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Investigating the Effects of Increased Salinity on Leaf Litter Decomposition and Mortality of an Aquatic Invertebrate Detritivore (Caecidotea sp.)

Zachary Gordon , Raymond Kidder II, Craig Aumack, Checo Colon

Abstract

Coastal freshwater wetlands and their associated communities are at an increased risk of salinity exposure due to a variety of contemporary and historical anthropogenic stressors. Salinization shifts the community structure of aquatic organisms, such as macroinvertebrates, leading to decreases in functional ecological integrity. These salinity-driven changes to communities have the potential to alter macroinvertebrate-mediated processes such as detrital decomposition. Our study aimed to examine the relationship between salinity exposure, leaf decomposition, and mortality of a common freshwater macroinvertebrate (Isopod: Genus Ceacidotea). Using an in-lab microcosm approach, we exposed tanks of isopods and detrital leaf material to varying salinity levels for 23 days after which isopod mortality and decomposition rate of detrital material were measured. We found that increases in salinity increased isopod mortality but had no effect on leaf disc decomposition. These findings demonstrate the negative effect of increased salinity on a common freshwater macroinvertebrate. Additional studies regarding the response of non-isopod decomposers, such as bacteria and fungi, are needed to provide a more complete understanding of the effects of salinity intrusion in at-risk freshwater habitats.

MF25029  Accepted 10 September 2025

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