The Biomagnification of Total Mercury (and its Methylated Form) during the Various Life Stages of Dragonflies (Anisoptera) from Montegut, LA

Presentation Type

Poster

Conference Date

Spring 4-17-2026

Abstract

Dragonflies (Anisoptera) can be effective indicators of aquatic ecosystem health. As larvae (naiads), they are predators, feeding on other aquatic invertebrates and small fish. In this stage, naiads are exposed to various environmental contaminants, including mercury (Hg) and methylmercury (MeHg; a toxic form). These contaminants can bioaccumulate and biomagnify through food webs. Upon metamorphosis, newly emerged adult dragonflies enter terrestrial ecosystems, potentially transporting mercury from aquatic to terrestrial food webs. These emergent adults often serve as prey for birds, spiders, and other terrestrial predators. Despite growing research on contaminant movement from water to land, it became apparent that limited research is being conducted in the Southern United States, which led me to explore this dynamic while residing in the Region. Our project involves collecting dragonflies (Anisoptera) at all life stages, as well as fishing spiders (Pisauridae), to illustrate the introduction of mercury and its methylated form into terrestrial ecosystems from aquatic ecosystems. As well as the collection of water and sediment from local wetlands in Motegut, LA, a shrimping and crabbing community in Terrebonne Parish. In the lab, the collected water, sediments, dragonflies (Anisoptera), and fishing spiders (Pisauridae) are analyzed for total mercury (THg) and methylmercury (MeHg). And with leftover tissue samples, to conduct stable isotope analysis to show the flow of energy and matter in the dragonflies (Anisoptera) and fishing spiders (Pisauride) by using carbon and nitrogen.

Presenter

MiKia Alexander

Faculty Mentor

Sydney Moyo

Award

3rd Place, LSU College of Agriculture

Academic Major

Natural Resource Ecology & Management

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