Thesis (Ph. D.)--University of Rhode Island, 2006. / Typescript. Includes bibliographical references (leaves 334-359).

Thesis (Ph. D.)--Washington State University, May 2006. / Includes bibliographical references (p. 75-78).

Thesis (Ph.D.) -- University of Adelaide, Dept. of Botany, 1979.

Dissertation (Ph. D.)--University of South Alabama, 2007. / Vita. Includes bibliographical references (leaves 108-122).

Seagrass beds are highly valuable ecosystems with a potential nursery function for rockfishes in British Columbia. Understanding how the nursery value of seagrass habitats differs for rockfish species, and what factors create this variability in habitat value, is important for effective conservation planning. In this study, the use of Zostera marina beds in Barkley Sound by juvenile rockfishes (Sebastes spp.) was investigated. Rockfish have been observed in Z. marina beds by many researchers, however, their abundance and distribution between beds has been shown to be variable. The abundance of juvenile rockfishes in five beds was assessed in 2005 and 2006 using visual surveys. Environmental and biological variables that could potentially influence this abundance were measured concurrently. These included supply of settling fish (hereafter “settlers”), biotic and abiotic habitat characteristics. The eelgrass beds that I studied were found to differ significantly in their habitat characteristics, the abundance of settlers arriving to them, as well as the abundance of juvenile recruits in the beds. Sebastes melanops and S. caurinus were found at the sites between June and September. There was no significant relationship between the abundance of settlers arriving at a bed, and the abundance of juveniles using it. However, many of the eleven habitat characteristics investigated were significantly correlated with the abundance of either S. melanops, or S. caurinus. It is likely that these relationships arose from multiple causes which acted both pre- and post-settlement. Habitat features that were identified as correlates with high juvenile abundance value included lower epiphyte biomass, nearness to kelp habitats, lower water temperature, lower shoot density, and higher leaf width.

Seagrass beds are highly valuable ecosystems with a potential nursery function for rockfishes in British Columbia. Understanding how the nursery value of seagrass habitats differs for rockfish species, and what factors create this variability in habitat value, is important for effective conservation planning. In this study, the use of Zostera marina beds in Barkley Sound by juvenile rockfishes (Sebastes spp.) was investigated. Rockfish have been observed in Z. marina beds by many researchers, however, their abundance and distribution between beds has been shown to be variable. The abundance of juvenile rockfishes in five beds was assessed in 2005 and 2006 using visual surveys. Environmental and biological variables that could potentially influence this abundance were measured concurrently. These included supply of settling fish (hereafter “settlers”), biotic and abiotic habitat characteristics. The eelgrass beds that I studied were found to differ significantly in their habitat characteristics, the abundance of settlers arriving to them, as well as the abundance of juvenile recruits in the beds. Sebastes melanops and S. caurinus were found at the sites between June and September. There was no significant relationship between the abundance of settlers arriving at a bed, and the abundance of juveniles using it. However, many of the eleven habitat characteristics investigated were significantly correlated with the abundance of either S. melanops, or S. caurinus. It is likely that these relationships arose from multiple causes which acted both pre- and post-settlement. Habitat features that were identified as correlates with high juvenile abundance value included lower epiphyte biomass, nearness to kelp habitats, lower water temperature, lower shoot density, and higher leaf width.

Thesis (M.Env.Sc.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: leaf 83-98.

Seagrass beds are highly valuable ecosystems with a potential nursery function for rockfishes in British Columbia. Understanding how the nursery value of seagrass habitats differs for rockfish species, and what factors create this variability in habitat value, is important for effective conservation planning. In this study, the use of Zostera marina beds in Barkley Sound by juvenile rockfishes (Sebastes spp.) was investigated. Rockfish have been observed in Z. marina beds by many researchers, however, their abundance and distribution between beds has been shown to be variable. The abundance of juvenile rockfishes in five beds was assessed in 2005 and 2006 using visual surveys. Environmental and biological variables that could potentially influence this abundance were measured concurrently. These included supply of settling fish (hereafter “settlers”), biotic and abiotic habitat characteristics. The eelgrass beds that I studied were found to differ significantly in their habitat characteristics, the abundance of settlers arriving to them, as well as the abundance of juvenile recruits in the beds. Sebastes melanops and S. caurinus were found at the sites between June and September. There was no significant relationship between the abundance of settlers arriving at a bed, and the abundance of juveniles using it. However, many of the eleven habitat characteristics investigated were significantly correlated with the abundance of either S. melanops, or S. caurinus. It is likely that these relationships arose from multiple causes which acted both pre- and post-settlement. Habitat features that were identified as correlates with high juvenile abundance value included lower epiphyte biomass, nearness to kelp habitats, lower water temperature, lower shoot density, and higher leaf width. / Science, Faculty of / Botany, Department of / Graduate

