- Marine Ecology of Specific Areas
- Published:
Rostock zooplankton studies off West Africa
Helgoländer Meeresuntersuchungen volume 49, pages 829–847 (1995)
Abstract
Since the beginning of the seventies, upwelling research has become increasingly popular in the path of the Canary and Benguela Current, because of economic consideration, particularly in the relation to fisheries and marine geology. Many expeditions were carried out between 1970 and 1977, including 8 cruises of the German R. V. “A. v. Humboldt” operating from Rostock. Measurements covered scales ranging in time from minutes to several years and in space from hundreds of metres to several thousands of kilometres. Zooplankton studies focussed on quantitative, metabolic, taxonomic, and parasitological aspects. Plankton was collected with a WP-2-UNESCO standard net to a maximum depth of 200 m. The epipelagic mesozooplankton consists mainly of copepods, especially calanoids with developmental times of about 20 to 23 days. After an upwelling event, zooplankton is able to double its biomass. This typical biomass increase is independent of coastal distance and depth. The upwelling response lasts about 3 weeks in nearsurface waters, and 6 to 8 weeks in depths below 75m. A relationship was observed between the duration of seasonal upwelling (that means the numbers of single upwelling events) and the cumulative increase of biomass. This net growth rate of zooplankton biomass is most pronounced at the shelf break, the area with the highest fish biomass, and in the upper 25 m. Differences between the expected and the real rate values in conjunction with the known amount of nutritive demands of fishes allow the estimation of the fish biomass in a given area. The near coastal Ekman upwelling, which is an event in the time scale of about two weeks, also shows seasonality in some areas. Off Northwest Africa the largest expansion was recorded in the first half of the year, extending from 10° N to 24° N, more than 400 km offshore and at least down to 200 m. It contracts in the second half of the year to an area between 20°N and 22°N, 100 to 200 km off the coast and in an average depth of 25 m. These zooplankton biomass patterns are superimposed by mesoscale phenomena, originated by other than Ekman upwelling events. Those are, for example, long coastal parallel waves, producing cells of intensified upwelling and downwelling, and eddies, caused by instabilities in a frontal zone parallel to the coast. Different water masses can be distinguished by indicator species, species combinations or the significant absence of species. This was demonstrated for chaetognaths. The calanoidCalanus helgolandicus (Claus, 1863), a typical species of the North Atlantic, indicates North Atlantic Central Water, whereasCalanoides carinatus (Krøyer, 1849) is an indicator of South Atlantic Central Water. Finally, comparisons of near coastal current regimes, transport velocities, and developmental rates of calanoids allow one to conclude that a suitable mechanism is present to maintain plankton in the coastal environment.
Literature Cited
Arndt, E. A. & Brenning, U., 1977. The zooplankton biomass and its relation to abiotic and biotic factors in the upper 200 m of the upwelling region off North West Africa. — Wiss. Z. Univ. Rostock (Math.-nat. R.)26 (2), 137–146.
Arndt, E. A. & Köller, S., 1977. The taxonomy and ecology of the Chaetognaths in the epipelagial of the NWA upwelling region. — C.M./ICES,L:24, 1–4.
Arndt, E. A. & Wranik, W. 1977. Studies on the taxonomy and distribution of Thaliaceans off NWA. —C.M./ICES,L:23, 1–4.
Brenning, U., 1980. Zur Struktur und Dynamik von Calanoidenpopulationen (Crustacea, Copepoda) in den Aufquellgebieten vor Nordwest- und Südwestafrika.—Habil.Schr., Univ. Rostock, 394 pp.
Brenning, U., 1981a. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. I. Die Vertreter der FamilieCalanoidae. — Wiss. Z. Univ. Rostock (Math.-nat. R.)30 (4/5), 1–12.
Brenning, U., 1981b. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. II. Die Vertreter der FamilieEucalanidae. — Wiss. Z. Univ. Rostock (Math.-nat. R.)30 (4/5), 13–21.
Brenning, U., 1982a. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. III. Die Vertreter der FamilieParacalanidae. — Wiss. Z. Univ. Rostock (Math.-nat. R.)31 (6), 1–9.
Brenning, U., 1982b. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. IV. Die Vertreter der FamiliePseudocalanidae. — Wiss. Z. Univ. Rostock (Math.-nat. R.)31 (6) 9–17.
Brenning, U., 1983. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. V. Die Vertreter der FamilieActiteidae. — Wiss. Z. Univ. Rostock (Math.-nat. R.)32 (5), 1–8.
