Abstract
During the “Pros IV Cruise” of the R. V. “Korotneff” (March, 1979), continuous surface measurements of hydrobiological parameters were made across the divergence zone of the Ligurian Sea (North-Western Mediterranean). Principal component analysis (PCA) applied to data of two transects provided a graphic description with a high resolution of their spatial structure. Data from the first transect (Marth 12) confirmed the well known classification of the area into coastal, intermediate and central zones. The distribution of the data points reveals a simple and direct gradient between the coastal and intermediate zones and a great complexity of hydrological structures and chlorophyll a in the intermediate zone and its transition with the central area. Projection of the variables enabled this distribution to be interpreted as an irregular succession of small areas where vertical mixing is indicated by high salinity and nutrient concentration and patches of high chlorophyll a concentration. The second transect (March 15) included two parts: one parallel to the coastline, the other perpendicular to the coast. The PCA analyses show that similar hydrobiological structures exist along the two parts of the transect, and reveal the existence of either an isotropic patch of water with the characteristics of the intermediate zone or a meander in the front between the coastal and intermediate zones. Moreover, the analyses distinguish small phytoplankton patches (500 to 700 m wide) and group them according to their interrelationships between the variables. The resolution of PCA graphs is equivalent to several sampling steps, enabling similar interpretation of the major features from a smaller set of data and thus the simultaneous analysis of all the cruise data. Throughout the 15 d duration of the cruise the delimitation of the divergence area into 3 zones persisted. The spatial structure of the coastal and central areas was very stable, while the intermediate area displayed an important time-dependent variability in hydrobiological patterns.
Similar content being viewed by others
Littérature citée
Béthoux, J. P., L. Prieur et M. Albuisson: Apports de la télédétection infrarouge à la connaissance de la circulation superficielle dans la partie Nord-Ouest du bassin occidental. Rapp. P.-v. Réun. Commn int. Explor. scient. Mer Méditerr. 25/26, 83–84 (1979)
Braun, J. M.: Etude des séries chronologiques multiples par l'analyse des données. Rapp. CEA R-4561, 1–183 (1974)
Coste, B., J. Gostan et H. J. Minas: Influence des conditions hivernales sur les productions phyto- et zooplanctoniques en Méditerranée Nord-occidentale. I. Structures hydrologiques et distribution des sels nutritifs. Mar. Biol. 16, 320–348 (1972)
Coste, B. et H. J. Minas: Production organique primaire et sels nutritifs au large des côtes occidentales corso-sardes en février 1966. Recl Trav. Stn mar. Endoume 60, 49–61 (1968)
Cruzado, A. and J. C. Kelley: Continuous measurements of nutrient concentrations and phytoplankton density in the surface water of the Western Mediterranean, winter 1970. Thalassia jugosl. 9, 19–24 (1973)
Demers, S., P. E. Lafleur, L. Legendre and C. L. Trump: Shortterm covariability of chlorophyll and temperature in the St. Lawrence estuary. F. Fish. Res. Bd Can. 36, 568–573 (1979)
Denman, K. L.: Covariability of chlorophyll and temperature in the sea. Deep-Sea Res. 23, 539–550 (1976)
Denman, K., A. Okubo and T. Platt: The chlorophyll fluctuation spectrum in the sea. Limnol. Oceanogr. 22, 1033–1038 (1977)
Denman, K. L. and T. Platt: Coherences in the horizontal distributions of phytoplankton and temperature in the upper ocean. Mém. Soc. r. Sci. Liège (6e sér.) 7, 19–30 (1975)
Fasham, M. J. R. and P. R. Pugh: Observations on the horizontal coherence of chlorophyll a and temperature. Deep-Sea Res. 23, 527–538 (1976)
Gostan, J. et P. Nival: Distribution hivernale des caractéristiques hydrologiques en mer Ligure et estimation de l'abondance du phytoplancton par la méthode des pigments. C. r. hebd. Séanc. Acad. Sci., Paris 257, 2872–2875 (1963)
Hela, I.: Surface currents of the Ligurian Sea. Bull. Inst. océanogr. Monaco 60, 1–15 (1963)
Jacques, G., H. J. Minas, M. Minas et P. Nival: Influence des conditions hivernales sur les productions phyto-et zooplanctoniques en Méditerranée Nord-occidentale. II. Biomasse et production phytoplanctonique. Mar. Biol. 23, 251–265 (1973)
Kelley, J. C. and A. Cruzado: Fluctuations and interrelationships among nutrient concentrations and phytoplankton density in the Western Mediterranean, winter 1970. Thalassia jugost. 9, 25–31 (1973)
Lacombe, H. et P. Tchernia: Quelques traits généraux de l'hydrologie méditerranéenne d'après diverses campagnes hydrologiques récentes en Méditerranée, dans le proche Atlantique et dans le détroit de Gibraltar. Cah. océanogr. 12, 527–547 (1960)
Lebart, L. et J. P. Fénelon: Statistique et informatique appliquées, 439 pp. Paris: Dunod 1975
Okubo, A.: Horizontal dispersion and critical scales for phytoplankton patches. In: Spatial pattern in plankton communities, pp 21–41. Ed. by J. H. Steele. New York: Plenum Press 1978. (NATO Conf. Ser. IV: Mar. Sciences)
Prieur, L.: Structures hydrologiques, chimiques biologiques dans le bassin liguro-provençal. Rapp. P.-v. Réun. Commn int. Explor. scient. Mer Méditerr. 25/26, 75–76 (1979)
Prieur, L.: Hétérogénéité spatio-temporelle dans le bassin liguroprovençal. Rapp. P.-v. Réun. Commn int. Explor. scient. Mer Méditerr. 27, 177–179 (1981)
Tréguer, P. et P. Le Corre: Manuel d'analyse des sels nutritifs dans l'eau de mer (utilisation d'AutoAnalyser II Technicon), 110 pp. Brest: laboratoire d'Océanologie chimique, Université de Bretagne occidentale 1975
Wald, L.: Utilisation du satellite NOAA 5 à la connaissance de la thermique océanique. Etude de ses variations saisonnières en Mer Ligure et de ses variations spatiales en Méditerranée, Thèse 3ème cycle, Université Pierre et Marie Curie, Paris 1980
Author information
Authors and Affiliations
Additional information
Communicated by J. M. Pérès, Marseille
Rights and permissions
About this article
Cite this article
Belluau, M., Blanc, F. & Coste, B. Structures hydrologiques à petite échelle dans la zone de divergence de la Mer Ligure (Méditerranée nord-occidentale): Etude par l'analyse en composantes principales de séries spatio-temporelles multiples. Mar. Biol. 70, 283–293 (1982). https://doi.org/10.1007/BF00396847
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00396847