Syntrophic relationships between algae and bacteria in a fresh-water stream and in culture /

Interactions between freshwater algae and bacteria were examined in a natural stream habitat and a laboratory model. Field observations provided circumstantial evidence, in statistical correlation for syntrophy between the microbial populations. This relation is probably subject to control by the temperature and pH of the aquatic environment. Several species of a pond community were isolated in axenic culture and tests were performed to determine the nature of mixed species interactions. Isolation procedures and field studies indicated that selected strains of Chlorella and Azotobacter were closely associated in their natural habitat. With the suspected controlling parameters, pH and temperature, held constant, mixed cultures of algae and bacteria were compared to axenic cultures of the same organisms, and a mutual stimulation of growth was observed. A mixed pure culture apparatus was designed in this laboratory to study the algal-bacterial interaction and to test the hypothesis that such an interaction may take place through a diffusable substance or through certain medium-borne conditions, Azotobacter was found to take up a Chlorella-produced exudate, to stimulate protein synthesis, to enhance chlorophyll production and to cause a numerical increase in the interacting Chlorella population. It is not clear whether control is at the environmental, cellular or genetic level in these mixed population interactions. Experimental observations in the model system, taken with field correlations allow one to state that there may be a direct relationship governing the population fluctuations of these two organisms in their natural stream surroundings.

Introduced taxa in disturbed ecosystems

In the literature, introduced taxa are assumed to be present, more abundant, and occupy greater physical space in portions of ecosystems disturbed by human activity. This study tested this principle in two sites, Short Hills provincial Park ("SHU) and Backus Woods ("B~l"). spatial distribution of introduced taxa of vegetation, isopods, and earthworms was determined with the runs test along 300m transects encompassing gradients of anthropogenic disturbance severity. The hypothesis was that introduced taxa would be aggregated along these transects; the null hypothesis was that they would not be aggregated. The null hypothesis was rejected for the introduced taxa as a unit, and vegetation and earthworms individually. Introduced taxa were aggregated along 53.33% (N~30) and 57.14% (N~21) of the transects in SH and BW (respectively). Introduced vegetation (90.00%, N~10 and 100.00%, N~7) and earthworms (50.00%, N~10 and 50.00%, N~8) were also significantly aggregated within the sites. Introduced isopods, however, were not significantly aggregated at either place (20. 00%, N-=10 and 16. 67%, ~J~6). This study demonstrated that introduced taxa are aggregated within ecosystems disturbed by human activity. However, since introduced isopods were not significantly aggregated it was also shown that taxa respond differently.

A tour from the City of New-York, to Detroit, in the Michigan Territory, made between the 2d of May and the 22d of September, 1818 : the tour extends from New-York, by Albany, Schenectady, and Utica to Sacket's Harbor, and thence throught Lake Ontario, to St. Lawrence river, and down that stream to Hamilton village. Thence along both banks of the St. Lawrence, from Hamilton to the Thousand Islands; thence to Sacket's Harbor by water; from that place by the route of great Sodus, Geneva, Cananaigua and Batavia, to Buffalo; and from thence to Black Rock, Fort Erie, the Falls of Niagara, Queenston, Lewiston, and the memorable fields of Bridgewater and Chippewa after viewing the interesting place of Niagara, the author traversed the south shore of Lake Erie to the City of Detroit, and visited in the latter range, Dunkirk, Erie, Cleveland, Sandusky, and other places of less note. The tour is accompanied with a map upon which the route will be designated; a particular map of the Falls andRiver of Niagara, and the environs of the City of Detroit /

Errata slip inserted.

Flow regime prediction via froude number calculation in a rock-bedded stream

Mathematical predictions of flow conditions along a steep gradient rock bedded stream are examined. Stream gage discharge data and Manning's Equation are used to calculate alternative velocities, and subsequently Froude Numbers, assuming varying values of velocity coefficient, full depth or depth adjusted for vertical flow separation. Comparison of the results with photos show that Froude Numbers calculated from velocities derived from Manning's Equation, assuming a velocity coefficient of 1.30 and full depth, most accurately predict flow conditions, when supercritical flow is defined as Froude Number values above 0.84. Calculated Froude Number values between 0.8 and 1.1 correlate well with observed transitional flow, defined as the first appearance of small diagonal waves. Transitions from subcritical through transitional to clearly supercritical flow are predictable. Froude Number contour maps reveal a sinuous rise and fall of values reminiscent of pool riffle energy distribution.