Brenning, U., 1984. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. VI. Dié Vertreter der FamilieEuchaetidae, Phaennidae undScolecithricidae. —Wiss. Z. Univ. Rostock (Math.-nat. R.)33 (6), 1–9.
Brenning, U., 1985a. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. VII. Die Vertreter der FamilieCentropagidae undTemoridea. — Wiss. Z. Univ. Rostock (Math.-nat. R.)34 (6), 5–16.
Brenning, U., 1985b. Structure and development of Calanoid populations (Crustacea, Copepoda) in the upwelling regions off North and South West Africa. — Beitr. Meeresk.52, 3–33.
Brenning, U., 1986. Beiträge zur Calanoidenfauna (Crustacea, Copepoda) vor Nordwest- und Südwestafrika. VIII. Die Vertreter der FamilieMetridiidae, Lucicutiidae, Heterorhabdididae, Augaptilidae undArietellidae. — Wiss. Z. Univ. Rostock (Math.-nat. R.)35 (5), 5–16.
Brenning, U. & Fadschild, K., 1979. Untersuchungen über die Calanoidenpopulation (Crustacea, Copepoda) auf einer Dauerstation vor Cap Blanc (NWA) im März 1973. — Wiss. Z. Univ. Rostock (Math.-nat. R.)35 (6), 515–524.
Chagouri, G., 1989. Untersuchungen über den Zusammenhang zwischen Aufquellvorgängen und der Entwicklung vonCalanus carinatus (Krøyer, 1849), (Copepoda, Calanoidea) im Seegebiet vor Nordwest-Afrika. — Diss., Univ. Rostock, 173 pp.
Dantzler, H. L., 1977. Potential energy maxima in the tropical and subtropical North Atlantic. — J. phys. Oceanogr.7, 512–519.
Flood, P. R., Gosselck, F. & Braun, J. G., 1982.Branchiostoma larvae in the upwelling area off Northwest Africa. — Rapp. P.-v. Réun. Cons. int. Explor. Mer180, 307–314.
Gosselck, F., 1975. The distribution ofBranchiostoma senegalense (Acrania, Branchiostomidae) in the offshore shelf region off North West Africa. — Int. Revue ges. Hydrobiol.60, 199–207.
Gosselck, F. & Hagen, E., 1973. Vorkommen und Verbreitung der Larven vonBranchiostoma senegalense (Acrania, Branchiostomidae) vor NW Afrika. — Fisch.-Forsch.11, 101–106.
Gosselck, F., Kell, V. & Spittler, P., 1978. Feeding ofBranchiostoma senegalense (Acrania, Branchiostomidae). — Mar. Biol.46, 175–181.
Gosselck, F. & Kühner, E., 1973. Investigations on the biology ofBranchiostoma senegalense larvae off Nortwest African coast. — Mar. Biol.22, 67–73.
Gosselck, F. & Spittler, P., 1979. Age structure, growth and weight ofBranchiostoma senegalense (Acrania, Branchiostomidae) off NW Africa. — Int. Revue ges. Hydrobiol.64, 541–550.
Hagen, E., 1977. Zur Problematik mesoskaler Verwirblungen in den Schelfgebieten des küstennahen Kaltwasserauftriebs. — Beitr. Meeresk.39, 61–87.
Hagen, E., 1981. Mesoscale upwelling variations off the West African coast. In: Coastal and estuarine series 1. Coastal upwelling. Ed. by F. A. Richards. American Geophysical Union, Washington, 72–78.
Hagen, E., Schemainda, R., Michelchen, N., Postel, L., Schulz, S. & Below, M., 1981. Zur küstensenkrechten Struktur des Kaltwasserauftriebs vor der Küste Namibias. — Geod. geophys. Veröff. (Reihe 4)36, 1–99.
Hernández-León, S., Postel, L., Arístegui, J., Gómez, M., Montero, M., Torres, S., Almeida, C., Kühner, E., Brenning, U. & Hagen, E., 1992. Large scale and mesoscale patterns of metabolic activity of epipelagic micro and mesoplankton in the northeastern Central Atlantic at 21° N. —C.M./ICESL:20, 1–11.
Kaiser, W. & Postel, L., 1979. The importance of the vertical nutrient flux for the biological production in the Equatorial Undercurrent region at 30° W. — Mar. Biol.55, 23–27.
Klein, B., 1992. Die Kapverden—Frontalzone. — Ber. Inst. Meeresk., Kiel227, 1–191.
