![]() 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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