The early marine period for juvenile salmon is a critical life history stage for growth and survival. The health of near-shore ecosystems where juvenile salmon spend their early marine life, and the capacity of these habitats to provide prey are thus important for overall salmon returns. While near-shore habitat is generally accepted as being of critical importance, few studies have examined how juvenile salmon use this habitat during their early marine life. Understanding the trophic dynamics in these ecosystems and the characteristics of these habitats that are important for food provision will help us gauge the value of near-shore areas to the early marine phase of juvenile salmon. The importance of this avenue of research is underscored by declined rates of early marine survival of salmon, and suggestions that the rapid development of the shoreline is contributing to this decreased survival. My project investigates the role that near-shore habitat plays in promoting growth and survival of juvenile salmon by evaluating eelgrass as foraging grounds for juvenile salmon in the Comox Estuary, British Columbia. In 2015, we compared juvenile Chum salmon diets to prey availability in zooplankton tows and in epifaunal and infaunal eelgrass samples across a gradient of eelgrass shoot density. We complemented diet analysis with the use of stable isotope ratios of carbon (δ13C) and nitrogen (δ13N) to examine the relative contribution of zooplankton, eelgrass, and terrestrial invertebrates to juvenile Chum salmon diet. In 2016, we collected additional eelgrass samples to cover a wider range of eelgrass density, and compared juvenile Chinook salmon diets to prey availability in eelgrass. Prey invertebrates, such as polychaete worms, harpacticoid copepods, and amphipods, increased with eelgrass shoot density. Juvenile Chum salmon and juvenile Chinook salmon assessed in this study fed primarily on benthic species, specifically on harpacticoid copepods, which were only abundant in epifaunal eelgrass samples. The abundance of prey invertebrates in eelgrass beds and the benthic diet of juvenile salmon in the Comox Estuary leads us to conclude that the presence of eelgrass is an important habitat feature for juvenile salmon. / Graduate

The ability to map nearshore habitat (i.e. submerged aquatic vegetation) is an integral component of marine conservation. The main goal of this thesis was to examine the ability of high resolution, multispectral satellite imagery and a single-beam acoustic ground discrimination system to map the location of marine habitats in Bag Harbour, found in the Gwaii Haanas National Marine Conservation Area Reserve. To meet this goal, two objectives were addressed: (1) Using the QTC View V sing-beam acoustic ground discrimination system, identify which frequency (50 kHz or 200 kHz) is best suited for mapping marine habitat; (2) evaluate the ability to map nearshore marine habitat using WorldView-2 high resolution, multispectral satellite imagery and compare the results of marine habitat maps derived from the acoustic and satellite datasets. Ground-truth data for both acoustic and satellite data were collected via towed underwater video camera on June 3rd and 4th, 2012. Acoustic data (50 and 200 kHz) were collected on June 23rd and 24th, 2012, respectively. The results of this study are organized into two papers. The first paper focuses on objective 1 where the QTC View V single-beam acoustic ground discrimination system was used to map nearshore habitat at a site within the Gwaii Haanas National Marine Conservation Area using two survey frequencies – 50 kHz and 200 kHz. The results show that the 200 kHz data outperformed the 50 kHz data set in both thematic and spatial accuracy. The 200 kHz dataset was able to identify two species of submerged aquatic vegetation, eelgrass (Zostera marina) and a red algae (Chondrocanthus exasperatus) while the 50 kHz dataset was only able to detect the distribution of eelgrass. The best overall accuracy achieved with the 200 kHz dataset was 86% for a habitat map with three classes (dense eelgrass, dense red algae and unvegetated substrate) compared to the 50 kHz habitat classification with two classes (dense eelgrass and unvegetated substrate) that had an overall accuracy of 70%. Neither dataset was capable if discerning the distribution of green algae (Ulva spp.) or brown algae (Fucus spp.), also present at the site. The second paper examines the benthic habitat maps created using WorldView-2 satellite imagery and the QTC View V single-beam acoustic ground discrimination system (AGDS) at 200 kHz (objective 2). Optical and acoustic remote sensing technologies both present unique capabilities of mapping nearshore habitat. Acoustic systems are able to map habitat in subtidal regions outside of the range of optical sensors while optical sensors such as WorldView-2 provide higher spatial and spectral resolution. The results of this study found that the WorldView-2 achieved the highest overall accuracy (75%) for mapping shallow (<3 m) benthic classes (green algae, brown algae, eelgrass and unvegetated substrate). The 200 kHz data were found to perform best in deeper (>3 m) regions and were able to detect the distribution of eelgrass, red algae and unvegetated substrate. A final habitat map was produced composed of these outputs to create a final, comprehensive habitat map of Bag Harbour. These results highlight the benefits and limitations of each remote sensing technology from a conservation management perspective. The main benefits of the WorldView-2 imagery stem from the high resolution (2 x 2 m) pixel resolution, with a single image covering many kilometers of coastline, and ability to discern habitats in the intertidal region that were undetectable by AGDS. However, the main limitation of this technology is the ability to acquire imagery under ideal conditions (low tide and calm seas). In contrast, the QTC View V system requires more hours spent collecting acoustic data in the field, is limited in the number of habitats it is able to detect and creates maps based on interpolated point data (compared to the continuous raster data of the WorldView-2 imagery). If, however, the objectives of the conservation management to create high resolution benthic habitat maps of subtidal habitats (e.g. eelgrass and benthic red algae) at a handful of sites (in contrast to continuous coastal coverage), the QTC View V system is more suitable. Whichever system is used ground-truth data are required to train and validate each dataset. / Graduate / 0799 / luba.reshitnyk@gmail.com