Köller, S., Breuel, G. & Arndt, E. A., 1976. Untersuchungen zur geographischen Verbreitung und Ökologie der Chaetognathen vor Nordwestafrika unter besonderer Berücksichtigung ihrer Indikatorarten. — Wiss. Z. Univ. Rostock (Math.-nat. R.)25 (3), 239–247.
Lovegrove, T., 1966. The determination of dry weight of plankton and the effect of various factors on the values obtained. In: Some contemporary studies in marine science. Ed. by H. Barnes. Allen & Unwin, London, 462–467.
Postel, L., 1982. Mesoscale investigations on space-temporal variability of the zooplankton biomass in the upwelling regions off Northwest and Southwest Africa. — Rapp. P.-v. Réun. Cons. int. Explor. Mer.180, 274–279.
Postel, L., 1985. The pelagic cross-shelf and alongshore boundaries of the North West African upwelling region and their annual variability in terms of zooplankton biomass. In: Simposio internacional sobre áreas de afloramiento más importantes del O africano (Cabo Blunco y Benguela). Ed. by C. Bas, R. Margalef & P. Rubiés. Instituto de Investigaciones Pesqueras, Barcelona,1, 479–487.
Postel, L., 1987. Einfluß des Nouakchott-Caňons (Mauretanien) auf ozeanologische Feldverteilungen im März 1984. 6. Zooplanktonbiomasse. — Beitr. Meeresk.57, 85–94.
Postel, L., 1990. The mesozooplankton response to coastal upwelling off West Africa with particular regard to biomass. — Meereswiss. Ber.1, 1–127.
Reimer, L. W., 1977. Larval cestodes in plankton invertebrates of the Atlantic near the shore of North West Africa. — Parazitologija11, 309–315.
Reimer, L. W., Hnatiuk, S. & Rochner, J., 1975. Metacercarien in Planktontieren des mittleren Atlantik. — Wiss. Z. pädag. Hochsch. Güstrow (Math.-nat. Fak.)2, 239–258.
Schemainda, R. & Schulz, S., 1976. Investigations on space-temporal variations of oceanological fields and their effect on primary production in the upwelling region off Cap Blanc from 1971 to 1974. — Geod. geophys. Veröff. (Reihe 4)18, 4–54.
Smed, J., 1982. The oceanographic data base for the CINECA region. — Rapp. P.-v. Réun. Cons. int. Explor. Mer180, 11–28.
Speth, P., Detlefsen, H. & Sierts, H. W., 1978. Meteorological influence on upwelling off Northwest Africa. — Dt. hydrogr. Z.31, 95–104.
Sverdrup, H. U., Johnson, M. W. & Fleming, R. H., 1942. The oceans, their physics, chemistry and general biology. Prentice Hall, Englewood Cliffs, 1087 pp.
Tomczak, M., 1973. An investigation into the occurence and development of cold water patches in the upwelling region off NW Africa, “Meteor” cruise No. 19. — “Meteor” Forsch. Ergebn. (Reihe A)13, 1–42.
Tomczak, M. & Hughes, P., 1980. Three-dimensional variability of water masses and currents in the Canary Current upwelling region. — Meteor-Forsch. Ergebn. (Reihe A)21, 1–24.
Tomczak, M. & Large, D. G. B., 1989. Optimum multiparameter analysis of mixing in the thermocline of Eastern Indian Ocean. — J. geophys. Res. (Reihe C)94, 16141–16149.
Tranter, D. J. (Ed.), 1968. Monographs on oceanographic methodology 2: Zooplankton sampling. Unesco, Paris, 174 pp.
Weiß, R. & Postel, L., 1991. Relationships between the mesozooplankton net growth and the Chub Mackerel stock off Northwest Africa. — C.M./ICESL:14.
Wolf, G. & Kaiser, W., 1978. Über den Jahreszyklus der T-S-Eigenschaften quasipermanenter Wasserarten und Variationen produktionsbiologischer Parameter auf dem Schelf vor Cap Blanc. — Geod. geophys. Veröff. (Reihe 4)24, 1–81.
Wranik, W. & Arndt, E. A., 1978. Untersuchungen zur Systematik und Verbreitung der Thaliaceen vor Nordwestafrika. — Wiss. Z. Univ. Rostock (Math.-nat. R.)27 (4), 381–388.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Postel, L., Arndt, E.A. & Brenning, U. Rostock zooplankton studies off West Africa. Helgolander Meeresunters 49, 829–847 (1995). https://doi.org/10.1007/BF02368406
Issue Date:
DOI: https://doi.org/10.1007/BF02368406