Environmental gradients in a southern Europe estuarine system: Ria de Aveiro, Portugal implications for soft bottom macrofauna colonization
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Four seasonal sampling surveys were carried out between December 1985 and September 1986 in Canal de Mira (Ria de Aveiro, Portugal). A total of 40 sampling stations, distributed over 13 transects, was used. Salinity, temperature, dissolved oxygen and pH of the water mass were measured. Sediment temperature, and salinity and pH of interstitial water were determined. Sediment variables also included granulometric composition and organic matter contents. Bottom macrofauna samples were collected at each station.
Ordination (PCA and MDS) and classification of the sampling stations were performed, using the physicochemical and the biological data sets separately. Average linkage cluster analysis using the unweighted paired-group method, arithmetic averages, was used for both sets of data.
With a salinity range from 35.1‰ to 0.0‰, Canal de Mira behaves like a tidally and seasonally poikilohaline estuary. Water temperature (8.5–24.7°C) decreased along the channel towards its inner part during the cold season; an inverse and more pronounced trend was observed during the hot season. Dissolved oxygen contents was generally high during the day (50% to 240% saturation). Oversaturation was observed throughout the growing season, with peaks in areas with large amounts of rooted vegetation. The pH values, largely correlated with dissolved oxygen, ranged from 6.8 to 8.9. Four types of sediment were present in Canal de Mira, medium and muddy sands being dominant.
Two major gradients were identified: (i) a typical longitudinal estuarine gradient, associated with distance from the mouth, representing physicochemical variables such as tidal amplitude, salinity and temperature; this gradient was accompanied by an upstream increase in dominance; the community composition changes were mainly related to salinity; (ii) a lateral gradient, related to current velocity, depth and sediment composition; the subtidal community had a comparatively low species richness and abundance. Groups of stations could be recognized along the environmental gradients. Benthic community changes, however, appeared to be gradual rather than marked by abrupt transitions.
Key Wordsenvironmental gradients benthos multivariate analysis estuaries Portugal
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- ANDRADE, F. A., 1986. O Estuário do Mira: Caracterização geral e análise quantitativa da estrutura dos macropovoamentos bentónicos. Dissertação de Doutoramento, Universidade de Lisboa.Google Scholar
- BARROSA, J. O., 1985 Breve caracterização de Ria de Aveiro. In: Actas das Jornadas da Ria de Aveiro. Vol II. Recursos da Ria de Aveiro. Câmara Municipal de Aveiro, Aveiro, p. 9–14.Google Scholar
- BOESCH, D. F., 1977. A new look at the zonation of benthos along the estuarine gradient. In: B. C. Coull, Ed., Ecology of Marine Benthos. University of South Carolina Press, Columbia, p. 245–266.Google Scholar
- CUNHA, M. R., 1990. Caracterização da comunidade de macroinvertebrados bênticos e estudo das condiçöes ambientais na zona do Areäo (Ria de Aveiro, Canal de Mira). Provas de Aptidäo Pedagógica e Capacidade Cientifica, Universidade de Aveiro.Google Scholar
- GARVINE, R. W., 1975. The distribution of salinity and temperature in the Connecticut River estuary. J. Geoph. Res., 80: 1176–1183.Google Scholar
- GAUCH, H. G., Jr., 1982. Multivariate Analysis in Community Ecology. Cambridge University Press, Cambridge.Google Scholar
- HALL, A., 1982. Water quality problems in Ria de Aveiro. In: Actual Problems of Oceanography in Portugal. JNICT and NATO Marine Sciences Panel, Lisbon, p. 159–169.Google Scholar
