Thesis (M.S.)--Eastern Illinois University, 2009. / Includes bibliographical references (leaves [117]-125).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 184-198).

Consumers in marine and estuarine environments have a strong reliance on planktonic and benthic primary production. These two basal resources form the foundation of aquatic food webs, yet the abundance of phytoplankton and benthic algae are frequently inversely related due to competition for light and nutrients. As a result, optimal habitats for benthic and planktonic consumers vary spatially and temporally. To investigate these trends, three studies were conducted focusing on light attenuation and basal resources in a bay, river, and on a continental shelf. δ13C and δ15N stable isotopes can be used as endogenous tracers to determine both the trophic level and basal resource use of consumers. δ13C values of primary producers are determined by the isotopic values of available CO2 and by the degree of photosynthetic fractionation (εp) that occurs during photosynthesis. εp by aquatic algae is greater in high CO2concentrations, high light, during slow growth rates, and for cells with a small surface area to volume ratio. Interaction among these parameters complicates prediction of algal εp in a natural setting, prompting the investigation as to which factors would impact εp and δ13C in a dynamic estuary. Community-level fractionation of an assemblage of filamentous algae, pennate diatoms, and centric diatoms grown on glass plates was found to be positively correlated with photosynthetically active radiation (PAR), resulting in higher δ13C values for organic matter in low-light conditions. These results support the concept that the low-light benthic environment may contribute to the widely observed phenomenon of ~5 / higher δ13C values in benthic algae compared to phytoplankton. Spatial and temporal variability in the isotopic baseline provides evidence of shifting biogeochemical controls on primary production. The West Florida Shelf in the eastern Gulf of Mexico transitions from a eutrophic ecosystem near the Mississippi River to an oligotrophic ecosystem in offshore continental shelf waters. Spatiotemporal variability in the δ13C and δ15N signatures of primary producers and fish populations were examined along this gradient. Muscle δ15N from three widely distributed fish species exhibited strong longitudinal isotopic gradients that coincided with the principal trophic gradient, whereas δ13C values of fish muscle and benthic algae were correlated with depth. The three fish species had relatively high site fidelity, as isotopic gradients were consistent between seasons and years. Isotopic mixing models showed all three fish species had a significant reliance on benthic algae as a basal resource. Dynamic models of the West Florida Shelf isotopic baseline were created using spatial data and satellite-derived water quality characteristics as predictors. Models were constructed using data from three fish species and tested on four other species to determine if the models could be extrapolated to new taxa. Both dynamic and static δ15N models had similar predictive capabilities, indicating a fairly stable δ15N baseline. The satellite-derived dynamic variables explained more variation in baseline δ13C than static spatial descriptors. Planktonic primary production can directly impact benthic food chains through phytoplankton deposition. A novel phytoplankton deposition detection method that combined water-column and benthic fluorometry with surficial sediment sampling was developed and assessed in a two-year study of the Caloosahatchee River estuary. Classifications based upon this detection method showed phytoplankton deposition dominated the upstream region and deposition was associated with reduced dissolved oxygen concentrations. Benthic algae dominated in downstream regions, particularly during low freshwater flow conditions when light absorption by colored dissolved organic matter was low. This same Caloosahatchee River estuary study was used to determine if zooplankton aggregate in regions with optimal basal resource availability. The isopod Edotia triloba was found to associate with chlorophyll peaks when freshwater velocity was constant. Chlorophyll peaks were offset downstream or upstream from isopod aggregations when freshwater flow was accelerating or decelerating, implying that phytoplankton and isopods have different response times to changes in flow. Temporal and spatial fluctuations in water quality and primary production introduce instability to aquatic consumers that primarily rely on one basal resource. The current global trends in eutrophication and increasing planktonic production are likely to be a liability for benthic consumers due to increased benthic hypoxia and light attenuation. The results of these studies indicate that both the location of consumers and their isotopic signatures can be impacted by factors, such as light attenuation, that control benthic and planktonic primary production.

