Date of Award

Winter 2022

Project Type

Thesis

Program or Major

Biological Sciences

Degree Name

Master of Science

First Advisor

Gregg E Moore

Second Advisor

Megan Tyrrell

Third Advisor

Raymond E Grizzle

Abstract

Salt marsh invertebrates play a vital role in salt marsh ecosystems by aerating the marsh, cycling nutrients, and forming connections between trophic levels, but the impacts of large-scale natural and anthropogenic sediment addition on their community structure and species composition is poorly understood. During winter storm Grayson in January of 2018, ice rafting caused large areas of sediment to deposit on significant areas of the Great Marsh in Massachusetts. I hypothesized that sediment addition would influence the abundance and richness of invertebrates in the marsh, because they tend to take years to recover after a disturbance. Sediment cores were taken from 3 sites to identify and quantify infaunal macroinvertebrates. A Thin Layer Placement (TLP) study was also conducted in Great Bay NERR in Durham, NH. Sediment was added to the marsh, and I hypothesized that this sediment addition would also influence the abundance and richness of invertebrates on the marsh. Epifaunal and infaunal macroinvertebrates were collected and identified both morphologically and using metagenomic methods to examine the effects of sediment addition. Invertebrate diversity and abundance were not significantly different between sediment thicknesses or between sites at the natural sediment addition sites using morphological identification methods, but sediment addition was positively correlated with richness when examined with genomic methods. For the TLP experiment, neither analysis method revealed differences between the control and treatment plots. This suggests that sediment addition could be a useful tool for salt marsh management in New England in the future, as the sediment addition had a neutral to positive effect on macroinvertebrate richness.

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