A laboratory study on feeding plasticity of the shredder Sericostoma vittatum Rambur (Sericostomatidae)

Abstract

Since litter input and availability of leaves in many streams is highly seasonal in Portugal, we investigated whether Sericostoma vittatum, a typical shredder, was able to grow using alternative food sources. To test this hypothesis we fed S. vittatum with Alnus glutinosa (alder, CPOM, coarse particulate organic matter), leaf powder from A. glutinosa and Acacia dealbata and FPOM (fine particulate organic matter) from a 5th and a >6th order river, the macrophyte Myriophyllum aquaticum and biofilm. Growth in S. vittatum was significantly influenced by the food item given (ANOVA, P = 0.0082). The food item promoting the highest growth was A. glutinosa, in the form of FPOM (6.48% day -1 ) and CPOM (4.24% day -1 ); all other forms of FPOM and biofilm provided relatively low growth rates (0.77-1.77% day -1 ). The macrophyte M. aquaticum was also used as food source by S. vittatum and promoted intermediate growth (1.96% day -1 ). Neither nitrogen, phosphorus nor caloric content was correlated with growth. However, since higher growth was achieved with alder, in the form of CPOM and FPOM, we concluded that the chemical content of food was more important for S. vittatum than the physical form of such food. This may partially explain why shredders are able to survive when leaves are scarce in streams.

Sericostoma vittatum (Trichoptera) Larvae Are Able to Use Pine Litter as an Energy Source

“…Moreover, they emphasized the high feeding plasticity showed by some detritivores that allow them to grow using much differing diets. Such suggestion is in accordance with the results found by both JACOBSEN (1999) with S. personatum andCARVALHO andGRAÇA (2007) with S. vittatum, who found that these Sericostoma species can use to grow leaf detritus differing in nutrient content and toughness, algae, fine detritus and aquatic macrophytes. We suggest that certain detritivore species, such as S. vittatum, may cope with foods of so much differing characteristics that include low-conditioned pine litter.…”

Stoichiometric imbalances between detritus and detritivores are related to shifts in ecosystem functioning

“…Although alder is commonly regarded a high‐quality resource for detritivores, and is typically preferred over other litter species (Friberg and Jacobsen , Carvalho and Graça ), detritivore preferences for alder over birch in our study depended on the degree of stoichiometric imbalance between consumer and resource. The greatest increase in alder decomposition when mixed with birch was caused by Sericostoma , the otherwise most N‐limited of our detritivores.…”

Biogeochemical properties of fine particulate organic matter as an indicator of local and catchment impacts on forested streams

“…2005). Some putative shredder species have been reported to directly feed on FPOM (Carvalho & Graça 2007), so opportunistic consumption of FPOM S by this shredder species is also possible.…”