The seasonal biological surveys of 1971 / John C. Ayers, Samuel C. Mozley, John A. Stewart.

effects of temperature as mentioned above.
If convergence concentration were going on one would expect it to be
shown by higher numbers of phytoplankton along the bar. Figure 5 does not
exhibit such concentration; again, if it was going on it was being masked,
probably by the effects of temperature as mentioned above.
BACTERIA
Techniques
Total bacteria and coliform bacteria were determined by the nutrient pad
method using the Millipore Portable Water Analysis Kit and Field Monitors.
The Analysis Kit provides a pump and an incubator; the Field Monitors are
ready-to-use sterile nutrient pads and filters in incubating dishes and come
with ampouled nutrient media. M-TGE Broth was used for total counts, and MEndo Broth for coliforms. Water samples ranging from 16 to 30 ml were pumped
through the Field Monitors. Water from 1-m depth was collected by Nansen
bottle and immediately drawn off into sterile plastic bottles for refrigeration until the Field Monitors could be prepared. Because of limited space in
the incubator, bacteria were not run at all stations.
Station DC-1 was not sampled for bacteria in April, July, or September.
It was accidently omitted in April, and in July and September the station
position was occupied by dredges.
Counts of total bacteria were not made after April because of the extreme
degree of subjectivity inherent in making the counts from the incubated plates.
Results
The bacteria results are given in Table 2. The counts of total bacteria
for April are presented but are considered to be unreliable.
The numbers of coliforms exhibited great variation both spatially and
temporally. Numbers of coliforms rose from April through July and became
extremely high in September before falling to very low levels in November.
In 1971 Labor Day fell on 6 September, and the high numbers of coliforms
found on 2 September are tentatively associated by us with the peak of summer
usage of the lake and lakeshore property. We tentatively attribute the low

13