Abstract
An oceanographic transet,, extending from Yugoslavia across the Northern Adriatic Sea to the Po delta in Italy, was occupied during 1972 and 1973 to establish the effect of Po river discharge on the phytoplankton communities of the region. Density distribution showed distinct seasonal features: a winter-spring period of low stability throughout the water column, and a summer period of stratification. The total water-column plant nutrients (nitrate, nitrite, phosphate, silicate) showed a 1.3 to 4.5-fold decrease eastward, with semi-eutrophic conditions restricted to an area off the Po delta. Nannoplankton usually dominated the phytoplankton community, in terms of cell density, surface chlorophyll a concentrations, and surface primary production rates. However, all significant maxima in these characteristics resulted from increases in the microplankton component. Changes in the frequency of major microplankton groups characterized three periods of the annual cycle: September–December, neritic, temperate diatom flora with some littoral elements (e.g. Nitzschia seriata); January–May, neritic, temperate diatom flora of different composition (e.g. Lauderia borealis, Skeletonema costatum); May–August, dinoflagellates (e.g. Prorocentrum micans) at western stations and dinoflagellates plus neritic, warm-water diatoms at eastern stations. The seasonal cycle was characterized by spring and fall maxima tending to coincide with maximum Po river discharge and/or periods of low water-column stability and vertical mixing. The higher nutrient input at western stations was correlated with the co-dominance of only a few species of microplankton during bloom periods, suggesting that these species (S. costatum, N. seriata, and 5 others) can serve as indicators of eutrophic conditions in this region. Assimilation ratios of both the micro- and nannoplankton suggested borderline nutrient conditions. Phosphate was implicated as the limiting nutrient.
Similar content being viewed by others
Literature Cited
Anderson, G.C.: The seasonal and geographic distribution of primary productivity off the Washington and Oregon coasts. Limnol. Oceanogr. 9, 282–302 (1964)
—: Fractionation of phytoplankton communities off the Washington and Oregon coasts. Limnol. Oceanogr. 10, 477–480 (1965)
Beers, J.R. and G.L. Stewart: The vertical distribution of microzooplankton and some ecological observations. J. Cons. int. Explor. Mer 33, 30–44 (1969)
Brambati, A., D. Bregant, G. Leonardon and D. Stolfa: Transport and sedimentation in the Adriatic Sea. Pubbl. Inst. sper. talassogr. 489, 1–60 (1973)
Buljan, M.: Fluctuations of salinity in the Adriatic Izvj. Inst. Oceanogr. Ribarst. 2, 1–64 (1953)
Caperon, J., S.A. Catell and G. Krasnick: Phytoplankton kinetics in a subtropical estuary: eutrophication. Limnol. Oceanogr. 16, 599–607 (1971)
Curl, H. and L.F. Small: Variations in photosynthetic assimilation ratios in natural, marine phytoplankton communities. Limnol. Oceanogr. 10 (Suppl.), R67-R73 (1965)
Degobbis, D.: On the storage of seawater samples for ammonia determination. Limnol. Oceanogr. 18, 146–150 (1973)
Degobbis, D.: The nitrogen cycle and budget in the Northern Adriatic. [In Croatian], 154 pp. M.Sc. thesis, University of Zagreb 1974
Doty, M.S. and M. Oguri: Selected features of the isotopic carbon primary production techniques. Rapp. P.-v. Réun. Cons. perm. int. Explor. Mer 144, 47–55 (1958)
Eppley, R.W.: Temperature and phytoplankton growth in the sea. Fish. Bull. U.S. 70, 1063–1085 (1972)
—, J.N. Rogers and J.J. McCarthy: Half-saturation constants for uptake of nitrate and ammonium by marine phytoplankton. Limnol. Oceanogr. 14, 912–920 (1969)
— and J.D.H. Strickland: Kinetics of marine phytoplankton growth. In: Advances in microbiology of the sea, Vol. 1 pp 23–62. Ed. by M.R. Droop and E.J.P. Wood. New York: Academic Press 1968
— and W.H. Thomas: Comparison of half-saturation constants for growth and nitrate uptake by marine phytoplankton. J. Phycol. 5, 375–379 (1969)
