Stream-riparian meta-ecosystems are connected by resource flows of materials, organisms and energy, with emerged aquatic insects acknowledged as an integral component of riparian food webs. Agricultural land use is a primary cause for lost or impaired connectivity in stream-riparian systems. Here we assessed the role of forested buffers in mitigating the effects of agricultural land use on streams and riparian (spider) food webs using a paired-reach approach, with upstream reaches lacking woody riparian vegetation and downstream reaches having well-developed forested buffers. Richness of emerged insects captured on sticky traps differed between reach types and with season. Dipterans (Chironomidae) and beetles were more abundant at unbuffered reaches with emergence peaks in spring, whilst disturbance sensitive EPT taxa were more abundant at forested reaches and had emergence peaks in summer and autumn. Spider assemblages correlated with both riparian characteristics and the emergence of aquatic insects. Partial redundancy analysis showed that variation in spider composition was explained by aquatic insect composition and emergence. Results of fatty acid analyses and prey DNA from riparian spiders corroborated the significance of emerged aquatic insects for terrestrial (spider) communities, underpinning the importance of forested buffers for biodiversity and cross-ecosystem connectivity in modified landscapes.

Primary Presenter: Richard Johnson, Swedish University of Agricultural Sciences (richard.johnson@slu.se)

Authors:

Jasmina Sargac, Swedish University of Agricultural Sciencees  (jasmina.sargac@slu.se)

Brendan McKie, Swedish University of Agricultural Sciences  (brendan.mckie@slu.se)