Thesis (M. Phil.)--University of Hong Kong, 1980.

Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2005. / Includes author's previously published papers. "July 2005" Bibliography: p. 178-194. Also available in print form.

Thèse (Docteur dÈtat-Sciences)--Université dÀix-Marseille II, 1985. / Bibliographie: 445-466.

Thesis (doctoral)--Universität Bremen, 1992. / Includes bibliographical references (leaves 107-114).

Various aspects of the biology of the intertidal agarophyte, Gelidium pristoides, were investigated, with the aim of providing information that would assist in formulating a management policy for this economic seaweed resource. G.pristoides occurs as tufts comprising as many as 40 individual plants, representing all three conspicuous life history stages, that are linked by the intertwining of their basal creeping axes. Individual plants consist of a system of branched creeping axes, which is largely responsible for colonizing surrounding substrata, from which one or more erect flattened fronds arise. These erect fronds may reach a height of 15 cm, and are irregularly bipinnately branched. Internal vegetative anatomy is generally typical of the genus. Morphological variation in mature plants is limited to increased plant height and branch density during the summer season. A dorso-ventrally flattened creeping habit was seen during early recruitment on flat rock surfaces and limpet shells within grazer exclusion plots, which developed into typical erect plants. Although there is a close taxonomic affinity between G.pristoides and the low-growing Gelidium turf, which occurs on wave-cut platforms in the eastern Cape (both produce bispores), the turf appears to represent a genetically divergent ecotype of the typical G.pristoides habit. In the light of present observations, it is suggested that the recent inclusion of G.pristoides in the new Onikusa genus should be questioned. Reproduction in G.pristoides is typical of the genus, except for the production of bispores, instead of tetraspores, in the sporophyte generation. The smaller nuclei in the binucleate bispores, in comparison to carpospores, suggested they are the product of normal meiosis (meiospores). This was confi rmed by chromosome counts of germl i ngs deri ved from bispores (n = 13-17) and carpospores (2n = 28-33). Throughout the geographical range of the seaweed, the bisporophyte generation is dominant over the combined male and female gametophyte generati on by a ratio of about 3 : 1. This imbalance may be due to bispores. G.pristoides a greater germination success of carpospores over plants are fertile throughout the year, while at Port Alfred there is no apparent seasonality in spore release. Growth of carpospore and bispore germlings is similar under various temperature treatments in culture. Optimum temperatures for growth were from 15-23°C, which corresponds with the sea temperatures experienced within the geographical range of the species . At Port Alfred, growth (linear frond elongation) and standing crop levels were maximal during summer . Ory weight levels were significantly inversely related to both growth and ash levels. Agar contents (% of dry weight) were generally greater in summer (48% ) than in winter (30%), and were inversely correlated with thallus nitrogen levels. Agar contents of distal plant halves were higher (8-15%) than in proximal halves. Regrowth of G.pristoides to original biomass or standing crop levels after harvesting, is similar for plucking and shearing at different times of the year. Regrowth is more rapid after spring and summer harvests (2-3 months) than after winter harvests (4-5 months). During the summer season, harvesting at monthly intervals showed significantly greater total yields, and production rates (e.g . 3.13 g. dry wt. / m2 / day for plucking) than under 3-monthly intervals (1.42 g. dry wt. / m2 / day for plucking). In contrast, average yields per harvest were Significantly greater when recovery period was longer (e.g. 3 months). Quadrats that were completely denuded failed to recover after a year, while regrowth was also retarded with increased elevation on the shore. Agar contents did not differ Significantly between plucked (38%) and sheared (42%) plant material. G.pristoides is distributed from about 0 . 2-0.75 m above MLWS, with a reduction in stature and frequency corresponding to increased elevation on the shore. Frond elongation rates, germling survival and recruitment within grazer-exclusion plots, is retarded with increased elevation level. Plants transplanted above the normal vertical range of the seaweed became severely bleached and died, while plants transplanted below the normal range of the seaweed (sub littoral fringe) senesced due to overgrowth by the epiphytic encrusting coralline, Polyporolithon patena (Hook . et Harv . ) Mason . G.pristoides recrui t ment in the sublittoral fri nge was enhanced with the exclusion of grazers . However, successful recruits were displaced due to smothering by articulated corallines (e.g. Corallina sp. and Jania sp. ) . G.pristoides is largely restricted to cracks and crevices in the rock, and also occurs on a large proportion of the available shells of the limpet Patella oculus Born., and to a lesser extent, shells of the barnacle Tetraclita serrata. G.pristoides recruitment was significantly enhanced by the exclusion of grazers (using toxic antifouling paint barriers). G.pristoides recruitment within the exclusion plots was significantly greater on artificially attached limpet shells (almost 100% cover) than on rock surfaces (20-30% cover), which occurred largely within cracks and crevies in the rocky substratum. ly attached to limpet G.pristoides plants are significantly more strongand barnacle shells than to rock and epilithic encrusting corallines (Lithothamnion sp.). Removal of G.pristoides from limpet shells revealed pits of a uniform size in the surface of the shells, into which the rhizoidal attachment organs of the seaweed penetrate. It is concluded that the horizontal distribution of G.pristoides is largely controlled by grazers (and "escapes" from grazing) and resistance to dislodgement by wave action. Based on present results, and considering some of the socio-economic factors associated with the Gelidium industry in South Africa, suggestions are made concerning the management and long-term maintenance of G.pristoides resources in the eastern Cape.

Various aspects of the biology of the intertidal agarophyte, Gelidium pristoides, were investigated, with the aim of providing information that would assist in formulating a management policy for this economic seaweed resource. G.pristoides occurs as tufts comprising as many as 40 individual plants, representing all three conspicuous life history stages, that are linked by the intertwining of their basal creeping axes. Individual plants consist of a system of branched creeping axes, which is largely responsible for colonizing surrounding substrata, from which one or more erect flattened fronds arise. These erect fronds may reach a height of 15 cm, and are irregularly bipinnately branched. Internal vegetative anatomy is generally typical of the genus. Morphological variation in mature plants is limited to increased plant height and branch density during the summer season. A dorso-ventrally flattened creeping habit was seen during early recruitment on flat rock surfaces and limpet shells within grazer exclusion plots, which developed into typical erect plants. Although there is a close taxonomic affinity between G.pristoides and the low-growing Gelidium turf, which occurs on wave-cut platforms in the eastern Cape (both produce bispores), the turf appears to represent a genetically divergent ecotype of the typical G.pristoides habit. In the light of present observations, it is suggested that the recent inclusion of G.pristoides in the new Onikusa genus should be questioned. Reproduction in G.pristoides is typical of the genus, except for the production of bispores, instead of tetraspores, in the sporophyte generation. The smaller nuclei in the binucleate bispores, in comparison to carpospores, suggested they are the product of normal meiosis (meiospores). This was confi rmed by chromosome counts of germl i ngs deri ved from bispores (n = 13-17) and carpospores (2n = 28-33). Throughout the geographical range of the seaweed, the bisporophyte generation is dominant over the combined male and female gametophyte generati on by a ratio of about 3 : 1. This imbalance may be due to bispores. G.pristoides a greater germination success of carpospores over plants are fertile throughout the year, while at Port Alfred there is no apparent seasonality in spore release. Growth of carpospore and bispore germlings is similar under various temperature treatments in culture. Optimum temperatures for growth were from 15-23°C, which corresponds with the sea temperatures experienced within the geographical range of the species . At Port Alfred, growth (linear frond elongation) and standing crop levels were maximal during summer . Ory weight levels were significantly inversely related to both growth and ash levels. Agar contents (% of dry weight) were generally greater in summer (48% ) than in winter (30%), and were inversely correlated with thallus nitrogen levels. Agar contents of distal plant halves were higher (8-15%) than in proximal halves. Regrowth of G.pristoides to original biomass or standing crop levels after harvesting, is similar for plucking and shearing at different times of the year. Regrowth is more rapid after spring and summer harvests (2-3 months) than after winter harvests (4-5 months). During the summer season, harvesting at monthly intervals showed significantly greater total yields, and production rates (e.g . 3.13 g. dry wt. / m2 / day for plucking) than under 3-monthly intervals (1.42 g. dry wt. / m2 / day for plucking). In contrast, average yields per harvest were Significantly greater when recovery period was longer (e.g. 3 months). Quadrats that were completely denuded failed to recover after a year, while regrowth was also retarded with increased elevation on the shore. Agar contents did not differ Significantly between plucked (38%) and sheared (42%) plant material. G.pristoides is distributed from about 0 . 2-0.75 m above MLWS, with a reduction in stature and frequency corresponding to increased elevation on the shore. Frond elongation rates, germling survival and recruitment within grazer-exclusion plots, is retarded with increased elevation level. Plants transplanted above the normal vertical range of the seaweed became severely bleached and died, while plants transplanted below the normal range of the seaweed (sub littoral fringe) senesced due to overgrowth by the epiphytic encrusting coralline, Polyporolithon patena (Hook . et Harv . ) Mason . G.pristoides recrui t ment in the sublittoral fri nge was enhanced with the exclusion of grazers . However, successful recruits were displaced due to smothering by articulated corallines (e.g. Corallina sp. and Jania sp. ) . G.pristoides is largely restricted to cracks and crevices in the rock, and also occurs on a large proportion of the available shells of the limpet Patella oculus Born., and to a lesser extent, shells of the barnacle Tetraclita serrata. G.pristoides recruitment was significantly enhanced by the exclusion of grazers (using toxic antifouling paint barriers). G.pristoides recruitment within the exclusion plots was significantly greater on artificially attached limpet shells (almost 100% cover) than on rock surfaces (20-30% cover), which occurred largely within cracks and crevies in the rocky substratum. ly attached to limpet G.pristoides plants are significantly more strongand barnacle shells than to rock and epilithic encrusting corallines (Lithothamnion sp.). Removal of G.pristoides from limpet shells revealed pits of a uniform size in the surface of the shells, into which the rhizoidal attachment organs of the seaweed penetrate. It is concluded that the horizontal distribution of G.pristoides is largely controlled by grazers (and "escapes" from grazing) and resistance to dislodgement by wave action. Based on present results, and considering some of the socio-economic factors associated with the Gelidium industry in South Africa, suggestions are made concerning the management and long-term maintenance of G.pristoides resources in the eastern Cape.

The chlorophyll and carotenoid pigments obtained from a number of algae were studied in gross acetone extracts. A method proposed by Richards and Thompson was used to calculate the relative proportions of chlorophylls a, b, and c, astacin and non-astacin carotenoids present. Complete absorption spectra from 350 mμ to 700 mμ were obtained for several algae, chiefly those belonging to the Chlorophyta. It was found that the presence of chlorophyll b could be detected as a small irregularity in the spectral curve at 460 mμ. The xanthophyll pigments of twenty-eight different species of algae were investigated. Chromatographic columns were used to isolate the individual pigments. A mixture of magnesia (Micron Brand) and Hyflo Super Cel was used as the adsorbent. Ethylene chloride was used as the solvent. Fourteen different xanthophyll pigments were found. Twenty two species of Green Algae were investigated in an attempt to show that the presence or absence of certain pigments may indicate phylogenetic relationships. Individual xanthophyll pigments appear to be of little phylogenetic significance. Groups of these pigments, however, seem to be more significant. Fairly uniform and closely related groups such as the Zygnematales and the Ulvales contain certain characteristic groups of pigments. Less uniform groups such as the Volvocales and the Cladophorales appear to lack characteristic groups of pigments. The results agree fairly well with modern phylogenetic relationships, based on the morphology and methods of reproduction. More extensive work with more genera and species is needed before generalizations at the ordinal level can be made. / Science, Faculty of / Botany, Department of / Graduate

No description available.

The nature and magnitude of experimental errors due to ⁶⁵Zn adsorption by inorganic surfaces was examined in a laboratory system designed to measure ⁶⁵Zn uptake by marine phytoplankton. In the pH range, 6.3±.1 to 7.5±.1, a precipitate formed in the algal nutrient medium selected for the system. To this seawater-base medium, zinc was added only as carrier-free ⁶⁵Zn. The precipitate increased in both volume and tendency for ⁶⁵Zn uptake as the pH increased. At a pH of 7.5±.1 the particles, predominantly orthophosphates, accumulated 70 percent of the ⁶⁵Zn in the medium in 24 hours. It was therefore concluded that ⁶⁵Zn adsorption by undetected precipitates could result in serious errors in measurements of ⁶⁵Zn uptake by marine phytoplankton. Equilibrium of ⁶⁵Zn adsorption by Pyrex glass surfaces was attained between .50 and 2.0 hours elapsed time. Found to be negligible at pH values less that 6.0±.1, such uptake was a linear function of the hydrogen ion concentration in the pH range, 6.7±.1 to 8.2±.1. Pretreatment of the glass surfaces with dimethyldichiorosilane (General Electric "Dry Film") reduced ⁶⁵Zn adsorption by over 80 percent. The relationship between percent ⁶⁵Zn sample adsorption and wetted glass surface area/pipette sample volume was shown to be linear for volumetric pipettes of the size range, 1-15 ml. At a pH of 7.5±.1, ⁶⁵Zn adsorption was negligible for most laboratory glassware, but increased with increased pH. At a pH value of about 8.0, glassware having surface area/sample volume ratios as small as those of 15 and 20 ml volumetric pipettes adsorbed 7 to 11 percent of the contained sample activity. Two prerinses with the sample liquid were required to reduce such errors by a factor of one half. / Graduation date: 1971

Clinocardium nuttallii from Yaquina Bay, Oregon, were found to harbor an algal symbiont in the siphon, mantle and occasionally the foot tissues. Approximately 35 percent of the population in the study area was infected to some degree with the alga; however, no cockles under two years of age were infected. The degree and frequency of infection increases in the older age groups. Symbiont cells were removed from the host and grown on artificial media and the temperature tolerances on these media were determined. Mantle fluid from variously infected and noninfected cockles from several age groups was used to fortify the artificial media and no difference between the fluids was noticed; however, a two month lag period in unfortified media was shortened to ten days by the addition of as little as ten percent mantle fluid filtrate. Chromatographic pigment analysis shows the alga to be a chlorophyte. Chloroplast structure, cell size and growth characteristics are very similar to algae of the genus Chlorella; this alga will be tentatively placed in this genus. Cockles under one year of age are not susceptible to infection by the symbiont, whereas mature cockles become infected by feeding on either fresh or cultured symbiont. Blood amoebocytes in vitro will readily engulf either fresh or cultured symbiont cells. Microscopic examination of infected tissues showed amoebocytic cells in the algal colonies, sometimes carrying several algal cells. The algal colonies in situ are dense masses which grossly displace the host tissue; however, there is no overt reaction by the host to the presence of these colonies. / Graduation date: 1973