Thesis
Physiological plasticity and response to food availability of two freshwater mussel species (Sagittunio nasutus and Utterbackiana implicata)
Master of Science (M.S.), Drexel University
Jun 2024
DOI:
https://doi.org/10.17918/00010687
Abstract
Freshwater mussels (Order Unionida) are diverse and widely distributed, with high levels of both biodiversity and imperilment in North America. Hatchery propagation and subsequent pond grow-out of juvenile mussels is a tool used for restoration of native mussel populations. When mussels are moved from eutrophic ponds to restoration sites, they may encounter drastic and immediate changes in food quantity and quality. Freshwater mussels adjust their physiological rates to account for gradual seasonal shifts in food quantity and quality, but there is a lack of literature on how quickly those physiological rates can adjust or whether there are consequences for condition or growth. To address this, two experiments were designed. First, a field reciprocal transplantation occurred for 402 days from April 2022 until July 2023 between a hydrologically-connected pond and stream site which were similar in physical and chemical water quality, but differed significantly in particulate seston (i.e., food quantity and quality). During this experiment, physiological assessments measured clearance rate and absorption efficiency for the different treatment groups. Mussel shell growth, condition index (CI), and mortality were also assessed periodically. In the second experiment, mussels were fed laboratory diets in recirculating systems for 16 days in July and August, 2022, and the same suite of physiological and growth metrics were collected as in the field experiment. Results from the field experiment suggest that mussels begin adjusting their clearance rates and absorption efficiencies immediately after being placed in a new environment, suggesting that Unionids are highly physiologically plastic. Condition index takes longer to adjust. While CI was adjusting, shell growth was temporarily either increased or reduced when compared to non-transplanted mussels. Results from the laboratory experiment were less clear, but provide lessons for improving future laboratory studies of freshwater mussels. The results from these experiments provide considerations for restoration practitioners when they are selecting metrics for monitoring freshwater mussels following translocation. Absorption efficiency correlated positively with mussel growth, and clearance rate correlated negatively. The mussels in these experiments exhibited high levels of physiological plasticity, and had higher absorption efficiencies and growth rates in treatments with higher food quality, rather than higher food quantity.
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Details
- Title
- Physiological plasticity and response to food availability of two freshwater mussel species (Sagittunio nasutus and Utterbackiana implicata)
- Creators
- Matthew James Gentry
- Contributors
- Danielle Kreeger (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xi, 65 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES); College of Arts and Sciences; Drexel University
- Other Identifier
- 991021889713704721