Senior Project Advisor

Angela Strecker

Document Type

Project

Publication Date

Spring 2024

Keywords

Mount St. Helens, phytoplankton, ponds, succession

Abstract

Freshwater biodiversity is declining worldwide, and ponds have been found to be incredibly biodiverse freshwater habitats that provide important ecosystem services and create critical terrestrial-aquatic linkages. Phytoplankton are fundamental components of aquatic communities and provide ecosystems with oxygen, send energy throughout the food web, and are an important food source for organisms like zooplankton. The 1980 eruption of Mount St. Helens led to the formation of over 100 diverse ponds in the Mount St. Helens National Volcanic Monument. This study aims to shed light on phytoplankton community dynamics and assemblages as well as regional differences in community dynamics in previously unstudied early successional ponds. Samples were collected from twelve ponds in the Mount St. Helens National Volcanic Monument in July and August 2023, concentrated, and counted on a compound microscope using five fields of view or 500 natural units per sample. Samples were analyzed for community abundance (cells/mL), richness (number of species/pond), diversity (Shannon-Weiner Diversity Index), and biovolume (m3/mL). Paired t-tests were performed on the community parameters to investigate differences by sampling month. A PERMANOVA test was used to analyze differences in community composition by month. T-tests with Welch’s modification were used to analyze community differences by region. All analyses reported no significant differences. Results of this study indicate that phytoplankton communities are stable during July and August. I hypothesize that the lack of difference could be due to the stability of environmental conditions like temperature, sunlight, nutrients, and predation during the sampling period. The modest regional differences between the Maratta and Hummocks may indicate that the ponds are more similar in their successional age despite differences in the terrestrial landscape around them. An important big-picture takeaway from this study is that sampling in July and August would yield similar results, which is important when considering monitoring efforts. Future goals for this research should include sampling live phytoplankton samples as well as increasing sampling efforts to further our understanding of these unique and crucial ecosystems.

Department

Environmental Sciences

Type

Text

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf

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