Heterotrophic bacterioplankton plays a pivotal role in marine food webs and biogeochemical cycling. However, their temporal dynamics and underlying factors are still poorly understood in many regions, including the tropical waters of the Red Sea. The main goal of the MS project was to describe the seasonality and assess the impact of top-down controls (viruses and heterotrophic nanoflagellates) in parallel to bottom-up controls (substrate availability) on coastal bacterioplankton on a weekly basis. To that end, we monitored the abundance of the different planktonic groups by flow cytometry together with a set of environmental variables including temperature, salinity, dissolved organic carbon (DOC) and nitrogen (DON) and chlorophyll a concentration. We analyzed a weekly dataset collected over 2017 at the surface water of KAUST Harbor. The abundance of heterotrophic bacteria ranged from 1.55 to 4.97 x 105 cells ml-1, with that of autotrophic bacteria 4 to 14 fold less on average and presents 1 x 104 to 1.19x105 cells ml-1, while viruses ranged from 1.30 x 106 to 1.59 x 107 particles ml-1, and heterotrophic nanoflagellates (HNF) ranged from 8.62 x 10 to 1.63 x 103 cells ml-1. We distinguished between five groups of heterotrophic bacteria depending on the relative nucleic acid content, membrane state and cell-specific metabolic activity, two groups of Synechococcus, as well as three groups of viruses based on relative nucleic acid content. We found unexpected inverse relationship between viruses and HNFs. Based on a strong negative correlation, the results suggest that viruses controlled heterotrophic bacteria during summer until early winter period. HNFs showed a selective grazing behavior based their apparent preference to prey on both high (HNA) and low nucleic acid bacteria (LNA). Our results demonstrates that top-down control are key agents of heterotrophic bacterioplankton mortality and more important than bottom-up control in governing heterotrophic bacterioplankton abundances in the coastal tropical waters of the Red Sea.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-02-26T13:11:23Z No. of bitstreams: 1 PGPV16MA195.pdf: 1061407 bytes, checksum: 748e5f4b89d71d8c524a68b2c4e6fa21 (MD5) / Made available in DSpace on 2018-02-26T13:11:23Z (GMT). No. of bitstreams: 1 PGPV16MA195.pdf: 1061407 bytes, checksum: 748e5f4b89d71d8c524a68b2c4e6fa21 (MD5) Previous issue date: 2016-04-28 / This study was accomplished to analyze the maturation indexes and quality of apples that occur at harvest to the commercial level as well as the variability of these indexes due to the harvest year. A database was built by the analysis of 62,807 apple samples of Gala and their mutant clones 'Gala' and 29,053 apple samples of Fuji and its mutant clones 'Fuji' for eleven years (2005 and 2015) in a commercial company. Apples analyzed were collected from commercial orchards of Fraiburgo (60%) and São Joaquin (30%) in Santa Catarina State and the Vacaria region of Rio Grande do Sul State (10%). Each sample consisted of 100 apples representing different orchards, variety and date of harvest analyzed within 36 hours after the harvest. The apples were analyzed for appearance and size. The appearance parameters were intensity of red color, frequency and size of superficial injuries and damage. Based on the analysis of appearance, each fruit was ranked in one of the following categories: Extra, Cat1, Cat2, Cat3, Cat4, Out of category undeveloped defects ‘OCUD’, Out of category developed defects ‘OCDD’ according to legal regulations. Each fruit was ranked in a size class (caliber) following legal regulations based on their mass. The commercial harvest extends from the 3rd to the 15th week of the year for Gala and from 10th to 22th week of the year for ‘Fuji’, although about 70% of ‘Gala’ and ‘Fuji’ production was harvested in 4 and 6 weeks, respectively. Maturity indexes and quality of apples vary significantly among the years for both cultivars. The average of 'Gala' firmness ranges from 15.7 to 18.2 lb, and from 14.5 to 16.8 lb for 'Fuji'. Regarding the soluble solids 'Gala' average ranged from 11.9% to 13.3% and for 'Fuji' ranged from 12.8% to 15.4%. The