Catalogo Articoli (Spogli Riviste)


Pelagic production at the Celtic Sea shelf break
Joint, I; Wollast, R; Chou, L; Batten, S; Elskens, M; Edwards, E; Hirst, A; Burkill, P; Groom, S; Gibb, S; Miller, A; Hydes, D; Dehairs, F; Antia, A; Barlow, R; Rees, A; Pomroy, A; Brockmann, U; Cummings, D; Lampitt, R; Loijens, M; Mantoura, F; Miller, P; Raabe, T; Alvarez-Salgado, X; Stelfox, C; Woolfenden, J;
NERC, Ctr Coastal & Marine Sci, Plymouth Marine Lab, Plymouth PL1 3DH, Devon, England NERC Plymouth Devon England PL1 3DH Lab, Plymouth PL1 3DH, Devon, England Free Univ Brussels, Lab Oceanog Chim & Geochim Eaux, B-1050 Brussels, Belgium Free Univ Brussels Brussels Belgium B-1050 aux, B-1050 Brussels, Belgium Plymouth Marine Lab, Sir Alister Hardy Fdn Ocean Sci, Plymouth PL1 2PB, Devon, England Plymouth Marine Lab Plymouth Devon England PL1 2PB L1 2PB, Devon, England Free Univ Brussels, Dienst Analyt Scheikunde, B-1050 Brussels, Belgium Free Univ Brussels Brussels Belgium B-1050 nde, B-1050 Brussels, Belgium Southampton Oceanog Ctr, Southampton SO14 3ZH, Hants, England Southampton Oceanog Ctr Southampton Hants England SO14 3ZH Hants, England Univ Hamburg, Inst Biochem & Lebensmittelchem, D-20146 Hamburg, Germany Univ Hamburg Hamburg Germany D-20146 ittelchem, D-20146 Hamburg, Germany Inst Invest Marinas, E-36208 Vigo, Spain Inst Invest Marinas Vigo Spain E-36208 vest Marinas, E-36208 Vigo, Spain
Titolo Testata:
fascicolo: 14-15, volume: 48, anno: 2001,
pagine: 3049 - 3081
Tipo documento:
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Physical, Chemical & Earth Sciences
Indirizzi per estratti:
Indirizzo: Joint, I NERC, Ctr Coastal & Marine Sci, Plymouth Marine Lab, Prospect Pl,PlymouthPL1 3DH, Devon, England NERC Prospect Pl Plymouth Devon England PL1 3DH H, Devon, England
I. Joint et al., "Pelagic production at the Celtic Sea shelf break", DEEP-SEA II, 48(14-15), 2001, pp. 3049-3081


This paper reviews the data obtained in the OMEX I Project on biological production in the surface waters of the Celtic Sea shelf break. The study focused on two regions- the Goban Spur and La Chapelle Bank. Satellite imagesof the Celtic Sea frequently show a region of cooler water at the shelf break, which results in the mixing of cooler, nutrient-rich waters to the seasurface. To examine the hypothesis that the Celtic Sea shelf break might be a region of enhanced production and sedimentation, observations were madeat five regions. These were four sites along a transect of the Goban Spur,from the Celtic Sea shelf (water depth < 200 m), through stations at waterdepths of 500-1000, 1500, and 3600 m; the fifth region was at La Chapelle Bank, which offered a contrasting site where the slope is steeper and influenced by canyons. Estimates are made of seasonal production of phytoplankton, bacterioplankton, microzooplankton, and mesozooplankton. The region has a spring bloom which is of short duration at the oceanic sites and occurs earliest on the Celtic Sea shelf, phytoplankton biomass in the summer months is greatest at La Chapelle Bank. Photosynthetic pigments analyses indicate that prymnesiophytes are present throughout the year and are often the dominant group of phytoplankton; diatoms are most abundant in the spring bloom. Primary production is estimated to be ca. 160 gCm(-2) a(-1), with cells < 5 mum in diameter accounting for almost half of the annual primary production. New production is estimated to be equivalent to 80 gCm(-2) a(-1) the f-ratio is generally <0.25 during the summer and autumn months, 0.7-0.8 during the spring bloom, and ca. 0.5 during the winter. Microzooplankton biomass and herbivory were measured from April to Octoberat the Goban Spur regions. The biomass of mesozooplankton was determined from the records of the Continuous Plankton Recorder (CPR) survey, and was used to estimate the amount of primary production removed by mesozooplanktongrazing. Bacterial production is estimated to be ca. 12 gCm(-2) a(-1). Thesum of microzooplankton and mesozooplankton grazing and the carbon demandsof bacteria were significantly lower than primary production from Novemberthrough May, but heterotrophic processes were quantitatively greater than phytoplankton production from July to October. The data suggest that up to 62 gCm(-2) a(-1) of primary production was not grazed by micro- or mesozooplankton in the surface mixed layer, or utilised directly by bacteria. Depending on the region, up to 38% of the primary production at the Celtic Sea margin was apparently not grazed in the surface mixed layer and would be available for heterotrophic organisms in mid-water and the benthos. The estimated respiration of the heterotrophic community of the surface mixed layer estimated also suggested that between 37% and 60% of the carbon fixed by photosynthesis in the euphotic zone was not remineralised in the surface mixedlayer. Data from satellite remote sensing are used in conjunction with the experimental data to extend the seasonal coverage of the observations made in OMEX I. The archive of the coastal zone color scanner provides mean monthly values of chlorophyll concentration, and these agree well with the seasonal variation of "green colour" of the CPR survey. Primary production has been estimated from the satellite-derived chlorophyll concentrations for the period April-September and is calculated to be 90 gCm(-2) for the 6-month period; the estimated production for the same period from in situ experiments suggests that primary production was ca. 116 gCm(-2). Nitrate concentrations in the surface water were correlated with sea-surface temperature, and thisrelationship was applied to temperature measurements from the advanced very high resolution radiometer sensor to estimate the potential nitrate concentrations over the region. The f-ratio was related to nitrate concentrationby a simple hyperbolic function (r(2) = 0.73). which was applied to the images of potential nitrate concentration for the region to estimate new production based on satellite data. For the period April through September, newproduction was calculated to be 46 gCm(-2) from satellite estimates of temperature, nitrate, and f-ratio, which compares favourably with the estimated new production of 57 gCm(-2) by direct measurement. (C) 2001 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/08/20 alle ore 07:02:15