Thesis (Ph. D.)--University of Hawaii at Manoa, 1996. Includes bibliographical references (leaves 113-115). / ix, 143 leaves, bound : ill. ; 29 cm.

Thesis (Ph.D.)--University of Washington. / Bibliography: l. [202]-208.

Thesis (Ph. D.)--Oregon State University, 1995. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Proefschrift--Rijksuniversiteit te Utrecht. / Includes bibliographical references.

All developing embryos contain an extracellular matrix (ECM) consisting of proteins, glycoproteins, and proteoglycans. These components are important for morphogenetic processes such as cell migration, cell differentiation and cell death. The ECM of the starfish, Pisaster ochraceus, consists of three major components: A hyaline layer which coats the external surface of the embryo; a basal lamina which lines the basal surfaces of the epithelia; and a blastocoelic component which fills the embryonic cavity or blastocoel. Observations of chemically fixed asteroid embryos have revealed the hyaline layer to contain five sub-layers of fibrous strands encrusted with amorphous material. Strands of a similar nature form a meshwork within the fluid-filled blastocoel. Recent studies of the living embryo, however, have suggested that the ECM within the blastocoel of echinoderms, including the asteroid, is a gel-like substance and not a fluid with extracellular fibres. Since artefacts imposed by chemicals such as aldehydes and osmium are well documented, a method of preservation, which does not involve the use of these chemicals, may resolve the apparent conflict over the nature of the ECM of the asteroid embryo. Freeze substitution, an expensive cryofixation technique which has proven successful in fixing vertebrate tissue, does not require the use of aldehydes and osmium. The initial objective of this study was to devise an inexpensive, easily employable freeze substitution technique which would allow good preservation of cellular and extracellular elements of the embryonic starfish, Pisaster ochraceus. A plunge freezing apparatus was constructed which consisted of a Dewer flask filled with liquid nitrogen, a small cup was filled with cryogen and inserted into the nitrogen, and a motor which constantly stirred the cryogen. Embryos were isolated on copper freeze-fracture grids and plunged into the cryogen. After considering four different cryogens and four separate cryoprotectants, cryoprotecting asteroid embryos with propylene glycol and plunging them into supercooled propane was found to provide optimal preservation. Frozen embryos were freeze substituted in anhydrous ethanol at -90 °C, osmicated, and embedded for ultrastructural and histochemical analysis. Following freeze substitution, the blastocoel appears to contain a gel-like substance, rich in sulfated GAG's, with extracellular fibres and not a fluid with fibres. In addition, the hyaline layer was found to consist of at least six sub-layers of greater thickness than was seen in chemically fixed embryos. Histochemical studies demonstrated that both sulfated and unsulfated GAG's were present in these layers. The morphological differences among the sub-layers suggest that some sub-layers may have unique functions while others may have functions shared by other sub-layers. Freeze substitution also revealed the presence of microvillus associated bodies, structures which may represent major attachment points of the hyaline layer to the epithelium. Although the fixation of asteroid embryos by freeze substitution is a lengthy process, taking four to five days, the resulting preservation, particular!ly of the ECM components, justifies its use over chemical fixations. Material preserved by freeze substitution can be used for histochemical studies and, since aldehydes and heavy metals are not necessary for successful preservation, may also prove useful for immunocytochemical studies. / Medicine, Faculty of / Graduate

It has been estimated by the Department of the Interior that by 1985 nearly one-quarter of all surface water in the United States will be used in removal of waste heat produced in electric generation. This will involve subjecting tremendous quantities of plankton to rapid fluctuations in temperature. The biological effect of such treatment on primary productivity and composition of zooplankton populations is not fully understood. To date little published information is available on the effect of rapid temperature fluctuations on plankton. Such temperatures are the result of heat exchange found in the cooling system of a steam-generating electric station. Patiria miniata is a dominant member of many subtidal and intertidal communities and consequently is an ecologically important species. Additionally, the adults can be induced to spawn throughout the year on demand, providing a constant source of larvae for experiments Larvae of P. miniata may be cultured from egg to juvenile in the laboratory with relative ease. The first 3 sections of this thesis describe techniques and baseline data used to conduct the primary experiment. The first section determines the minimum concentration of l-methyladenine required to induce spawning and if variations in quantity or concentrations had any significant effect on spawning times. Development and growth, the second section, sets limits for what will be considered “normal” larvae. The third section of this project describes the use of biological stains as a means to identify larvae receiving varying treatments when cultured en masse. The primary purpose and last section of this report is to answer the question how much of a thermal shock can the larvae of P. miniata withstand and still continue normal development.

The persistence of predator-prey systems in evolutionar time is a function of the efficiency with which the predator obtains its food, and the ability of the prey to avoid ex- tinction. One of the important components of survival of the system is environmental heterogeneity (Huffaker 1958). Along rocky intertidal regions of the northern Pacific coast of North America, a major predator, the starfish Pisast ochraceus has a dominant effect upon patterns of distribution of many intertidal organisms (Paine 1966). Likewise, the distribution of intertidal fauna exert an effect upon the activities of Pisaster. Other biological interactions such an grazing activities of limpets and predatory behavior of emails also affect the intertidal distribution of species (Connell 1961, 1970, Dayton 1971).

