Migratory Responses of Benthic Diatoms to Light and Temperature Monitored by Chlorophyll Fluorescence

Abstract

As an important adaptation for survival in the sediments of intertidal flats, benthic diatoms move up and down in response to a wide range of environmental stimuli. We investigated the vertical migration of two diatomsCylindrotheca closterium (Agradh) Kützing (B-25) and Nitzschia sp. (B-3)-under different combinations of light intensity and temperature conditions. An imaging pulse amplitude modulated (PAM) fluorometer was used to measure the minimum fluorescence (F 0 ) in order to monitor variations in diatom biomass in surface sediments. Rapid light curves (RLCs) were applied to assess their photosynthetic activities. Both species had increased motility under higher temperatures, with the longer valved C. closterium being twice as fast as the shorter valved Nitzschia sp. The former was also influenced by exposure to light intensities of 100 or 250 μmol m −2 s −1 , whereas the latter was not. Consequently, no light/temperature interaction effect was associated with the vertical migration of Nitzschia sp., perhaps because of its lower photosynthetic capacity and smaller cell size. Therefore, we conclude that motile benthic diatoms exhibit species-specific responses to light and temperature due to differences in their photosynthetic capability and morphological characteristics.

Response of intertidal benthic microalgal biofilms to a coupled light–temperature stress: evidence for latitudinal adaptation along the Atlantic coast of Southern Europe

“…Additionally, high temperature alone is known to directly affect the motility of MPB diatoms, i.e. over 35°C cell motility significantly drops‐down (Cohn et al ., ; Du et al ., ). Such feature might partly explain the stronger photoinhibition observed at 37°C in Lat A free samples, together with a direct impact of temperature on physiological mechanisms.…”

“…Epipelic diatoms generally exhibit a low NPQ, in comparison with non‐motile ones (Barnett et al ., ). This does not preclude the existence of interspecific variability between organisms sharing the same life style, considering both behavioural (Underwood et al ., ; Du et al ., 2010; 2012) and physiological photoprotective mechanisms (Barnett et al ., ). Furthermore, the occurrence of N. phyllepta s.l.…”

Physiological response of temperate microphytobenthos to freezing temperatures

“…MPB, which is usually dominated by diatoms, can attain a biomass of~300 mg chlorophyll-a m 22 (Kromkamp et al, 2006;Koh et al, 2007). There have been many studies of the effects of temperature on MPB, identifying it as one of the main environmental factors regulating production (Blanchard & Guarini, 1996;Barranguet et al, 1998;Du et al, 2012), but very few have investigated the effects of extreme temperatures. There have been many studies of the effects of temperature on MPB, identifying it as one of the main environmental factors regulating production (Blanchard & Guarini, 1996;Barranguet et al, 1998;Du et al, 2012), but very few have investigated the effects of extreme temperatures.…”

Microphytobenthos of Korean tidal flats: A review and analysis on floral distribution and tidal dynamics

“…Later, various issues relating to the vertical migration followed by tidal dynamics of MPBs have been addressed, including the first report of the tidal resuspension of MPBs in the Branford Harbor Estuary, USA (Baillie and Welsh, 1980). Meantime, couple of studies focusing on the vertical migration rhythm of benthic diatoms have also been introduced in the Korean tidal flats (Du et al, 2010(Du et al, , 2012Kwon et al, in press), but such topics have not been much highlighted in Korea, compared to other topics (Table 1).…”