Factors influencing macroinvertebrate colonization of seasonal wetlands: responses to emergent plant cover

Abstract

1. We conducted field experiments to examine factors influencing macroinvertebrate colonization of seasonally flooded marshes. Few macroinvertebrate species were found aestivating in soils within non-flooded wetlands indicating that most taxa colonize these marshes from other flooded habitats. 2. We manipulated amounts of salt grass (Distichlis spicata) to examine how emergent plant cover affects aerial colonization by macroinvertebrates. Areas mowed 3 weeks before flooding had low plant cover, areas mowed 5 and 9 weeks before flooding had medium and high plant cover, respectively, and non-mowed control areas had the most plant cover. Macroinvertebrate numbers and biomass were generally higher in mowed treatment areas than in control areas, but overall diversity was generally higher in high plant cover and control areas than in low plant cover areas. 3. Mosquitoes (Culicidae), brine flies (Ephydridae) and hover flies (Syrphidae) were positively correlated with amount of plant cover, and waterboatmen (Corixidae), midges (Chironomidae) and water scavenger beetles (Hydrophilidae) were negatively correlated with plant cover. Species assemblages changed seasonally among treatment areas because these taxa colonize wetlands at different times in the year. 4. These results demonstrate that invertebrate communities may be different within plant stands with heterogeneous amounts of emergent cover, and management practices that alter the structure of wetland vegetation can influence macroinvertebrate communities colonizing seasonal marshes.

The direct and indirect effects of a glyphosate‐based herbicide and nutrients on Chironomidae (Diptera) emerging from small wetlands

“…While an increase in the abundance of emerging chironomids may be viewed favorably by some, any change from the natural condition of an ecosystem indicates that the fundamental functioning and structure of the system has been shifted and may be cause for concern. Emergent plant cover has been hypothesized to play an important role in structuring the chironomid assemblage in wetlands, possibly through habitat cues and physical structure of the pond [15,17,40,41]. We were unable to find a strong relationship between the abundance of emerging chironomids and the percent cover of macrophytes in these wetlands under normal conditions.…”

Straw and Winter Flooding Benefit Mosquitoes and Other Insects in a Rice Agroecosystem

“…Thus, wetland managers face similar issues as rice growers regarding air quality, the resource base for their systems and invertebrate populations. Mosquitoes are more vulnerable to predators and wind action in open water, so, in general, vegetation control can reduce mosquito numbers in wetlands (e.g., Batzer and Resh 1992, Walton and Workman 1998, De Szalay and Resh 2000. Results from our project indicate that mosquitoes could be less of a problem in wetlands that are burned, rather than mowed.…”

Diversity in Mediterranean farm ponds: trade‐offs and synergies between irrigation modernisation and biodiversity conservation

“…Vegetation, both submerged and emergent, in shallow lakes and ponds, enhances local diversity of many animal groups (Hazell et al, 2004;Sánchez-Zapata et al, 2005;Moreno-Ostos et al, 2008) including macroinvertebrates (De Szalay & Resh, 2000;Della Bella, Bazzanti & Chiarotti, 2005;Abellán et al, 2006;Markwell & Fellows, 2008). Accordingly, local diversity increased with marginal vegetation cover in our ponds, but as this covaried with pond type, their relative effects are difficult to disentangle.…”