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Abstract:

This is the first study on diatom spatial patterns in relation to major oceanographic features along a megascale transect in the Southwestern Atlantic Ocean and provides a comparison with diatom distribution in surface sediments. Absolute abundances of diatoms, silicoflagellates and dinoflagellates (>10-μm fraction) were assessed in 80 bottle samples from 5 to 50 m, retrieved in November 1993 at 20 stations (30-61°S) along 53°W. Siliceous phytoplankton were scarce in the northern half of the transect and in the south of 57°S (100-150 cells L-1), with a strong peak in the vicinity of the Polar Front (∼200 000 cells L-1), whereas dinoflagellates were more abundant at the northern stations (up to 24 000 cells L-1). In the south of 50°S phytoplanktonic cell densities were loosely (but significantly, r = 0.54, P < 0.01) associated with chlorophyll a, whereas in the north of this latitude, this relationship disappeared (r = 0.018, P > 0.1). In total, 191 diatoms and 4 silicoflagellates were recorded. Changes in diatom assemblage compositions along the transect allowed identification of five discrete areas: Subtropical (29°S), Northern Transitional (34-41°S), Southern Transitional (43-48°S), Subantarctic (49-54°S) and Antarctic (55-59°S), each characterized by a set of typical species. Diversity changed little with latitude, but numbers of species were higher in the north of 40°S. Comparison of diatom assemblage makeup in the plankton and in the surface sediments shows very strong disagreements, whereby cold water species are very significantly over-represented in the sedimentary record, suggesting enhanced preservation and strong subsurface equatorward advection of the cold water taxa. © The Author 2006. Published by Oxford University Press. All rights reserved.

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Documento: Artículo
Título:Distribution of spring phytoplankton (mainly diatoms) in the upper 50 m of the Southwestern Atlantic Ocean (30-61°S)
Autor:Olguín, H.F.; Boltovskoy, D.; Lange, C.B.; Brandini, F.
Filiación:Facultad de Ciencias Exactas Y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA-Buenos Aires, Argentina
Museo Argentino de Ciencias Naturales, A. Gallardo 470, C1405DJR-Buenos Aires, Argentina
Consejo Nacional de Investigaciones Científicas Y Técnicas, Argentina
Departamento de Oceanografía, Centro de Investigacion Oceanografica en El Pacifico Sur-Oriental (FONDAP-COPAS), Universidad de Concepción, Casilla 160-C, Concepción, Chile
Centro de Estudos Do Mar, Universidade Federal Do Paraná, Av. Beira Mar s/n, Pontal do Sul, PR 83255-000, Brazil
Palabras clave:abundance; advection; chlorophyll; community composition; diatom; dinoflagellate; phytoplankton; surficial sediment; transect; vertical distribution; Atlantic Ocean; Atlantic Ocean (Southwest); Bacillariophyta; Dictyochophyceae; Dinophyceae
Año:2006
Volumen:28
Número:12
Página de inicio:1107
Página de fin:1128
DOI: http://dx.doi.org/10.1093/plankt/fbl045
Título revista:Journal of Plankton Research
Título revista abreviado:J. Plankton Res.
