Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity?

Abstract

Amazonian biodiversity is notorious, this is also valid for the fauna of the mineral-deficient waters of the Rio Negro System. Some 25 years of research on the benthic fauna of Central Amazonian streams resulted in species-rich foodwebs with a high degree of omnivory within dense animal communities. To exemplify the taxonomic range of omnivorous consumers, the detailed resource spectra of 18 consumer species, including Protozoa (2 species), Platyhelminthes (1 species), insects (2 species), fish (6 species) and shrimps (Decapoda, 7 species), associated primarily with the benthic habitats of Rio Negro tributaries, are presented. Special features of omnivory are characterized, and the importance of litter-decomposing fungi as essential energy input into the foodwebs is documented. It is shown that general omnivory -diverse omnivore consumers sharing most of the resource types-is a prevalent feature. The relevance of this general omnivory for the maintenance of biodiversity is discussed.

Trophic ecology of the freshwater prawn, <i>Pseudopalaemon bouvieri</i> (Decapoda: Palaemonidae) in Northeastern Argentina, with remarks on population structure.

“…Many authors have shown that Palaemonidae species also have a diet made up of a number of different items, although detritus is usually an important and quite common component (Howard 1984, Collins & Paggi 1998, Albertoni et al 2003, Walker 2009). Not only does this group, but also those members of the Peneidae family present in estuarial environments, use the detritus (Masitah & Chong 2002).…”

“…In the theoretical concepts, omnivores in aquatic continental systems help stabilize populations and communities by combining the resources with different conversion efficiencies (Krivan & Diehl 2005, Walker 2009). This characteristic regulates the flow of energy and the recycling of nutrients (Evans-White et al 2001, Buck et al 2003, Williner 2010.…”

“…However, several research studies have shown that these organisms can capture live animals in an active action, and are present in different habitats such as aquatic plants, the water column or benthic communities (Collins 1997, Collins & Paggi 1998, Jayachandra 2001, Collins et al 2004, Collins et al 2006. Other studies have suggested that prawns are essentially omnivorous (Walker 2009) and have an important role as shredders in tropical waters (Rosemond et al 1998). In addition, numerous studies have indicated that the freshwater prawns and crabs are important components of the diets of fishes, reptiles, birds and mammals (Collins et al 2006, Borteiro et al 2009.…”

“…In subtropical wetlands, the aquatic vegetation provides habitat of high complexity that structured the invertebrate assemblages (Poi de Neiff & Neiff 2006, Thomaz et al 2008). P. bouvieri diet has not been studied but Walker (2009) mentioned the feeding habits of other species of Pseudopalaemon. In the present study, we compared the feeding ecology of the freshwater prawn P. bouvieri, in lagoons having a different composition and abundance of aquatic macrophytes.…”

A closer look at the main actors of Neotropical floodplain food webs: functional classification and niche overlap of dominant benthic invertebrates in a floodplain lake of Paraná River

“…was its most important prey followed by copepods (Cyclopoda) and Cladocera. Although vegetal tissues and detritus were found in the diet of this genus, probably these items were in the stomach of digested prey organisms as suggested by Walker (2009). However, some copepods and cladocerans can inhabit benthos and littoral plankton and their presence in the diet of Sympetrum sp.…”