Date Approved

3-14-2016

Date Posted

9-16-2016

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School

Biology

Committee Member

Steven Francoeur, Ph.D., Chair

Committee Member

Kristin Judd, Ph.D.

Committee Member

Ulrich Reinhardt, Ph.D.

Abstract

The objective of this observational study was to determine if there was a difference in aquatic invertebrate communities between areas dominated by Phragmites australis and areas dominated by Typha spp. in a freshwater coastal marsh. The hypothesis was that aquatic invertebrate diversity and abundance would be greater in Typha-dominated locations as opposed to Phragmites-dominated locations. Sampling took place at Lake Erie Metropark in southeast Michigan during the summer of 2013. Invertebrates were collected using Hester-Dendy samplers and identified in the laboratory. Invertebrates were assessed using the Shannon-Wiener Index, taxon richness, and abundance values which were all analyzed using t-tests and Mann-Whitney U-tests. Invertebrate community structure was analyzed using principal component analysis (PCA) and multivariate analysis of variance (MANOVA) was used to compare factor scores. Environmental variables of water temperature, pH, dissolved oxygen concentration, and percent dissolved oxygen saturation were measured and analyzed using repeated measures analysis of variance and Spearman correlations. There was no significant difference in invertebrate richness or diversity (p>0.05), nor were there any significant differences in the abundance of individual invertebrate taxa between the two plant types (p>0.05), except for Helobdella modesta, which was significantly more abundant in Typha-dominated areas (p70% of total variance in community structure in the first two factors (55.4% and 15.6%, respectively). Plotted sites on PCA axes showed no grouping patterns with respect to dominant plant species, suggesting invertebrate communities were not different based on plant type, and MANOVA confirmed the lack of groupings based on plant type (p>0.05). PCA suggested three groupings of invertebrate taxa which occurred together frequently. In regards to invertebrate functional feeding groups (FFG), there were no significant differences in mean FFG abundance based on plant type (p always >0.05), except for the predator group, which was statistically greater at Typha sites (p80% of total variance in community structure in the first two factors (46.1% and 34.3%, respectively). Plotted sites on PCA axes showed no grouping patterns based on plant type, suggesting FFGs were not different based on plant type, and MANOVA confirmed the lack of groupings (p>0.05). In conclusion, these findings suggest that freshwater Phragmites and Typha marshes are equally capable of supporting abundant and diverse aquatic invertebrate communities.

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