ISSN:01427873
CODEN:JPLRD
PDF:https://bibliotecadigital.exactas.uba.ar/download/paper/paper_01427873_v28_n12_p1107_Olguin.pdf
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01427873_v28_n12_p1107_Olguin

Referencias:

  • Acha, M.E., Mianzan, H.W., Guerrero, R.A., Favero, M., Bava, J., Marine fronts at the continental shelves of South America. Physical and ecological processes (2004) J. Mar. Syst, 44, pp. 83-105
  • Balech, E., De nuevo sobre la oceanografía frente a la Argentina. Publ. Serv. Hidr. Nav. Argentina (1986) H, 645, pp. 1-23
  • Barlow, R.G., Aiken, J., Holligan, P.M., Cummings, D.G., Maritorena, S., Hooker, S., Phytoplankton pigment and absorption characteristics along meridional transects in the Atlantic Ocean (2002) Deep-Sea Res. I, 47, pp. 637-660
  • Beklemishev, C.W., (1969) Ekologiya i biogeografiya pelagiali, , Nauka, Moskva
  • Boltovskoy, E., Masas de agua (características, distribución, movimientos) en la superficie del Atlántico sudoeste, según indicadores biológicos - Foraminíferos (1970) Serv. Hidrogr. Naval, Argentina, H 643, pp. 1-99
  • (1981) Atlas del Zooplancton del Atlántico Sudoccidental y Métodos de Trabajo Con el Zooplancton Marino, , Boltovskoy, D, ed, Instituto Nacional de Investigación y Desarrollo Pesquero, Mar del Plata
  • Boltovskoy, D. (1986) Biogeography of the Southwestern Atlantic: current problems and prospects. In Pierrot-Bults, A. C., Van der Spoel, S., Zahuranec, B. J. and Johnson, R. K. (eds), Pelagic Biogeography. UNESCO Technical Paper Marine Science 49. UNESCO Press, Paris, pp. 14-24; Boltovskoy, D., Equatorward sedimentary shadows of near-surface oceanographic patterns (1988) Specul. Sci. Technol, 11, pp. 219-232
  • Boltovskoy, D., The sedimentary record of pelagic biogeography (1994) Prog. Oceanogr, 34, pp. 135-160
  • (1999) South Atlantic Zooplankton, , Boltovskoy, D, ed, Backhuys Publishers, Leyden
  • Boltovskoy, E., Boltovskoy, D., Correa, N., Brandini, F., Planktonic foraminifera from the southwestern Atlantic (30 to 608S): Species-specific patterns in the upper 50 m (1996) Mar. Micropaleontol, 28, pp. 53-72
  • Boltovskoy, D., Correa, N., Boltovskoy, A., Marine zooplanktonic diversity: A view from the South Atlantic (2003) Oceanol. Acta, 25, pp. 271-278
  • Boltovskoy, D., Gibbons, M.J., Hutchings, L., Binet, D., General biological features of the South Atlantic (1999) South Atlantic Zooplankton, pp. 1-42. , Boltovskoy, D, ed, Backhuys Publishers, Leiden, pp
  • Brandini, F.P., Boltovskoy, D., Piola, A., Kocmur, S., Röttgers, R., Abreu, P.C., Mendes Lopes, R., Multiannual trends in fronts and distribution of nutrients and chlorophyll in the southwestern Atlantic (30-62°S) (2000) Deep-Sea Res. I, 47, pp. 1015-1033
  • Briggs, J.C., (1996) Global Biogeography, , Elsevier, Amsterdam
  • Burckle, L.H., Cooke, D.W., Late Pleistocene Eucampia antarctica abundance stratigraphy in the Atlantic Sector of the Southern Ocean (1983) Micropaleontology, 29, pp. 6-10
  • Burckle, L.H., Stanton, D., Distribution of displaced diatoms in the Argentina Basin (1975) Nova Hedwigia Beih, 53, pp. 283-292
  • Burkill, P., Ciliates and other microplankton components of a nearshore food-web: Standing stock and production processes (1982) Ann. Inst. Oceanogr. Paris, 58, pp. 335-350
  • Ciechomski, J.D., Sánchez, R.P., Relation between icthyoplankton abundance and associated zooplankton biomass in shelf waters off Argentina (1983) Biol. Oceanogr, 3, pp. 77-101
  • The surface of the ice-age earth. Quantitative geologic evidence is used to reconstruct boundary conditions for the climate 18,000 years ago (1976) Science, 191, pp. 1131-1144. , CLIMAP Project Members
