) data. Our work indicates that the advection of the Atlantic Water acts as a trophic link between the Algerian Basin and the Tyrrhenian Sea, determining a flux of 8.8–37.9 × 1012 g DOC yr−1 into the basin. Thus, surface transport of DOC can redistribute chemical energy among regions with different trophic regimes. We hypothesize that this overlooked mechanism plays an important role also in the global ocean.

2014 ◽  
Vol 36 (1) ◽  
pp. 104-117 ◽  
Author(s):  
Daniela Giordano ◽  
Adriana Profeta ◽  
Barbara Busalacchi ◽  
Roberta Minutoli ◽  
Letterio Guglielmo ◽  
...  

2017 ◽  
Vol 98 (5) ◽  
pp. 1003-1009 ◽  
Author(s):  
Luca Bittau ◽  
Mattia Leone ◽  
Adrien Gannier ◽  
Alexandre Gannier ◽  
Renata Manconi

Sowerby's beaked whale (Mesoplodon bidens) was previously known in the Mediterranean Sea from a single live stranding of two individuals in the French Riviera. We report here on two live sightings in the western Mediterranean, central-western Tyrrhenian Sea off eastern Corsica (Montecristo Trough) and off eastern Sardinia (Caprera Canyon) in 2010 and 2012, respectively. In both cases single individuals, possibly the same individual, occurred within groups of Cuvier's beaked whales (Ziphius cavirostris) suggesting inter-specific interactions. Based on our close observations of mixed-species groups of Sowerby's and Cuvier's beaked whales, we hypothesize that some previous long-distance sightings of beaked whales in the Mediterranean may not be reliably attributed to Z. cavirostris. The present sightings and previous live stranding indicate that the western Mediterranean Sea is the easternmost marginal area of M. bidens within the North Atlantic geographic range. Notes on behaviour are also provided.


2021 ◽  
Author(s):  
Jaime Hernandez-Lasheras ◽  
Baptiste Mourre ◽  
Alejandro Orfila ◽  
Alex Santana ◽  
Emma Reyes ◽  
...  

Abstract. The impact of the assimilation of HFR (High-Frequency Radar) observations in a high-resolution regional model is evaluated, focusing on the improvement of the mesoscale dynamics. The study area is the Ibiza Channel, located in the Western Mediterranean Sea. The resulting fields are tested against trajectories from 13 drifters. Six different assimilation experiments are compared to a control run (no assimilation). The experiments consists in assimilating (i) Sea surface temperature, sea level anomaly and Argo profiles (generic observation dataset); the generic observation dataset plus (ii) HFR total velocities and (iii) HFR radial velocities. Moreover, for each dataset two different initialization methods are assessed: a) restarting directly from the analysis after the assimilation or b) using an intermediate initialization step applying a strong nudging towards the analysis fields. The experiments assimilating generic observations plus HFR total velocities with the direct restart provides the best results, improving by 53 % the average separation distance between drifters and virtual particles after the first 48 hours of simulation in comparison to the control run. When using the nudging initialization step, the best results are found when assimilating HFR radial velocities, with a reduction of the mean separation distance by around 48 %. Results show the capability of the Ensemble Optimal Interpolation data-assimilative system to correct surface currents not only inside but also beyond the HFR coverage area. The assimilation of radial observations benefits from the smoothing effect associated with the application of the intermediate nudging step.


2010 ◽  
Vol 7 (5) ◽  
pp. 6971-6995 ◽  
Author(s):  
G. Civitarese ◽  
M. Gačić ◽  
M. Lipizer ◽  
G. L. E. Borzelli

Abstract. Analysis of 20-year time-series of the vertically averaged salinity and nutrient data in the South Adriatic shows that the two parameters are subject to strong decadal variability. In addition, nutrient and salinity variations are out of phase. Nutrients in the Ionian and in the Adriatic vary in parallel except that often the nutrient content in the Adriatic is lower than in the Ionian, a fact that has been attributed to primary producer consumption following the winter convective mixing. Horizontal distribution of the nitracline depth in the Ionian suggests that nutrient content in the Adriatic is a function of the circulation pattern in the Ionian that wells up or wells down the nitracline: cyclonic circulation causes a downwelling of the nitracline along the borders of the Northern Ionian Gyre (NIG) and a decrease in the nutrient content of the water flowing into the Adriatic across the Otranto Strait, and vice versa. The circulation variations are due to the Bimodal Oscillating System, i.e. the feedback mechanism between the Adriatic and Ionian. Inversion of the sense of the NIG results in the advection of Modified Atlantic Water or of the Levantine/Eastern Mediterranean (EMed) waters in the Adriatic. Here, we show that the presence of allochtonous organisms from Atlantic/Western Mediterranean (WMed) and EMed/temperate zone in the Adriatic are concomitant with the anticyclonic and cyclonic circulations, respectively, of the NIG. As a consequence of the NIG inversions, in the Ionian, this highly oligotrophic zone shows annual blooms in its central area only during cyclonic circulation. On the basis of the results presented, a revision of the theory of Adriatic ingressions formulated in the early 1950s is proposed.


2020 ◽  
Vol 8 (5) ◽  
pp. 372
Author(s):  
Simona Saviano ◽  
Daniela Cianelli ◽  
Enrico Zambianchi ◽  
Fabio Conversano ◽  
Marco Uttieri

Surface gravity waves retrieved by a network of HF (High Frequency) radars and measured in situ by an ADCP (Acoustic Doppler Current Profiler) current meter connected to an elastic beacon were used to carry out a multiple-year characterization of the wave field of the Gulf of Naples (south-eastern Tyrrhenian Sea, western Mediterranean). The aim of the work was to create a climatology of the study area and to demonstrate the potential of an integrated platform for coastal studies. The patterns recorded by the different instruments were in agreement with the wave climatology of the southern Tyrrhenian Sea as well as with previous scores for the same area. The results presented in this work also highlight seasonal and interannual consistency in the wave patterns for each site. In a wider context, this study demonstrates the potential of HF radars as long-term monitoring tools of the wave field in coastal basins, and supports the development of integrated observatories to address large-scale scientific challenges such as coastal ocean dynamics and the impact of global change on the local dynamics.


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