Finenko, Z.Z. and D.K. Krupatkina-Akinina: Effect of inorganic phosphorus on the growth rate of diatoms. Mar. Biol. 26, 193–201 (1974)
Fossato, V.U.: Ricerche idrologiche e chimicofisiche sul fiume Po a Polesella. 2. Luglio 1970-Giugno 1972. Archo Oceanogr. Limnol. 18, 59–70 (1973)
Franco, P.: Oceanography of Northern Adriatic Sea. 1. Hydrologic features: cruises July–August and October–November 1965. Arch. Oceanogr. Limnol. 16, 1–93 (1970)
—: Oceanography of Northern Adriatic Sea. 3. Distribution of the water transparency: cruises July–August and October–November 1965, January–February and April–May 1966. Archo Oceanogr. Limnol. 17, (Suppl.), 99–113 (1972)
Gilmartin, M. and N. Revelante: The “island mass” effect on the phytoplankton and primary production of the Hawaiian Islands. J. exp. mar. Biol. Ecol. 16, 181–204 (1974)
Gilmartin, M., S. Kveder, D. Degobbis, N. Revelante and N. Smodlake: Hydrographic data collected during cruises in the Northern Adriatic, July–December 1972. Thalassia jugosl. (In press, a)
Gilmartin, M. S. Kveder, D. Degobbis, N. Revelante and N. Smodlaka: Hydrographic data collected during cruises in the Northern Adriatic, January–December 1973. Thalassia jugosl. (In press, b)
Grese, V.N., E.P. Delalo, E.V. Palvola et A.A. Shmeleva: Sur la compositition et la répartition quantitative du zooplancton dans la Méditerranée orientale. Rapp. P.-v. Réun. Commn int. Explor. Mer Méditerr. 19, p.427 (1968)
Hepher, B.: Primary production in fish ponds and its application to fertilization experiments. Limnol. Oceanogr. 7, 131–136 (1962)
Holmes, R.W.: Size fractionation of photosynthetic phytoplankton. Spec. scient. Rep. U.S. Fish Wildl. Serv. (Fish.) 279, 69–71 (1958a)
—: Surface chlorophyll a, surface primary production, and zooplankton volumes in the Eastern Pacific Ocean. Rapp. P.-v. Réun. Cons. perm. int. Explor. Mer 144, 109–116 (1958b)
Ichimura, S.: Environmental gradient and its relation to primary productivity in Tokyo Bay, Rec. oceanogr. Wks Japan 9, 115–128 (1967)
Jacques, G.: Aspects quantitatifs du phytoplancton de Banyuls sur Mer (Golfe du Lion), 1965–1968. Vie Milieu 20, 91–126 (1969)
—, G. Cahet, M. Fiala et M. Panouse: Enrichissement de communautés phytoplanctoniques néritiques de Méditerranée nord occidentale. J. exp. mar. Biol. Ecol. 11, 287–295 (1973)
Jerlov, N.G.: Adriatic Thalassiographic cruise 1955. II. Distribution of suspended material in the Adriatic Sea. Archo Oceanogr. Limnol. 11, 227–250 (1958)
Kveder, S., N. Revelante, N. Smodlaka and A. Škrivanić: Some characteristics of phytoplankton and phytoplankton productivity in the Northern Adriatic, Thalassia jugosl. 7, 151–158 (1971)
Lund, J.W.G., C. Kipling and E.D. Le Cren: The inverted microscope method of estimating algal numbers and the statistical bases of estimation of counting. Hydrobiologia 11, 143–170 (1958)
Malone, T.C.: The relative importance of netplankton and nannoplankton as primary producers in neritic and oceanic tropical waters. Limnol. Oceanogr. 16, 633–639 (1971a)
—: The relative importance of nannoplankton and netplankton as primary producers in the California Current System. Fish. Bull. U.S. 69, 799–820 (1971b)
Martin, J.H.: Phytoplankton-zooplankton relationships in Narragansett Bay. Limnol. Oceanogr. 10, 185–191 (1965)
McAllister, C.D., N. Shah and J.D.H. Strickland: Marine phytoplankton photosynthesis as a function of light intensity: a comparison of methods. J. Fish. Res. Bd Can. 21, 159–181 (1964)
McCarthy, J.J., W.R. Taylor and M.E. Loftus: Significance of nanoplankton in the Chesapeake Bay Estuary and problems associated with the measurement of nanoplankton productivity. Mar. Biol., 24, 7–16 (1974)
Ministero dei Lavori Pubblici, Servizio Idrografico (Italia): Boll. idrol. mens. June–December, (1972)
Ministero dei Lavori Pubblici, Servizio Idrografico (Italia): Boll. idrol. mens. 30 January–December, (1973)
Mommaerts, J.: The relative importance of nannoplankton in the North Sea primary production. Br. phycol. J. 8, 13–20 (1973)
Mosetti, F.: Alcune ricerche sulle correnti nel golfo di Trieste. Riv. ital. Geofis. 21, 33–38 (1972). (Boll. Ass. Geofis. ital.)
