For my first post on this blog, I wanted to share the following paper with you, The virus’s tooth: cyanophages affect an African flamingo population in a bottom-up cascade (see below). It captured my attention after Dr. Brian Jones visited my lab earlier in 2014 where he gave a lecture on flamingos in Kenya (Lesser Flamingo, Phoeniconaias minor). As an extremophile specialist he had been invited to a workshop organized by the Kenyan government to find out why the flamingos have disappeared from Lake Nakuru, a local alkaline lake. According to Brian, many theories were offered up during the workshop, but none of them with sufficient evidence, mainly because of a lack of long-term monitoring of the lakes’ ecosystem.
The following paper presents a possible explanation: Phages caused it! The researchers hypothesize that cyanophages are at the root of a bottom-up cascade causing the flamingo’s main food source, the cyanobacterium Arthrospira fusiformis, to be broken down causing massive drops in flamingo numbers.
A question of where did the flamingos go, was partly answered accidently at a sampling expedition of my lab, the Centre for Microbial Ecology and Genomics (CMEG, University of Pretoria). Each year a bunch of researchers of CMEG and collaborators make a trip to the Namib Desert to investigate the local arid ecosystems. When driving to the closest town, Walvis Bay, about a 90 minute away located at the Atlantic Ocean, many people stop at the actual bay to watch huge gatherings of the Lesser Flamingo. Sadly, we have no records of how many years the flamingos have been gathering there and if there stay there year-round or not.
The virus’s tooth: cyanophages affect an African flamingo population in a bottom-up cascade
Trophic cascade effects occur when a food web is disrupted by loss or significant reduction of one or more of its members. In East African Rift Valley lakes, the Lesser Flamingo is on top of a short food chain. At irregular intervals, the dominance of their most important food source, the cyanobacterium Arthrospira fusiformis, is interrupted. Bacteriophages are known as potentially controlling photoautotrophic bacterioplankton. In Lake Nakuru (Kenya), we found the highest abundance of suspended viruses ever recorded in a natural aquatic system. We document that cyanophage infection and the related breakdown of A. fusiformis biomass led to a dramatic reduction in flamingo abundance. This documents that virus infection at the very base of a food chain can affect, in a bottom-up cascade, the distribution of end consumers. We anticipate this as an important example for virus-mediated cascading effects, potentially occurring also in various other aquatic food webs.