THE DISTRIBUTION OF THE COCCOLITHOPHORE COMMUNITY OFF LISBON (PORTUGAL), DURING JUNE 1999 (CODENET II CRUISE): ECOLOGICAL INTERPRETATION
Mário Cachão (1); Jeremy Young (2); Hanno Kinkel (3); Anabela Oliveira (4); Maria Teresa Moita (5); Kees van Lenning (6); Alexandra Duarte (7); Markus Geisen (2); Patrizia Ziveri (8); Christine Klaas (9); Ian Probert (10); Ana Sofia Palma (5); Annelies Kleijne (8); Llu•sa Cros (6); José Carlos Mendes (5)
1 Centro e Departamento de Geologia, Faculdade de Ciências, University of Lisbon, Rua Escola Politécnica, No 58, P-1294 Lisboa CODEX, Portugal, mcachao@fc.ul.pt
2 Palaeontology Department, The Natural History Museum, Cromwell Road, London
3 Dept. of Marine Biogeochemistry and Toxicology, Nederlands Instituut for Onderzoek der Zee, PO Box 59, 1790 AB Den Burg, Texel, Nederlands, kinkel@nioz.nl
4 University of Algarve / Marinha - Instituto Hidrogr‡fico, Rua das Trinas, No 49, P-1200 Lisboa, Portugal, aboliveira@mail.telepac.pt
5 Instituto de Investigacão das Pescas e do Mar (IPIMAR), Av. de Bras’lia 1400 Lisboa, Portugal. tmoita@ipimar.pt
6 Consejo Superior de Investigaciones Cientificas, Institut de Ciencias del Mar, Passeig Joan de Borbo s/n, 08039 Barcelona, Spain, kees@icm.csic.es
7 Dep. Zoologia e Antropologia, Faculdade de Ciências, University of Lisbon, Ed. C2, 3¼ Piso, P-1749-016 Lisboa, Portugal, alexandra.ds@mail.telepac.pt
8 Faculteit der Aardwetenschappen, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081HV Amsterdam, The Netherlands, zivp@geo.vu.nl
9 The University of Chicago, Department of the Geophysical Sciences, 5734 South Ellis avenue, Chicago, Illinois 60637, USA, cklaas@starbuck.uchicago.edu
10 Laboratoire de Biologie et Biotechnologies Marines, Université de Caen Basse Normandie 14032 CAEN, France, Billard@ibba.unicaen.fr
CODENET is a research network of eight European geological and marine biological teams, funded by the EC Training and Mobility of Researchers programme to carry out an integrated multidisciplinary study of six coccolithophore key-taxa. The research strategy focus on different types of studies on these taxa (Calcidiscus leptoporus, Coccolithus pelagicus, Gephyrocapsa spp., Helicosphaera carteri, Syracosphaera pulchra, Umbilicosphaera sibogae) following and developing the strategy that already proved successful with the Global Emiliania Modelling (GEM) initiative and the MAST funded EC project EHUX, centred only on the species Emiliania huxleyi. One of the main research task subjects of the CODENET is based on studies of coccolithophore assemblages collected during oceanographic cruises which sample sets can be used by different research teams each studying particular taxa (e.g. for culture studies) or specific studies based on coccolithophores such as marine biomarkers (alkenones, pigment analysis), coccolith Ca-Sr ratios or molecular genetic analysis (see further details at http://www.nhm.ac.uk/hosted_sites/ina/CODENET/). In the present work it will be described the coccolithophore community component of the data obtained during the CODENET II cruise, held during June 1999.
The shelf off western Portugal is relatively narrow and during the summer northerly coast-parallel winds promote upwelling along it. As a result there is a sharp productivity gradient from inshore eutrophic water to offshore oligotrophic conditions. Previous phytoplankton studies in the area have shown that coccolithophores form a significant part of the phytoplankton and that all the CODENET key-taxa occur in the area. These provided excellent conditions for a detailed analysis of their autecology along a eutrophic-oligotrophic transect.
To meet the operational objectives we carried out a transect across the shelf (Fig. 1) collecting samples with two sampling protocols: (a) Multi cast stations - at five stations we stayed for a prolonged period (1-2 hours) collecting all the sample types. This included (1) use of deck pump for bulk sampling from approx. 5m depth. (2) two rosette casts from the top of the thermocline (10-30m) for bulk sampling (3) one or two rosette casts to sample from 4 depths for phytoplankton, nutrient, chlorophyll and coccolithophore samples; (b) Single cast samples - at six stations we stayed for a short period only (15-20 minutes) conducting a single CTD-rosette cast in order top collect samples for 4 depths for phytoplankton, nutrient, chlorophyll and coccolithophore samples. In addition the deck pump was used to collect samples for these analyses from 5m water depth.
The data was subdivided in two data matrixes: (1) one with the biological counts of the phytoplankton main groups (diatoms, dinoflagellates and coccolithophores) together with nutrient and pigment data; (2) the second one gathering the coccolithophore individual taxa counts together with physical parameters such as temperature, salinity and nephelometry. The Factorial Analysis performed in these two data matrixes allowed us to confirm the upwelling as the main controlling factor of the phytoplankton distribution in general and of the coccolithophores in particular.
Map of cruise locations
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