— and A. Lavenia: Ricerche oceanografische in Adriatico nel periodo 1966–1968. Boll. geofis teor. appl. 11, 191–218 (1969)
Mullin, M.M.: Some factors affecting the feeding of marine copepods of the genus Calanus. Limnol. Oceanogr. 8, 239–250 (1963)
Munk, W.H. and G.A. Riley: Absorption of nutrients by aquatic plants. J. mar. Res. 11, 215–240 (1952)
Parsons, T.R. and R.J. Le Brasseur: The availability of food to different trophic levels in the marine food chain. In: Marine food chains, pp 325–343. Ed. by J.D. Steele. Berkeley: University of California Press 1970
—— and J.D. Fulton: Some observations on the dependence of zooplankton grazing on cell size and concentration of phytoplankton blooms. J. oceanogr. Soc. Japan 23, 10–17 (1967)
— and M. Takahashi: Environmental control of phytoplankton cell size. Limnol. Oceanogr. 18, 511–515 (1973)
Pigorini, B.: Sources and dispersion of recent sediments of the Adriatic Sea. Mar. Geol. 6, 187–229 (1968)
Pojed, I.: Nutrients as limiting factors of primary production in the Northern Adriatic. [In Croatian], 65 pp. M. Sc. thesis, University of Zagreb 1975
Pucher-Petković, T.: Recherches préliminaires sur la photosynthèse du nanoplancton et du microplancton dans les eaux de l'Adriatique moyenne. Rapp. P.-v. Réuen. Commn int. Explor. Mer Méditerr. 21, 445–448 (1973)
Smayda, T.J.: The suspension and sinking of phytoplankton in the sea. Oceanogr. mar. Biol. A. Rev. 8, 353–414 (1970)
Solorzano, L.: Determination of ammonia in natural waters by the phenolhypochlorite method. Limnol. Oceanogr. 14, 799–801 (1969)
Sournia, A.: La production primaire planctonique en Méditerranée. Essai de mise à jour. News. co-op. Invest. Mediterr., (spec. Issue) 5, 1–121 (1973). (Bull. Etud. commun Méditerr., Monaco)
Steemann-Nielsen, E. and E.A. Jensen: Primary oceanic production. The autotrophic production of organic matter in the ocean. Galathea Rep. 1, 49–136 (1957)
Štirn, J.: Pelagial Severnega Jadrana. Raspr. slov. Akad. Znan. Umet. 12, 1–92 (1969)
Strickland, J.D.H.: Production of organic matter in the primary stages of the marine food chain. In: Chemical oceanography, Vol 1 pp 477–610. Ed. by J.P. Riley and G. Skirrow. New York: Academic Press 1965
— and T.R. Parsons: A practical handbook of seawater analysis. Bull. Fish. Res. Bd Can. 167, 1–311 (1968)
Teixeira, C.: Relative rates of photosynthesis and standing stock of net phytoplankton and nanoplankton. Bolm Inst. Oceanogr., S Paulo 13, 53–60 (1963)
Thomas, W.H.: On nitrogen deficiency in tropical Pacific Ocean phytoplankton: photosynthetic parameters in poor and rich waters. Limnol. Oceanogr. 15, 380–385 (1970)
Van Straaten, L.M.J.V.: Sedimentation in the northwestern part of the Adriatic Sea. Proc. Symp. Colston Res. Soc. 17, 143–162 (1965)
Varagnolo, A.M. e G. Monte: Sulla composizione e distribuzione dello zooplancton nell'alto Adriattico nell'inverno e nella primavera 1966. Atti Ist. veneto Sci. 127, 413–441 (1969)
——: Osservazioni sulla composizione e distribuzione dello zooplancton nell'alto Adriatico nell'estate e nell'autunno 1965. Atti Ist. veneto Sci. 129, 229–255 (1971)
Voltolina, D.: Phytoplankton in the Gulf of Venice, April 1965–June 1966. Archo Oceanogr. Limnol. 17, 43–70 (1971)
Von Brand, T., N.W. Rakestraw and C.E. Renn: The experimental decomposition and regeneration of nitrogenous organic matter in sea water. Biol. Bull. mar. biol. Lab., Woods Hole 72, 165–175 (1937)
—— and J.W. Zabor: Decomposition and regeneration of nitrogenous organic matter in sea water. V. Factors influencing the length of the cycle, observations upon the gaseous and dissolved organic nitrogen. Biol. Bull. mar. biol. Lab., Woods Hole 83, 273–282 (1942)
Yentsch, C.S. and J.H. Ryther: Relative significance of the net phytoplankton and nannoplankton in the waters of Vineyard Sound. J. Cons. perm. int. Explor. Mer 24, 231–238 (1959)
Zore-Armanda, M.: On gradient currents in the Adriatic Sea. Acta adriat. 8, 1–38 (1956)
Author information
Authors and Affiliations
Additional information
Communicated by G.F. Humphrey, Sydney
Rights and permissions
About this article
Cite this article
Revelante, N., Gilmartin, M. The effect of Po river discharge on phytoplankton dynamics in the Northern Adriatic Sea. Marine Biology 34, 259–271 (1976). https://doi.org/10.1007/BF00388803
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00388803