1991; Balbín et al. 2014; García-Martínez et al. 2019), with values ranging from
~3.2 to 3.9 mlÁl
À1 (Balbín et al. 2014; García-Martínez et al. 2019). Manca et al.
(2004) reported averaged nutrient values in the LIW layer for the whole Alboran
basin, with concentrations of nitrate 8.49 μM, phosphate 0.37 μM, and silicate
8.36 μM. Other studies have reported a maximum of nitrate and phosphate associated to the oxygen minimum in the Northern Alboran Sea (García-Martínez et al.
2019), which has been detected at depths ~300 m and 500 m in the Western and the
Eastern Alboran Sea, respectively, coinciding with the depth level of the LIW. The
average concentrations at the nitrate maximum range from ~9 μM to 11 μM, with
lower values in autumn and higher in summer associated to the LIW in this sector of
the Alboran (García-Martínez et al. 2019). However, former studies (Packard et al.
1988; Minas et al. 1991) did not found a nutrient maximum associated to the salinity
maxima of the LIW (at ~400 m depth) in the Western Alboran Sea. The average
vertical profiles for nitrate, phosphate, silicate, and dissolved oxygen for the Alboran
Sea (annual climatologies) are shown in Fig. 7.1.
Below the LIW layer, denser less saline, and colder WMDW is found occupying
the deepest part of the Alboran Sea basin (Parrilla and Kinder 1987; Minas et al.
1991; Manca et al. 2004). The WMDW is formed in winter in the Gulf of Lions
(Millot 1999) and flows towards the Alboran Sea (see Chap. 5 of this book). Due to
its recent origin, the WMDW is characterized by higher dissolved oxygen levels than
the LIW (Minas et al. 1991). Thus in the NW Mediterranean Sea dissolved oxygen
concentrations of this deep water mass are ~4.6–4.7 mlÁl
À1 (Minas et al. 1991).
0
200
400
600
800
1000
1200
1400
1600
1800
0
5
1 0
1 5
NO3 (µM)
PO4 (µM)
SiO4 (µM)
0.00
0.15
0.30
0.45
0.60
0.75
3
4
5
6
7
8
Nitrate
Phosphate
Silicate
Oxygen
Pressure (dbar)
mmol/m 3 (NO 3
- )
mmol/m 3 (PO 4
3- )
ml/l (O 2 )
mmol/m 3 (Si(OH) 4 )
Fig. 7.1 Average vertical profiles (annual climatologies) of inorganic nutrients and dissolved
oxygen in the Alboran Sea (Manca et al. 2004). Source: Data and metadata are provided by the
Italian National Oceanographic Data Center of the OGS Istituto Nazionale di Oceanografia e
Geofisica Sperimentale (NODC/OGS), acting within the International Oceanographic Data
Exchange System of the UNESCO Intergovernmental Oceanographic Commission (IOC) since
27/6/2002
7 The Biogeochemical Context of Marine Planktonic Ecosystems
211
~3.2 to 3.9 mlÁl
À1 (Balbín et al. 2014; García-Martínez et al. 2019). Manca et al.
(2004) reported averaged nutrient values in the LIW layer for the whole Alboran
basin, with concentrations of nitrate 8.49 μM, phosphate 0.37 μM, and silicate
8.36 μM. Other studies have reported a maximum of nitrate and phosphate associated to the oxygen minimum in the Northern Alboran Sea (García-Martínez et al.
2019), which has been detected at depths ~300 m and 500 m in the Western and the
Eastern Alboran Sea, respectively, coinciding with the depth level of the LIW. The
average concentrations at the nitrate maximum range from ~9 μM to 11 μM, with
lower values in autumn and higher in summer associated to the LIW in this sector of
the Alboran (García-Martínez et al. 2019). However, former studies (Packard et al.
1988; Minas et al. 1991) did not found a nutrient maximum associated to the salinity
maxima of the LIW (at ~400 m depth) in the Western Alboran Sea. The average
vertical profiles for nitrate, phosphate, silicate, and dissolved oxygen for the Alboran
Sea (annual climatologies) are shown in Fig. 7.1.
Below the LIW layer, denser less saline, and colder WMDW is found occupying
the deepest part of the Alboran Sea basin (Parrilla and Kinder 1987; Minas et al.
1991; Manca et al. 2004). The WMDW is formed in winter in the Gulf of Lions
(Millot 1999) and flows towards the Alboran Sea (see Chap. 5 of this book). Due to
its recent origin, the WMDW is characterized by higher dissolved oxygen levels than
the LIW (Minas et al. 1991). Thus in the NW Mediterranean Sea dissolved oxygen
concentrations of this deep water mass are ~4.6–4.7 mlÁl
À1 (Minas et al. 1991).
0
200
400
600
800
1000
1200
1400
1600
1800
0
5
1 0
1 5
NO3 (µM)
PO4 (µM)
SiO4 (µM)
0.00
0.15
0.30
0.45
0.60
0.75
3
4
5
6
7
8
Nitrate
Phosphate
Silicate
Oxygen
Pressure (dbar)
mmol/m 3 (NO 3
- )
mmol/m 3 (PO 4
3- )
ml/l (O 2 )
mmol/m 3 (Si(OH) 4 )
Fig. 7.1 Average vertical profiles (annual climatologies) of inorganic nutrients and dissolved
oxygen in the Alboran Sea (Manca et al. 2004). Source: Data and metadata are provided by the
Italian National Oceanographic Data Center of the OGS Istituto Nazionale di Oceanografia e
Geofisica Sperimentale (NODC/OGS), acting within the International Oceanographic Data
Exchange System of the UNESCO Intergovernmental Oceanographic Commission (IOC) since
27/6/2002
7 The Biogeochemical Context of Marine Planktonic Ecosystems
211