Suspension-feeding bivalves produce biodeposits (faeces and pseudofaeces) that have much higher sinking velocities than their constituent particles. Consequently they cause sedimentation of material that might otherwise not be deposited. The benthic remineralisation of biodeposits increases sediment oxygen demand and nutrient regeneration, thus enhancing the benthic-pelagic coupling of nearshore ecosystems. In New Zealand the mussel Perna canaliculus has a high natural abundance and is also intensively cultured. This thesis examines the dispersal and remineralisation characteristics of mussel P. canaliculus biodeposits and the impacts of sedimentation from a mussel farm in the Firth of Thames on sediment biogeochemistry by combining laboratory, field and modelling studies. Dispersal characteristics were examined in the laboratory by measuring sinking velocities and erosion thresholds of biodeposits produced by mussels of a wide size range fed three experimental diets. The results show that biodeposit dispersal is a function of mussel diet and size and thus could differ significantly between locations and seasons. Estimates of dispersal distances based on these results demonstrated that the initial dispersal of biodeposits produced by cultured mussels is not far. Depending on the hydrodynamic conditions, secondary dispersal via resuspension potentially plays a more important role in the dispersal of biodeposits from mussel farms than initial dispersal and almost certainly serves as the major means of transport of biodeposits from natural mussel beds. Biodeposit mineralisation was studied by incubating coastal sediments with added biodeposits and measuring oxygen and nutrient fluxes as well as sediment characteristics over an 11 d period. Sediment oxygen consumption and ammonium release increased immediately after biodeposit addition and remained elevated compared to control cores without additions for the incubation period. A biodeposit decay rate (0.16 d-1) was calculated by fitting a first-order G model to the observed increase in oxygen consumption. This rate is 1 - 2 orders of magnitude higher than published decay rates of coastal sediments without organic enrichment or plant material. Nutrient fluxes during the incubation period illustrated that biodeposit remineralisation alters the stoichiometry of the nutrients released from the sediments which may potentially be more significant than the changes of the individual fluxes. To determine the impact of a mussel farm in the Firth of Thames I measured sediment oxygen and nutrient fluxes by deploying benthic chambers, sediment characteristics by collecting sediment cores and sedimentation rates by deploying sediment traps in four seasons. Oxygen consumption and sediment nutrient release rates were generally higher under the farm compared to a reference site, demonstrating the typical response to increased organic input. Unusually low nitrogen release rates measured in summer may indicate enhanced denitrification under the farm. A simple budget demonstrated the importance of benthic nutrient regeneration in maintaining primary production in this region and that mussel culture can lead to a redistribution of nutrients. This study showed that site-specific hydrodynamic and biogeochemical conditions have to be taken into account when planning new mussel farms to prevent excessive modifications of nutrient dynamics. Results of the laboratory and field studies conducted in this thesis were used to parameterise, calibrate and validate models of mussel biodeposit dispersal and remineralisation. A particle tracking model showed that the maximum initial dispersal of faecal pellets from the mussel farm is approximately 300 m and that pellets can be transported several times this distance via resuspension. The remineralisation model was able to simulate the increased nitrogen fluxes from the sediments well and highlighted the need for thorough calibration and parameterisation of the model. This thesis contributed to the current understanding of the ecosystem impacts of mussel culture and provided numerical models and model parameters that will assist in the assessment of mussel culture sustainability and the contribution of mussels to the nutrient cycling in nearshore ecosystems.

