CONTRIBUTION OF PHYTOPLANKTON AND PERIPHYTON TO THE PRODUCTION IN A RESERVOIR OF S.W. SPAIN

The phytoplanktonic and periphytic communities of La Minilla reservoir were studied from September 1987 to August 1988. The aim of the present paper is to assess their contribution to total primary production. The sampling station for phytoplankton was situated in the middle of the reservoir, 500 m from the dam, above the deepest point. The periphyton was studied in a closed bay using slates as experimental substrata. Two kinds of samplers were used with these experimental substrata: potential production samplers (PPS) that always had the same position with respect to the water top, and real production samplers (RPS) that always had the same position with respect to the bottom. The dominant species in both communities were small and unicellular: Cyclotella ocellata, Rhodomonas minuta and Chrysidcilis peritaphrena in phytoplankton, and Achnanthes minutissima, A. linearis and Geitleribactron periphyticum in periphyton. The production of both communities was estimated by the amounts of chlorophyll a. In order to compare the contribution of each community to the total production, the volume of water in the reservoir was estimated and the surface able to be colonized was determined by echosounding. The annual mean of potential production of the periphytic community was the 5% of the total production (maximum 16% in spring) and the annual mean of real production was 2.44% of the total production (maximum 6% in spring). The differences between potential and real periphytic production were due to the water level fluctuations in autumn and winter and because of grazing in spring and summer.The phytoplanktonic and periphytic communities of La Minilla reservoir were studied from September 1987 to August 1988. The aim of the present paper is to assess their contribution to total primary production. The sampling station for phytoplankton was situated in the middle of the reservoir, 500 m from the dam, above the deepest point. The periphyton was studied in a closed bay using slates as experimental substrata. Two kinds of samplers were used with these experimental substrata: potential production samplers (PPS) that always had the same position with respect to the water top, and real production samplers (RPS) that always had the same position with respect to the bottom. The dominant species in both communities were small and unicellular: Cyclotella ocellata, Rhodomonas minuta and Chrysidcilis peritaphrena in phytoplankton, and Achnanthes minutissima, A. linearis and Geitleribactron periphyticum in periphyton. The production of both communities was estimated by the amounts of chlorophyll a. In order to compare the contribution of each community to the total production, the volume of water in the reservoir was estimated and the surface able to be colonized was determined by echosounding. The annual mean of potential production of the periphytic community was the 5% of the total production (maximum 16% in spring) and the annual mean of real production was 2.44% of the total production (maximum 6% in spring). The differences between potential and real periphytic production were due to the water level fluctuations in autumn and winter and because of grazing in spring and summer

Protocolo para la detección y seguimiento de Didymosphenia geminata (Lyngbye) Schmidt en el área andina patagónica, Argentina : Propuesta técnica elaborada por la Unidad de Gestión de Calidad del Agua

Fil: Casco, María Adela. División Ficología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Sala, Silvia Estela. División Ficología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Colonization of a Neotropical Reservoir (Córdoba, Argentina) by Ceratium hirundinella (O. F. Müller) Bergh

Blooms of Ceratium hirundinella (O. F. Müller) Bergh. have been detected in different water bodies in the Neotropical Region since 1990. The colonization began in southern lakes, and during the last decade the dinoflagellate arrived and bloomed in subtropical reservoirs. In this context the colonization of C. hirundinella and its population development have been analyzed from its first record in the Río Tercero Reservoir (February 1999 to February 2001). Phytoplankton and physicochemical samples were obtained from three sampling stations at the Reservoir, one in the outlet of the water cooling channel of the nuclear power plant, and one in the nearest tributary (Quillinzo River). Two blooms of C. hirundinella were detected during the warm seasons with temperatures higher than 18°C, and pH ranging between 8.5 and 8.9. Environmental conditions such as certain light intensity range and percentage of dissolved oxygen mentioned as favorable for Ceratium development were always recorded in Río Tercero Reservoir. Cysts were observed in spring and summer months. Another dinoflagellate (Peridinium gatunense Nygaard) bloomed in previous summer in this water body but its population density decreased during the invasive phase of colonization of C. hirundinella. Asplanchna girodi, became the dominant zooplankter after the first bloom of C. hirundinella. We believe that the presence of this dinoflagellate in the Neotropical Region could be a regional phenomenon associated with some dispersal mechanisms and favorable local conditions for its proliferation like those recorded in the Rio Tercero ReservoirFil: Mac Donagh, María Elicia. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casco, Maria Adela. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Claps, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Effect of environmental variables on epiphyton in a pampean lake with stable turbid- and clear-water states

