The Effect of Temperature and Mixed Species Composition on Diatom Motility and Adhesion

Abstract

Four species of biraphid pennate diatoms (Craticula cuspidata (Kiitzing) D.G. Mann, Stauroneis phoenicenteron (Nitzsch) Ehrenberg, Nitzschia linearis (Agardh) W. Smith, and Pinnularia viridis (Nitzsch) Ehrenberg) were studied to determine the effect of temperature changes on their motility and adhesion to the substratum. The pattern of cell movement in response to temperature was similar in all species; the average cell speed increased with temperature, with a maximal speed at 30-35°C. Temperatures > 35OC caused a rapid decrease in cell speed, with cells showing little movement at 40°C; the shape of the temperature profile was nearly identical in all species. The loss of motility above the threshold was not due to cell death as cells exposed to 42°C could recover movement when cooled. In contrast to temperature effects on cell movement, its effect on adhesion for all four species showed distinct qualitative differences. The adhesion of P. viridis and S. phoenicenteron to a glass substrate decreased from 20°C to 35"C, but increased slightly at 45OC. The loss of adhesion in S. phoenicenteron was not quite as severe as in P. viridis, with the latter showing little ability to remain adhered at higher temperatures. Nitzschia linearis demonstrated a higher degree of cell adhesion between 5 and 45°C than C. cuspidata, with both species showing little change in adhesion over the temperature range. Flume studies also demonstrated that P. viridis decreased its adhesion as temperature increased, while S. phoenicenteron maintained or slightly increased its adhesion. The lack of correlation between the adhesion and speed responses to temperature changes and the uniformity in the shape of the temperature/speed profile for all four species suggest that alterations in adhesion characteristics are not directly responsible for regulating cell speed. Both cell speed and adhesion were sensitive to the presence of a second species. Pinnularia viridis displayed lower adhesion in dual-species test samples, and exhibited significantly reduced average speed in the presence of S. phoenicenteron, but not when co-incubated with C. cuspidata. In contrast, S. phoenicenteron showed no change in adhesion in the presence of P. viridis. Additional species had no effect on the cell speed of either C. cuspidata or S. phoenicenteron, while C. cuspidata did show reduced adhesion in the presence of P. viridis. Our results suggest that ecologically important behaviours such as movement and adhesion can respond not only to environmental factors such as temperature, but also to the presence or absence of other diatom species.

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

“…Generally, higher but not extreme temperatures increase the motility of unicellular organisms (Maeda et al 1976;Burchard and Marchant 1983). In the study presented here, both species showed greater movement at warmer temperatures, which is consistent with results reported by Cohn et al (2003). By contrast, chilling at 2°C can markedly reduce the migration rhythm of diatoms (Round and Palmer 1966).…”

Comparative analysis of light-stimulated motility responses in three diatom species

“…In contrast, S. phoenicenteron cells are more likely to stay at a lower position in algal communities, where (because of light irradiance and prior absorbance by other algae) they are more likely to encounter less blue light and more low-level red light. Due to its relatively low light sensitivity as well as its strong adhesion and circular path of motility (Edgar & Pickett-Heaps 1984, Cohn & Weitzell 1996, Cohn et al 2003, P. viridis, is likely to be less sensitive to light cues for its placement within the algal assemblage, less able to actively move longer distances, and more sensitive to the abundance and types of available substrata upon which it can move.…”

Potentiodynamic study of Al–Mg alloy with superhydrophobic coating in photobiologically active/not active natural seawater

“…As a matter of fact, attached diatoms glide on colonized surfaces. Although diatom motility is a rather complex process [13], a general consensus exists about a mechanism involving adhesive proteins and secretion of EPS, with possible modification of the surrounding environment by mucilage [57]. Hence, the combination of diatom motility with production of adhesive biopolymers can induce degradation M a n u s c r i p t of the fine sized topography of the SH coating.…”