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Temporal and vertical distribution of ciliophoran communities in the benthos of a small eutrophic loch with particular reference to the redox profile
Author(s) -
FINLAY B. J.
Publication year - 1980
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1980.tb01176.x
Subject(s) - benthic zone , benthos , sediment , eutrophication , ciliate , bioturbation , ecology , environmental science , organic matter , flux (metallurgy) , oceanography , biology , geology , chemistry , nutrient , paleontology , organic chemistry
SUMMARY. The ciliate communities occurring at three benthic sites in a small eutrophic loch have heen investigated over a 2‐year period. Two characteristics of the community were studied in detail, the pattern of vertical distribution within the sediment and the temporal distribution of ciliates occurring in the surface sediment. The relationships between ciliate distributions and the environmental factors recorded were analysed by multiple regression. Significant relationships were revealed between vertical distribution of ciliates and the sediment redox (Eh) profile, the larger ciliate communities being associated with regions of higher potential. Other factors such as sediment density, organic matter, temperature and daylength, combined with other indicators of benthic metabolism (sulphide ion activity (Es 2− ), pH, oxygen flux) were selected in the regression analysis as accounting for much of the variation in the depth distribution of ciliates. In analysing the temporal distribution of ciliates in the surface sediment, numbers were inversely related to Eh, Es 2− and oxygen flux, a result of the upwards migration of reducing conditions and greater microbial activity in the sediment surface during the summer. Daylength, temperature, organic carbon and benthic chlorophyll‐ a were also selected as accounting for much of the variation in ciliate number. It is proposed that the large increases in number and biomass of surface‐sediment cilates in the summer months resulted from an intolerance of reducing conditions developing immediately beneath the surface and the increased productivity of the benthos as a whole during this period. Methods are also described for the construction, calibration and operation of electrodes used in measuring Eh, Es 2− and oxygen flux in the freshwater benthos. Data recorded for these three variables revealed similar seasonal patterns at each site in each of two consecutive years.