Οι πράσινοι καρποί φέρουν ενεργούς χλωροπλάστες, οι οποίοι επιτελούν φωτοσύνθεση και αναπτύσσονται σε ένα ιδιαίτερο μικροπεριβάλλον, που διαφέρει σημαντικά από αυτό των φύλλων. Συγκεκριμένα, χαρακτηρίζεται από υποξία, πολύ υψηλές συγκεντρώσεις CO2 και χαμηλές εντάσεις φωτός, ιδιαίτερα στα εσώτερα σημεία του καρπού. Οι συνθήκες αυτές διαμορφώνονται από τα ανατομικά χαρακτηριστικά των καρπών και από τον υψηλό μεταβολικό ρυθμό που επιδεικνύουν. Τα ιδιαίτερα χαρακτηριστικά του εσωτερικού του καρπού επηρεάζουν αντίστοιχα τα επίπεδα των συνολικών χλωροφυλλών (Chla+b) και τις σχετικές αναλογίες των φωτοσυνθετικών χρωστικών του (Chla/b, Car/Chla+b). Στην παρούσα εργασία, το ενδιαφέρον μας εστιάζεται στη μελέτη των φωτοσυνθετικών χρωστικών των καρπών και στη σύγκριση του προτύπου που διαμορφώνεται μεταξύ φύλλων, περικαρπίων και σπερμάτων, σε όσο το δυνατόν περισσότερα φυτικά είδη. Για τον σκοπό αυτό επιλέξαμε να αξιοποιήσουμε τους αντίστοιχους δείκτες της in vivo ανακλαστικότητας (NDI, δείκτης Chla/b και PRI) ως μια γρήγορη, ευαίσθητη και μη καταστρεπτική μέθοδο εκτίμησης των φωτοσυνθετικών χρωστικών. Παράλληλα, θέλοντας να ελέγξουμε την αξιοπιστία των ανωτέρω δεικτών ανακλαστικότητας και στους καρπούς, προσδιορίσαμε τα επίπεδα των φωτοσυνθετικών χρωστικών και των σχετικών αναλογιών τους και με την παραδοσιακή μέθοδο της εκχύλισης-φασματοφωτομέτρησης. Τα αποτελέσματά μας έδειξαν ότι σε όλες τις περιπτώσεις, τα περικάρπια περιέχουν σαφώς λιγότερες συνολικές χλωροφύλλες και ακολουθούν τα σπέρματα με ακόμα λιγότερες. Η σχετική αναλογία Chla/b είναι χαμηλότερη στα περικάρπια και τα σπέρματα έναντι των φύλλων, γεγονός που μπορεί εν μέρει να ερμηνευθεί ως σκιόφιλη προσαρμογή (περίπτωση σπερμάτων). Ωστόσο, οι εξωτερικές (πλήρως φωτιζόμενες) και οι εσωτερικές (σκιαζόμενες) πλευρές των περικαρπίων εμφανίζουν ίδια επίπεδα του λόγου Chla/b στα περισσότερα είδη που μελετήθηκαν. Αυτό μας υποδεικνύει ότι, ενδεχομένως, άλλοι παράγοντες πέραν του φωτός επηρεάζουν τη σχετική αναλογία των δύο χλωροφυλλών. Επιπρόσθετα, παρατηρήθηκε μη αναμενόμενη, αυξημένη σχετική αναλογία των συνολικών καροτενοειδών σε σχέση με τις συνολικές χλωροφύλλες (Car/Chla+b) των περικαρπίων και των σπερμάτων έναντι των αντίστοιχων φύλλων, εύρημα που χρήζει επίσης περαιτέρω μελέτης. / Green fruits contain active chloroplasts, which are driving the reactions of photosynthesis and function in a particular microenvironment, completely different from that of leaves. This microenvironment is characterized by hypoxia, extremely high internal CO2 concentrations and low light intensity, especially in the inner part of the fruit. The above conditions are shaped by fruit anatomical features and their high metabolic rhythm. The special characteristics of the fruit’s internal affect the total chlorophyll concentration (Chla+b), the ratio of Chla to Chlb (Chla/b) and the carotenoid to chlorophylls ratio (Car/Chla+b). In this study, the photosynthetic pigment profile of green fruits (pericarps and seeds) of 15 different species was investigated, with the corresponding leaves serving as controls. To this aim, the appropriate in vivo spectral reflectance indices (NDI, Chla/b index and PRI) were used, as a rapid, sensitive and non-destructive method for photosynthetic pigment estimation. In order to assess the reliability of the above indices in fruits, we estimated in parallel the photosynthetic pigment levels and their ratios with traditional extracting methods. Our results indicated that compared to leaves, pericarps are characterized by lower levels of total chlorophylls followed by seeds with even lower. The Chla/b ratio is lower in pericarps and seeds. As a consequence the lower Chla/b ratio could only partly be attributed to a shade adaptation. However, the exposed and shaded sides of pericarps displayed similar values for Chla/b ratio in the most of the species tested. Moreover, pericarps and seeds showed unexpectedly, higher carotenoid/chlorophyll ratios.

