Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

The Microbiology and Decomposition of Seston in Open Water and Experimental Enclosures in a Productive Lake

J. G. Jones
Journal of Ecology
Vol. 64, No. 1 (Mar., 1976), pp. 241-278
DOI: 10.2307/2258694
Stable URL: http://www.jstor.org/stable/2258694
Page Count: 39
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Microbiology and Decomposition of Seston in Open Water and Experimental Enclosures in a Productive Lake
Preview not available

Abstract

(1) In a study of a small eutrophic lake and large experimental enclosures therein, an attempt was made to determine the chemical and biological nature of the seston and to investigate its fate within the lake system. (2) Most of the sedimented seston was algal in origin and the degree of colonization by other micro-organisms often reflected the state of health of the algal `host'. Examination of material from phytoplankton net tows showed that the degree of colonization of Asterionella by fungi, bacteria and protozoa was much higher as the alga reached the end of its active growth phase. Further study of bacterial attachment showed that this trend was true of other `hosts'. The material which eventually formed part of the detritus fraction was often, therefore, a mixture of the four main microbial groups. (3) The seston in the epilimnion, hypolimnion, the outflow, one of the inflowing streams, and in sediment traps set below the thermocline and above the mud surface, was analysed for carbon, nitrogen and phosphorus. Calculation of C/N/P ratios suggested that nitrogen loss from the particulate form was more rapid than that of phosphorus, with carbon occupying an intermediate position. Possible inaccuracies in the conclusions drawn about decomposition processes from the use of elemental ratios are discussed. (4) Rates of sedimentation combined with measurements of material carried in the outflow and inflows, and estimates of standing crops, indicated that the tarn was more productive than the experimental tubes during the period of study. This was thought to be due to nutrient depletion in the latter; qualitative and quantitative changes in the bacterial population supported this view. (5) Areal deficits calculated over short time periods at the beginning of the period of stratification agreed with O2 uptake measurements in isolated mud cores. The average areal deficit estimated over the whole period of de-oxygenation was somewhat lower. Calculation of the time required for de-oxygenation of the hypolimnion was in good agreement with that derived from the long term areal deficit applied as an average rate to the whole hypolimnion. A similar de-oxygenation period was derived from mud core uptake rates or short term estimates of areal deficit if allowance was made for decreased O2 uptake at lower O2 concentrations and the changing mud area/water volume ratio with depth. The latter factor had by far the more significant effect. Estimates of CO2 accumulation in the hypolimnion suggested that mineralization values derived from O2 uptake figures (assuming a respiratory quotient of 1) probably underestimated the process. (6) A summary of carbon transfers is made, which suggests that most of the net production of seston in the epilimnion eventually sedimented into the hypolimnion, and a smaller proportion was lost via the outflow. Respirometric studies and deficit calculations suggested that carbon mineralization continued, possibly at a higher rate, under anaerobic conditions, and that hypolimnetic respiration would account for most of the sedimented material. Comparisons of results from this survey with previously published work show that in most cases estimated mud respiration exceeded net production, which may be interpreted as an indication of the importance of the sediment as a site of mineralization.

Page Thumbnails

  • Thumbnail: Page 
241
    241
  • Thumbnail: Page 
242
    242
  • Thumbnail: Page 
243
    243
  • Thumbnail: Page 
244
    244
  • Thumbnail: Page 
245
    245
  • Thumbnail: Page 
246
    246
  • Thumbnail: Page 
247
    247
  • Thumbnail: Page 
248
    248
  • Thumbnail: Page 
249
    249
  • Thumbnail: Page 
250
    250
  • Thumbnail: Page 
251
    251
  • Thumbnail: Page 
252
    252
  • Thumbnail: Page 
253
    253
  • Thumbnail: Page 
254
    254
  • Thumbnail: Page 
255
    255
  • Thumbnail: Page 
256
    256
  • Thumbnail: Page 
257
    257
  • Thumbnail: Page 
258
    258
  • Thumbnail: Page 
259
    259
  • Thumbnail: Page 
260
    260
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
261
    261
  • Thumbnail: Page 
262
    262
  • Thumbnail: Page 
263
    263
  • Thumbnail: Page 
264
    264
  • Thumbnail: Page 
265
    265
  • Thumbnail: Page 
266
    266
  • Thumbnail: Page 
267
    267
  • Thumbnail: Page 
268
    268
  • Thumbnail: Page 
269
    269
  • Thumbnail: Page 
270
    270
  • Thumbnail: Page 
271
    271
  • Thumbnail: Page 
272
    272
  • Thumbnail: Page 
273
    273
  • Thumbnail: Page 
274
    274
  • Thumbnail: Page 
275
    275
  • Thumbnail: Page 
276
    276
  • Thumbnail: Page 
277
    277
  • Thumbnail: Page 
278
    278