Ecological interactions between zooplankton and photosynthetic bacteria in Crawford Lake, Ontario

The present study was carried out to test the hypothesis that photosynthetic bacteria contribute a large portion of the food of filter feeding zooplankton populations in Crawford Lake, Ontario. The temporal and spatial variations of both groups of organisms are strongly dependent on one another. 14 By using C-Iabelled photosynthetic bacteria. the ingestion and clearance rates of Daphnia pulex, ~. rosea, and Keratella spp were estimated during summer and fall of 1982. These quantitative estimations of zooplankton ingestion and clearence rates on photosynthetic bacteria comprised an original addition to the literature. Photosynthetic bacteria comprised a substantial portion of the diet of all four dominant zooplankton species. The evidence for this is based on the ingestion and clearance rates of the dominant zooplankton species. Ingestion rates of D. pulex and D. rosea ranged 5 5 -1 -1 - -- 5 - -- 5 from 8.3X10 -1 to 14.6XlO -1 cells.ind. hr and 8.1X10 to 13.9X10 cells.ind. hr • Their clearance rates ranged from 0.400 to 1.000 -1 -1 -1 -1 ml.ind. hr. and 0.380 to 0.930 ml.ind. hr • The ingestion and clearance -1 -1 -1 -1 rates of Keratella spp were 600 cell.ind. hr and 0.40 ul.ind. hr respectively. Clearance rates were inversely proportional to the concentration of food cells and directly proportional to the body size of the animals. It is believed that despite the very short reg~neration times of photosynthetic bacteria (3-8 hours) their population densities were controlled in part by the feeding rates of the dominant zooplankton in Crawford Lake. By considering the regeneration times of photosynthetic bacteria and the population clearance rates of zooplankton, it was estimated that between 16 to 52% and 11 to 35% of the PHotosynthetic bacteria were' consumed· by Daphnia· pulex. and Q.. rosea per day. The temporal and spatial distribution of Daphnia pulex, !.. rosea, Keratella quadrata, K. coChlearis and photosynthetic bacteria in Crawford Lake were also investigated during the period of October, 1981 to December, 1982. The photosynthetic bacteria in the lake, constituted a major food source for only those zooplankton Which tolerate anaerobic conditions. Changes in temperature and food appeared to correlate with the seasonal changes in zooplankton density. All four dominant species of zooplankton were abundant at the lake's surface (O-4m) during winter and spring and moved downwards with the thermocline as summer stratification proceeded. Photosynthetic bacteria formed a 2 m thick layer at the chemocline. The position of this photosynthetic bacterial J-ayer changed seasonally. In the summer, the bacterial plate moved upwards and following fall mixing it moved downwards. A vertical shift of O.8m (14.5 to 15.3m) was recorded during the period of June to December. The upper limit of the photosynthetic bacteria in the water column was controlled by dissolved oxygen, and sulfide concentrations While their lower limit was controlled by light intensity. A maximum bacterio- 1 chlorophyll concentration of 81 mg Bchl.l was recorded on August 9, 1981. The seasonal distribution of photosynthetic bacteria was controlledinpart' by ·theg.-"z1ai'_.Q;~.zoopl. ank:tCm;-.Qther -ciactors associated with zooplankton grazing were oxygen and sulfide concentrations.

Factors influencing the seasonal changes in primary productivity of the photosynthetic bacteria of Crawford Lake, Ontario

A naturally occurring population of photosynthetic bacteria, located in the meromictic Crawford Lake, was examined during two field seasons (1979-1981). Primary production, biomass, light intensity, lake transparency, pH and bicarbonate concentration were all monitored during this period at selected time intervals. Analysis of the data indicated that (l4C) bacterial photosynthesis was potentially limited by the ambient bicarbonate concentration. Once a threshold value (of 270 mg/l) was reached a dramatic (2 to 10 fold) increase in the primary productivity of the bacteria was observed. Light intensity appeared to have very little effect on the primary productivity of the bacteria, even at times when analyses by Parkin and Brock (1980a) suggested that light intensity could be limiting (i.e., 3.0-5.0 ft. candles). Shifts in the absorption maxima at 430 nrn of the .bacteriochlorophyll spectrum suggested that changes in the species or strain composition of the photosynthetic bacteria had occurred during the summer months. It was speculated that these changes might reflect seasonal variation in the wavelength of light reaching the bacteria. Chemocline erosion did not have the same effect on the population size (biomass) of the photosynthetic bacteria in Crawford Lake (this thesis) as it did in Pink Lake (Dickman, 1979). In Crawford Lake the depth of the chemocline was lowered with no apparent loss in biomass (according to bacteriochlorophyll data). A reverse current was. proposed to explain the observation. The photosynthetic bacteria contributed a significant proportion (10-60%) of the lake1s primary productivitya Direct evidence was obtained with (14C) labelling of the photosynthetic bacteria, indica.ting that the zooplankton were grazing the photosynthetic bacteria. This indicated that some of the photosynthetic bacterial productivity was assimilated into the food chain of the lake. Therefore, it was concluded that the photosynthetic bacteria made a significant contribution to the total productivity of Crawford Lake.

Photograph of Rev. and Mrs. Wright and Family signed to Mrs. Mary Bell [n.d.]

An undated black and white studio portrait of Rev. and Mrs. Wright and family presented to Mrs. Mary Bell. The photograph is mounted in a decorative board frame and bears the handwritten inscription "Mrs. Mary Bell from Mrs. and Rev. Wright" on the reverse. This photograph was included in memorabilia owned by the Richard Bell family of St. Catharines, Ontario.

Photograph of Mary Bell by F. Pfaff, Photographer, Erie, Pa. [n.d.]

A cabinet card believed to be of Mary Bell, photographed by F. Pfaff, Artistic Photographer, of Erie, Pennsylvania. A handwritten entry on the reverse of the photo lists the address "231 Duke St.", however, the company's logo identifies its address as 1011 State St., Ground Floor Gallery. This photograph was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Sloman - Bell family includes relatives who are former Black slaves from the United States."Cabinet card photographs were first introduced in 1866. They were initially employed for landscapes rather than portraitures. Cabinet cards replaced Carte de visite photographs as the popular mode of photography. Cabinet cards became the standard for photographic portraits in 1870. Cabinet cards experienced their peak in popularity in the 1880's. Cabinet cards were still being produced in the United States until the early 1900's and continued to be produced in Europe even longer. The best way to describe a cabinet card is that it is a thin photograph that is mounted on a card that measures 4 1/4″ by 6 1/2″. Cabinet cards frequently have artistic logos and information on the bottom or the reverse of the card which advertised the photographer or the photography studio's services. " Source: http://cabinetcardgallery.wordpress.com/category/cabinet-card-history/

Mary Bell with Rick Bell, early 1950s

A black and white photograph of a very young Rick Bell with his grandmother, Mary Bell. The location is not recorded on the photo, however, it is likely to be Niagara Falls or St. Catharines, Ontario. This photograph was in the possession of Rick Bell, who retrieved family memorabilia from the attic of his mother, Iris, in the 1980s. The Bell family ancestry includes former African American slaves who settled in Canada.

Mary Tyrell Bell [n.d.]

A cabinet card portrait of a young Mary Tyrell (later Bell). The photograph is undated, however, it is believed to be from the 1880s or 1890s. Mary Tyrell married Charles Bell in 1894 in St. Catharines, Ontario. They initially settled in Erie, Pennsylvania but relocated to St. Catharines less than three years later. This photograph was in the possession of Mary Tyrell Bell's grandson, Rick Bell. The Bell family is descended from Black slaves from the United States.

Freshwater dinoflagellates as proxies of cultural eutrophication: a case study from Crawford Lake, Ontario

Crawford Lake, Ontario, provides an ideal natural laboratory to study the response of freshwater dinoflagellates to cultural eutrophication. The anoxic bottom waters that result from meromixis in this small (2.4 ha) but deep (24 m) lake preserve varved sediments that host an exceptional fossil record. These annual layers provide dates for human activity (agriculture and land disturbance) around the lake over the last millennium by both Iroquoian village farmers (ca. A.D. 1268-1486) and Canadian farmers beginning ~A.D. 1883. The well established separate intervals of human activity around Crawford Lake, together with an abundance of available data from other fossil groups, allow us to further investigate the potential use of the cyst of freshwater dinoflagellates in studies of eutrophication. Cyst morphotypes observed have been assigned as Peridinium willei Huitfeldt-Kaas, Peridinium wisconsinense Eddy and Peridinium volzii Lemmermann and Parvodinium inconspicuum (Lemmermann) Carty. The latter two cyst-theca relationships were determined by culturing and by the exceptional preservation of thecae of P. inconspicuum in varves deposited at times of anthropogenic reductions in dissolved oxygen.

Photograph - Mary E. Field

A photograph of Mary E. Field. The rear of the photo reads "Dear Cousin Ester, I send you this photo which is somewhat soiled but is the only one I have at present. Some other time I will send you a better. Yours with Love Mary E. Field".

Genealogical notes of Cyrus and Mary Sumner

Genealogical notes of Cyrus and Mary Sumner, n.d.; includes birth and some death dates of children. Listed are eleven names of children with birth dates and one child's death dated at two months of age.

Mary Bell Sumner Silhouette

A photographic copy of Mary Bell Sumner silhouette n.d.

Entrance Examination Certificate Collegiate Institutes and High Schools of Ontario - Mary Willson

A certificate from the Collegiate Institutes and High Schools of Ontario of the Education Department of Ontario stating: "It is hereby certified that Mary Willson has passed the entrance examination required by the Education Department for admission to a Collegiate Institute or High School. Dated at Welland August 1st, 1908. Signed John W. Marshall, B.A. Inspector of Public Schools.

Photograph - Mary Jane (Dolly) Cowan

A photograph of Mary Jane (Dolly) Cowan, date unknown. She is the correspondent for many letters in the collection. James Ware writes several letters and postcards to "Dolly" during his time in the military (World War I).

Indenture between Patrick and Mary Burns and Samuel DeVeaux Woodruff

Indenture of mortgage in fee with dower between Patrick and Mary Burns of the Township of Grantham and Samuel DeVeaux Woodruff of St. Catharines regarding parts of Lots no. 19 and 23 in the 5th Concession in the Town of Grantham - instrument no. 14820. Listed in Book E, folio 339, October 3, 1864.

Indenture between Henry and Mary Ellen Rogers and John Young

Indenture of bargain and sale between Henry and Mary Ellen Rogers of the Township of Niagara and John Young of the Township of Niagara regarding part of Lot no. 113 in the Township of Niagara - instrument no. 15071. Registered in the County of Lincoln on January 16, 1865 in Book C, folio 344, January 13, !865.

Indenture between Patrick and Mary Burns to Samuel DeVeaux Woodruff

Indenture of bargain and sale between Patrick and Mary Burns of Grantham to Samuel DeVeaux Woodruff of St. Catharines regarding part of Lot 23 in the 5th Concession in the Township of Grantham - instrument no. 491, December 10, 1868.