In the present study, we examined the variation in composition and biomass of epi-phyton growing on the bulrush Schoenoplectus californicus in a pampean lake that passed through a turbid- and a clear-water period within an annual cycle. Monthly sampling was performed year-round at the center and periphery of a bulrush stand. We measured the physicochem-ical parameters in the water column using standardized field and laboratory methods. The epiphy-ton was sampled by sectioning bulrush stems into segments for pigment analysis, abundance measurements, and biovolume quantification. Two different types of communities were observed during the annual cycle. In the turbid-water period, epiphyton biomass and diversity remained low despite sufficient levels of phosphates. An abrupt increase in epiphyton biomass, along with structural changes in the community, occurred after an improvement in water transparency, suggesting that the epiphyton was strongly dependent on underwater light conditions. Differences in epiphyton composition and biomass between the center and the periphery of the bulrush stand were negligible. We conclude that the availability of colonizing surface is not a relevant driver for the colonization and growth of these epiphyton assemblages. The epiphyton in pampean lakes may remain stable and resilient for relatively long periods, even when confronted with environmental perturbations, and changes in these communities will only occur in relation to radical alterations in light and nutrient availability.Facultad de Ciencias Naturales y Muse

Epipelon dynamics in a shallow lake through a turbid-and a clear- water regime

Fil: Cano, María Gabriela. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Ficología; ArgentinaFil: Casco, María Adela. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Ficología; ArgentinaFil: Claps, María Cristina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; Argentin

Epipelon dynamics in a shallow lake through a turbid-and a clear-water regime

In Pampean lakes, very little information is available on epipelon structure and dynamics or the effect of environmental variables on those parameters. We anticipate that light may have the greatest influence on this community and that the nutrient concentration and substrate instability may exert secondary effects. Our objective was to analyze variations in descriptive parameters and in the algal species composition of the epipelon in the Pampean Lake Lacombe over space and time to establish the most influential environmental forces (light climate, wave action, nutrients). Sediment was collected from the benthos with a 3.5-cm-diameter corer in a year-round sampling every month at four sites in the lake that differed from each other in depth, distance from the shore, and the presence of emergent and submerged macrophytes. Although Lacombe is a shallow lake, differences occurred in community descriptive variables and in the epipelon composition (especially diatoms) over space and time. In particular, differences between the site nearest to the shore and the rest of the sites were found with respect to environmental variables (sediment-particle size, total phosphorus, organic matter content, light climate), epipelon descriptive parameters (abundance, chlorophyll a and Margalef’s index) and epipelon composition (especially specific biovolume and diatom-size classes). The epipelon also reflected, though slightly, the change from the turbid- to clear-water states in the lake. Sediment erosion or deposition was evidenced by differences in the sediment-particle composition and the predominant particle-size classes at each site. Statistical analyses indicated linear correlations between the epipelon parameters and variables related to the light climate in the water column. Conductivity and sediment total phosphorus and density were also correlated, but to a lesser extent, with epipelon composition. The epipelon variations in Lacombe Lake would exemplify the reference communities developed during clear or turbid regimes in Pampean shallow lakes. We found evidence for the influence of light climate and wave action (through instability of the substrate) on this community, but the effect of nutrients was negligible. We emphasize that the close relationships maintained by the epipelon with other communities such as the phytoplankton and the epiphyton may superimpose the patterns of variation to those communities onto the epipelon dynamics.Facultad de Ciencias Naturales y MuseoInstituto de Limnología "Dr. Raúl A. Ringuelet

Epipelon dynamics in a shallow lake through a turbid-and a clear-water regime

In Pampean lakes, very little information is available on epipelon structure and dynamics or the effect of environmental variables on those parameters. We anticipate that light may have the greatest influence on this community and that the nutrient concentration and substrate instability may exert secondary effects. Our objective was to analyze variations in descriptive parameters and in the algal species composition of the epipelon in the Pampean Lake Lacombe over space and time to establish the most influential environmental forces (light climate, wave action, nutrients). Sediment was collected from the benthos with a 3.5-cm-diameter corer in a year-round sampling every month at four sites in the lake that differed from each other in depth, distance from the shore, and the presence of emergent and submerged macrophytes. Although Lacombe is a shallow lake, differences occurred in community descriptive variables and in the epipelon composition (especially diatoms) over space and time. In particular, differences between the site nearest to the shore and the rest of the sites were found with respect to environmental variables (sediment-particle size, total phosphorus, organic matter content, light climate), epipelon descriptive parameters (abundance, chlorophyll a and Margalef’s index) and epipelon composition (especially specific biovolume and diatom-size classes). The epipelon also reflected, though slightly, the change from the turbid- to clear-water states in the lake. Sediment erosion or deposition was evidenced by differences in the sediment-particle composition and the predominant particle-size classes at each site. Statistical analyses indicated linear correlations between the epipelon parameters and variables related to the light climate in the water column. Conductivity and sediment total phosphorus and density were also correlated, but to a lesser extent, with epipelon composition. The epipelon variations in Lacombe Lake would exemplify the reference communities developed during clear or turbid regimes in Pampean shallow lakes. We found evidence for the influence of light climate and wave action (through instability of the substrate) on this community, but the effect of nutrients was negligible. We emphasize that the close relationships maintained by the epipelon with other communities such as the phytoplankton and the epiphyton may superimpose the patterns of variation to those communities onto the epipelon dynamics.Facultad de Ciencias Naturales y MuseoInstituto de Limnología "Dr. Raúl A. Ringuelet

Contenido clorofílico del epifiton sobre scirpus californicus en la laguna La Rosita (partido de Castelli)

Fil: Dos Santos, Analía. Departamento Científico Ficología. Museo de La Plata. Facultad de Ciencias Naturales y Museo, UNLPFil: Cano, María Gabriela. Departamento Científico Ficología. Museo de La Plata. Facultad de Ciencias Naturales y Museo, UNLPFil: Casco, María Adela. Departamento Científico Ficología. Museo de La Plata. Facultad de Ciencias Naturales y Museo, UNL

Colonization of a Neotropical Reservoir (Córdoba, Argentina) by Ceratium hirundinella (O. F. Müller) Bergh

Blooms of Ceratium hirundinella (O. F. Müller) Bergh. have been detected in different water bodies in the Neotropical Region since 1990. The colonization began in southern lakes, and during the last decade the dinoflagellate arrived and bloomed in subtropical reservoirs. In this context the colonization of C. hirundinella and its population development have been analyzed from its first record in the Río Tercero Reservoir (February 1999 to February 2001). Phytoplankton and physicochemical samples were obtained from three sampling stations at the Reservoir, one in the outlet of the water cooling channel of the nuclear power plant, and one in the nearest tributary (Quillinzo River). Two blooms of C. hirundinella were detected during the warm seasons with temperatures higher than 18°C, and pH ranging between 8.5 and 8.9. Environmental conditions such as certain light intensity range and percentage of dissolved oxygen mentioned as favorable for Ceratium development were always recorded in Río Tercero Reservoir. Cysts were observed in spring and summer months. Another dinoflagellate (Peridinium gatunense Nygaard) bloomed in previous summer in this water body but its population density decreased during the invasive phase of colonization of C. hirundinella. Asplanchna girodi, became the dominant zooplankter after the first bloom of C. hirundinella. We believe that the presence of this dinoflagellate in the Neotropical Region could be a regional phenomenon associated with some dispersal mechanisms and favorable local conditions for its proliferation like those recorded in the Rio Tercero Reservoir.Instituto de Limnología "Dr. Raul A. Ringuelet"Museo de La Plat

Microfitobenton del canal Mercante en dos condiciones hidrológicas

Fil: Dos Santos, Analía. División Ficología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Casco, María Adela. División Ficología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Claps, María Cristina. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin