An assessment of the influence of recruitment from the sediment on the development of planktonic populations of cyanobacteria in a temperate mesotrophic lake

Abstract

1. A number of planktonic cyanobacteria species form resting stages that survive in the sediments of lakes. The significance of this life history strategy to the ecology of new planktonic populations was investigated in Esthwaite Water, a mesotrophic lake in the English Lake District. 2. A simple trapping technique was used to quantify vertical movements of five species of buoyant gas‐vacuolate cyanobacteria from close to the sediments, along a depth transect. 3. ‘Recruitment’ from the sediments was found to be widespread amongst the cyanobacteria species associated with the summer phytoplankton community. 4. Estimates of the vertical upward fluxes of cyanobacteria based upon trap catches could not account for observed increases in the planktonic populations suggesting that ‘recruitment’ was not a significant source of biomass. 5. Vertical upward movements of Anabaena solitaria were recorded prior to this species becoming established in the plankton suggesting that benthic populations might be a source of cells for initial pelagic growth of populations of this species. 6. Low numbers of vegetative filaments of Anabaena flos‐aquae, Aphanizomenon flos‐aquae and Oscillatoria agardhii were observed in the plankton through the winter. These small overwintering populations appeared to be the primary source of inocula for the large summer populations of these species.

The decline process and major pathways of Microcystis bloom in Taihu Lake, China

“…These findings indicate that during late autumn when ambient environmental factors such as temperature and light become unsuitable for growth and reproduction, Microcystis adapted its survival strategy to compensate for these conditions. These results indicate that colony disaggregation is one of most important survival strategies and is of vital ecological significance in the life cycle of Microcystis, which is similar to the results of other studies that have suggested Microcystis overwinters by settling on the surface of the sediment (Preston et al, 1980;Head et al, 1999;Brunberg and Blomqvist, 2002). Small colonies can absorb nutrients more efficiently than large colonies because they have larger specific The levels of significance of difference between two proximate measurements at each site are indicated by *, ** and *** for P < 0.05, P < 0.01 and P < 0.001, respectively.…”

“…Previous studies have indicated that most large colonies migrated downward in the water column and finally settled on a water-sediment interface for overwintering (Preston et al, 1980;Head et al, 1999). This phenomenon constitutes another important decline pathway of the Microcystis bloom and is termed colony settlement (Pathway II).…”

An overview of diversity, occurrence, genetics and toxin production of bloom-forming Dolichospermum (Anabaena) species

“…Akinete recruitment in the littoral zone is generally higher than that from deep water and contributes more to facilitating the initiation of the blooms; several factors could explain this phenomenon (Head et al, 1999;Faithfull and Burns, 2006;Kravchuk, 2009). First, the shallowness of the littoral zone facilitates akinete germination, as the adequate light and temperature requirements for germination are more readily met for shallow rather than deep sediments (Stå hl-Delbanco and Hansson, 2002).…”

“…Thus, Head et al (1999) indicated that, in the Esthwaite Water, northern England, the major source of inocula for Dolichospermum flos-aquae blooms in summer were overwintering populations in the water column. In the Murray River, Australia, Baker (1999) found that a small proportion of filaments of D. circinalis in the winter water column coexisted with a large number of akinetes in the sediment.…”

Seasonal variation in the net growth rate of the cyanobacterium Cylindrospermopsis raciborskii in a shallow artificial pond in northern Taiwan

“…Monitoring population dynamics together with growth rates would improve our understanding of the mechanisms of bloom formation in C. raciborskii, especially in light of the general importance of growth in determining the abundance of bloom-forming species (e.g. Head et al 1999, Brunberg & Blomqvist 2003. In this study, we investigated the seasonal change in the in situ net growth rate of C. raciborskii in a shallow pond in northern Taiwan.…”