![]() ![]() The effect of trophic cascades is assumed to be stronger in aquatic than in terrestrial food webs ( Shurin et al., 2002). This phenomenon occurs if, for example, a primary producer is removed, resulting in diminished population sizes through the community. Whereas top-down forcing is well documented ( Shurin et al., 2002), bottom-up cascading has been less discussed. For example, the anthropogenically mediated loss of apex consumers is discussed as leading to extensive top-down cascading effects in marine, terrestrial and freshwater ecosystems worldwide ( Eisenberg, 2010 Estes et al., 2011). Trophic cascades have been documented for all of the world’s major biomes, in terrestrial and aquatic systems, from the poles to the tropics. fusiformis breakdowns have remained a matter of speculation.Īt latest Eisenberg’s inspiring book ‘The Wolf’s Tooth’ ( Eisenberg, 2010) cemented awareness in the scientific community about how trophic cascades can impact food webs. This is thought to be the major cause for episodes of disappearance or significant irregular mass movements of flamingos between the lakes ( Krienitz and Kotut, 2010). However, the typically dense (up to >700 mg l −1 fresh weight Krienitz and Kotut, 2010) population of A. Fluctuations of this resource are reported as the overwhelming factor influencing Lesser Flamingo distribution ( Vareschi and Jacobs, 1985 Krienitz and Kotut, 2010). The Lesser Flamingo relies on the very fast-growing alkaliphilic cyanobacterium Arthrospira fusiformis as most important food source. Flamingos are filter feeders of photoautotrophic algal primary producers, putting them on top of a short and direct food chain ( Vareschi and Jacobs, 1985). The dense population of these pinkish waterfowl (1.5–2.5 million in Eastern Africa, which is around 75% of the worldwide occurrence) has been rated since decades as one of the most significant wildlife spectacles worldwide ( Jenkin, 1929). The Lesser Flamingo, Phoeniconaias minor, is the dominating and characteristic bird species of alkaline–saline lakes and pans of East Africa ( Krienitz and Kotut, 2010) and classified as ‘near-threatened’ ( IUCN Red List, 2012). Particularly cyanophages have been shown to cause mortality in important members of the phytoplankton ( Suttle and Chan, 1994). ![]() Beyond the potential to influence and control abundance and diversity of heterotrophic prokaryote hosts, viruses apparently infect a significant proportion of the photoautotrophic plankton community as well ( Wommack and Colwell, 2000 Weinbauer, 2004 Suttle, 2007). Typically, virus replication rates increase in conjunction with higher host growth rates ( Suttle, 2007). Exceptionally high virioplankton abundance (up to 2 × 10 9 ml −1) has been documented in the alkaline, hypersaline Mono Lake, California ( Brum et al., 2005). Peak values were found in very productive estuaries and lakes ( Peduzzi and Luef, 2009). Abundances of planktonic viruses are reported to commonly range between 10 4 (likely an underestimation due to bad storage conditions) and 10 8 ml −1, being generally higher in freshwater than in marine systems. Viruses are the most pervasive biological entities in aquatic ecosystems, the majority being bacteriophages ( Suttle, 2007). ![]()
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