Seagrass meadows are highly productive, ecologically and economically valuable ecosystems. However, increased human activities along the coastal areas leading to processes such as eutrophication have resulted in the rapid loss and deterioration of seagrass ecosystems worldwide. This thesis focuses on the responses of seagrasses to increases in nutrients, subsequent increases in ephemeral algae, and changes in the physical-chemical properties of seawater induced by interaction with other marine biota. Both in situ and laboratory experiments conducted on the tropical seagrasses Cymodocea serrulata and Thalassia hemprichii revealed that increased concentrations of water column nutrients negatively affected seagrass photosynthesis by stimulating the growth of the epiphytic biomass on the seagrass leaves. Interaction between seagrasses and other marine organisms induced different responses in seagrass photosynthesis. Ulva intestinalis negatively affected the photosynthetic performance of the temperate seagrass Zostera marina both by reducing the light and by increasing the pH of the surrounding water. On the other hand, the coexistence of mussels Pinna muricata and seagrass Thalassia hemprichii enhanced the photosynthetic activity of the seagrass, but no effect on the mussels' calcification was recorded. This study demonstrates that seagrass productivity is affected by a multitude of indirect effects induced by nutrient over-enrichment, which act singly or in concert with each other. Understanding the responsive mechanisms involved is imperative to safeguard the ecosystem by providing knowledge and proposing measures to halt nutrient loading and to predict the future performance of seagrasses in response to increasing natural and human perturbations. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Papers 1, 3 and 4: Submitted. Paper 2: Manuscript. / Swedish Agency for Research Cooperation (Sida/SAREC) marine bilateral programme

Banana production ranks fifth behind cereals as a food crop and has potential, along with other major crops, to feed the world's increasing population. Globally, continuous efforts and techniques including the use of plant tissue culture (PTC) have been devised for increasing the production of several Musa species. The choice of cytokinin (CK) is one of the most critical factors in developing a successful PTC protocol. Since the discovery of topolins as naturally occurring aromatic CKs, they have emerged as genuine alternatives to the long serving CKs (benzyladenine = BA, zeatin = Z and kinetin = KIN) in PTC. Globally, the past 15 years has witnessed a surge in the use of topolins and their derivatives in research laboratories. Topolins have demonstrated great potential during culture initiation and protocol optimization as well as for counteracting various in vitro induced physiological disorders in some species. In terms of general physiology (growth, phytochemical and photosynthetic pigment contents as well as genetic fidelity), the topolins were compared with BA using 'Williams' bananas with minimal residual exogenous CK carry-over effects. The five topolins tested were meta-Topolin (mT); meta-Topolin riboside (mTR); meta-Methoxy topolin (MemT); meta-Methoxy topolin riboside (MemTR) and meta-Methoxy topolin 9-tetrahydropyran-2-yl (MemTTHP). Based on evidence of potential CK- and auxin-like activity of smoke-water (SW) and karrikinolide (KAR1) at low concentrations, a similar comparative study involving both compounds and mT was performed. For a further understanding of banana physiology in vitro, the effect of supplementing either mT- or BA-requiring cultures with roscovitine (a cyclin-dependent kinase and N-glucosylation inhibitor) and INCYDE (an inhibitor of CK degradation) on the endogenous CK profiles was investigated. In addition, greenhouse experiments geared towards improving the acclimatization competence of tissue-cultured banana plantlets via application of different concentrations of SW and vermicompost leachate was conducted. Sterile shoot-tip explants were cultured on modified Murashige and Skoog (MS) media supplemented with 10, 20 or 30 μM of the tested CKs for 42 days while rooting experiments involved the use of classic auxins as well as SW and KAR1. Apart from 10 μM BA and 30 μM MemTTHP treatments, the number of shoots produced with all the CK treatments were significantly higher than the control. Treatment with 30 μM mT resulted in the highest number of shoots (7.3±1.0) which is an indication of the requirement of exogenous CK for increased shoot proliferation in 'Williams' bananas The use of 10 μM MemTTHP had the least root inhibitory effect during the shoot proliferation phase. As an indication of the toxicity of applied CK, MemT- and MemTR-regenerants were the most deformed while mTR-regenerated plantlets demonstrated the best quality across all the CKs tested. In mT- and BA-derived shoots, SW and KAR1 significantly increased the number and length of roots compared to the control. During the rooting phase, topolin treatments produced more off-shoots than BA-treated ones which inevitably improved the overall number of regenerated shoots. Total phenolic levels were highest in 10 μM mT- and 30 μM MemTTHP-treated plantlets detected in the aerial and underground