Spatial and temporal variability in filament length of a toxic cyanobacterium (Anabaena affinis)

Abstract

1. This study examines the distribution of Anabaena affinis filament lengths under natural conditions as a function of depth and season, and in the laboratory as a function of growth phase. Because Anabaena affinis is only toxic when consumed, both its filament length and position in the water column are important determinants of its potential impact on zooplankton populations. 2. Star Lake (Norwich, Vermont, U.S.A.), a natural, eutrophic pond, remained thermally stratified throughout the Anabaena bloom. Filament number and length differed significantly with both sampling date and water depth. Most filaments occurred at 0.5 m, particularly at the height of the bloom. Throughout the entire water colunm average filament length decreased from approximately 0.53 mm in May to 0.14 mm in July. The shortest filaments occurred at the 2.5 m depth. Filament length distributions (combined for all depths) for 29 May, 12 June and 3 July, corresponding to the beginning, middle and end of the bloom, respectively, differed significantly among the three dates. These patterns most likely reflect variable growth conditions, both during the season and in the water colunon. 3. In the laboratory, Anabaena filament length was affected by medium composition and growth phase. Filaments were significantly longer when grown in MBL than in ASM medium. Also, the average length of Anabaena filaments grown in MBL changed significantly as cultures aged; by day 13 filament length (2.01 ± 0.38 mm, mean ± SD) was twice that on day 0 (0.97 ± 0.71 mm). As cell concentration continued to increase, mean filament length gradually decreased.

Estimating the Precision of Filamentous Blue-Green Algae Cell Concentration From a Single Sample

“…The mean trichome size Z was higher during the bloom growth than decline, for a given number c of trichomes per ml. A somewhat similar growth pattern in which mean ®lament length ®rst increased and then declined as mean cell concentration increased was also observed by Smith and Gilbert (1995) in both ®eld and laboratory studies. The estimates m, f, Z, s and c display sucient regularity for global modelling of the cell counts to be contemplated.…”

Trichodesmium's strategies to alleviate phosphorus limitation in the future acidified oceans

“…The diazotrophic cyanobacterium Anabaena spp. also exhibited filament elongation when grown with lower concentrations of nitrogen and phosphorus (Smith and Gilbert, ). This was tightly coupled with heterocyst development and not with a reduction in the ratio of photosynthetic to heterocystous cells (Chan et al ., ).…”

Importance of large colony formation in bloom-forming cyanobacteria to dominate in eutrophic ponds

“…Previous field surveys have shown that the colony size of Anabaena species tends to decline with time, seemingly independently of abundance (Smith and Gilbert, 1995;Yamamoto and Nakahara, 2009). The colony size of An.…”