The predatory sea star, Heliaster kubiniji, has been hypothesized to be a "keystone species" that is instrumental in maintaining diversity in the intertidal zones of the northern Gulf of California (Paine 1966). Four hundred and one Heliaster stomach samples collected in 1974-1976 from Station Beach, Puerto Penasco, Sonora, Mexico indicated that Heliaster consumed a variety of prey but preferred barnacles, Chthamalus anisopoma (93% of all prey items). The catastrophic decline of Heliaster in the Gulf of California in 1978 resulted in mortalities approaching 100% (Dungan et al 1982). Pre-die-off community data from the intertidal reef at Station Beach (Mackie and Boyer 1977) were compared with post-die-off (1981-1984) data to determine effects of the Heliaster disappearance. Community structure data included abundance and intertidal distributions of 20 species of macro-invertebrates including 11 Heliaster prey and 9 non-prey species and consisted of 6 carnivores, 7 herbivores, 5 detritivores and 2 filter feeders. Comparisons were made in two distinct habitats: a basalt boulder habitat (Heliaster's preferred habitat) and a reef flat habitat. In the reef flat zone three prey species increased density while seven were unchanged; two non-prey species decreased while seven were unchanged. In the boulder zone six prey species increased, three decreased and two were unchanged; one non-prey increased, three decreased and five were unchanged. An examination of prey vs. non-prey guild structure indicated an increase in prey guild density in the boulder zone from 1976 to 1981 and a reshuffling of rank order of prey density. Analysis of trophic guild structure revealed an increase in carnivore guild density (but no change in ranks) in the boulder zone only and an increase in herbivore guild boulder density (with change in ranks) between 1976 and 1981. No significant changes in species diversity were observed during the study. Heliaster did not act as a keystone species in this community, but it influenced the abundance and structure of prey species and trophic guilds. A continuum is proposed for the potential effects of predation on community structure.

The importance of parental nutritional status on planktotrophic larvae was investigated in both laboratory-conditioned and field (populations) parents of two New Zealand echinoderms: the sea urchin Pseudechinus huttoni and the starfish Sclerasterias mollis. Three questions were addressed: (i) Does parental nutritional status affect the reproductive features (gonad index, gametogenesis, fecundity and biochemical composition) both in the laboratory and under natural conditions? (ii) Does parental nutritional status affect egg characteristics (diameter, number, dry weight, fertilization rate and biochemical composition)? (iii) Are the characteristics of larvae (growth, development, morphology, mortality rate and body composition) influenced by parental or larval nutrition (or both)? To answer the first question, adult P. huttoni and S. mollis were maintained in the laboratory with a low or high diet (in terms of quantity and quality for P. huttoni, and in terms of quantity for S. mollis) for one year. The effect of low and high diets on reproductive features was studied and the same parameters were studied in two parental populations with dissimilar food availability (for P. huttoni: Otago Shelf and Doubtful Sound populations; for S. mollis: Otago inshore and offshore populations). To address the second question, egg characteristics of the laboratory-held and field parents were measured. The third question was answered by rearing larvae of the laboratory and field parents with both low and high concentration planktonic diets. P. huttoni reared in the laboratory with a higher food ration had greater gonad indices and lipid concentration and larger oocyte area. Sea urchins from the Doubtful Sound population had higher food availability, greater gonad lipid concentration and larger oocytes. Parental nutrition had some effect on the characteristics of the egg in P. huttoni. The laboratory-held urchins fed a high diet produced larger eggs: P. huttoni from Doubtful Sound produced larger eggs with a greater carbohydrate concentration. P. huttoni larvae from low-fed laboratory and Otago Shelf parents had faster development The effect of larval nutrition was more important than parental food availability on larval growth and development. Feeding parents in the laboratory had no effect on larval morphology but larvae from Doubtful Sound, which had better food availability, had longer arms relative to body width. A higher cell concentration in the planktonic diet led to shorter larval arm relative to body width. In S. mollis reared in the laboratory, a higher food ration led to larger gonad and pyloric caeca indices. The starfish from an Otago inshore population mainly had a higher gonad index than those from an Otago offshore population. In the laboratory-held parents S. mollis, nutrition had no effect on the egg characteristics. In the field, starfish with higher food availability produced smaller eggs with lower carbohydrate concentration. There was no significant difference between development rates of S. mollis larvae from low and high fed laboratory parents. However, those from the Otago inshore parents, with better food availability, had faster development than the larvae from Otago offshore parents. In S. mollis larvae, the origin of the parents (either from the laboratory or the field) had no effect on larval shape. A higher concentration planktonic diet led to longer larvae relative to body width in larvae from high-fed laboratory parents. In both P. huttoni and S. mollis, parental and larval diet had no effect on rate of instantaneous larval mortality. In both P. huttoni and S. mollis larvae, biochemical composition of the larvae and the egg were different to each other. Egg reserves appear not to be a factor which affects larval characteristics in these species.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Su Ürünleri Temel Bilimleri Anabilim Dalı, 2008. / Kaynakça var.