  • Crosta, X., Romero, O., Armand, L.K., Pichon, J.J., The biogeography of mayor diatom taxa in Southern Ocean sediments: 2. Open ocean related species (2005) Palaeogeogr. Palaeoclimatol, 223, pp. 66-92
  • Cupp, E.E., Marine plankton diatoms of the west coast of North America (1943) Bull. Scripps Inst. Oceanogr, 5, pp. 1-238
  • Dadon, J.R., Distribución y abundancia de Pteropoda Thecosomata en el Atlántico Sudoccidental (1984) Physis A, 42, pp. 25-38
  • Dadon, J.R., Boltovskoy, D., Zooplanktonic recurrent groups (Pteropoda, Euphausiacea, Chaetognatha) in the southwestern Atlantic Ocean (1982) Physis A, 41, pp. 63-83
  • Deacon, G.E.R., Physical and biological zonation in the Southern ocean (1982) Deep-Sea Res, 29, pp. 1-15
  • Esnal, G.B., Appendicularia (1999) South Atlantic Zooplankton, pp. 1375-1399. , Boltovskoy D, ed, Backhuys Publishers, Leiden, pp
  • Esnal, G.B., Daponte, M.C., Salpida (1999) South Atlantic Zooplankton, pp. 1423-1444. , Boltovskoy, D, ed, Backhuys Publishers, Leiden, pp
  • Esteves, J.L., Santinelli, N., Sastre, V., Díaz, R., Rivas, O., A toxic dinoflagellate bloomand PSP production associatedwith upwelling in Golfo Nuevo, Patagonia, Argentina (1992) Hydrobiologia, 242, pp. 115-122
  • Eynaud, F., Giraudeau, J., Pichon, J.J., Pudsey, C.J., Seasurface distribution of coccolithophores, diatoms, silicoflagellates and dinoflagellates in the South Atlantic Ocean during the late austral summer 1995 (1999) Deep-Sea Res. I, 46, pp. 451-482
  • Fernandes, L.F., Brandini, F.P., Microplankton communities in the Southwestern Atlantic Ocean: Biomass and distribution in November/1992 (1999) Rev. Bras. Oceanogr, 47, pp. 189-205
  • Gayoso, A.M., Seasonal succession patterns of phytoplankton in the Bahia Blanca Estuary (1999) Bot, 42, pp. 367-375. , Mar
  • Gayoso, A.M., Podestá, G.P., Hydrography and phytoplankton of the Brazil-Malvinas Currents Confluence (1996) J. Plankton Res, 18, pp. 941-951
  • Gibb, S.W., Barlow, R.G., Cummings, D.G., Rees, N.W., Trees, C.C., Holligan, P., Suggett, D., Surface phytoplankton pigment distributions in the Atlantic Ocean: An assessment of basin scale variability between 50°N and 50°S (2000) Prog. Oceanogr, 45, pp. 339-368
  • Goni, G., Kamholz, S., Garzoli, S., Olson, D., Dinamics of the Brazil-Malvinas Confluence based on inverted echo sounders and altimetry (1996) J. Geophys. Res, 101, pp. 16273-16289
  • Guerrero, R.A., Baldoni, A., Benavides, H.R., Oceanographic conditions at the southern end of the Argentine continental slope (1999) INIDEP Doc. Cient. (Mar Del Plata), 5, pp. 7-22
  • Guerrero, R.A., Lasta, C., Acha, M., Mianzan, H., Framiñan, M., (1997) Atlas Hidrográfico del Río de la Plata, , Comisión Administradora del Río de la Plata, Buenos Aires
  • Guillard, R.R.L., Kilham, P., The ecology of marine planktonic diatoms (1977) The Biology of Diatoms. Botanical Monographs, 13, pp. 372-469. , Werner, D, ed, Blackwell Science Publishers, London
  • Hasle, G.R., An analysis of the phytoplankton of the Pacific Southern Ocean: Abundance, composition and distribution during the Brategg Expedition 1947-1948 (1969) Hvalraed. Skr, 52, pp. 1-168
  • Hasle, G.R., The biogeography of some marine planktonic diatoms (1976) Deep-Sea Res, 23, pp. 319-338
  • Hasle, G.R., Syvertsen, E.E., Marine diatoms (1996) Identifying Marine Phytoplankton, pp. 5-385. , Tomas, C. R, ed, Academic Press, San Diego, California, pp
  • Hayek, L.A., Buzas, M., (1997) Surveying Natural Populations, , Columbia University Press, New York
