The Impact of Hydrologic Connectivity on Macroinvertebrate Biodiversity in the Shiawassee National Wildlife Refuge

biodiversity;invertebrate;hydrology;School for Environment and Sustainability

Pollock, JacobRiseng, Catherine ;

University of Michigan

关键词: biodiversity;    invertebrate;    hydrology;    School for Environment and Sustainability;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/140072/Pollock_Jacob_Thesis.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Recovering obstructed hydrologic connectivity can be an important goal ofrestoration work in wetland ecosystems. Diked floodplain units, even when intensivelymanaged, are often variably disconnected from adjacent river systems and thus presentan interesting opportunity for studying the impacts of variations in hydrologicconnectivity on floodplain communities. Both diked and naturally connected floodplainsexist in the Shiawassee National Wildlife Refuge. The goal of my study was to assess howdiked unit location and configuration influence the structure of macroinvertebratecommunity richness.Using nested samples from vegetated microhabitats within larger floodplain units,aquatic macroinvertebrate surveys were conducted in the spring and summer of 2016.Water quality measurements were collected in the field while hydrologic connectivity wasdetermined from existing map and LIDAR data layers. Trophic diversity was also studiedthrough stable isotope analysis of top predators, common odonates, in the systems.Results suggest dike height (a proxy for flooding frequency) and channel distance fromthe river were important in determining community structure and richness within therefuge. Significant reductions in the taxonomic richness of floodplain macroinvertebratecommunities were seen with increasing height and channel distance; in the refuge, eachadditional 1-meter in dike height reduced floodplain richness on average by one genus.Flooding height also significantly reduced the crustacean and gastropod diversity,altering the food web as seen in the significantly variable carbon and nitrogen isotopevalues. Stable isotope data showed higher trophic diversity in strongly connected sites,supporting my findings with respect to community composition. These results will bebeneficial in assessing the impacts of the refuge’s recent and future hydrologic restorationprojects, and in general, my findings support the refuge’s goals of monitoringimprovements in wetland function and diversity.