Aerobic anoxygenic phototrophs (AAP) are a group of photoheterotrophic bacteria that use sunlight as a supplemental energy source, allowing them to be found in many illuminated environments. Here, we investigated their presence in Lake Winnipeg, Manitoba, Canada with spatial and temporal considerations to define the niche that they fill, and understand the biogeochemical pathways influenced or controlled by AAP. In addition, we explored their diversity and expanded upon the range of photosynthetic arrangements known, by looking into a variety of newly purified pigmented isolates to assess unique characteristics, all of which allowed us to better understand the AAP group as a whole. We described seasonal trends of microbial communities in Lake Winnipeg, where up to 1.49% of the sequenced community and 19.1% of the total culturable copiotrophic heterotrophs were AAP at littoral zones during their peak spring season, and they directly followed sunlight availability. Isolated and purified strains were capable of several metal transformations, including metal(loid) oxide reduction and production of siderophores or metallophores. This widespread physiology, particularly among lake isolates, suggested a potential ecological importance for AAP involving a metal(loid) collecting niche. AAP with elongated cells were established as both associated to, and possibly preyed upon by filter feeding mollusks Dreissena polymorpha, which provided insights into how these bacteria interact with the foodweb. Many pigmented and phylogenetically diverse strains were discovered from across the lakes euphotic zones. Representatives of each different species were physiologically, morphologically and phylogenetically compared and described, showing members of specific taxonomic families all shared heritable traits including pigments. This confirmed evolutionary age of photosynthesis in AAP, and suggested recent horizontal gene transfer events did not occur. Furthermore, unusual aerobic violet pigmented strains that came from under the frozen surface during winter were explored. Overall, the study of Lake Winnipeg microbial communities led to several important discoveries: Seasonal dynamics found that AAP followed daylight trends rather than any other environmental parameter; These phototrophs were likely preyed upon by filter feeding mollusks; Several new metal transformation capabilities were described; Unique pigmentation was found. All combined considerations confirmed the importance of AAP as regular members of this freshwater ecosystem, with high numbers and large diversity, likely contributing significantly to the foodweb.