  • Heinbokel, J.F., Diel periodicities and rates of reproduction in natural population of tintinnines in the oligotrophic water off Hawaii, September 1982 (1987) Mar. Microb. Food Webs, 2, pp. 1-13
  • Hemleben, C., Spindler, M., Anderson, O.R., (1989) Modern Planktonic Foraminifera, , Springer Verlag, New York
  • Hendey, N.I., An Introductory Account of the Smaller Algae of British Coastal Waters. Part V: Bacillariophyceae (Diatoms) (1964) Fishery Investigations Series, 4. , Ministry of Agriculture, Fisheries and Food, HMSO, London
  • Hustedt, F., Die Kieselalgen Deutschlands, Österreichs und der Schweiz (1930) Kryptogamen-Flora von Deutschlands, Österreichs und der Schweiz, pp. 1-920. , Rabenhorst, L, ed, Akademische Verlagsgesellschaft, Leipzig, pp
  • Hustedt, F., Diatomeen aus der Antarktis und dem Südatlantik. Deutsche Antarktische Expedition (1938), 2, 103-191. 39; Ikeda, Y., Siedler, G., Zwirz, M., On the variability of Southern Ocean Front locations between Southern Brazil and the Antarctic Peninsula (1989) J. Geophys. Res, 94, pp. 4757-4762
  • Jones, G.A., Johnson, D.A., Displaced Antarctic diatoms in Vema Channel sediments: Late Pleistocene/Holocene fluctuations in AABW flow (1984) Mar. Geol, 58, pp. 165-186
  • Kruskopf, M., Flynn, K.J., Chlorophyll content and fluorescence responses cannot be used to gauge reliably phytoplankton biomass, nutrient status or growth rate (2006) New Phytol, 169, pp. 525-536
  • Lange, K.B., Spatial and seasonal variations of diatom assemblages of the Argentinean coast (South Western Atlantic) (1985) Oceanol. Acta, 8, pp. 361-370
  • Lange, K.B., (1988) Variaciones estacionales de las asociaciones de diatomeas planctónicas de dos áreas marinas, el Atlántico Sudoccidental y el Pacífico Nordoriental, , Thesis Doctoral. University of Buenos Aires, 142 pp
  • Lange, K.B., Mostajo, E.L., Phytoplankton (diatoms and silicoflagellates) from the South Atlantic Ocean (1985) Bot, 28, pp. 469-476. , Mar
  • Lenz, W., Untersuchungen zur inneren hydrographischen Struktur des sudatl. Und mittleren Atlantiks (0-2000 m Tiefe) mit zoogeographischen Anmerkungen (1975) Ber. Deutsch. Wiss. Kommn. Meeresforsch, 24, pp. 1-21
  • Lundholm, N., Hasle, G.R., Fryxell, G.A., Hargraves, P.E., Morphology, phylogeny and taxonomy of species within the Pseudonitzschia americana complex (Bacillariophyceae) with descriptions of the two new species P. brasiliana and P. linea (2002) Phycologia, 41, pp. 480-497
  • Lundholm, N., Moestrup, O., The marine diatom Pseudonitzschia galaxiae sp. nov. (Bacillariophyceae), morphology and phylogenetic relationships (2002) Phycologia, 41, pp. 594-605
  • Lundholm, N., Moestrup, Ø., Hasle, G. R. and Hoef-Emden, K. (2003) A study of the Pseudo-nitzschia pseudodelicatissima/cuspidata complex (Bacillariophyceae): what is P. pseudodelicatissima? J. Phycol., 39, 797-813; Marañón, E., Holligan, P.M., Varela, M., Mouriño, B., Bale, A.J., Basin-scale variability of phytoplankton biomass, production and growth in the Atlantic Ocean (2000) Deep-Sea Res. I, 47, pp. 825-857
  • Mata, M.M., Garcia, C.A.E., Variabilidade da topografia oceânica superficial no Atlântico Sul Ocidental observada pela altimetria TOPEX/POSEIDON (1996) Anais do VIII Simpósio Brasileiro de Sensoramiento Remoto, pp. T67. , Salvador, Bahia, Brasil
  • Mazzoni, H., Abundancia y distribucion de Chaetognatha en el Atlantico Sudoccidental (Mar Argentino) (1983) Physis A, 41, pp. 157-171
  • Medlin, L.K., Priddle, J., (1990) Polar Marine Diatoms, , British Antarctic Survey, Cambridge
