The fjord is a characteristic, but biologically little studied marine habitat of British Columbia. The main objective of this study was to determine the annual cycle of primary organic production in Indian Arm, one of the mainland fjords in this area, and to relate this production to the oceanographic factors of the environment. Data were gathered in Indian Arm at approximately monthly intervals from 1956 through 1959 on 35 cruises. A detailed analysis of the physical oceanography of the fjord was made and a study of primary production in relation to these data was undertaken. The annual patterns of distribution on salinity, temperature, dissolved oxygen, density, and climate were observed. Analyses of these environmental factors, combined with direct current measurements, were used to establish the circulation pattern and replenishment mechanisms of the fjord waters. During 1958-1959, estimates of the annual cycle of primary production were made using three complementary techniques. Two of these were based on the oxygen budget of the fjord. This budget was established from a detailed study of the changes in oxygen distribution which occurred during the period. Changes in the total oxygen content of the fjord were corrected for non-biological processes and the resulting biological oxygen budget was used in the production estimates. In the first technique, the monthly net oxygen changes were considered to represent the amount of photosynthetic material produced in excess of the fjord's total biological requirements. The total for the year was calculated to be 380 g. C/m.²/yr. Secondly, the oxygen utilization budget of sub-euphotic waters provided an estimate of the organic material consumed within the fjord by non-photosynthetic organisms. This was estimated at 290 g. C/m.²/yr. The third method provided a method of measuring photosynthetic fixation in natural phytoplankton samples inoculated with carbon fourteen and incubated in situ. These values were corrected for the observed variations in production potential of various regions within the fjord. This value was estimated to be 460 g. C/m.²/yr. and is considered representative of the total net primary production of the fjord ecosystem. The difference between the net phytoplankton production and the sub-euphotic utilization provides a measurement of excess production, and indicates that approximately 25% of the fjord's production was transported out into neighbouring waters. The total gross production was estimated as 680 g. C/m.²/yr. by the oxygen budget method and 670 g. C/m.²/yr. by the radiocarbon method. These values are in excess of those usually found in continental shelf or oceanic waters, and approach the high values reported for regions of coastal upwelling. The relatively higher production in Indian Arm is primarily related to the seasonal stability of the water column and the effect of this stability in maintaining the phytoplankton population at favourable light intensities and periodically replenishing the depleted euphotic zone with nutrients. The nutrient source appears to be a biological accumulation in the deep basin of the fjord. In this region these nutrients may reach levels higher than those occurring at comparable depths in neighbouring waters. This study indicates that the estuarial waters of Indian Arm are probably more productive than coastal shelf waters in the same geographic region, and demonstrates that a fjord can be a highly productive ecosystem. / Graduate and Postdoctoral Studies / Graduate

A study of plankton communities in the Strait of Georgia was undertaken in order to determine qualitatively and quantitatively the distribution in time and space of both zooplankton and phytoplankton. In order to gain some picture of the seasonal, variations in the plankton communities two cruises were made in the Strait, one in June, 1955, and the other in November 1955. 165 plankton collections were taken. A complete count of zooplankton organisms was made in 5cc. of each sample and the number of diatoms cells per liter was tabulated. Copepods and diatoms were analysed to species; other groups to class or genera. Surface temperatures were taken. The physical and chemical data, used to account for the biological distributions were obtained largely from oceanographic data already available for the area. The correlation of these data have resulted in a number of conclusions concerning the distribution of plankton in the Strait of Georgia. The chief factor affecting the general distribution of plankton in the Strait of Georgia is the salinity gradient. The inflow of fresh water from the Fraser River forms zones of varying properties, and leads to the development of different plankton communities. The extent to which physical and chemical factors may determine the presence or absence of certain organisms from the zones described is discussed. / Science, Faculty of / Zoology, Department of / Graduate

