Interactions with Invertebrates

Woodland streams receive significant quantities of leaf litter and woody debris from the riparian vegetation. This allochthonous organic matter provides much of the carbon and energy for the detritus-based food chains that are common in streams. Initial studies of the interactions between fungi and invertebrates in streams focused on their role in the energy flow and trophic dynamics of such detritus-based food chains (Triska 1970; Kaushik and Hynes 1971). More recently, studies have also emphasized the role that these interactions may play in regulating both fungal (Barlocher 1982a) and invertebrate (Rossi 1985; Arsuffi and Suberkropp 1989) communities. Most attention has focused on shredders, the functional feeding group of invertebrates with morpho-behavioral adaptations to consume leaf detritus (Cummins 1973), and the effects of leaf-associated microbiota, particularly fungi, on shredder feeding. A variety of shredder taxa have been examined, including both crustaceans and insects (Table 6.1). With respect to fungi, aquatic hyphom.ycete species have received the most study, but other fungi (e.g. terrestrial hyphomycetes, Oomycetes and Zygomycetes) isolated from leaves in streams have also been examined. Although interactions may occur between fungi and other groups of invertebrates in streams (Anderson and Sedell 1979; Anderson and Cargill 1987), these interactions have not been extensively studied and will not be discussed here.