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Metabolism of a tide‐dominated reef platform subject to extreme diel temperature and oxygen variations
Author(s) -
Gruber Renee K.,
Lowe Ryan J.,
Falter James L.
Publication year - 2017
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.10527
Subject(s) - diel vertical migration , reef , oceanography , intertidal zone , benthic zone , seagrass , environmental science , primary production , autotroph , subtropics , ecology , atmospheric sciences , geology , habitat , biology , ecosystem , paleontology , bacteria
Benthic dissolved oxygen fluxes were measured on the reef flat of Tallon Island, an intertidal reef platform in the Kimberley region of northwestern Australia, for periods of 2 weeks in the wet and dry seasons. This reef flat is strongly tidally forced by semidiurnal tides (spring range > 8 m) and experiences highly asymmetric water level variability, with ebb durations lasting ∼10 h; this results in diel variations in water temperature and dissolved oxygen (DO) concentration (up to ∼11°C and 440 μM, respectively) that are among the most extreme recorded for reefs worldwide. Given the consistent tidal flow patterns, a one‐dimensional control volume approach was used to make continuous Eulerian measurements of net production and community respiration from observed changes in DO within two zones: an inner zone dominated by seagrass and an outer zone dominated by macroalgae. Community respiration ( R ) was controlled primarily by DO concentration; however, fluxes approached the limits of DO mass transfer at low flow speeds. Estimates of gross primary production ( P ) suggested that reef communities were able to fix carbon at rates comparable to other tropical seagrass and mixed reef flat communities despite short‐term (∼hours) extremes in light (up to 1800 μmol m −2 s −1 ) and temperature (> 35°C). Daily net community production fluctuated between net autotrophy and heterotrophy over a ∼15 d period depending on the phase difference between the solar and tidal cycles but was nonetheless metabolically balanced on time scales greater than weeks ( P : R = 1.0–1.1).