|Fortnightly light and temperature variability in estuarine intertidal sediments and implications for microphytobenthos primary productivity|Serôdio, J.; Catarino, F. (1999). Fortnightly light and temperature variability in estuarine intertidal sediments and implications for microphytobenthos primary productivity. Aquat. Ecol. 33(3): 235-241. hdl.handle.net/10.1023/A:1009989229098
In: Aquatic Ecology. Springer: Dordrecht; London; Boston. ISSN 1386-2588, more
Marine; Brackish water; Fresh water
intertidal areasphotosynthetically active radiationphotosynthesisTagus estuarytides
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Photosynthetically active radiation (PAR) and temperature were measured continuously at the surface of estuarine intertidal sediments in the Tagus estuary, Portugal, along two spring-neap tidal cycles. PAR and temperature were strongly conditioned by the periodic tidal inundation, with large and abrupt variations occurring during flooding and ebbing. PAR levels reaching the sediment surface decreased very rapidly to zero or very low values during most of the daytime immersion. Inundation during high tide had the general effect of attenuating the amplitude of daily temperature fluctuation, with the incoming water usually warmer than the sediment during the night or early morning and cooler during the day. The daily progression of tidal emersion resulted in a clear fortnightly variation in total daily PAR reaching the sediment surface, while both daily mean temperature and mean temperature of diurnal low tide periods failed to exhibit a well-defined fortnightly periodicity. The obtained results indicate that the estuarine intertidal environment is dominated, at sub-seasonal time scales, by fortnightly periodicity in irradiance and temperature conditions favourable for benthic photosynthesis.