Calanoid Copepods from the Forest to Prairie Transition in the Itasca Park Region of Minnesota

Calanoid copepods found in a summer survey of northwestern Minnesota lakes and ponds were: Epischura lacustris, Diaptomus oregonensis, D. leptopus, D. sakatchewanensis, D. nudus, and D. siciloides. Some diaptomid species correlated with vegetational type. E. lacustris, D. oregonensis, D. saskatchewanensis were characteristic of pine hardwood and mesic deciduous forest regions while D. nudus and D. siciloides were characteristic of Oak-Savanna and prairie regions. D. leptopus was characteristic in shallow water habitats and occurred on both sides of the transitional area

The Effects of DDT and Sevin on Litter Decomposition and Litter Fauna

A comparison of the effects of spraying with DDT, Sevin or water on litter decomposition and litter fauna was made, using a litter bag method. During the thirteen week experimental period no significant differences were found between the rate of decomposition in the litter receiving the three different treatments. Twenty-four hours after spraying the number of Collembola was greatly reduced in the Sevin treated plots. At the end of the experimental period the reduction of fauna other than mites or Collembola was significant at the .01 level as compared to the effects of Sevin or water

Copepoda and Cladocera Populations of Red Rock Reservoir, Iowa from April to November, 1970

The effects of nutrient renewal, conservation pool water level, and the average weekly discharge rate on the species composition, relative abundance, and population fluctuations of the Copepoda and Cladocera of Red Rock Reservoir were determined. The average retention time (flushing rate) was 11.2 days. Twenty-one species were identified with the dominants being Cyclops spp., Diaptomus spp., Daphnia spp., Bosmina longirostris, Moina micrura, Ceriodaphnia quadrangula, and Diaphano-soma spp. Three distinct seasonal peaks in population growth were noted. Population fluctuations showed slight correlation with temperature, transparency, discharge rate, nutrient levels and no relationship was seen with water level. A time interval of 18 to 32 days occurred between high nitrate and phosphate levels and population abundance peaks. Species composition showed distinct seasonal changes. Population numbers began increasing at the dam area and continued upstream with declines following the reverse pattern

The Fecal Coliform/Fecal Streptococcus Ratio as a Measure of Bacterial Contamination and Indicator of Its Source in the Des Moines River

The fecal coliform/fecal streptococcus (FC/FS) ratio and total coliform test were used in attempts to determine the degree and source of bacterial contamination present in the Des Moines River between April 18 and November 14, 1970. There were no predictable changes in the FC/FS ratio as the river passed from a rural area, through a metropolitan district, and on to another rural area; however, the total coliform counts did show variation with distance. The failure of the FC/FS ratio to indicate source of contamination was probably due to the highly varying external conditions acting upon the river

Primary Productivity in Lake Red Haw, Lucas County, Iowa

Primary production studies were conducted on an 83-acre lake in south central Iowa during the summer of 1970 and winter of 1971. Primary productivity was measured using the light­ dark bottle method. Summer values ranged from 2.74 to 6.25 grams of carbon assimilated/m2/day. This was correlated with water temperature, nitrate nitrogen, ortho phosphates, carbon dioxide, light penetration and plankton populations. Studies were continued during the winter using C14 and scintillation counting methods