Bioaccumulation of brevetoxin in filth flies during red tide events: Implications for trophic interactions

Authors: TAYLOR, CAITLIN - Northern Illinois University; BLOOMQUIST, JEFFREY - Northern Illinois University; Geden, Christopher - Chris; BURGESS, EDWIN - Northern Illinois University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Karenia brevis, a marine dinoflagellate, causes red tide events in the Gulf of Mexico resulting in mass mortality of marine vertebrates and terrestrial fauna. Brevetoxin (PbTx), the toxin produced by K. brevis, targets voltage-gated sodium channels (VGSC), leading to hyperexcitation and depolarization of nerve and muscle cells. During red tides, scavengers are attracted to the mass mortality, potentially exposing themselves to PbTx through multi-trophic interactions. This study focuses on filth flies as the primary colonizers of carcasses and their role in PbTx contamination. Larvae and adult filth flies collected from the carcasses of two separate K. brevis blooms were examined for PbTx using an enzyme-linked immunosorbent assay (ELISA) kit. Transstadial presence of PbTx was investigated by analyzing larvae, pupae, and adult flies from the Calliphoridae and Sarcophagidae families. Calliphoridae flies were identified to species using a key, while Sarcophagidae flies were identified through sequencing of the Cytochrome Oxidase I (CO1) gene. Flies collected from the beaches were also screened for brevetoxin presence. All flies and life stages tested positive for brevetoxin, including larvae, pupae, and adults, indicating transstadial persistence of the toxin. This study confirms the bioaccumulation of brevetoxins in filth flies during red tide events, suggesting potential trophic effects at the interface of marine and terrestrial food webs. This study provides the first evidence of brevetoxin bioaccumulation in invertebrates along the Gulf Coast during red tide events, highlighting the ecological implications and potential trophic interactions.

Technical Abstract: TKarenia brevis, a marine dinoflagellate, causes red tide events in the Gulf of Mexico resulting in mass mortality of marine vertebrates and terrestrial fauna. Brevetoxin (PbTx), the toxin produced by K. brevis, targets voltage-gated sodium channels (VGSC), leading to hyperexcitation and depolarization of nerve and muscle cells. During red tides, scavengers are attracted to the mass mortality, potentially exposing themselves to PbTx through multi-trophic interactions. This study focuses on filth flies as the primary colonizers of carcasses and their role in PbTx contamination. Larvae and adult filth flies collected from the carcasses of two separate K. brevis blooms were examined for PbTx using an enzyme-linked immunosorbent assay (ELISA) kit. Transstadial presence of PbTx was investigated by analyzing larvae, pupae, and adult flies from the Calliphoridae and Sarcophagidae families. Calliphoridae flies were identified to species using a key, while Sarcophagidae flies were identified through sequencing of the Cytochrome Oxidase I (CO1) gene. Flies collected from the beaches were also screened for brevetoxin presence. All flies and life stages tested positive for brevetoxin, including larvae, pupae, and adults, indicating transstadial persistence of the toxin. This study confirms the bioaccumulation of brevetoxins in filth flies during red tide events, suggesting potential trophic effects at the interface of marine and terrestrial food webs. This study provides the first evidence of brevetoxin bioaccumulation in invertebrates along the Gulf Coast during red tide events, highlighting the ecological implications and potential trophic interactions.