FONSECA, Renata Stock. Dinâmica da comunidade fitoplanctônica em um viveiro de engorda de camarão marinho (Litopenaeus vannamei) no Estado do Ceará. 2006. 90 f. Dissertação (Mestrado em Ciências Marinhas Tropicais) - Instituto de Ciências do Mar, Universitade Federal do Ceará, Fortaleza, 2006. / Submitted by Debora Oliveira (deby_borboletinha@hotmail.com) on 2012-01-26T13:32:07Z No. of bitstreams: 1 2006_dis_rsfonseca.pdf: 1354052 bytes, checksum: 73c27aa896090f12949d76d03a945ab7 (MD5) / Approved for entry into archive by Debora Oliveira(deby_borboletinha@hotmail.com) on 2012-01-26T14:06:07Z (GMT) No. of bitstreams: 1 2006_dis_rsfonseca.pdf: 1354052 bytes, checksum: 73c27aa896090f12949d76d03a945ab7 (MD5) / Made available in DSpace on 2012-01-26T14:06:07Z (GMT). No. of bitstreams: 1 2006_dis_rsfonseca.pdf: 1354052 bytes, checksum: 73c27aa896090f12949d76d03a945ab7 (MD5) Previous issue date: 2006 / In shrimp ponds, the phytoplankton community can exhibit development patterns associated with environmental, operational and biological factors. The present study characterized the weekly phytoplankton composition and biomass changes in a pond over the growth cycle of Litopenaeus vannamei. Shrimp of 1.35 ± 0.63 cm in body length were stocked in a 3.3 ha pond under 42.4 animals/m2. Water sampling took place in the estuary (E), water inlet canal (C), pond plateau (P) and near the pond water drainage outlet (D). Horizontal net sampling was carried out with a 20 μm mesh net for taxonomic identification of phytoplankton. For chlorophyll a and phytoplankton counting samplings were conducted on the water sub-surface. Simultaneously, water analysis was carried out for temperature, salinity, dissolved oxygen, pH, visibility, depth, phosphate, reactive silicate, ammonium nitrogen, nitrate, nitrite and suspended solids. Shrimp were harvested after 85 days of rearing and achieved 11.18 g in body weight, 1.85 FCR and 52.9% survival. Feed contributed with 92.1% and 95.8% of nitrogen and phosphorous inputs into the pond, with the remainder attributed to chemical fertilizers. Pond soil organic matter was statistically higher in D (31.99 ± 13.66 g/kg) when compared to P (4.10 ± 1.56 g/kg; P < 0.05). However, soil pH between these sampling stations did not show statistically significant differences (P > 0.05), achieving a mean of 7.86 ± 0.40 for P and 7.82 ± 0.65 for D. While water temperature showed a similar trend for all sampling stations (P > 0.05), water pH was statistically higher for P and D (8.45 and 8.47, respectively; P < 0.05). Water salinity varied between 10‰ (E) and 35‰ (C, P and D), with minimum levels observed in the initial phases of the study. Dissolved phosphate ranged from 0.01 mg/l (C) to 0.24 mg/l (P) and nitrate from 0.002 mg/l (C, P and D) to 0.05 mg/l (P). Total Dissolved Nitrogen showed no statistically significant differences throughout the growth cycle (P > 0.05), except for E. The N:P, N:Si and Si:P molar ratios were below Redfield suggested ratios, except for Si:P in E and C. Chlorophyll a varied between 1.63 μg/l (C) and 184.83 μg/l (D). In P and D, chlorophyll a increased progressively throughout the study period. In the pond, phytoplankton showed an ecological succession different from the E and C. In P and D, diatoms predominated initially, but it was followed by excessive blooms of cyanophytes and euglenophytes. High inputs of feed and fertilizers were the main contributors for these blooms, potentially harmful to shrimp. The dissolved nutrients ((N-NH3,4, N-NO2 -, N-NO3 -, P-PO4 3- e Si) carried out a larger influence on the phytoplankton development in the pond. / Em viveiros de camarão, a comunidade fitoplanctônica pode apresentar padrões de desenvolvimento associados aos fatores bióticos, abióticos e operacionais. O presente estudo objetivou caracterizar as mudanças semanais na composição e biomassa fitoplanctônica em um viveiro de engorda do camarão Litopenaeus vannamei. Camarões com 1,35 ± 0,63 cm de comprimento corporal foram povoados em um viveiro de 3,3 ha sob densidade de 42,4 indivíduos/m2. As amostragens de água foram realizadas no estuário (E), canal de abastecimento (C), no platô (P) e ponto de descarga (D) de água do viveiro. As amostragens qualitativas do fitoplâncton foram realizadas através de arrastos horizontais com rede de 20 μm. Para análise de clorofila a e contagem do número de organismos fitoplanctônicos foram coletadas amostras de sub-superfície. Simultaneamente, foram realizadas análises da temperatura, salinidade, oxigênio dissolvido, pH, transparência, profundidade, fosfato, silício reativo, nitrogênio amoniacal, nitrito, nitrato e material em suspensão da água. O camarão foi despescado após 85 dias de engorda, alcançado 11,18 g de peso médio, FCA de 1,85 e sobrevivência de 52,9%. A ração contribuiu com 92,1 e 95,8% de aportes de nitrogênio e fósforo no viveiro, com o restante atribuído a fertilizantes químicos. Os valores de matéria orgânica no solo do viveiro apresentaram-se estatisticamente mais elevados em D (31,99 ± 13,66 g/kg) quando comparado à P (4,10 ± 1,56 g/kg; P < 0,05). Contudo, o pH do solo destas estações não apresentou diferença estatística significativa (P > 0,05), alcançando média de 7,86 ± 0,40 para P e 7,82 ± 0,65 para D. Enquanto a temperatura da água foi semelhante para as estações de amostragem (P > 0,05), o pH apresentou-se estatisticamente mais elevado para P e D (8,45 e 8,47, respectivamente; P < 0,05). A salinidade oscilou entre 10‰ (E) e 35‰ (C, P e D), com níveis mais baixos no início do ciclo. O fosfato dissolvido oscilou entre 0,01 mg/l (C) e 0,24 mg/l (P) e o nitrito entre 0,002 mg/l (C, P e D) e 0,05 mg/l (P). O Nitrogênio Total Dissolvido não apresentou diferença estatística significativa ao longo do cultivo (P > 0,05), exceto para E. As razões de N:P, N:Si e Si:P foram abaixo da razão de Redfield em todas as estações de amostragem, exceto para Si:P nas estações E e C. A clorofila a variou entre 1,63 μg/l (C) a 184,83 μg/l (D). P e D apresentaram aumento progressivo de clorofila a ao longo do cultivo. O padrão da sucessão fitoplanctônica no estuário e canal foi distinto do observado no viveiro, onde foi observada inicialmente a predominância de diatomáceas seguida por florações excessivas de cianofíceas e euglenofíceas, intercalado por uma floração de dinoflagelados detectado no 22º. Dia de cultivo. Os aportes elevados de ração e fertilizantes no viveiro foram os fatores que tiveram maior contribuição para o desenvolvimento destas florações de microalgas potencialmente nocivas ao camarão. Os nutrientes dissolvidos (N-NH3,4, N-NO2 -, N-NO3 -, P-PO4 3- e Si) esempenharam uma maior influência sobre o desenvolvimento do fitoplâncton no viveiro de cultivo.

The study undertaken was an attempt to provide information on the effect that oceanographic features common in the Mozambique Channel have on primary production. Oligotrophic conditions dominated the Mozambique Channel at the time of sampling and the introduction of nutrients into the euphotic zone by upwelling processes were identified as cyclonic eddies. Differences in physico-chemical variables between surface and F-max across all sites proved to be stronger than the physico-chemical variables between 4 grouped oceanographic features. This was revealed by stronger variations in phytoplankton community structure and chlorophyll a concentration between surface and F-max compared to oceanographic features sampled. One of the hypotheses presented for the study was that diatoms would dominate phytoplankton communities within a cyclonic eddy. This was not the case as the coccolithophorid, Emiliania huxleyi Lohmann (Hay and Mohler 1967) dominated F-max and surface water in the cyclonic eddies and most other sites. Phytoplankton community structure did not differ significantly between the oceanographic features sampled which contradicted another one of hypotheses presented in the study. Chlorophyll a concentration in surface water of the cyclonic eddies was significantly higher than in surface waters within the anti-cyclonic eddy. F-max was not significantly different in phytoplankton biomass between these two system types. The cyclonic eddies and anti-cyclone had similar phytoplankton diversity which did not verify the hypothesis that there would be less phytoplankton species diversity within cyclonic eddies compared to the anti-cyclonic eddy. Phytoplankton community structure differed between F-max (depth at which maximum chlorophyll a is found) and the surface. This phytoplankton community difference was linked to differences in physico-chemical variables between the two depths. The diatoms Thalassionema nitzschioides, Pseudo-nitzschia sp.A, Pseudo-nitzschia sp.B, Thalassiosira sp.C, Thalassiosira sp.E, Bacteriastrum furcatum, Guinardia cylindrus, Nitzschia closterium, Hemiaulus hauckii, and Nitzschia braarudii revealed the only discernible ecological similarity amongst phytoplankton species across all sites and depths. This is important as it revealed that these species were regularly found occupying similar depths and potentially similar physico-chemical ranges in the water column which suggest these diatom species responded to a dominant source of variation. Distribution patterns of species and of ecologically defined groups support the hypothesis that diatom species and assemblages are good indicators of the changing character of an upwelling system. These statements lead to the assumption that the diatom grouping found in this study indicates areas of upwelling where water temperatures are reduced and nutrients are more readily available. One must keep in mind that ordination techniques are only descriptive and no significance is tested. The coccolithophorid D. anthos and the dinoflagellate Phalacroma spp. were noted as being most dissimilar to all other phytoplankton species with regards to their position in the water column and their response to physico-chemical variables. Finally, the dominance of E. huxleyi in the Mozambique Channel during November/December of 2009 reveals the potential vulnerability of phytoplankton in the channel to ocean acidification.

A balanced nitrogen (N) cycle is paramount for the ecology and biogeochemistry of planet Earth. Human activities are now causing an imbalance in the N cycle, with several negative effects on the marine environment. However, our knowledge of the marine N cycle remains incomplete, especially with regards to the role of dissolved organic N (DON). Therefore, there is need to study the role of DON more extensively to aid in restoring balance to Earth's ecosystems and biogeochemical cycles. This project investigated DON dynamics and influence on phytoplankton in coastal and shelf seas (CSS) to the west of Britain where DON was understudied. First, selected methods for the measurement of N uptake rates, urea and dissolved free amino acid (DFAA) concentrations were reviewed and tested. Then, they were used to study the spatial and temporal DON dynamics in the shelf region to the west of Britain (Irish Sea and adjacent shelf), the in-situ seasonal DON dynamics and N uptake in relation to phytoplankton community composition and abundance in Loch Creran, and the influence of DON on the phytoplankton community composition and abundance in controlled nutrient uptake kinetics and growth experiments and ecosystem modelling. The main findings were: DON was important in the N dynamics of the Irish Sea and adjacent shelf waters; DON was correlated with changes in phytoplankton community composition in Loch Creran; its seasonal cycle suggested its importance as an N source for the development of the spring bloom; these ideas were further supported by controlled laboratory experiments and ecosystem modelling.

The variability in surf-zone phytoplankton community composition together with variability in nutrient concentrations was studied at seven beaches along the coast near Port Elizabeth, South Africa over a one-year sampling period. The nutrient requirements of selected diatoms and dinoflagellates that co-occur at these beaches were studied. The highest nutrient concentrations were recorded at Brighton beach, with phosphate concentration being substantially higher than standards set out for both South African and European waters. Nitrate, ammonium and silicate concentrations were consistent (low variability) at all beaches. The species composition of beaches without surf diatoms was also not variable (except for King’s Beach – an artificial beach). Maitland beach was the only beach that could be identified as a surf diatom beach due to the presence of Anaulus australis. The surf diatom Anaulus australis was found to be a superior competitor compared to all other species tested: the other surf diatom Asterionellopsis glacialis, and the dinoflagellates Gonyaulax spinifera, Prorocentrum micans, and Scrippsiella trochoidea. Gonyaulax spinifera could possibly outcompete Anaulus australis in systems should nitrate become limiting.

A ¹⁴C primary productivity bioassay was developed to detect selenium limitation in marine phytoplankton. Addition of Na₂Se0₃ to Se-deplete cultures of Thalassiosira pseudonana stimulated carbon uptake rates by up to 40%, when uptake was expressed on a per cell volume or relative basis. Recovery from Se-starvation was verified by changes in the growth rate and morphology of T. pseudonana. Carbon uptake rates of Katodinium rotundatum, grown in nutrient enriched artificial seawater supplemented with 10⁻¹⁰ M or 10⁻⁶ M Se, were unaffected by Na₂SeO₃ additions. Since Katodinium rotundatum did not exhibit growth responses to Se additions, it was concluded that 10⁻¹⁰ M Se was sufficient for the growth of this alga, which has not displayed an obligate Se requirement. Natural phytoplankton assemblages in the Strait of Georgia were examined for Se limitation with this ¹⁴C bioassay. Relative carbon uptake rates did not change following Na₂SeO₃ addition, indicating that these assemblages were not Se-limited at the time of the study. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Laboratory and field experiments examined several aspects of the interaction of freshwater phytoplankton species and plankton communities with nitrogen and phosphorus nutrient resources. The laboratory studies focused on the following three main areas: 1) effects of nutrient 'patchiness' on phytoplankton community structure; 2) kinetics of phosphate (PO₄⁻³ ) and ammonium (NH₄⁺) uptake of phytoplankton grown under non-steady-state but limiting rates of nutrient supply; 3) the effect of different N:P supply ratios on phytoplankton NH₄⁺ and PO₄⁻³ uptake kinetics and community structure. Nutrient 'patchiness' was simulated by altering the frequency of nutrient addition to cultures. Under conditions of infrequent addition (once per 18 days) dominance shifted to a larger species, and the average cell size of another species increased. Observations of PO₄⁻³ uptake kinetics were not consistent with most other studies where kinetics were determined under steady-state conditions. With respect to PO₄⁻³, the duration over which maximum uptake rates were sustained was species specific. There was a short lag before maximum uptake rates were realized, and whether maximum uptake rates occurred at the lowest or at intermediate dilution rates depended on the time scale over which the uptake measurements were made. NH₄⁺ uptake rates were found to be greatly enhanced during the first few minutes of uptake. When natural plankton assemblages were grown under N:P supply ratios of 5:1, 15:1 and 45:1 (by atoms), the treatments selected for different competitive dominants. An N:P ratio of 45:1 resulted in total dominance by Synechococcus sp.; cultures grown under 5:1 and 15:1 supply ratios were dominated by Synedra radians, Nitzschia holsatica and Scenedesmus sp. NH₄⁺ and PO₄⁻³ uptake kinetics were not the same in cultures grown under different supply ratios, and ratios of saturated PO₄⁻³ to NH₄⁺ uptake rates were a good indicator of the N:P supply ratio under which the cultures were grown. This relationship was used to derive an index termed the Relative Field investigations were conducted on an oligotrophic coastal lake. NH₄⁺ and PO₄⁻³ uptake rates of size fractionated plankton (< and > 3 um), at a range of substrate concentrations, revealed that a large portion of the total uptake (50-90 % and 65-85 % for NH₄⁺ and PO₄⁻³, respectively) was attributable to cells in the < 3 um fraction. In addition, saturating PO₄⁻³, uptake rates of the > 3 um cells were less sensitive to incubation time than smaller cells. The ratio of saturated PO₄⁻³ to NH₄⁺ uptake rates were consistent with nutrient bioassay experiments, and indicated that N:P supply ratios in the lake were in the range where both N and P could be limiting to phytoplankton growth. / Science, Faculty of / Botany, Department of / Graduate