In der vorliegenden Studie wurde die Remineralisationswirkung von Fruchtgummi­produkten, die mit einer neuartigen calciumhaltigen Salzhydratschmelze angereichert waren, vergleichend in-vitro und in-situ getestet. Als Vergleich diente ein handelsübliches Fruchtgummiprodukt ohne Zusatz der zu testenden Salzhydratschmelze. Die remineralisierende Wirkung der calciumreichen Salzhydratschmelze beruhte auf dem Prinzip der forcierten dynamischen Remineralisation. Um die Mineralisationseffekte messbar zu machen, wurden künstliche, standardisiert hergestellte Schmelzplättchen den unterschiedlichen Fruchtgummiprodukten ausgesetzt und die Mineralisationseffekte in regelmäßigen Abständen gravimetrisch und radiographisch gemessen, sowie abschließend einer Härtemessung unterzogen. Dabei ergaben sich zusammengefasst folgende Resultate, die die Quantität an eingebautem Mineral betreffen: 1.Der Effekt aller salzhydratschmelzehaltigen Fruchtgummis ist signifikant größer als der der Plazebopräparate 2.Die schmelzehaltigen Fruchtgummis bewirken einen signifikant größeren Mineraleinbau als herkömmliche Fluoridpräparate in Zahnpasten, wie aus früheren gleichgearteten Untersuchungen abgeleitet werden kann. Aufgrund der vorliegenden Ergebnisse kann davon ausgegangen werden, dass trotz des Verzehrs zuckerhaltiger Fruchtgummiprodukte das Gleichgewicht zwischen Demineralisation und Remineralisation an der Zahnoberfläche nicht nur statiönär gehalten wird, sondern sogar zugunsten der Remineralisation verschoben wird, sofern die Fruchtgummiprodukte mit einer calciumhaltigen Salzhydratschmelze angereichert sind. / In a preceding investigation the remineralisational effects of fruit gum products, wich were enriched with a new calcium-containing salthydratic melt (here called verum), were tested in vitro and in vivo in comparison to usual fruit gum products without the calcium-melt (here called placebo). to be able to evaluate the effects, artificially made standardized enamel-dics where treated with the different fruit gum products. the mineralisating and demineralisating effects where detected by continuous gravimetric analyses, radiographic analyses, and finally by measurement of hardness of the enamel discs. important results: 1. the reminalisational effect of the verum product is significantly higher than the effects of the placebo. 2. the verum products even cause a significant higher rate of mineralintegration inside the enamel, than usual fluoridcompounds in toothpastes

In dieser Arbeit sollte das neuartige Zahnpflegeprodukt Tooth Mousse, das als Wirkstoff den CPP-ACP- Komplex (Caseinphosphopeptid-amorphes Calciumphosphat) enthält, experimentell auf seine Remineralisationsfähigkeit hin untersucht und diesbezüglich mit anderen Zahnpasten verglichen werden. Für die Vergleiche wurden eine 1400 ppm-fluoridhaltige Zahnpasta (Elmex rot), eine Placebozahncreme ohne Wirkstoff (Elmex Placebo) sowie eine weitere Neuentwicklung auf der Basis unterkühlter, amorpher Salzhydratschmelze mit hohem Calciumgehalt, herangezogen. Hierzu wurden Probekörper aus künstlichem Zahnschmelz in Form von Hydroxylapatitkörpern mit einer Dichte, wie sie bei porösem, demineralisierten humanen Schmelz üblich ist, hergestellt. Diese wurden mit allen genannten Zahnpasten behandelt und vor, während und nach Ablauf der Versuche gravimetrisch und radiographisch vermessen. Zwischen den in-vitro Behandlungen wurden die Hydroxylapatit-Tabletten in künstlichem Speichel aufbewahrt. Die Versuche ergaben, dass Tooth Mousse wie auch die schmelzehaltige Zahnpasta in-vitro geringere Remineralisation erzielten als Elmex Placebo. In-situ erreichte Elmex rot die höchsten Remineralisationswerte, dicht darauf folgte die schmelzehaltige Zahnpasta. Tooth Mousse lag als Schlusslicht noch hinter der Placebozahnpasta. / This thesis was to compare experimentally the novel dental care product “Tooth Mousse” containing CPP- ACP (Casein Phosphopeptide- amorphous Calcium Phosphate) as active agent, with other dentifrices concerning their remineralization qualities. The subject was compared with a 1400 ppm F – toothpaste (Elmex rot), a toothpaste without any active agents (Elmex Placebo) and a newly developed paste based on an calcium-containing salthydratic melt. Therefore artificial enamel discs were produced providing the same density as caries lesions in human enamel. They were treated with all products mentioned above and measured radiographically and gravimetrically before, while and after the experiments. Between the treatments discs were stored in artificial saliva. Examinations led to the conclusion that Tooth Mousse as well as the calcium-containing salthydratic melt paste achieved less remineralization values than Elmex Placebo. In situ Elmex rot reached highest remineralization, closely followed by the calcium-containing salthydratic melt paste. Tooth Mousse was last behind the Placebo group.

In dieser Studie sollte eine neuartige Zahncreme, die als Wirkstoff eine unterkühlte, amorphe Salzhydratschmelze enthielt, mit anderen handelsüblichen Zahncremes auf ihre Remineralisationsfähigkeit getestet und untereinander verglichen werden. Zu diesem Zweck wurde die besagte neuartige Zahncreme mit dem CPP- ACP (Caseinphosphopeptid- amorphes Calziumphosphat) angereicherten Produkt ´Tooth Mousse, einer mit 1400 ppm Aminfluoriden versehenen Zahncreme (Elmex rot) und einer fluoridfreien Plazebozahncreme (Elmex Placebo) verglichen. Als Testkörper dienten artifiziell hergestellte hydroxylapatithaltige Zylinder, deren Dichte der von demineralisiertem Zahnschmelz entsprach. Die besagten Probenkörper wurden mit den unterschiedlichen Substanzen behandelt, die Massenbelegung der Remineralisation wurde vor und nach der Behandlung gravimetrisch und radiographisch erfasst. Die ersten Versuchsreihen wurden ´in vitro durchgeführt, alle weiteren Versuche erfolgten mit einem ´in vitro - ´in situ Vergleich. Die höchste Mineralanreicherung konnte bei schmelzehaltiger Zahncreme mit Phosphat- und Fluoridzusatz beobachtet werden. Sie überstieg die Absorption gleichkonzentrierter schmelzehaltiger Zahncreme ohne Phosphat- und Fluoridzusatz um mehr als das Doppelte. Das Präparat Recaldent erbrachte keine besseren Ergebnisse als das Placebo. / The aim of this study was to compare a new developed tooth paste, based on a calcium- containing salthydratic melt, with other commercially available tooth pastes concerning it´s remineralization qualities. For this purpose, this new developed toothpaste, the product ´tooth mousse, based on the CPP- ACP- complex (Casein Phosphopeptide- amorphous Calcium Phosphate), a 1400 ppm aminfluoride containing toothpaste (Elmex rot) and a toothpaste without any active agents (Elmex Placebo) were used for comparison. We chose artificial manufacted hydroxylapatite containing discs as reference blocks which exhibited the density of demineralized human enamel. The reference blocks were treated with the different agents, the remineralization was collected gravimetically and radiographicaly before and after the treatment. The first experiments were conducted ´in vitro, the following examinations took place as an ´in vitro- ´in situ- analogy. The salthydratic- melt- paste added with phosphates and flourids showed the most accumulation of mineral. The conclusions of this toothpaste were twice as high as the agent without the additive of phosphates and fluorides. ´Tooth mousse never has shown better results than the placebo- paste.

Das Phänomen „dentale Erosionen an Zahnhartsubstanz“ als Folge des erhöhten Konsums von sauren Getränken stand im Mittelpunkt der vorliegenden in-vitro Studie. Das Ziel war, den remineralisierenden Einfluss einer neuartigen calciumhaltigen Salzhydratschmelze auf das erosive Potential handelsüblicher säurehaltigen Getränke wie Coca Cola, Orangensaft, Eistee u. a. zu untersuchen. Unterschiedliche Konzentrationen dieser calciumreichen Salzhydratschmelze (SHS) wurden den Testgetränken in Pulverform beigemischt. Die Experimente wurden an künstlich hergestellten, porösen Hydroxylapatitkörpern durchgeführt, die in ihren wesentlichen physikalischen und chemischen Eigenschaften dem Zahnschmelz weitgehend entsprachen. Die Veränderungen des Mineralgehaltes der Probekörper während der Exposition von sauren Flüssigkeiten wurden sowohl gravimetrisch als auch mit Hilfe einer hochauflösenden Online-Radiographie mit hoher Genauigkeit reproduzierbar gemessen. Aus den Ergebnissen konnte die Schlussfolgerung gezogen werden, dass es möglich ist, mit Hilfe der getesteten Salzhydratschmelze erosive Getränke so zu modifizieren, dass ihre demineralisierenden Wirkung auf Hydroxylapatit nicht nur gestoppt, sondern im Sinne einer Remineralisation umgekehrt wird. Es wurde stets eine reproduzierbare Mineraleinlagerung bei den Testgetränken beobachtet. Dieser Effekt beruhte auf dem Prinzip der forcierten dynamischen Remineralisation. Mit Hilfe der Salzhydratschmelze scheint es somit zumindest in-vitro möglich zu sein, die durch saure Getränke verursachten dentalen Erosionen zu vermeiden. / The phenomenon „dental erosion of the tooth’s hard tissue" as a result of higher consumption of acidic drinks stood as a central point in the current study in an artificial environment. The aim was to research the remineralization effect of a new type of calcium containing salthydratic melt (SHS) on the erosive potential of commercially traded common drinks such as Coca-Cola, orange juice, ice tea and others. Different concentrations of the calcium rich salthydratic melt were mixed with the tested drinks in powder form. The experiments were conducted on artificially created porous hydroxyapatite experimental bodies, the physical and chemical properties of which corresponded to a large extent to tooth enamel. The changes in the mineral content of the experimental bodies were measured with high precision in a reproducible manner during exposure to acidic liquids not only gravimetrically, but also with the help of high resolution online radiography. From the results it was possible to reach the conclusion that it is possible with the help of the tested salthydrated melt, to modify erosive drinks not only by preventing their remineralization effect on the hydroxyapatite, but in a sense to reverse the remineralization. A reproducible mineral incorporation was continuously observed with regard to the tested drinks. This effect is based on the principle of accelerated dynamic remineralization. It appears that it is possible, at least in an artificial environment, with the help of salthydratic melt to prevent dental erosion resulting from acidic softdrinks.

Universiẗat, Diss., 2005--Kassel.

This study analysed the effect of frequency of intake and amount of fluoride in milk on the remineralisation of artificial enamel and dentine caries lesions in situ. Predemineralised bovine enamel and dentine slabs were randomly allocated to 5 in situ phases. Twenty-three subjects wore removable appliances with 2 enamel and 2 dentine slabs for 7 days each phase (separated by a 7-day washout period), following a crossover double-blind protocol. In each phase, treatment was performed with milk containing 2.5 ppm fluoride (F) everyday (T1), 2.5 ppm F every other day (T2), 5.0 ppm F every day (T3), 5.0 ppm F every other day (T4) or no treatment (control; T5). The subjects were instructed to immerse the appliance in 100 ml of milk for 5 minutes and then drank 200 ml of the respective milk. The enamel alterations were quantified by surface hardness (%SHR) and transversal microradiography (TMR, Z) and dentine by TMR only. Data were analysed by repeated-measures ANOVA/Tukey´s tests (p<0.05). For enamel, the highest %SHR was found for groups treated with fluoridated milk every day compared to control, without significant differences between T1 and T3. All groups showed positive values of Z, except for T4; significant differences were seen between T1/T3 and T4. For dentine, the only group that presented remineralisation was T2. Fluoridated milk every day seems to have better remineralising effect on enamel than its use every other day, but no dose-response effect was seen. Dentine, however, does not seem to benefit from every day use of fluoridated milk. / O presente estudo teve como objetivo analisar o efeito do leite fluoretado com concentrações e frequências diferentes na remineralização de lesões de cárie de esmalte e dentina produzidas artificialmente in situ. Blocos de esmalte e dentina bovino previamente desmineralizados foram distribuídos aleatoriamente em cinco grupos. Vinte e três indivíduos usaram aparelhos removíveis contendo 2 blocos de esmalte e 2 blocos de dentina por 7 dias em cada fase (separadas por um período de washout de 7 dias), seguindo um protocolo duplo-cego, cruzado. Em cada fase, o tratamento realizado foi com leite contendo 2,5 ppm de flúor (F), todos os dias (T1), 2,5 ppm de F em dias alternados (T2), 5,0 ppm F todos os dias (T3), 5,0 ppm F em dias alternados (T4) ou sem tratamento (T5). Os sujeitos foram instruídos a mergulhar o aparelho em 100 ml de leite por 5 minutos e, em seguida, beberam 200 ml do mesmo leite. As alterações no esmalte foram quantificadas por dureza superficial e microradiografia transversal (TMR), e dentina apenas por microradiografia transversal. Os dados foram analisados por medidas repetidas ANOVA / Tukey (p <0,05). Para o esmalte, o mais alto valor de porcentagem de recuperação de dureza superficial foi encontrado para os grupos tratados com leite fluoretado todos os dias em relação ao controle, sem diferenças significativas entre T1 e T3. Todos os grupos apresentaram valores positivos de Z, com exceção de T4; foram observadas diferenças significativas entre T1/T3 e T4. Para a dentina, o único grupo que apresentou remineralização foi T2. O leite fluoretado todos os dias parece ter melhor efeito remineralizante sobre o esmalte do que seu uso em dias intercalados, mas nenhum efeito dose-resposta foi visto. A dentina, no entanto, não parece se beneficiar do uso diário de leite fluoretado.

This work investigated the design parameters necessary for the build and use of an in vitro artificial mouth model built for dental erosion research. It also ascertained the working knowledge of dentists concerning the Human Tissue Act (HTA) and explored an alternative tissue for erosion-testing to human enamel. The design inputs for the artificial mouth were acquired by an innovative observational study conducted upon human volunteers and used in the decisions made in the setting of the fluids’ kinematic behaviour and how the associated devices were to function. This novel system was sought to mimic the interaction of saliva and the dental substrate during the process of consuming an erosive beverage. The model allows researchers to gather data using customizable experimental diets without the technical burden of dealing with a non-realistic regime. The design and build of the artificial mouth model along with its associated equipment and parameters are described and a manual for operation of the model is appended. The device is designed on a fully adjustable multitask basis in which the operator can set several variables such as the desirable salivary kinematic behaviour, offensive beverage flow rate, and volume of consumption. This, subsequently, allows the samples preloaded on the system to be tested for surface characteristics (i.e. surface hardness and surface profilometry) to determine the extent of erosion if any. The model also allows the resultant solution to be analysed for traces of calcium and phosphate ions. To validate the capabilities of the artificial mouth system a set of diets was performed repeatedly. The high degree of agreement and the consistency of results showed that the model is able to mimic realistic scenarios and is capable of producing reliable, reproducible and accurate outcomes. Ostrich eggshell proved to be a potential alternative erosion substrate which is fortuitous as the lack of knowledge on the HTA had meant human enamel was less readily available.

This study analysed the effect of frequency of intake and amount of fluoride in milk on the remineralisation of artificial enamel and dentine caries lesions in situ. Predemineralised bovine enamel and dentine slabs were randomly allocated to 5 in situ phases. Twenty-three subjects wore removable appliances with 2 enamel and 2 dentine slabs for 7 days each phase (separated by a 7-day washout period), following a crossover double-blind protocol. In each phase, treatment was performed with milk containing 2.5 ppm fluoride (F) everyday (T1), 2.5 ppm F every other day (T2), 5.0 ppm F every day (T3), 5.0 ppm F every other day (T4) or no treatment (control; T5). The subjects were instructed to immerse the appliance in 100 ml of milk for 5 minutes and then drank 200 ml of the respective milk. The enamel alterations were quantified by surface hardness (%SHR) and transversal microradiography (TMR, Z) and dentine by TMR only. Data were analysed by repeated-measures ANOVA/Tukey´s tests (p<0.05). For enamel, the highest %SHR was found for groups treated with fluoridated milk every day compared to control, without significant differences between T1 and T3. All groups showed positive values of Z, except for T4; significant differences were seen between T1/T3 and T4. For dentine, the only group that presented remineralisation was T2. Fluoridated milk every day seems to have better remineralising effect on enamel than its use every other day, but no dose-response effect was seen. Dentine, however, does not seem to benefit from every day use of fluoridated milk. / O presente estudo teve como objetivo analisar o efeito do leite fluoretado com concentrações e frequências diferentes na remineralização de lesões de cárie de esmalte e dentina produzidas artificialmente in situ. Blocos de esmalte e dentina bovino previamente desmineralizados foram distribuídos aleatoriamente em cinco grupos. Vinte e três indivíduos usaram aparelhos removíveis contendo 2 blocos de esmalte e 2 blocos de dentina por 7 dias em cada fase (separadas por um período de washout de 7 dias), seguindo um protocolo duplo-cego, cruzado. Em cada fase, o tratamento realizado foi com leite contendo 2,5 ppm de flúor (F), todos os dias (T1), 2,5 ppm de F em dias alternados (T2), 5,0 ppm F todos os dias (T3), 5,0 ppm F em dias alternados (T4) ou sem tratamento (T5). Os sujeitos foram instruídos a mergulhar o aparelho em 100 ml de leite por 5 minutos e, em seguida, beberam 200 ml do mesmo leite. As alterações no esmalte foram quantificadas por dureza superficial e microradiografia transversal (TMR), e dentina apenas por microradiografia transversal. Os dados foram analisados por medidas repetidas ANOVA / Tukey (p <0,05). Para o esmalte, o mais alto valor de porcentagem de recuperação de dureza superficial foi encontrado para os grupos tratados com leite fluoretado todos os dias em relação ao controle, sem diferenças significativas entre T1 e T3. Todos os grupos apresentaram valores positivos de Z, com exceção de T4; foram observadas diferenças significativas entre T1/T3 e T4. Para a dentina, o único grupo que apresentou remineralização foi T2. O leite fluoretado todos os dias parece ter melhor efeito remineralizante sobre o esmalte do que seu uso em dias intercalados, mas nenhum efeito dose-resposta foi visto. A dentina, no entanto, não parece se beneficiar do uso diário de leite fluoretado.

Nanoflagellates were found to be abundant in a coastal area of the northern Bothnian Sea. The maximum concentration of nanoflagellates, approximately 8000 cells ml-1, was observed in July, coinciding with a decrease in the abundance of cyanobacteria. Pigmented and non-pigmented nanoflagellates were approximately equally distributed throughout the year. Most of the identified genera are known as being phagotrophic, independent if autotrophic or not. A non-cyst-forming pigmented flagellate, Ochromonas sp., was isolated and nutritionally characterized. This chrysophycean flagellate was shown to be a mainly heterotrophic organism: Photosynthesis was too poor to support multiplication of the cells, whereas when feeding on bacteria, high growth rates were obtained. The biological function of the photosynthetic apparatus is suggested to be a survival mechanism during poor bacterial conditions. The flagellate grazed bacteria selectively, preferring cyanobacteria and large cells of heterotrophic bacteria, presumably depending on size-selective grazing. Despite higher growth rates of the bacteria in the sea during summer (July) than spring (May), heterotrophic bacteria in the sea was observed to be smaller in the summer. Nanoflagellates showed a maximum in July, and by selective grazing of large bacteria they might have caused the decrease in the average size of the bacteria and the decrease in the abundance of cyanobacteria. During the consumption of bacteria the flagellate was shown to remineralize nutrients at high rates and excrete dissolved free amino acids. Assuming the existence of a protozoan predator-prey chain of several trophic levels, it seems likely that a significant part of the nutrients fixed by primary producers is remineralized in the euphotic zone. Furthermore, data from this work indicate that flagellate activity may be a significant source of dissolved free amino acids, utilizable for the heterotrophic bacteria. / digitalisering@umu