Population dynamics of the krill Meganyctiphanes norvegica (M. Sars, 1857) (Crustacea: Euphausiacea) in the Ligurian Sea (NW Mediterranean Sea). Size structure, growth and mortality modelling

Abstract. Data obtained during the monthly cruises of the DYFAMED time-series study (northwestern Mediterranean Sea) in the period 1995–2007 were compiled to examine the hydrological changes and the linked evolution of some biogeochemical characteristics. A regular increase of temperature and salinity (0.005 °C y−1, 0.0022 psu y−1) was recorded in deep waters of the NW Mediterranean Sea (2000 m depth) during 1995–2005. In February 2006 an abrupt increase in T (+0.1 °C) and S (+0.03 psu) was measured as the result of successive intense winter mixing events during the 3 previous years. The February 2006 event led to the mixing of the whole water column (0 to > 2000 m) and increased salt and heat content of the Western Mediterranean Deep Water by mixing with saltier and warmer Levantine Intermediate Water. The deficit in fresh water inputs to the western Mediterranean basin in three successive years (2003–2005) was suspected to be the major cause of this event since an increase of salinity in surface waters was monitored during these years. The measured phytoplankton biomass was specifically high after the periods of intense mixing. Chlorophyll a integrated biomass reached 230 mg m−2 in 1999, 175 mg m−2 in 2003, and 206 mg m−2 in 2006. The high levels of biomass were related to the particularly high increases in nutrients content in surface layers following the intense water column mixing and the subsequent development of a diatom bloom (as seen by fucoxanthin content). The frequency of extreme events (high mixing, high nutrients, and high biomass) increased in recent years. Our results suggested that the NW Mediterranean Sea could have an increased productivity and was not deriving towards the decreased productivity predicted by models.

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Ecosystem dynamics in the Liguro-Provençal Basin: the role of eddies in the biological production.

Mediterranean Marine Science ◽

10.12681/mms.520 ◽

2014 ◽

Vol 15 (2) ◽

pp. 274 ◽

Cited By ~ 4

Author(s):

E. CASELLA ◽

P. TEPSICH ◽

X. COUVELARD ◽

R.M.A. CALDEIRA ◽

K. SCHROEDER

Keyword(s):

Mediterranean Sea ◽

Spring Bloom ◽

Chlorophyll Concentration ◽

Ecosystem Dynamics ◽

Regional Ocean Modeling System ◽

Concentration Data ◽

Ligurian Sea ◽

Nw Mediterranean ◽

Nw Mediterranean Sea

We study numerically the role of mesoscale structures in the Ligurian Sea (NW Mediterranean Sea) as a possible factor affecting the spatial distribution of the chlorophyll spring bloom. We use the Regional Ocean Modeling System (ROMS) configured for the NW Mediterranean Sea (ROMS_NWMed) and satellite derived Altimetric, Sea Surface Temperature and Chlorophyll concentration data, for years 2009 and 2010. Comparison of model output with satellite and in situ data shows agreement between numerical results and observations. There is a significant interannual variability in concentration and distribution of chlorophyll in the basin during the two years of the study. The ROMS_NWMed simulation reveals the formation of a number of mesoscale eddies along the Northern rim Current characterized by a long lifetime and closed streamlines. A significant higher number of eddies is found during the chlorophyll-rich year 2010. The high number of eddies, due to the “eddy pumping mechanism”, generate spatially and temporally localised fluxes of nutrient into the euphotic zone, thus contributing to the fertilization of the Ligurian Sea. Therefore, eddies in the Ligurian rim current can have important effects on the location of development of the main patch of chlorophyll spring bloom and consequently on the local ecosystem dynamics.

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Influence of meteorological variability on primary production dynamics in the Ligurian Sea (NW Mediterranean Sea) with a 1D hydrodynamic/biological model

Journal of Marine Systems ◽

10.1016/s0924-7963(97)00098-5 ◽

1998 ◽

Vol 16 (1-2) ◽

pp. 23-50 ◽

Cited By ~ 33

Author(s):

G. Lacroix ◽

P. Nival

Keyword(s):

Primary Production ◽

Mediterranean Sea ◽

Biological Model ◽

Ligurian Sea ◽

Nw Mediterranean ◽

Nw Mediterranean Sea ◽

Production Dynamics

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Immediate and delayed effects of a mass mortality event on gorgonian population dynamics and benthic community structure in the NW Mediterranean Sea

Marine Ecology Progress Series ◽

10.3354/meps305127 ◽

2005 ◽

Vol 305 ◽

pp. 127-137 ◽

Cited By ~ 107

Author(s):

C Linares ◽

R Coma ◽

D Diaz ◽

M Zabala ◽

B Hereu ◽

...

Keyword(s):

Population Dynamics ◽

Community Structure ◽

Mediterranean Sea ◽

Benthic Community ◽

Mass Mortality ◽

Benthic Community Structure ◽

Delayed Effects ◽

Mass Mortality Event ◽

Nw Mediterranean ◽

Nw Mediterranean Sea

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Hydrological changes in the Ligurian Sea (NW Mediterranean, DYFAMED site) during 1995–2007 and biogeochemical consequences

Biogeosciences ◽

10.5194/bg-7-2117-2010 ◽

2010 ◽

Vol 7 (7) ◽

pp. 2117-2128 ◽

Cited By ~ 81

Author(s):

J. C. Marty ◽

J. Chiavérini

Keyword(s):

Mediterranean Sea ◽

Water Column ◽

Heat Content ◽

Subsequent Development ◽

Western Mediterranean ◽

Intermediate Water ◽

Ligurian Sea ◽

Hydrological Changes ◽

Nw Mediterranean ◽

Nw Mediterranean Sea

Abstract. Data obtained during the monthly cruises of the DYFAMED time-series study (northwestern Mediterranean Sea) in the period 1995–2007 were compiled to examine the hydrological changes and the linked variation of some biogeochemical characteristics (nutrients and pigments). A regular increase of temperature and salinity (0.005 °C y−1, 0.0022 psu y−1) was recorded in deep waters of the NW Mediterranean Sea (2000 m depth) during 1995–2005. In February 2006 an abrupt increase in T (+0.1 °C) and S (+0.03 psu) was measured at 2000 m depth as the result of successive intense winter mixing events during the 3 previous years. The February 2006 event led to the mixing of the whole water column (0 to >2000 m) and increased salt and heat content of the Western Mediterranean Deep Water by mixing with saltier and warmer Levantine Intermediate Water. The deficit in fresh water inputs to the western Mediterranean basin in three successive years (2003–2005) was suspected to be the major cause of this event since an increase of salinity in surface waters was monitored during these years. The measured phytoplankton biomass was specifically high after the periods of intense mixing. Chlorophyll a integrated biomass reached 230 mg m−2 in 1999, 175 mg m−2 in 2003, and 206 mg m−2 in 2006. The high levels of biomass were related to the particularly high increases in nutrients content in surface layers following the intense water column mixing and the subsequent development of a diatom bloom (as seen by fucoxanthin content). The occurrence of extreme events (high mixing, high nutrients, and high biomass) increased in recent drought years (2003 to 2006). Our results indicated that the NW Mediterranean Sea productivity is increasing.

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