FOOD-WEB STRUCTURE IN A SUBTROPICAL LAKE ECOSYSTEM

This study considered trophic interactions in the pelagic and littoral regions of Lake Okeechobee, a large subtropical lake ecosystem in Flo rida, USA. Food web models were developed from species lists and diet information, and web attributes were utilized to compare and contrast the structurally-simple pelagic and structurally-complex littoral habi tats, in terms of taxonomic structure and consumer-resource relationsh ips. Consumers in four major trophic guilds (wading birds, fish, benth ic macroinvertebrates, and zooplankton) were identified, in most cases to their biological species level, and their trophic interactions wer e determined based on a combination of direct measurements (for 37% of the consumers) and published diet information. Complex food webs were documented in both the pelagic and littoral habitats. The littoral we b contained more species (324), links, and trophic guilds, than the pe lagic web (218 species). In both webs, macroinvertebrates were the mos t speciose group, and periphyton/detritus was the most frequently util ized food resource. Most consumers were omnivores that exploited perip hyton/detritus and some other living component of the community. A hig h degree of omnivory and detritus-feeding appear to be general feature s of aquatic food webs.