Periphyton control on stream invertebrate diversity: is periphyton architecture more important than biomass?

Abstract

There is little consensus on the form of the periphyton biomass–macroinvertebrate diversity relationship in streams. One factor that these relationships do not account for is the growth form of primary producers. We (1) examined the periphyton biomass–macroinvertebrate diversity relationship in 24 streams of Cantabria, Spain, in July 2007, and (2) determined whether this relationship was underpinned, and better explained, by specific responses to the growth form of the periphyton community. We hypothesised that macroinvertebrate diversity would be a log-linear function of periphyton biomass and would respond differently to two coarse divisions of the periphytic community; i.e. positively to %cover of non-filamentous algae and negatively to %cover of streaming filamentous algae. There was no relationship between benthic periphyton biomass and macroinvertebrate diversity in these streams but, as predicted, this relationship was underpinned by responses to the growth form of periphyton community. Generally, macroinvertebrate diversity responded positively to %cover of non-filaments and negatively to %cover of streaming filaments, although results were variable. These findings suggest that periphyton biomass–macroinvertebrate diversity relationships in streams can be underpinned by interactions with specific growth forms of periphyton. We suggest that further research is required to develop robust thresholds of %cover of filamentous algae cover that would benefit managers wishing to minimise negative effects of eutrophication on stream communities.

Shifts in community size structure drive temperature invariance of secondary production in a stream‐warming experiment

“…Although Ulva is palatable to some invertebrates (Guidone and McGlathery 2001, Kamermans et al 2002, Guidone et al 2010, gut-content analysis of invertebrates in the experimental stream indicates that it was rarely consumed and contributed <25% to total consumer production (D. Nelson, unpublished data). The presence of macroalgae, such as Ulva, however, can have significant non-trophic effects on invertebrate community structure and densities of many invertebrate groups (Dudley et al 1986, Koksvik and Reinertsen 2008, Tonkin et al 2014. Macroalgae provide food, trap detritus, and create substrate on which to attach; they also block sunlight and exclude insects by competing for space (Dudley et al 1986).…”

Legacy effects of drought alters the aquatic food web of a northern boreal peatland

“…Further evidence for selective grazing was demonstrated by the disproportionate abundance of coccoid and colonial green algae and a similar proportion of edible (40%) and inedible (60%) taxa in the control and raised treatments where grazers were lower in abundance. It is also important to note that dense growths of filamentous algae can provide refuge for macroinvertebrates and reduce the negative effects of predators (Liston, Newman, & Trexler, ; Tonkin, Death, & Barquín, ). It is possible that, in addition to resource provisioning, biofilm architecture had a supporting role in the development of the macroinvertebrate community during peak algal biomass.…”

Substratum‐Associated Microbiota

“…Rather than temperature or time, an increase in periphyton biomass, correlated with an increase in total macroinvertebrate biomass and abundance of scrapers in stream reaches located along a disturbance gradient of canopy cover and with agriculturally derived nutrients (Braccia et al, 2014). Variation in the architecture of periphytic algae with algal succession influenced macroinvertebrate biomass (Tonkin et al, 2014). Increases in non-filamentous forms promoted a positive response in macroinvertebrates and increases in streaming filaments resulted in a negative response.…”