Are blue-green algae a suitable food for zooplankton? An overview

Abstract

One of the reasons suggested to explain the dominance of blue-greens in eutrophic lakes is that they are not used as food by zooplankton; and even when ingested, they are poorly utilized.An increase in herbivores might be the expected result of biomanipulation of the aquatic food chain. This attempt at controlling the algae population is, however, destined to fail if zooplankton do not also utilize blue-greens as food. In this respect, a series of in-lake experimental results indicates that after the food chain has been biomanipulated, there is a decrease in blue-green density in periods when there is an increase in herbivores. Is this only an accidental result or are the two facts interrelated; in other words, can the decrease in the density of blue-greens be attributed to the increased use of them by zooplankton herbivores?The suitability of blue-greens as food for zooplankton has been widely investigated by many authors with contrasting and inconclusive results. Two main factors seem to play important role in determining their suitability as food: the biochemical properties of the different species, or even different strains of the same species; and the shape and size of the colonies.In particular, biochemical properties can result in toxic effects on zooplankton, while size and shape may strongly interfere with filtering, thus reducing the possibility of gathering food.

Changes in species composition during annual cyanobacterial dominance in a tropical reservoir: physical factors, nutrients and grazing effects

“…Cyanobacterial dominance is mostly related to favourable bottom-up factors (Briand et al 2002, Marinho & Huszar 2002), since they are widely known for their ability to minimize grazing pressure, through different effects on zooplankton community: mechanical interference (difficulty in manipulating and ingesting large colonies or filaments), assimilation (low amounts of essential nutrients) and toxicity (De Bernardi & Giussani 1990). However, some zooplankton species have developed physiological resistance to cyanotoxins (Fulton & Paerl 1988) or behavioural adaptations to avoid toxic cells (Reinikainen et al 1998).…”

In situ study on the control of toxic Microcystis blooms using phytoplanktivorous fish in the subtropical Lake Taihu of China: A large fish pen experiment

“…However, the ability of natural populations of zooplankton to control phytoplankton is still under debate, especially in the water dominated by cyanobacterial blooms (Bernardi and Giussani, 1990). In tropical or subtropical regions, for instance, zooplankton does not seem able to control algal biomass, a role that is played instead mainly by omnivorous, filter-feeding fish (Xie and Liu, 2001).…”

Seasonal variation of the abiotic parameters and the cladoceran assemblage of Lake Vela: comparison with previous studies

“…This means that small Ceriodaphnia can flourish, while large Daphnia are decimated by zooplanktivorous fish. Additionally, Lampert (1982), De Bernardi and Giussani (1990) and Vasconcelos (1990) claimed that small species are more resistant to cyanobacteria (e.g. Microcystis aeruginosa) than Daphnia.…”