Kelp are central components of marine ecosystems that are found on the west coast of South Africa and in temperate regions around the world. They are ecologically important in providing vertical habitats, and sustaining diverse life-forms. The kelp species that are investigated in this study are Ecklonia cava, Ecklonia maxima, Ecklonia radiata, Laminaria pallida and Laminaria ochroleuca. Ecklonia maxima, E. radiata and L. pallida are dominant South African kelps, therefore studying these species provides information about their distributions and environmental preferences. E.cava and L. ochloleuca are of interest as they are close relatives to South African kelp species, and add to the understanding of Ecklonia and Laminaria in a more global context. The aims of this study were to map the biogeographical distribution of each species, and model their potential niches based on the environmental conditions that facilitate their growth. Species Distribution Modelling was used to map the fundamental niche of each species. The Maxent method was used to model predictive niches by layering known coordinates of where each species is found, along with the Bio-ORACLE dataset of 23 environmental variables, consisting of satellite and in-situ data. The Carto cloud computing platform was used to map the current distribution of each species. The major environmental predictors of each species distribution were identified in the modelling process and contributed to the final predicted habitat suitability maps. The results of this study show that Maxent identified maximum, minimum, mean and range in sea surface temperature to be associated with all species' distribution. Measures of irradiance or light availability (specifically Photosynthetically Active Radiation, Diffuse Attenuation and cloud cover), were important predictors of four of the species' distributions. Chlorophyll, a proxy for nutrients, emerged as an important correlate of most distributions, whilst silicate, phosphate and calcite were important, particularly to the distribution of kelp species found outside of South Africa. There were regions identified 7 where each species could potentially grow, but are not found. The results show that while E.maxima and L.pallida are distributed along the west coast of southern Africa, L.pallida could potentially grow along the west coast of South America, whilst E.maxima appears to have a niche endemic to South Africa. Ecklonia radiata is distributed along the south coast of South Africa as well as southern Australia, New Zealand, whilst it could potentially grow in the north Atlantic, northeast Pacific and southeast Pacific. Ecklonia cava's distribution is endemic to the Japanese and South Korean coast and is predicted to be able to spread down the coast of China. Laminaria ochroleuca is distributed along the coasts of Spain, Portugal, France and Northern Africa with a widespread distribution on the British coastline, with a predicted potential to extend to western Ireland. Other suitable habitats for L.ochroleuca were southern Australia and New Zealand. Ecklonia maxima and L.pallida have overlapping distributions, whilst all other species have different distributions. The ecological preferences of each of these species differed in parameter, but were related to the same variables; temperature, light and nutrients. The South African species, E.maxima, E.radiata and L.pallida, differed in their preferences, including those occupying the same coastline. All species of kelp had variably unique distributions and varying environmental preferences compared to their congenerics. The possible causes for species not being able to grow in identified niches are likely to be temperature limits, light and nutrient limits, physical barriers and limitations to movement and establishment, as well as geographical and associated evolutionary adaptations that may limit dispersal. Besides the environmental variables analysed, biological, oceanographic and in-situ data is deemed important in gaining a complete and causal understanding of species distributions and their drivers. This study provides insight into South African kelp systems and their close relatives in a global context, and shows the successful use of niche modelling methods that can be more widely applied in marine research, conservation and management

More than 750 white perch, Morone americana, were collected from each of two major tributaries of southern Chesapeake Bay to compare the age structures, growth rates, and mortality rates of the two populations.The James River is characterized by heavy domestic and industrial pollution, whereas the York River is only slightly polluted. Maximum ages determined by scale analysis were 7 and 10 years for males and females respectively in each river. Males and females from the James River were larger than those from the York up to ages IV and V, respectively. Older fish were larger in the York . Females from both rivers were larger and heavier than males at all ages. Length increments of both sexes were greatest early in life. Males predominated in young age groups but females were more abundant at age IV and older. An analysis of relative age frequency suggested dominant year-classes in 1964 and 1965 in the James River, but the 1968 year-class was weak. No dominant year-classes were apparent from the York River collections. Growth histories for white perch are similar in the two estuaries and show constant yearly growth increments for different year-classes at corresponding ages. Mortality rates were calculated from age frequency distributions. Total annual mortality in the James River was about 70% for males after age IV and for remailes after age VI. In the York River, males at age III and older die at a rate of about 59%, whereas females older than age V have an annual mortality of 57%. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