- KIKKAWA, J. and ANDERSON, D. J., 1986. Community ecology, patterns and processes. Blackwell Scientific Publication, Melbourne.Google Scholar
- KINNE, O., 1971. 4. Salinity. In: O. Kinne, Ed., Marine ecology, a comprehensive integrated treatise on life in the oceans and coastal waters, Vol. 1(2). Wiley, London, p. 683–1244.Google Scholar
- LAMBSHEAD, P. J. D., PLATT, H. M. and SHAW, K. M., 1983. The detection of differences among assemblages of marine benthic species based on an assessment of dominance and diversity. J. Nat. Hist., 17: 859–874.Google Scholar
- LARSONNEUR, C., 1977. La cartographie des dépots meubles sur le plateau continental français: méthode mise au point et utilisé en Manche. J. Rech. Oceanogr. 2: 33–39.Google Scholar
- LEGENDRE, L. and LEGENDRE, P., 1979. Écologie numérique. 2. La structure des données écologiques. Masson, Paris.Google Scholar
- LUDWIG, J. A. and REYNOLDS, J. F., 1988. Statistical ecology: a primer on methods and computing. John Wiley and Sons, New York.Google Scholar
- MEYEBECK, M., CAUWET, G., DESSERY, S., SOMVILLE, M., GOULEAU, D. and BILLEN, G., 1988. Nutrients (organic C, P, N, Si) in the eutrophic River Loire (France) and its estuary. Estuar. Coast. Shelf Sci., 27: 595–624.Google Scholar
- MOREIRA, M. H., 1988. Estudo da comunidade bêntica num banco de lodo intertidal da Ria de Aveiro, com especial incidência no crescimento, biomassa e produção do berbigão, Cardium edule (L.). Ciên. Biol. Ecol. Syst., 8(1/2): 47–75.Google Scholar
- MORGANS, J. F. C., 1956. Notes on the analysis of shallow-water soft substrata. Journ. Anim. Ecol. 25: 367–387.Google Scholar
- NICHOLS, M. and ALLEN, G. P., 1978. Sedimentary processes in lagoons. Seminar on present and future research in coastal lagoons. UNESCO, Division of Marine Science, Beufort, NC.Google Scholar
- NOBRE, A., AFREIXO, J. and MACEDO, J., 1915. A Ria de Aveiro. Relatório ofícial do regulamento da Ria, de 28 de Dezembro de 1912. Imprensa Nacional, Lisboa.Google Scholar
- PASSEGA, R., 1957. Texture as characteristic of clastic deposition. Bull. Am. Ass. petrol. Geol., 41: 1952–1984.Google Scholar
- PRITCHARD, D. W., 1952. Salinity distribution and circulation in the Chesapeake Bay estuarine system. J. Mar. Res., 11: 106–123.Google Scholar
- PRITCHARD, D. W., 1967. What is an Estuary: Physical Viewpoint. In: G. E. Lauff, Ed., Estuaries. American Association for the Advancement of Science, Publication No. 83, Washington, p. 3–5.Google Scholar
- RELEXANS, J. C., MEYEBECK, M., BILLEN, G., BRUGEAILLE, M., ETCHERBER, H. and SOMVILLE, M., 1988. Algal and microbial processes involved in particulate organic matter dynamics in the Loire estuary. Estuar. Coast. Shelf Sci., 27: 625–644.Google Scholar
- SNEATH, P.H.A. and R.R. SOKAL 1973. Numerical Taxonomy. W.H. Freeman and Company, San Fransisco.Google Scholar
- SOKAL, R. and ROHLF, F., 1969. Biometry. The principles and practice of statistics in biological research. W. H. Freeman and Company. San Francisco.Google Scholar
- STRICKLAND, J. D. H. and PARSONS, T. R., 1972. A Practical Handbook of Seawater Analysis. Fisheries Research Board of Canada, Bul. 167, 2nd ed., Ottawa.Google Scholar
- VICENTE, C. M., 1985. Caracterização hidráulica e aluvionar da Ria de Aveiro. Utilização de modelos hidráulicos no estudo de problemas da Ria. In: Jornadas da Ria de Aveiro. Vol III. Ordenamento da Ria de Aveiro. Câmara Municipal de Aveiro, Aveiro, p. 41–58.Google Scholar
- VIEIRA, N. and FONTOURA. P. 1985. Influência da qualidade da água e da exploração de sal nas comunidades bentónicas da Ria de Aveiro. In: Jornadas da Ria de Aveiro. Vol. I. Câmara Municipal de Aveiro. Aveiro. p. 87–100.Google Scholar
- WHITTAKER, R. H., 1967. Gradient analysis of vegetation. Biol. Rev., 49: 207–264.Google Scholar