parts, respectively. It is interesting that in the underground parts, 10 μM mT resulted in the production of the highest amount of proanthocyanidins which was approximately five-fold higher than in the control plants. On the other hand, 10 μM MemTTHP-treated plantlets had significantly higher total flavonoids within the aerial parts. In view of the stimulation of secondary metabolites in the majority of the CK-treated plantlets, the current results indicate the role of the type and concentration of applied CK as potential elicitors in PTC. Generally, the maximum photosynthetic pigment content was attained between 40-50 days. The control plantlets had the highest pigment content (1150 μg/g FW) while 10 μM MemTTHP had the best pigment stimulatory effect among the tested CKs. Nevertheless, in vitro propagation of banana devoid of CKs is not a practical option due to low shoot proliferation rates. Scanning electron microscopy (SEM) of the foliar surface showed that the stomatal density was highest in 10 μM MemTTHP-treated and lowest in 10 μM MemTR-treated plantlets. Prolonging the culture duration as well as increasing CK concentrations reduced the pigment content. However, the drastic breakdown in chlorophyll pigments beyond 50 days was slightly inhibited by the presence of mT, mTR, MemTTHP and BA compared to the control. Current findings indicate the potential anti-senescence activity of the topolins such as mT, mTR and MemTTHP under in vitro conditions. This study articulates that the right choice and concentration of CKs applied during in vitro propagation may alleviate photomixotrophic-induced physiological stress that usually accompanies the transfer of plantlets to ex vitro conditions. Findings indicate that the effect of subculturing contributed significantly to the higher rate of variation in 'Williams' bananas in vitro. The presence of CK in the culture media apparently aggravated the stress on the explants as indicated in the relatively higher percentage polymorphic bands compared to the controls. Among the tested CKs, the use of mTR and MemTTHP caused the least detrimental effect on the regenerants while mT-treated plantlets had the most polymorphic bands. Hence, it is recommended that subculturing cycles from the initial explant establishment should be limited to a maximum of five. The use of SW and KAR1 improved the level of photosynthetic pigment and phenolic compounds in the micropropagated bananas. However, they had a negative effect on shoot proliferation; hence their inclusion is more desired when used at the rooting phase of micropropagation. Perhaps, these compounds could be used in conjunction with auxin to increase the number of roots prior to the acclimatization stage. The enhanced photosynthetic pigment level resulting from addition of SW and KAR1 would also play a vital role during acclimatization of the micropropagated plants. The present finding serves as an alternative approach, available to researchers for improving the quantity of secondary metabolites in micropropagated plants. The highest regeneration rate (93%) was observed in BA + roscovitine treatment while mT + INCYDE-treated plantlets produced most shoots. Treatment with BA + roscovitine had the highest shoot length and biomass. Although not significant, there was more proanthocyanidins in BA + roscovitine treatments compared to the treatment with BA alone. On the contrary, total phenolics were significantly higher in mT + roscovitine treatment than in the mT-treated regenerants. The presence of roscovitine and/or INCYDE had no significant effect on the photosynthetic pigments of the banana plantlets. Forty-seven aromatic and isoprenoid CKs categorized into nine CK-types were detected at varying concentrations. The presence of mT + roscovitine and/or INCYDE increased the levels of O-glucosides, while 9-glucosides remained the major derivative in the presence of BA. Generally, the underground parts had higher CK levels than the aerial parts; however the presence of INCYDE increased the level of CK quantified in the aerial parts of both CK treated plantlets. Apparently, the presence of INCYDE serves to enhance transportation of the CK towards the aerial regions. From a practical perspective, the use of roscovitine and INCYDE in PTC could be crucial in the alleviation of commonly observed in vitro-induced physiological abnormalities. Soil drenching with SW significantly increased the root length (1:1000 and 1:500 dilutions) as well as fresh and dry weight (1:1000; 1:500 and 1:250 dilutions) when compared to foliar application. Vermicompost leachate (1:10 and 1:5 dilutions) significantly enhanced the shoot length, root length, leaf area and dry weights. Vermicompost leachate (1:20; 1:10 and 1:5 dilutions) also significantly increased the number of off-shoots. The positive effect on rooting is beneficial for acclimatization and establishment of tissue-cultured banana plantlets in nurseries and subsequent transfer to the field. However, field trials will be necessary to substantiate the effects demonstrated by these compounds. In an attempt to contribute to improving banana micropropagation, the current findings provide additional evidence on the increasing advantage of topolins over BA. Nevertheless, some detrimental physiological effects observed with some of the topolins (for example, MemT and MemTR) are clear indication that they should not be taken as a panacea in PTC. Besides optimizing efficient PTC protocols through stringent choice of CKs, other associated physiological and metabolic events taking place in culture during the optimization process need more in-depth investigation. In addition to contributing towards the better understanding of the mode of action of these CKs, such an approach will help solve associated physiological and developmental problems in vitro. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