The results of this study suggest that NO^ uptake in many (but not all) species of marine phytoplankton is mediated by a membrane-bound (NO⁻₃, Cl⁻)-activated adenosine triphosphatase. In the presence of NO⁻₃ and Cl⁻, semi-purified membrane preparations exhibit enhanced adenosine triphosphatase activity. The enzyme has characteristics common to other membrane-bound proteins: a break in the Arrhenius plot of 30.9 Kcal/mole at 2.9 C, parallel purification with the (Na⁺ + K⁺)-activated transport adenosine triphosphatase, and activation of catalytic activity by non-ionic and anionic detergents. It is inferred from parallel purification of the (NO⁻₃,Cl⁻)-activated adenosine triphosphatase and the physiological kinetics of NO⁻₃ uptake by intact cells, that the enzyme translocates NO⁻₃ across the cell membrane, into the cytoplasm, against the chemical concentration gradient of the ion. The half-saturation constants for activation of the adenosine triphosphatase by NO⁻₃ are less than 1 µM for most species tested and correlate with half-saturation constants for NO⁻₃ uptake by whole cells. The three dinoflagellates tested did not exhibit any relationship between NO⁻₃ concentrations and ATP hydrolysis, and it is inferred that the (NO⁻₃,Cl⁻)-activated adenosine triphosphatase is probably absent from this group. Results of metabolic inhibitor studies (including KCN, 2,4-dinitrophenol, dichlorodimethylurea, and carbonyl cyanide m-chlorophenylhydrozone) imply that the source of ATP for the NO⁻₃ transport is primarily cyclic photo-phosphorylation in vivo. These results are consistent with observations of selective inhibition of NO⁻₃ uptake in unialgal cultures as well as in natural populations. Field studies with natural phytoplankton communities from Knight Inlet, B. C, suggest a physiological adaptation to external nitrogen concentrations may occur. This adaptation is characterized by increased intracellular chlorophyll a synthesis in response to 10-15% nitrogen enrichment over a 6-8 hr period. During the adaptive period carbon fixation is temporarily suppressed, apparently due to competition between inorganic carbon and inorganic nitrogen for high-energy nucleotides from the light reactions. The results of this study are related to previous proposals for the metabolic pathway of nitrogen in marine phytoplankton. In conclusion, a modified pathway is proposed stressing (1) group differences, in that nitrogen assimilation in dinoflagellates appears different from other groups, and (2) the energetics and biochemical feed-back controls of nitrogen assimilation. / Science, Faculty of / Botany, Department of / Graduate

In the spring of 1973 continuous horizontal measurements were made of temperature, salinity, oxygen and chlorophyll a. in British Columbia coastal waters. The sampling procedure involved a towed pumping system and on-board instrumentation. An effort is made to describe the distributions of the measured parameters with particular emphasis on the smaller scales, less than 250 m. To this end, techniques of power spectral analysis were utilized to examine the data. Results show that there is variability in the nature of the distributions and that the relatedness of the parameters is not consistent, but that on average different experiments show similarities. It appears that to a large extent the distribution of chlorophyll a in an estuarine environment is related to physical transport processes. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The sensitivitiy of several species of marine phytoplankton to copper was investigated. No specific trends were found with respect to any general differences between diatoms and dinoflagellates or between different sized cells. Further investigation using a single bioassay species, Nitzschia lonqissima, indicate it to be very sensitive to cupric ion activity. Several physiological systems appear to be affected to different degrees, with cell division being more affected than photosynthetic pigment production or ¹⁴C uptake. The activity of the enzyme nitrate reductase is greatly increased by the addition of low concentrations of copper. / Science, Faculty of / Zoology, Department of / Graduate

Iron-rich colloidal material was found to be associated with diatoms in the natural environment. To determine if this association could be important to the organism, the supply of iron from colloidal forms to phytoplankton was investigated. Laboratory bioassays with the marine diatom Thalassiosira pseudonana demonstrated that freshly precipitated colloidal iron could readily support diatom growth. However, when these colloids were aged or subjected to short periods of heating, the iron availability was drastically reduced. The iron availabilty was not increased with addition of the complexing agent EDTA. The reduction in availability appears to be linked to increased thermodynamic stability of the colloidal hydrous ferric oxides. The probable mechanism of this reduction is decreased colloidal dissolution rates. The supply of iron from colloids to phytoplankton appears to be determined by the chemistry of the colloidal iron material rather than by the physical association of colloidal iron and cell walls. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate