The green alga Enteromorpha intestinalis (L. Link) has been observed to grow over a wide range of salinities, from 0.1% to 100% sea water, the optimum grown range being between about 30% and 70% sea water. The range of salinities in which the alga occurs is unusually wide for a marine alga, and an investigation of its ionic relationships was therefore undertaken. Measurements have therefore been made of concentrations of the major ions (Na, K and C1) in the plant cells and in sea water together with measurements of cell membrane potential and ion flux rates. Measurements of the electrical potential difference across the plasmalemma and the influx and efflux of each ion indicate that K and C1 are actively imported and Na actively exported over the whole salinity range. Estimates of cell permeability to the passive diffusive fluxes of these three ions alone have been used to explain the origin of the cell membrane potentials over the range of salinities. Tracer ion kinetics are taken as showing that the tonoplast is more permeable than the plasmalemma to each ion. The ion fluxes against their electro-chemical potential gradients consist of at least two components, one active, the other passive, the passive component has been calculated, for each ion, from the Goldman flux equations. The remaining putative active flux components have been compared with the measured active fluxes and the interlinkages of the latter have been determined. None of the active transport mechanisms for each ion appear to be electrogenic neither do they appear to be 1:1 coupled exchange transport as all the active fluxes are affected by the lowering of temperature and by certain metabolic inhibitors. Use of such inhibitors has enabled division of the fluxes into their component parts. A component of the active K influx and a component of the active Na efflux are linked through a ouabain sensitive transport mechanism. A further component of the active K influx is ouabain insensitive but is dependent upon c1, and further, a part of this C1 dependent K influx requires light while the remainder does not. the active C1 influx has a light dependent component, part of which appears to require both K and Na specifically, the remainder being cation independent. This interlinkage of active fluxes appears to be maintained at all dilutions of sea water as the influxes and effluxes of each ion remain in constant proportion to one another and to the fluxes of other ions over the whole salinity range investigated. The ratio of internal concentration to external concentration, for each ion, increases with increasing dilution although the rations of the internal ions to one another remain reasonably constant. When plants are maintained in solutions of varying sodium to potassium ratio the internal sodium to potassium ratio differs markedly from that found in plants growing in sea water; the plants in such experimental solutions, however, appear to be able to tolerate these internal ionic rations and have remained healthy in such solutions for at least seven days. The majority of plants require a constant internal ionic environment for efficient functioning of their metabolism. This does not appear to be the case with D. intestinalis which may account for its ability to inhabit regions of widely varying salinity.

Ulva intestinalis är en fotoautotrof grönalg som är utspridd i stora delar av världen och har ett flertal användningsområden, däribland som matråvara samt som biobränsle. Matindustrin står idag för en fjärdedel av världens utsläpp av växthusgaser. För att FN:s globala mål ska uppnås innan år 2030 måste dessa utsläpp minska. Ett sätt att bidra till att målen nås är att ändra vilka livsmedel som produceras, där alger kan vara en del av den framtida mera hållbara maten. Syftet Med detta arbete var att undersöka möjligheterna för en hållbar algodling för matkonsumtion.Målet var att genom en litteraturstudie hitta en parameter som potentiellt kan påverka tillväxten av Ulva intestinalis och planera ett experiment i en odlingsanläggning på norra Öland som undersöker den valda parametern. I litteraturstudien undersöktes det vilken parameter som skulle kunna testas i en framtida odlingsanläggning. Resultatet som erhölls från litteraturstudien var att substrat är viktigt för algens sporsättning och i kombination med projektets begränsande faktorer blev substrat den parameter som bör testas i experimentet. Utifrån att substrat valdes som parameter lades ett förslag på ett experiment fram. Slutligen diskuterades potentiella felkällor samt så gavs det förslag på eventuella fortsatta studier. / Ulva intestinalis is a photoautotroph green algae that is found in large parts of the world, and has a variety of uses, for example as food and as biofuel. The food industry is responsible for one fourth of the world’s green gas emissions, and for the United Nations’ Sustainable Development Goals to be reached before the year 2030, these emissions must be reduced. One way to contribute to the achievement of these goals is to change what kind of food is being produced,and algae could be part of the more sustainable future food. The purpose with the project was to examine the possibilities for a sustainable land-based algal cultivation for food use. The goal was to find a parameter that could potentially influence the growth of Ulva intestinalis, and to plan an experiment in a cultivation plant in northern Öland that examines the selected parameter. The method that was selected to fulfill the goal of the project was a literature study, in which some potential growth parameters were identified, so a conclusion of which parameter should be tested in a future experiment could be made. The result from the study was that substratum is important for the settlement of the spores, and in combination with the limits of the project it was chosen to be the parameter to be tested in the planned experiment. On the basis of substratum as the selected parameter, a proposal for an experiment was presented. Finally, potential sources of error were discussed, and suggestions for future studies were made.

Thesis (Ph. D.)--University of California, Los Angeles, 2003. / Vita. Includes bibliographical references.

The effects of seawater inflows and macrophyte beds on community metabolism and phosphorus dynamics in the seasonally-closed Swartvlei estuary were investigated. Metabolic rates were determined by diurnal oxygen curve analysis. Gross primary production ranged from 0,7 to 14,9 g 0₂ m⁻² day⁻¹, and respiration from 0,9 to 25,2 g 0₂ m⁻² day⁻¹. The highest production rates were recorded inside the dense beds of Zostera capens is Setchell (x- = 7,8 g 0₂ m⁻² day⁻¹ ). Metabolism was positively correlated to submersed macrophyte cover, and decreased upstream of the mouth region. No seasonal variation in gross production could be detected, and mouth closure had no detectable effect on metabolic rates. Growth of the green alga Enteromorpha sp. in winter, and the effect of decay of this alga on dissolved oxygen, total inorganic carbon and total dissolved phosphorus in the water column is discussed. High day-time respiration values, measured in a darkened polythene enclosure, indicate that photorespiration occurs in Zostera. Apparently the annual amount of oxygen respired throughout the estuary exceeded that produced by 2 7100 tonnes, i.e. the estuary was heterotrophic. This is discussed in relation to the effectiveness of the diurnal curve method as a way of measuring metabolic rates, and to the possibility of organic matter input via river inflows. There is a net gain of up to 17,4 kg of particulate phosphorus over mean tides. Diurnal phosphorus studies indicate that Zostera releases phosphate into the water column in the light. Enteromorpha takes up phosphate in the morning, which it appears to release over the rest of the day. The cycling of phosphorus between seawater, sediments, macrophytes and the water column is discussed.

Typescript Thesis (Ph. D.)--University of Oregon, 1983 Includes vita and abstract Bibliography: leaves 134-145 Another copy on microfilm is located in Archives