A comparison of effects of conditioning adult oysters (Crassostrea virginica) with Cornstarch and/or Tetraselmis suecica and raw water were determined on subsequent larval growth, vigor and successful metamorphosis. Possible correlations of lipid content of eggs and larval growth, vigor and metamorphosis was also examined. Results illustrated the effectiveness of Cornstarch when used as a supplemental conditioning agent for producing larvae and spat in greater quantity and of better quality than the other conditioning diets employed. Investigation revealed that lipid content of eggs is an important indicator for larval growth, vigor, set and successful metamorphosis. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

Larvae of the American oyster Crassostrea virginica (Gmelin) were subjected to thermal shocks of varying magnitude at different larval ages. The effects were assessed in terms of mortality, growth, and setting success. Growth of larvae acclimated at 25 C and 20% salinity was not affected by a thermal shock of 10 C or 15 C, but a 20 C thermal shock had detrimental effect on growth. Mortality of oyster larvae increased significantly following thermal chocks of 10, 15, and 20 C, and was higher for older than for younger larvae. Setting rates of the control and 10 C shocked larvae were not significantly different, but larvae receiving 15 or 20 C shocks had significantly lower setting success. Growth rate and setting also seemed affected by the age at which the larvae received a thermal shock. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

Acute bioassays were conducted to determine the effects of thermal shock and chlorine exposure on the estuarine copepod Acartia tonsa. Laboratory conditions simulated power plant conditions using 8 C elevated temperatures and slug chlorination. A factorial design having temperatures at two levels and multiple chlorine additions, showed isolated effects of temperature and chlorine and their interaction. Adult Acartia tonsa withstood thermal shocks of 8 C above ambient summer temperatures of 20 to 25 C. No adverse effects were noted after 96 hours following an 8 ⃤ T over 5 seconds, holding at the elevated temperature for 5 minutes, and slowly returning to ambient within 20 minutes of exposure. Chlorine additions produced mass mortalities . At 20 C a chlorine residual of 0.75 ppm proved fatal to 30 percent of the organisms. Increasing the residual to 1.15ppm yielded 100 percent mortalities. At 25 C mortalities increased from 30 percent to 70 percent at the same 0.75 ppm residual levels. Temperature greatly governed copepods susceptibility to chlorination. Much of the equipment and techniques used in these experiments have not been previously described and are therefore explained in detail. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

The macrobenthic fauna in three dredged areas in Hampton Roads, Virginia was sampled for 14 months. Repopulation occurred very rapidly after the cessation of dredging, but the dominant species were generally not those previously recorded as mud-bottom dominants in the Hampton Roads area. The faunal changes through time somewhat agreed with those reported in classical successional sequences. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

A quantitative comparison of the phytoplankton in the surface microlayer of an estuary and that a depth of one meter was made using a Garrett-type screen and a Frautschy bottle for sample collection. Results showed that the surface microlayer contained a significantly greater number of phytoplankton cells than the water at one meter. Species diversity at the surface tended to be somewhat lower than one meter, due to a greater number of individuals of the dominant species. Investigation revealed that the presence of a monomolecular film of slick material absorbed onto the water surface resulted in a decrease in the number of phytoplankton cells in the surface microlayer. Species succession and seasonal abundance were also examined. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

Three concentrations of cornstarch, 0 . 6 ppm, l.l ppm, 4.0 ppm, were fed to clams and mussels during the spring, summer, and fall of 1970 . Parameters measured were shell length, shell thickness, total weight, wet meat weight, and percentage glycogen based on wet meat weight. Starch had no effect on size parameters but did influence glycogen content of meats . Mussels showed an increase of glycogen in all three seasons . Clams showed an increase only in the fall. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.