  • Negri, R., Fitoplancton y producción primaria en el área de la plataforma bonaerense próxima al talud continental (1993) Inf. Técn. INIDEP (Mar Del Plata), 1, pp. 1-7
  • Olson, D.B., Podestá, G.P., Evans, R.H., Brown, O.B., Temporal variations in the separation of Brazil and Malvinas currents (1988) Deep Sea Res, 35, pp. 1971-1990
  • Peterson, R.G., The boundary currents in the western Argentine Basin (1992) Deep-Sea Res, 39, pp. 623-644
  • Peterson, R.G., Stramma, L., Upper-level circulation in the South Atlantic Ocean (1991) Prog. Oceanogr, 26, pp. 1-73
  • Piola, A.R., Campos, E.J.D., Möller Jr., O.O., Charo, M., Martínez, C., The Subtropical Shelf Front off eastern South America (2000) J. Geophys. Res, 105, pp. 6565-6578
  • Podestá, G.P., Utilización de datos satelitarios en investigaciones oceanográficas y pesqueras en el Océano Atlántico Sudoccidental (1997) El Mar Argentino y sus Recursos Pesqueros Tomo 1, pp. 195-222. , Boschi, E, ed, Instituto Nacional de Investigación y Desarrollo Pesquero, Mar del Plata, Argentina, pp
  • Poelchau, H., Distribution of Holocene silicoflagellates in North Pacific sediments (1976) Micropaleontology, 22, pp. 164-193
  • Priddle, J., Fryxell, G., (1985) Handbook of the Common Plankton Diatoms of the Southern Ocean, , British Antarctic Survey, Cambridge
  • Reid, J.L., Nowlin, W.D., Patzert, W.C., On the characteristics and circulation of the Southwestern Atlantic Ocean (1977) J. Phys. Oceanogr, 7, pp. 62-91
  • (1993) Species Diversity in Ecological Communities, , Ricklefs, R. E. and Schluter, D, eds, University of Chicago Press, Chicago
  • Rines, J.E.B., Morphology and taxonomy of Chaetoceros contortus Schütt 1895, with preliminary observations on Chaetoceros compressus Lauder 1864 (Subgenus Hyalochaete, Section Compressa) (1999) Bot, 42, pp. 539-551. , Mar
  • Romero, O., Armand, L.K., Crosta, X., Pichon, J.J., The biogeography of mayor diatom taxa in Southern Ocean surface sediments: 3. Tropical/Subtropical species (2005) Palaeogeogr., Palaeoclimatol., Palaeoecol, 223, pp. 49-65
  • Romero, O., Hensen, C., Oceanographic control of biogenic opal and diatoms in surface sediments of the southwestern Atlantic (2002) Mar. Geol, 186, pp. 263-280
  • Romesburg, H.C., (1984) Cluster Analysis for Researchers, , Lifetime Learning Publications, Belmont
  • Sar, E.A., Sunesen, I., Castaños, C., Marine diatoms from Buenos Aires coastal waters (República Argentina). I. Thalassiosiraceae (2001) Nova Hedwigia, 73, pp. 199-228
  • Sar, E.A., Sunesen, I., Lavigne, A.S., The diatom genus Thalassiosira: Species from the northern San Matías Gulf (Río Negro, Argentina) (2002) Nova Hedwigia, 74, pp. 373-386
  • Saraceno, M., Provost, C., Piola, A., On the relationship between satellite retrieved surface temperature fronts and chlorophyll-a in the Western South Atlantic (2005) J. Geophys. Res, 110, pp. C11016. , doi: 10.1029/2004JC002736
  • Saraceno, M., Provost, C., Piola, A., Bava, J., Gagliardini, A., Brazil Malvinas Frontal System as seen from 9 years of advanced very high resolution radiometer data (2004) J. Geophys. Res, 109, pp. C05027. , doi: 10.1029/2003JC002127
  • Sarno, S., Kooistra, W., Medlin, L., Percopo, I., Zingone, A., Diversity in the genus Skeletonema (Bacillariophyceae). II. An assessment of the taxonomy of S. costatum-like species with the description of four new species (2005) J. Phycol, 41, pp. 151-176
  • Shannon, C.E., Weaver, W., (1949) The Mathematical Theory of Communication, , University of Illinois Press, Urbana