average of starch index ranging from 4.1 to 6.4 for 'Gala' and from 3.9 to 5.9 for 'Fuji'. The tritatable acidity ranged between 4.2 meq/100 ml and 6.1 meq/100ml for 'Gala' and between 4.4 meq/100 ml and 5.3 meq/100ml for 'Fuji'. The severity of russeting for 'Gala' ranged from 1.1 to 1.7 and for 'Fuji' from 1.1 to 1.8. The average size, represented by fruit caliber for 'Gala' varied between 138 and 174 and for 'Fuji' between 120 and 145. At the beginning of the harvest period, the average firmness was 17.9 lb and 17.1 lb, soluble solids of 12.2% and 12.9%, starch index 4.0 and 3.9 and titratable acidity 5.7 meq/100 ml and 6.2 meq/100ml for 'Gala' and 'Fuji' respectively. In the average from 2005 to 2016, the quality distribution in terms of category Extra, Cat1, Cat2, Cat3, ‘OCUD’, ‘OCDD’ was for ‘Gala’, 6%, 31,5%, 34,4%, 22%, 5,6% e 0,7% respectivelly and for ‘Fuji’the same distribution was 4,6%, 38,4%, 33,6%, 18,6%, 4,3%, 0,6%. At the end of the harvest period (last week) the average firmness was 14.2 lb and 14.3 lb, soluble solids of 13.1 and 14.4, starch index of 6.1 and 6.4 and titratable acidity 3.9 and 3.8 meq/100ml for 'Gala' and 'Fuji' respectively. The size of both cultivars of apples does not vary consistently throughout the commercial harvest period / Este estudo foi realizado para analisar os índices de maturação e qualidade de maçãs que ocorrem no momento da colheita em nível comercial, bem como a variabilidade desses índices devido ao ano de colheita. Um banco de dados foi construído através da análise de 62.807 amostras de maçã da cultivar Gala e seus clones ('Gala') e 29.053 amostras de maçã da cultivar Fuji e seus clones ('Fuji') ao longo de 11 anos (2005 a 2015), em empresa na região de Fraiburgo. As maçãs analisadas foram colhidas em pomares comerciais de Fraiburgo (60%) e São Joaquin (30%), em Santa Catarina e da região dos Campos de Cima da Serra no Rio Grande do Sul (10%). Cada amostra foi composta por 100 maçãs representativas de diferentes unidades de produção de 6 a 19 toneladas de maçãs e analisada em até 36 horas após a colheita. A qualidade das maçãs foi analisada quanto a aparência e tamanho. Os parâmetros de aparência foram a intensidade de cor vermelha, a frequência e tamanho de lesões e danos visíveis na superfície do fruto. Com base na análise da aparência, cada fruto, foi classificado em uma das seguintes categorias de qualidade: Extra, Cat1, Cat2, Cat3, fora de categoria não evolutivo (‘FCNE’), e fora de categoria evolutivo (‘FCE’) de acordo com os regulamentos legais. Cada fruta foi classificada em um calibre com base em sua massa, seguindo as normas legais. O período de colheita comercial se estendeu da 3ª à 15ª semana do ano para a ‘Gala’ e da 10ª a 22ª semana do ano para a 'Fuji', embora cerca de 70% da produção de 'Gala' e 'Fuji' foram colhidas num período de 4 e 6 semanas, respectivamente. Os índices de maturação e qualidade das maçãs variaram significativamente entre anos para ambas as cultivares. As variações da firmeza da polpa entre anos foram de 15,7 lb a 18,2 lb para ‘Gala’ e de 14,5 lb a 16,8 lb para 'Fuji'. . Os teores médios anuais de sólidos solúveis variaram de 11,9 a 13,3% em 'Gala' e 12,8 a 15,4 % em 'Fuji' entre 2005 e 2011. A média anual do índice de iodo-amido variou de 4,1 a 6,4 para 'Gala' e 3,9 a 5,9 para 'Fuji'. O índice de russeting variou entre anos de 1,1 a 1,7 para 'Gala' e de 1,1 a 1,8 para ‘Fuji’. O calibre médio anual variou entre anos de 138 a 174 para a 'Gala' e de 120 a 145 para a 'Fuji'. Os índices de maturação e qualidade também variaram ao longo do período de colheita. No início do período de colheita (primeira semana), a firmeza média foi de 17,9 e 17,1 lb, os sólidos solúveis de 12,2 e 12,9%, o índice de iodo-amido de 4, e 3,9 e a acidez 5,7 e 6,2 meq/100ml para 'Gala' e 'Fuji' respectivamente. A distribuição de frequência média de 2005 a 2015, nas categorias Extra, Cat1, Cat2, Cat3, FCNE, FCE, para a ‘Gala’ foi respectivamente de 6%, 31,5%, 34,4%, 22%, 5,6% e 0,7% e para a ‘Fuji’ a mesma distribuição foi de 4,6%, 38,4%, 33,6%, 18,6%, 4,3%, 0,6%. O tamanho das maçãs de ambas cultivares não variou de forma consistente ao longo do período de colheita comercial