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Metabolism of a desert stream
Author(s) -
BUSCH DAVID E.,
FISHER STUART G.
Publication year - 1981
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.1365-2427.1981.tb01263.x
Subject(s) - benthic zone , photosynthesis , cladophora , algae , biomass (ecology) , periphyton , autotroph , ecology , biology , epiphyte , plant litter , botany , primary production , respiration , algal mat , photosynthetically active radiation , environmental science , ecosystem , genetics , bacteria
SUMMARY. Rates of photosynthesis and community respiration were determined for benthic assemblages in Sycamore Creek, a Sonoran Desert stream in Arizona. Benthos in this stream can be separated into (1) mats of Cladophora glomerata and associated epiphytes and (2) assemblages of epipelic diatoms and blue‐green algae. Community respiration and net photosynthesis were measured for these assemblages using submerged light‐dark chambers in situ . Multiple regression analysis was used to predict (1) gross photosynthesis as a function of photosynthetically active radiation, temperature and chlorophyll‐α concentration; and (2) community respiration as a function of temperature and biomass. Calculations suggest that Sycamore Creek is autotrophic during the summer ( P/R = 1.7) and that the rates of gross photosynthesis ( P =8.5 g O 2 m −2 day −1 ) and community respiration ( R = 5.1 g O 2 m −2 day −1 ) are high for a small stream. Considerable difference exists between the Cladophora mat assemblages, in which mean P is 12.5gO 2 m −2 day −1 and the P/R ratio is 2.3, and the epipelic assemblages in which mean P is 4.4 g O 2 m −2 day −1 and P/R is 0.96. The high rate of gross photosynthesis, low litter inputs, high biomass of algae and the intermittent but severe floods that characterize Sycamore Creek indicate that this stream and other similar desert streams are net exporters of organic matter and are, thereby, truly autotrophic stream ecosystems.