  • Simonsen, R., The diatom plankton of the Indian Ocean expedition of RV Meteor 1964-1965 (1974) Meteor Forsch.-Ergeb., D, 19, pp. 1-66
  • Spindler, M., Hemleben, C., Bayer, U., Bé, A.W.H., Anderson, O.R., Lunar periodicity of reproduction in the planktonic foraminifer Hastigerina pelagica (1979) Mar. Ecol. Prog. Ser, 1, pp. 61-64
  • Sullivan, C.W., Arrigo, K.R., McClain, C.R., Comiso, J.C., Firestone, J., Distributions of phytoplankton blooms in the Southern Ocean (1993) Science, 262, pp. 1832-1837
  • Takahashi, K., Seasonal fluxes of silicoflagellates and Actiniscus in the subarctic Pacific during 1982-1984 (1987) J. Mar. Res, 45, pp. 397-425
  • Takahashi, K., Blackwelder, P.L., The spatial distribution of silicoflagellates in the region of the Gulf Stream warm-core ring 82B: Application to water mass tracer studies (1992) Deep-Sea Res, 39, pp. 327-346
  • Tarling, G., Ward, P., Sheader, M., Williams, J., Symon, C., Distribution patterns of macrozooplankton assemblages in the southwest Atlantic (1995) Mar. Ecol. Prog. Ser, 120, pp. 29-40
  • Thompson, G.A., (2001) Distribución y abundancia del microzooplancton en el Atlántico Sudoccidental, con especial énfasis en la biogeografía de Tintinnina (Protozoa, Ciliata), , Tesis de Doctorado. FCEyN, UBA
  • Thompson, G.A., Tintinnid diversity trends in the southwestern Atlantic Ocean (29-60°S) (2004) Aquat Microb. Ecol, 35, pp. 93-103
  • Thompson, G.A., Alder, V.A., Boltovskoy, D., Tintinnids (Ciliophora) and other microzooplankton (>30 mm) in Southwestern Atlantic shelf break waters (2001) Mar. Ecol, 22, pp. 343-355
  • Thompson, G.A., Alder, V.A., Boltovskoy, D., Brandini, F., Abundance and biogeography of tintinnids (Ciliophora) and associated microzooplankton in the Southwestern Atlantic Ocean (1999) J. Plankton Res, 21, pp. 1265-1298
  • Tsuchiya, M., Talley, L.D., McCartney, M.S., Water-mass distributions in the western South Atlantic. A section from South Georgia Island (54°S) northward across the equator (1994) J. Mar. Res, 52, pp. 55-81
  • Utermöhl, H., Zur Vervollkommnung der quantitativen Phytoplankton-Methodik (1958) Mitt. Int. Ver. Limnol, 9, pp. 1-38
  • Venrick, E.L., Recurrent groups of diatom species in the North pacific (1971) Ecology, 52, pp. 614-625
  • Willson, H.R., Rees, N.W., Classification of mesoscale features in the Brazil-Falkland Current confluence zone (2000) Prog. Oceanogr, 45, pp. 415-426

Citas:

---------- APA ----------
Olguín, H.F., Boltovskoy, D., Lange, C.B. & Brandini, F. (2006) . Distribution of spring phytoplankton (mainly diatoms) in the upper 50 m of the Southwestern Atlantic Ocean (30-61°S). Journal of Plankton Research, 28(12), 1107-1128.
http://dx.doi.org/10.1093/plankt/fbl045
---------- CHICAGO ----------
Olguín, H.F., Boltovskoy, D., Lange, C.B., Brandini, F. "Distribution of spring phytoplankton (mainly diatoms) in the upper 50 m of the Southwestern Atlantic Ocean (30-61°S)" . Journal of Plankton Research 28, no. 12 (2006) : 1107-1128.
http://dx.doi.org/10.1093/plankt/fbl045
---------- MLA ----------
Olguín, H.F., Boltovskoy, D., Lange, C.B., Brandini, F. "Distribution of spring phytoplankton (mainly diatoms) in the upper 50 m of the Southwestern Atlantic Ocean (30-61°S)" . Journal of Plankton Research, vol. 28, no. 12, 2006, pp. 1107-1128.
http://dx.doi.org/10.1093/plankt/fbl045
---------- VANCOUVER ----------
Olguín, H.F., Boltovskoy, D., Lange, C.B., Brandini, F. Distribution of spring phytoplankton (mainly diatoms) in the upper 50 m of the Southwestern Atlantic Ocean (30-61°S). J. Plankton Res. 2006;28(12):1107-1128.
http://dx.doi.org/10.1093/plankt/fbl045