Fung, Nicole2026-02-092026-02-092023https://hdl.handle.net/1828/23302Energy and carbon transfer from phytoplankton to fish is regulated by zooplankton in marine systems, acting as a link to higher trophic levels and exporting carbon to deeper waters. To determine the relative magnitude of these processes, the biomass and biometrics of zooplankton are often studied. Biomass is generally estimated based on wet mass, dry mass, or carbon mass; however these methods involve a destructive method, ceasing possibilities of future analysis of samples. The alternative method of estimating biomass via measuring biovolume (BV) through image-analysis provides a permanent electronic record of samples. Though an issue with this method is shrinkage observed in formalin-preserved zooplankton, which would provide an underestimated biomass. Therefore, this study investigates the response of different zooplankton taxa when preserved in formalin to determine taxa-specific conversion factors that can provide the means for more accurate biomass estimates. By tracking biovolume changes of different taxa over a two-month period and comparing percent biovolume of taxa in their fresh and preserved state, it was determined that taxa shrink at different rates and by different amounts. Copepods (and specifically Eucalanus sp.), decapod megalops, euphausiids, small hyperiids (BV < 60 mm3), and gastropod veliger larvae had statistically significant differences in the fresh and preserved percent biovolume. Additionally, the acquired conversion factors for several taxa can now be used to correct for the underestimated biovolumes obtained through image-analysis, as a proxy for biomass. This highlights the bias in estimates from previous applications that have investigated ecosystem energy flow or determined how biomass changes in differing oceanographic conditions. While this method has advantages, it is limited to a coarser taxonomic resolution of samples than what could be accomplished with microscopic analysis. Future work could include more taxa to obtain more conversion factors and higher sample size of taxa for more accurate conversion factors.enHonours thesisDepartment of Biology