The purpose of this research is to study the effects of environments on the growth of Thalassia hemprichii in cement ponds. The growth index include¡Gchlorophyll concentration, leaf length , hairy root length and their wet weight during experimental periods. Environmental factors use in this study included¡Gsalinity (3 levels), water depths¡]8 levels¡^, sediment types (4 groups) and sun light energy. The results showed that¡G¡]1¡^Salinity significantly affected growth of seagrass, especially hairy root and chlorophyll concentration¡FA negative effect of high salinity on root growth.¡]2¡^ Sediment had no significant effect on seagrass growth, althought a bigger sediment particle, a higher growth rate in root. Analysis of variance from general linear model showed that the sequence of importance to the chlorophyll concentration of leaves are the coefficient of light decline, salinity, time, water depth and cumulated sun light.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 114-124). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : [57]-62).

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : [33]-36).

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : 110-116).

No description available.

No description available.

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: [87]-88)

Les Invertébrés de l’épifaune vagile présents dans les herbiers de Magnoliophytes marins ont un rôle essentiel dans le transfert d’énergie des producteurs primaires vers les niveaux trophiques supérieurs. L’objectif de ce travail a été d’analyser la relation entre la complexité de l’herbier et la structure des communautés de l’épifaune vagile, et d’étudier le rôle de ce compartiment dans le fonctionnement des réseaux trophiques des herbiers à Thalassia testudinum. Deux sites d’herbiers ont été comparés, l’un proche de la mangrove côtière et l’autre près de la barrière récifale, au cours de deux saisons. L’utilisation de différentes sources trophiques par les Invertébrés a été montrée en utilisant les méthodes des isotopes stables du carbone et de l’azote et de la composition en acides gras. L’herbier côtier, qui présente une structure complexe du fait de ses longues feuilles, de sa litière abondante et de sa forte charge en épiphytes, abrite une faune abondante et diversifiée de Crustacés. La préférence alimentaire de ces Invertébrés pour les micro-algues et les fines particules détritiques favorise la contribution du biofilm au réseau trophique de l’herbier côtier. L’herbier du large, moins complexe, abrite une communauté d’Invertébrés dominée par les Gastéropodes Cerithiidae. La limitation de la disponibilité en nourriture existant dans cet herbier explique la contribution plus élevée de la litière et des feuilles vivantes de Thalassia au réseau trophique par rapport à l’herbier côtier. Le couplage de l’analyse des isotopes stables à celle des contenus stomacaux réalisé sur les poissons a montré le rôle essentiel des Crevettes en tant que proies. L’herbier côtier, qui présente des ressources en nourriture plus abondantes et diversifiées, assure mieux son rôle de « nurserie » pour les juvéniles de poissons que l’herbier du large. / In seagrass beds, vagile epifauna plays a major role in the energy transfer from primary producers to higher trophic levels. The main aim of the work was to examine the relationship between the seagrass complexity and the vagile epifauna community structure, and to study the role of this compartment within the food web of Thalassia testudinum seagrass beds. Two seagrass sites were compared, one near the coastal mangrove and another one near the barrier reef, during two seasons. Trophic resources used by primary consumers were assessed by combining stable isotopes analysis and fatty acid compositions. The coastal seagrass bed is complex due to its long leaves and its great biomass of litter and epiphytes. It shelters a great abundance and diversity of Crustaceans. The feeding preference of them for micro-algae and detrital particles promotes biofilm contribution to food web of the coastal seagrass bed. The seagrass bed located seawards, lesser complex, harbors an Invertebrate community dominated by the Gastropods Cerithiidae. The reduced food availability in that seagrass bed explains the higher contribution of litter and Thalassia leaves to that food web compared to the coastal seagrass bed. By coupling stable isotopes and stomach contents analyses, it was possible to highlight the major role of shrimps in the feeding diet of fishes. The coastal seagrass bed, where the trophic resources are more abundant and diverse, better plays its role of nursery for juveniles fishes than the seaward seagrass bed.

During the growing seasons of 1999 and 2000 five experiments were performed to test growth of the seagrass Halodule beaudettei (shoal-grass) in nursery pond conditions. Sediment oxidation state, sediment source, container type, flow regime, and light transmittance were tested to improve nursery pond cultivation techniques and to test assumptions about the decline of seagrasses in Galveston Bay, Texas. Oxidized and reduced sediments exhibited no statistical difference as mean percent change in the number of stems of shoal-grass, after 47 days. Sediment from three source locations, West Bay, East Beach Lagoons, and the experimental pond bottoms, showed no significant difference in the mean percent change in the number of stems of shoal-grass at 48 and 95 days. A statistical difference was seen in the container type experiment, trays versus pots, at 48 days where shoal-grass had double the number of stems produced in trays; however no significant difference was found at 93 days. A significant difference was found in the flow regime experiment, no-flow versus flow, at 47 days in the mean percent change of shoal-grass with double the number of stems produced in the flow regime. Significant differences were observed between the low light and high light treatments with shoal-grass, widgeongrass (Ruppia maritima), star grass (Halophila engelmannii), and turtlegrass (Thalassia testudinum), with survival and growth occurring in the high light treatment and decline and death occurring in the low light treatment. The importance of reduced sediment may have been overstated in the past as sediment reduction occurs rapidly with submersion. It appears that while West Bay sediment did not have a deleterious effect on shoal-grass, West Bay simulated light conditions did. Container type seems to be important at first but not so much in the long term. Some flow, water movement, or current appears to be important.