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Culture medium for isolating chitinolytic bacteria from seawater and plankton

SOUZA, Claudiana P.; BURBANO-ROSERO, E. M.; ALMEIDA, Bianca C.; MARTINS, Gislaine G.; ALBERTINI, Lilian S.; RIVERA, Irma N. G.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.99%
Chitin degradation is a key step in the cycling of nutrients in marine ecosystems and chitinolytic bacteria are the primary agents of this process. Chitinases, produced by bacteria, have potential applications in agriculture, medicine and in a wide range of biotechnological processes. We utilized a simple, rapid and cost-effective method of colloidal chitin preparation and a culture medium, in which colloidal chitin is the sole carbon source for the purpose of counting and isolating chitinolytic bacteria from seawater and plankton. This culture medium could be useful to isolate bacteria with the ability to produce extracellular chitinases for biotechnological applications.

Predator-prey models: an application for the plankton dynamics of lake Geneva

ACHCAR, Jorge Albertor; MAZUCHELI, Josmar; COELHO-BARROS, Emlio Augusto
Fonte: SPRINGER; AMSTERDAM Publicador: SPRINGER; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.99%
In this paper we present a hierarchical Bayesian analysis for a predator-prey model applied to ecology considering the use of Markov Chain Monte Carlo methods. We consider the introduction of a random effect in the model and the presence of a covariate vector. An application to ecology is considered using a data set related to the plankton dynamics of lake Geneva for the year 1990. We also discuss some aspects of discrimination of the proposed models.; CNPq[300235/2005-4]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP/Brazil[2007/01379-2]

Ultraviolet radiation enhances Arctic net plankton community production

Garcia-Corral, Lara S.; Agustí, Susana; Regaudie de Gioux, Aurore; Iuculano, Francesca; Carrillo-de-Albornoz, Paloma; Wassmann, Paul; Duarte, Carlos M.
Fonte: São Francisco Publicador: São Francisco
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.99%
In this study we report the response of net community production (NCP) of plankton communities in the Arctic surface waters exposure to natural ultraviolet radiation (UVR) conditions. A possible bias in previous measurements performed using borosilicate glass bottles (opaque to most UVR) can underestimate NCP. Here we show that 77% of the sampled communities suffer, on average, 38.5% of net increase in NCP when exposed to natural UV-B condition, relative to values when UV-B radiation is excluded. UV-B tends to shift communities toward autotrophy, with the most autotrophic communities responding the strongest. This is likely explained by the inhibition of bacterial respiration during the continuous day period of the Arctic summer, corroborated by experiments where bacterial production influenced by UV-B directly affect NCP. Whereas Arctic warming is expected to lead to lower NCP, our results show that increased UV-B radiation may partially compensate this negative effect in surface waters.

Desenvolvimento de um sistema semi-automático para coleta e fracionamento do plâncton, medição de variáveis físicas e químicas da água e determinação do espectro de tamanho e biomassa do zooplâncton; Development of semi-automatic system for sampling and fractioning of plankton, measurement of chemical and physical variables of water, and determination of the size spectra and biomass of plankton

Arantes Junior, João Durval
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/12/2006 PT
Relevância na Pesquisa
37.32%
Um dos principais problemas relacionados aos estudos limnológicos realizados manualmente em laboratório consiste no grande esforço, tempo de análise e trabalho especializado necessário. Esses fatores limitam a quantidade de amostras possíveis de serem analisadas em um determinado estudo, já que recursos sejam eles reagentes, recursos financeiros ou tempo são limitados. No presente trabalho foi utilizado um sistema semi-automatizado de medidas de variáveis físicas e químicas da água. O sistema é composto por uma sonda multi-parâmetro (Horiba U-22) e um sistema de posicionamento global (GPS) acoplados a um micro-computador, que realizam medidas georeferenciadas em curtos intervalos de tempo, permitindo um rastreamento horizontal das características da água. Foi ainda desenvolvido um sistema semi-automático para coleta fracionada da comunidade planctônica por meio de bomba de sucção operada por bateria e filtro coletor com rede de plâncton de diferentes aberturas de malha. O material coletado foi fotografado por meio de sistema de aquisição digital de imagens (microscópio Zeiss equipado com câmera AxionCan). Neste trabalho foi produzido um software (Planktonscan) que a partir da análise das imagens capturadas permite produzir dados com estimativas das medidas e dimensões dos organismos...

Frequência e diversidade de colifagos somáticos isolados de amostras de água do mar, plâncton e bivalves da baixada santista, canal de São Sebastião e Ubatuba.; Frequency and diversity of somatic coliphages isolated from seawater, plankton and bivalves samples from baixada Santista, Canal de São Sebastião e Ubatuba.

Rosero, Edith Mariela Burbano
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/07/2009 PT
Relevância na Pesquisa
37.14%
Os colifagos somáticos (CS) são os melhores indicadores de poluição fecal. Neste trabalho, foi determinada a abundância de CS em amostras de água do mar, plâncton, e bivalves coletadas em Santos, São Sebastião e Ubatuba. Houve correlação positiva entre CS e as bactérias marinhas viáveis, coliformes termotolerantes, E.coli e enterococos intestinais, e a correlação foi negativa com a temperatura. As maiores contagens de CS foram obtidas em Santos. As freqüências das famílias encontradas nas amostras de água do mar e plâncton foram: Siphoviridae (50% e 65,8%), Podoviridae (36% e 15,8%), Microviridae (9% e 15,8%) e Myoviridae (5%, 2,6%), respectivamente. Em bivalves, só foi observada Siphoviridae. Os morfotipos observados foram A1 (3%), B1 (63%), C1 (21%) e D1 (13%). As técnicas de RFLP e rep-PCR não foram discriminatórias. 9,6% dos colifagos apresentaram os genes que codificam para as toxinas ST e/ou LT. O presente estudo está identificando os colifagos como perigos microbiológicos e gerando subsídios para avaliação de riscos microbiológicos no ecossistema marinho.; The somatic coliphages (SC) are the better indicator for fecal pollution. In this research, it was obtained the SC abundance in seawater, plankton and bivalves samples collected from Santos...

Diversidade de bactérias quitinolíticas isoladas em amostras de água do mar e plâncton coletadas na região costeira do estado de São Paulo.; Diversity of Chitinolytic bacteria isolated from seawater and plankton samples collected at São Paulo Coast, Brazil.

Sales, Claudiana Paula de Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/08/2009 PT
Relevância na Pesquisa
37.14%
Bactérias quitinolíticas são autóctones do ecossistema marinho e tem um importante papel no processo de degradação de quitina. Relativamente pouco é conhecido sobre a diversidade e potencial enzimático de bactérias quitinolíticas isoladas de ambientes tropicais costeiros. Amostras de água do mar e de plâncton foram coletadas no Canal de São Sebastião, Baixada Santista e Ubatuba. As bactérias quitinolíticas foram enumeradas e isoladas em meio mínimo contendo quitina coloidal e caracterizadas através de métodos fenotípicos e genotípicos. As maiores contagens de bactérias quitinolíticas foram observadas em amostras de água do mar e plâncton coletadas na Baixada Santista. A diversidade de bactérias quitinolíticas e o potencial de produção de quitinases foram influenciados pelo nível de contaminação fecal presente no ecossistema marinho. Uma maior diversidade foi encontrada em ambiente com médio e baixo impacto antropogênico, mas bactérias quitinolíticas isoladas de ambiente com alta atividade antropogênica mostraram os maiores valores de produção de quitinases.; Chitinolytic bacteria are autochthonous in marine ecosystems and have an important role in chitin degradation process. A very little is know about the diversity and enzymatic potential of chitinolytic bacteria isolated from coastal tropical environments. Seawater and plankton samples were collected at Canal de São Sebastião...

