Abstract

Constructed wetlands in the agricultural landscape are known to harbor immense arthropod biodiversity, however, riparian arthropod communities have often been neglected compared to aquatic communities when studying environmental responses. These wetlands are highly productive, but vary in form and composition based on its purpose, which influences the communities that inhabit them. Both biotic and abiotic wetland characteristics are known to drive aquatic arthropod community compositions, whereas knowledge is currently lacking as to the influence from characteristic wetland properties on riparian arthropods.

This thesis aimed to shed a light on characteristic wetland drivers on riparian arthropod populations and communities. We explored how chironomid emergence rates and diversities responded to wetland nutrient loads and primary production (Chapter I), and subsequently if trophic cascading relationships could be observed across the aquatic-terrestrial boundary to riparian predator abundances (Chapter II). We also explored how riparian arthropod community compositions responded to wetland hydrologic dynamism, shoreline inclines and vegetation height, and grazing management (Chapter III), and finally how characteristic wetland shoreline properties influenced riparian arthropod diversities and habitat specializations (Chapter IV).

In Chapter I we found that emergence rates and diversities of chironomids increased with aquatic chlorophyll concentrations during parts of the season but decreased during others, and that chironomid taxonomic diversity correlated with the aquatic concentration of methane. These findings support previously suggested trade-offs relationship between emerging chironomids and methane. We expanded on these findings in Chapter II, where we found that both primaryand secondary consumer abundances responded to wetland nutrient loads and chlorophyll concentrations, but that this trophic pathway was more complex than from primary producers, through primary consumers to secondary consumers. In Chapter III we found that some riparian arthropods responded to hydrological dynamism, but that surprisingly many groups were unaffected. We also found that many groups responded to shoreline vegetation height, but that responses were group specific. Similarly, in Chapter IV we found that shoreline properties greatly influenced spider, beetle and predatory Diptera diversities in constructed wetlands, and that their habitat specialized species richness varied greatly between groups.

Altogether, these findings illustrate the complexity of wetland arthropod ecology, and the need for attention to these previously understudied systems. It also highlights the importance of comprehension regarding constructed biodiversity wetlands if the aim is to improve biodiversity across multiple taxa.