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Title: Modelling new production from nitrate reductase activity and light in the Peru current upwelling
Authors: Salas-Collado, Laura
Gómez, May 
Dugdale, Richard C.
Martínez, Ico 
Blasco, Dolors
Barber, Richard T.
Wilkerson, Frances P.
Packard, Theodore T. 
UNESCO Clasification: 251007 Oceanografía física
251002 Oceanografía química
241708 Fitobiología
Keywords: Primary production
Nitrogen uptake
Nitrate reductase
Issue Date: 2023
Publisher: Servicio de Publicaciones y Difusión Científica de la Universidad de Las Palmas de Gran Canaria (ULPGC) 
Conference: VIII International Symposium on Marine Sciences (ISMS 2022) 
Abstract: New Production (NP) is limited by NO3−, NH4+, and light (hv). Here we use a model derived from Michaelis-Menten kinetics to calculate NP from euphotic-zone phytoplankton NR activity and hv. NP = − ∂[NO3−]/ ∂t = [NR] ∗ [hv]/(Klt + [hv]) We calculated Peruvian upwelling NP at 15° S (C-Line) during austral fall, March-April-May 1977 from R/V WECOMA data of the Coastal Upwelling Ecosystem Analysis program. NP, at 50% hv, ranged from 1.37 μM C h−1 at the upwelling centre, to 0.15 μMC h−1 9 km downstream, to 0.37 μM C h−1 57 km further downstream over the Peru Trench. It compared well with 14C carbon productivity measurements ranging from 0.29 - 2.65 μMC h−1 and 0.04 - 1.37 μM C h−1 for the 6 h (gross) and 24 h (net) productivity. Oceanographic conditions during April 1977 made the C-Line an ideal site to compare spring 1977 NP with fall 1976 NP data collected by the R/V Eastward. Those 1976 NP values ranged slightly higher (0.15 to 3.49 μM C h−1) than those we found. The surface temperature background at the upwelling-centre in April 1977 reached 16.41 °C whereas in September 1976 it was 14.07 °C. For the C-Line, NO3− stayed above 10 μM, and NH4 + stayed below 0.1 μM. C-Line Chlorophyll, averaging 1.39 μg L−1 in April 1977, was lower than what it was for the same stations 6 months earlier (3.85 μg L−1). NR, averaging 0.045 μM h−1 for C-Line stations in April 1977, was a fourth of what it was 6 months earlier in September 1976 (0.20 μM h−1). In conclusion, overall NP for austral fall 1977, in nitrogen units, ranged from 22.6 to 206.8 nM N h−1. In carbon units, median NP in austral fall was only 42% (0.76 μM C h−1) of NP in austral spring (1.82 μM C h−1).
ISBN: 978-84-9042-477-3
Source: Abstracts Volume VIII International Symposium on Marine Sciences, July 2022 / coordinación, María Esther Torres Padrón, p. 183
Appears in Collections:Póster de congreso
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