A novel electrode was constructed and tested in a bio-battery. This configuration consisted of a composite electrode with immobilized bacteria (Escherichia coli K-12) in the anode and a composite electrode with immobilized Carbon Nanoparticles (CNP) and algae (Chlorella vulgaris/Scenedesmus sp.) suspended in the cathode. The composite electrode consisted of three parts: a 304L stainless steel mesh base, an electro-polymerized layer of pyrrole, and an electro-polymerized layer of methylene blue. The bacteria were immobilized on the anode electrode using a technique incorporating CNP and a Teflontm emulsion. The anode and cathode electrodes were tested separately in conjunction with chemical cathodes and anodes respectively. The composite electrode with immobilized bacteria was tested in a bioanode setup. The cathode chamber of the cell contained a potassium ferricyanide and buffer solution with a graphite electrode. Factors affecting electrode performance, such as Teflontm and carbon nanoparticle concentration, were investigated to find optimum values. The maximum power density generated by the composite electrode with immobilized bacteria and a chemical cathode was 378 mW/m2. This electrode configuration produced approximately 69% more power density and 53% more current density than composite electrodes with bacteria suspended in solution. Electrochemical Impedance Spectroscopy analysis determined that a significant portion of the bio-battery’s resistance to charge transfer occurred at the surface of the anode and this resistance was significantly lowered when using immobilized bacteria (51% lower than bio-batteries with suspended bacteria). Similarly, biocathodes containing composite electrodes coated with CNP were tested using two algae species, Chlorella vulgaris and Scenedesmus sp., suspended in solution. This electrode configuration was compared with composite electrode without CNP coating. The anode chamber contained potassium ferrocyanide solution with a graphite counter electrode. The composite electrode with CNP produced approximately 23% more current density than composite electrode without CNP. A complete bio-battery was designed using a composite electrode with immobilized bacteria anode and a CNP coated composite electrode with algae suspended in the cathode. EIS analysis showed that the resistance was higher in the biocathode than in the bioanode and a significant portion of the ohmic resistance was contributed by the membrane.

Photosynthetic biofilms have much higher cell density than suspended cultures and when grown in a stacked waveguide configuration, can have orders of magnitude higher areal productivity. Evanescent and plasmonic growth of biofilm cultures have been demonstrated, solving issues with light penetration impeding growth, but thus far the technology has been limited to biofuel production applications. In this thesis, plasmonically excited cyanobacterial biofilms are used to produce electrical power in a photosynthetic-plasmonic-voltaic device. This approach uses red lasers to deliver light to cells via an optical waveguide through the generation of surface plasmons at the interface between a metal and dielectric, in this case a glass-gold-air interface. This gold film serves a dual purpose as a current collector for electrons generated at the cell surface. Experiments presented here demonstrate positive power output light response under both direct light and plasmonic excitation and produced equivalent power output of 6 uW/m2 under similar light power intensities.

Photosynthetic biofilms have much higher cell density than suspended cultures and when grown in a stacked waveguide configuration, can have orders of magnitude higher areal productivity. Evanescent and plasmonic growth of biofilm cultures have been demonstrated, solving issues with light penetration impeding growth, but thus far the technology has been limited to biofuel production applications. In this thesis, plasmonically excited cyanobacterial biofilms are used to produce electrical power in a photosynthetic-plasmonic-voltaic device. This approach uses red lasers to deliver light to cells via an optical waveguide through the generation of surface plasmons at the interface between a metal and dielectric, in this case a glass-gold-air interface. This gold film serves a dual purpose as a current collector for electrons generated at the cell surface. Experiments presented here demonstrate positive power output light response under both direct light and plasmonic excitation and produced equivalent power output of 6 uW/m2 under similar light power intensities.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 4 uppsatser.