Computer vision for continuous plankton monitoring; Visão computacional para o monitoramento contínuo de plâncton

Matuszewski, Damian Janusz
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/04/2014 EN
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37.46%
Plankton microorganisms constitute the base of the marine food web and play a great role in global atmospheric carbon dioxide drawdown. Moreover, being very sensitive to any environmental changes they allow noticing (and potentially counteracting) them faster than with any other means. As such they not only influence the fishery industry but are also frequently used to analyze changes in exploited coastal areas and the influence of these interferences on local environment and climate. As a consequence, there is a strong need for highly efficient systems allowing long time and large volume observation of plankton communities. This would provide us with better understanding of plankton role on global climate as well as help maintain the fragile environmental equilibrium. The adopted sensors typically provide huge amounts of data that must be processed efficiently without the need for intensive manual work of specialists. A new system for general purpose particle analysis in large volumes is presented. It has been designed and optimized for the continuous plankton monitoring problem; however, it can be easily applied as a versatile moving fluids analysis tool or in any other application in which targets to be detected and identified move in a unidirectional flux. The proposed system is composed of three stages: data acquisition...

Plankton and particle biomass size spectra on the Southwest Atlantic: Case studies in tropical and subtropical areas; Espectro de tamanho e biomassa do plâncton e de partículas no Atlântico Sudoeste: Estudos de caso em áreas tropicais e subtropicais

Marcolin, Catarina da Rocha
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/12/2013 EN
Relevância na Pesquisa
37.46%
This thesis is centered on the application of the Normalized Biomass Size Spectra (NBSS) theory to the study of plankton systems in shelf and oceanic areas of the tropical and subtropical Southwest Atlantic. I evaluated NBSS parameters over different environmental settings and their utility as proxies for system in Brazilian waters. The LOPC and the ZooScan are recently developed optical systems to automatically detect and measure plankton and particle size distributions in situ and in laboratory, respectively. I present two case studies: the first deals with the spatial variability over the Abrolhos Bank and adjacent oceanic areas in tropical latitudes, and the second focuses on temporal variability of plankton communities along a 5-year time series on a fixed station on the inner shelf at a subtropical location (Ubatuba, São Paulo). The data sets consisted of vertical profiles obtained with a LOPC and plankton preserved samples collected with a 200-m-mesh net. I observed in both data sets the accumulation of small particles (< 1 mm) above and within the pycnocline. NBSS slopes and intercepts were significantly different according to the contrasting environmental conditions observed in both areas; higher intercepts and steeper slopes were associated with higher productivity. The results highlight: i) water-column stratification as a key feature driving particle and plankton vertical distribution...

Estimation of Cu, Cd and Hg transported by plankton from a contaminated area (Ria de Aveiro)

Monterroso, P.; Abreu, S. N.; Pereira, E.; Vale, C.; Duarte, A. C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Outros
ENG
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The efficiency of plankton to sorb/incorporate anthropogenic metals discharged in a contaminated area of the Ria de Aveiro and the amount exported to the rest of the lagoon were examined. Suspended particulate matter and material collected in 63 and 200 μm plankton nets were sampled hourly on a semi-diurnal spring tidal cycle. The collected material was analysed for total Cu, Cd, Hg and Pb. Higher metal concentrations were registered in material collected during the ebb period, which indicates their incorporation into the plankton biomass previously transported into the area during the flood period. On the basis of the water volume variation, plankton biomass associated to the 63 and 200 μm nets and metal concentrations, mass balances were calculated for Cu, Cd and Hg. Clearly, metals associated with plankton were exported from the contaminated area to the rest of the lagoon. The net exported metals (63 μm net) were 223–336% of the imported metals corresponding to 2.4 g of Cd, 67 g of Cu, and 11 g of Hg, over the spring tidal cycle.

Effect of coastline properties and wastewater on plankton composition and distribution in a stressed environment on the north coast of Olinda-PE (Brazil)

Pereira,Luci Cajueiro Carneiro; Jiménez,José Antonio; Koening,Maria Luise; Porto Neto,Fernando F.; Medeiros,Carmen; Costa,Rauquírio Marinho da
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2005 EN
Relevância na Pesquisa
37.25%
A study of the structure of the plankton community along the coastal zone of the Casa Caiada-Rio Doce area (Pernambuco, Brazil) is presented. The results obtained indicated that in the protected zones the water presented high turbidity, high temperature, low salinity and high nutrient and oxygen rates. All of these conditions were responsible for the reduction in plankton diversity and an increase in the biomass of the most opportunistic (r-strategist) species e.g. Gyrosigma balticum and Bacillaria paxillifera (Phytoplankton) and Euterpina acutifrons (Zooplankton). The differences found with respect to others area studies performed in pristine conditions indicated that plankton structure could be used as an environmental health indicator and that, in this specific area, it was indicative of a poor quality coastal environment.

Hydrology, plankton, and corals of the Maracajaú reefs (Northeastern Brazil): an ecosystem under severe thermal stress

Mayal,Elga Miranda; Neumann-Leitão,Sigrid; Feitosa,Fernando Antônio do Nascimento; Schwamborn,Ralf; Silva,Tâmara de Almeida e; Silva-Cunha,Maria da Glória Gonçalves da
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
Relevância na Pesquisa
37.14%
This study provides baseline information on the hydrological conditions and on the coral and plankton communities at the Maracajaú reef ecosystem (Northeastern Brazil). Studies were performed from February to June 2000, covering the transition from dry to rainy season. In this area, there is an offshore coral reef formation, where corals were observed in loco; the water samples were collected to obtain the hydrological and plankton data. Six scleractinian species were identified. Stable isotope analysis on the carbonate fraction of Favia gravida fragments showed that these corals were under severe thermal stress. Chlorophyll-a varied from 1.1 to 9.3 mg m-3, with higher values during the rainy season. Average zooplankton wet weight biomass were 117.0 (microzooplankton) and 15.7 mg m -3(mesozooplankton). A total of 136 Phytoplankton and 61 zooplankton taxa were identified. Seasonal forcing determined the phyto-micro-and mesozooplankton community structure, rather than the coastal-offshore gradient.

Application of statistical learning theory to plankton image analysis

Hu, Qiao, Ph. D. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 173 leaves
ENG
Relevância na Pesquisa
37.42%
A fundamental problem in limnology and oceanography is the inability to quickly identify and map distributions of plankton. This thesis addresses the problem by applying statistical machine learning to video images collected by an optical sampler, the Video Plankton Recorder (VPR). The research is focused on development of a real-time automatic plankton recognition system to estimate plankton abundance. The system includes four major components: pattern representation/feature measurement, feature extraction/selection, classification, and abundance estimation. After an extensive study on a traditional learning vector quantization (LVQ) neural network (NN) classifier built on shape-based features and different pattern representation methods, I developed a classification system combined multi-scale cooccurrence matrices feature with support vector machine classifier. This new method outperforms the traditional shape-based-NN classifier method by 12% in classification accuracy. Subsequent plankton abundance estimates are improved in the regions of low relative abundance by more than 50%. Both the NN and SVM classifiers have no rejection metrics. In this thesis, two rejection metrics were developed.; (cont.) One was based on the Euclidean distance in the feature space for NN classifier. The other used dual classifier (NN and SVM) voting as output. Using the dual-classification method alone yields almost as good abundance estimation as human labeling on a test-bed of real world data. However...

Consequences of UV-enhanced community respiration for plankton metabolic balance

Agustí, Susana; Gioux, Aurore Regaudie de; Arrieta, Jesús M.; Duarte, Carlos M.
Fonte: Waco, Texas Publicador: Waco, Texas
Tipo: Artigo de Revista Científica
ENG
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37.14%
The net community production (NCP) of plankton communities affects their role as sources or sinks of atmospheric CO2. Most estimates of NCP have been made by enclosing communities in bottles, generally glass borosilicate, that remove ultraviolet (UV)B and part of UVA wavelengths. A series of experiments were conducted to test whether NCP values from communities incubated excluding UVB (+ part of UVA) radiation (i.e., in glass borosilicate) differ from those of communities receiving the full solar radiation spectrum (i.e., incubated with quartz bottles) and to explore the effect of UV radiation on the respiration rates and bacterial production in these communities. Plankton NCP tended to be 43% lower, on average, when the rates were measured under full solar radiation than when UVB (+ part of UVA) was removed. Dark respiration was significantly enhanced after exposure to the full solar spectrum for most communities, showing lower values when previously incubated in a light environment free of UVB (−50%) or in the dark (−62%). Bacterial production was inhibited by natural sunlight but increased, as observed for community respiration, when transferred to the dark. Communities previously exposed to full solar spectrum showed the greatest increase in bacterial production when allowed to recover in the dark. The net result of these responses were an increase in community respiration and decline in net community production over 24 h...

Plankton biomass in secondary ponds treating piggery waste

Barthel,Lígia; Oliveira,Paulo Armando Victória de; Costa,Rejane Helena Ribeiro da
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
37.14%
This study aimed at analyzing the plankton biomass found in a piggery waste treatment system, composed of a high rate algal pond (HRAP), two maturation ponds (MP1, MP2) (System A) and a water hyacinth pond (WHP) (System B). The ponds were disposed in series and the study was performed for 32 weeks. The physicochemical variables monitored were: pH, temperature, dissolved oxygen, soluble chemical oxygen demand, nitrogen compounds and total phosphorus. The plankton biomass was identified at genus level and the ecology index was calculated so as to describe its development in the ponds. Results showed lower specific richness, which was associated to the mono-specific Chlorella sp population. The protozoa density was conversely proportional to the green algae density. The higher species diversity occurred in the WHP and MP2. The green algae presented high relative density (>97 %). The Jaccard index reached 100% if Chlorella sp and sometimes diatoms were found in the system's inlet and outlet. The productivity of algal biomass was lower than 10 gTSS/m²/d in the maturation ponds, which was maintained in the HRAP. The green algae coefficient of variation (CV) varied from 0 to 1.5 in the HRAP and WHP, but was constant at 0.9 to the 10th week in MP1 and around 0.5 during all the experimental period for MP2. For the chlorophyll a...

Fingerprinting petroleum hydrocarbons in plankton and surface sediments during the spring and early summer blooms in the Galician coast (NW Spain) after the Prestige oil spill

Salas, N.; Ortiz Vera, Laura; Gilcoto, Miguel; Varela, Manuel; Bayona Termens, Josep María; Groom, S.; Álvarez-Salgado, Xosé Antón; Albaigés Riera, Joan
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 19968 bytes; application/msword
ENG
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37.25%
26 pages, 7 figures, 6 tables.-- Printed version published Dec 2006.; Plankton samples (20-350 microm and >350 microm) collected at three transects along the Galician coast (NW Spain) were analysed for individual aliphatic and aromatic hydrocarbons by GC-MS. Sample collection was performed in April-July 2003, after the Prestige oil spill (November 2002), to determine whether the hydrocarbons released into the water column as a consequence of the spill were accumulated by the planktonic communities during the subsequent spring and early summer blooms. Surface sediments were also collected to assess the presence of the spilled oil, removed from the water column by downward particle transport. Plankton concentrations of PAHs (Sigma14 parent components) were in the range of 25-898 ng g(-1)dw, the highest values being close to coastal urban areas. However, the individual distributions were highly dominated by alkyl naphthalenes and phenanthrenes, paralleling those in the water dissolved fraction. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes, and methyl phenanthrenes and dibenzothiophenes) showed the occurrence of background petrogenic pollution but not related with the Prestige oil, with the possible exception of the station off Costa da Morte in May 2003...

Predicting plankton net community production in the Atlantic Ocean

Serret, Pablo; Robinson, Carol; Fernández, Emilio; Teira, Eva; Tilstone, Gavin H.; Pérez, Valesca
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 918459 bytes; application/pdf
ENG
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37.25%
13 pages, 7 figures, 2 tables.-- Available online Nov 17, 2008.-- Issue title: "The Atlantic Meridional Transect Progamme".; We present, test and implement two contrasting models to predict euphotic zone net community production (NCP), which are based on 14C primary production (PO14CP) to NCP relationships over two latitudinal (ca. 30°S–45°N) transects traversing highly productive and oligotrophic provinces of the Atlantic Ocean (NADR, CNRY, BENG, NAST-E, ETRA and SATL, Longhurst et al., 1995 [An estimation of global primary production in the ocean from satellite radiometer data. Journal of Plankton Research 17, 1245–1271]). The two models include similar ranges of PO14CP and community structure, but differ in the relative influence of allochthonous organic matter in the oligotrophic provinces. Both models were used to predict NCP from PO14CP measurements obtained during 11 local and three seasonal studies in the Atlantic, Pacific and Indian Oceans, and from satellite-derived estimates of PO14CP. Comparison of these NCP predictions with concurrent in situ measurements and geochemical estimates of NCP showed that geographic and annual patterns of NCP can only be predicted when the relative trophic importance of local vs. distant processes is similar in both modeled and predicted ecosystems. The system-dependent ability of our models to predict NCP seasonality suggests that trophic-level dynamics are stronger than differences in hydrodynamic regime...

Variability in plankton community structure, metabolism, and vertical carbon fluxes along an upwelling filament (Cape Juby, NW Africa)

Arístegui, Javier; Barton, Eric D.; Tett, Paul; Montero, María F.; García-Muñoz, Mercedes; Basterretxea, Gotzon; Cussatlegras, Anne-Sophie; Ojeda, Alicia; Armas, Demetrio de
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 918459 bytes; application/pdf
ENG
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37.14%
19 pages, 10 figures, 4 tables.-- Printed version published in issue Aug-Sep 2004.-- Issue title: "The Canary Islands Coastal Transition Zone - Upwelling, Eddies and Filaments".; Full-text version available Open Access at: http://www.iim.csic.es/~barton/html/pdfs.html; The variability in dissolved and particulate organic matter, plankton biomass, community structure and metabolism, and vertical carbon fluxes were studied at four stations (D1–D4), placed along a coastal-offshore gradient of an upwelling filament developed near Cape Juby (NW Africa). The filament was revealed as a complex and variable system in terms of its hydrological structure and distribution of biological properties. An offshore shift from large to small phytoplankton cells, as well as from higher to lower autotrophic biomass, was not paralleled by a similar gradient in particulate (POC) or dissolved (DOC) organic carbon. Rather, stations in the central part of the filament (D2 and D3) presented the highest organic matter concentrations. Autotrophic carbon (POCChl) accounted for 53% (onshore station, D1) to 27% (offshore station, D4) of total POC (assuming a carbon to chlorophyll ratio of 50), from which nano- and pico-phytoplankton biomasses (POC(A<10 μm)) represented 14% (D1) to 79% (D4) of POC(Chl). The biomass of small hetrotrophs (POC(H<10 μm)) was equivalent to POC(A<10 μm)...

Nitrate uptake rates in freshwater plankton: the effect of food web structure

Rojo, Carmen; Rodrigo, María A.; Salazar, Guillem; Álvarez Cobelas, Miguel
Fonte: Commonwealth Scientific and Industrial Research Organization (Australia) Publicador: Commonwealth Scientific and Industrial Research Organization (Australia)
Tipo: Artículo Formato: 438284 bytes; application/pdf
ENG
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37.14%
9 pages, 3 figure, 1 table; Nitrate incorporation rates by primary producers and the transfer of nitrogen to upper planktonic food web levels in different seasons (spring and summer of different years) were studied using a microcosm experimental approach. The study communitieswere natural plankton communities from Colgada Lake (central Spain),which is heavily polluted by nitrate. Natural δ15N in phytoplankton and zooplankton was measured and experiments were performed on the 15N supply. Naturally derived δ15N varied from 7.4 to 8.6‰ and from 10.0 to 16.8‰ in phytoplankton and zooplankton respectively. Nitrogen incorporation rates ranged from 0.006 to 0.036μMh−1 and from 0.0004 to 0.0014μMh−1 in phytoplankton and zooplankton respectively. The differences in natural δ15N levels and nitrogen incorporation rates between plankton fractions from seasonally different communities reported in the present study suggested that the nitrogen uptake by planktonic communities in Colgada Lake depend on different combinations of dominant zooplankters and phytoplankton size structure. A higher level of nitrogen uptake by phytoplankton occurred when small algae were dominant without competitors (larger algae) or main predators (herbivorous zooplankters). This was because copepods...

Plankton blooms in vortices: The role of biological and hydrodynamic time scales

Sandulescu, Mathias; López, Cristóbal; Hernández-García, Emilio; Feudel, Ulrike
Fonte: Copernicus Publications Publicador: Copernicus Publications
Tipo: Artículo Formato: 2373 bytes; 2084851 bytes; text/plain; application/pdf
ENG
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ArXiv pre-print: http://arxiv.org/abs/0802.3973.-- Final full-text version of the paper available at: http://www.nonlin-processes-geophys.net/14/443/2007/.; The paper is licensed under a Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en), which allows broad distribution of it.; We study the interplay of hydrodynamic mesoscale structures and the growth of plankton in the wake of an island, and its interaction with a coastal upwelling. Our focus is on a mechanism for the emergence of localized plankton blooms in vortices. Using a coupled system of a kinematic flow mimicking the mesoscale structures behind the island and a simple three component model for the marine ecosystem, we show that the long residence times of nutrients and plankton in the vicinity of the island and the confinement of plankton within vortices are key factors for the appearance of localized plankton blooms.; M. Sandulescu and U. Feudel acknowledge financial support by the DFG grant FE 359/7-1. E. Hernández-García and C. López acknowledge financial support from MEC (Spain) and FEDER through project CONOCE2 (FIS2004-00953), and PIF project OCEANTECH from Spanish CSIC. Both groups have benefitted from a MEC-DAAD joint program.

Cross-shelf distribution of nutrients, plankton, and fish larvae in the San Blas Archipelago, Caribbean Panamá

D'Croz,Luis; Ross Robertson,D.; Martínez,José A.
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 EN
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To investigate possible seasonal patterns in water quality and plankton distribution, weekly samples were collected in a coral reef lagoon and in surrounding nearshore waters over a two year period. Additionally, two oceanographic surveys were also conducted in a larger area surrounding the primary study site during the seasonal extremes. The resulting information corroborated previous observations that this area is as an oligotrophic environment. The larger-scale sampling revealed seasonal variation in cross-shelf gradients in plankton, fish-egg and larval densities that are probably related to the strong onshore winds that are typically present during the dry season. Although some limited nutrient enrichment occurs in parts of the nearshore area during the rainy season, the highest plankton density and biomass were recorded in shallow nearshore waters during the windy dry season. Larvae of numerous fish taxa were collected in these nearshore areas during the dry season, suggesting seasonal aggregation. During the rainy season, fish larvae were spread more evenly across the shelf and into nearshelf waters.