The responses of an unexploited population of lake whitefish (Coregonus clupeaformis) to fertilization of Lake 226 (L226), the Experimental Lakes Area, northwestern Ontario, were measured for 4 yr (1973–77). A vinyl sea curtain separated the lake into a northeast (NE) basin, which received P, N, and C additions, and a southwest (SW) basin, which received only N and C additions. Lake whitefish in the NE basin grew faster, had higher coefficients of condition, and had greater recruitment and production than those in the SW basin during the 2nd through 4th yr of fertilization. No differences between basins were detected in annual survival for fish , but survival of age 0 fish was greater in the NE basin. Whitefish production in L226NE averaged twice that in L226SW from the 2nd to the 4th yr of fertilization, though significant variations occurred between years in both the NE and SW populations.

Responses of Lake Whitefish (Coregonus clupeaformis) to Fertilization of Lake 226, the Experimental Lakes Area

High elevation alpine and subalpine Rocky Mountain lakes in Colorado and southeastern Wyoming were examined to determine regional variability in water chemistry and their sensitivity to atmospheric deposition. Acid neutralizing capacity, pH, conductivity and concentrations of major anions and cations were compared. Regional differences in water chemistry are evident. The south-eastern most lakes have significantly higher pH, conductivity, ANC, and sums of acid and base concentrations than lakes in the other regions of the state. In contrast the north-western most lakes are significantly more dilute than those from other regions. Despite these two regional differences, most regions are similar in having a wide range of variability in potential sensitivity of their lakes to acidification and nitrogen export. Many wilderness areas in western and eastern regions contains lakes that are extremely sensitive and other lakes not susceptible to deposition. Overall, 70% of the Colorado lakes are sensitive to acidification and 15% are extremely sensitive to acidification. All of the regions had lakes that are classified as susceptible or sensitive to acidification, with 12 of the 17 areas having all of their sampled lakes susceptible or sensitive. Generally NO concentration in surface waters decreased from mid-season to late season; yet a large number of the lakes export NO late in the season, suggesting nitrogen saturation. The results confirm the sensitivity of high elevation wilderness aquatic ecosystems in all regions of Colorado to acidification and nitrogen deposition.

Water chemistry of high elevation Colorado wilderness lakes

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=8230&context=rtd

Effects of varying concentrations of certain major and minor nutrients on the interaction between a blue-green alga and a diatom

Primary production and limiting nutrients were studied by 14C techniques in a small, shallow, subalpine lake. There was no relationship between productivity at any depth and light intensity at that depth. Samples taken near the lake bottom always had higher productivity than samples taken near the surface, probably due to more optimal nutrient conditions. Nutrient enrichment experiments support this hypothesis, since sediment extract and ethylenediamine-tetraacetic acid were always effective in enhancing productivity. The effects of other nutrients and nutrient combinations were less consistent, and tended to change through the summer. A large number of significant three, four and five factor interactions in midsummer indicated that the nutrient requirements of the algal community were most complex at this time. Although retention time increased through the summer from 10 to 71 hours, productivity tended to more closely parallel water temperature. Studies of currents showed that the western end o...

John F. Wagner

Papers

Primary Production and Limiting Nutrients in a Small, Subalpine Wyoming Lake