Investigating Dissolved Harmful Algal Blooms Phycotoxins in New Jersey Aquatic Environments

Harmful algal blooms (HABs) are recurring problems in New Jersey (NJ). Some HABs produce organic phycotoxins that are detrimental to both ecosystem organisms and human health. While most studies on HABs and phycotoxins focus on freshwater in NJ, comparative measurements of phycotoxins in marine coastal environments are understudied. In the summer of 2025, surface water from 11 freshwater, 3 brackish rivers, and 10 coastal sites in northern and central NJ was collected and analyzed for 12 dissolved phycotoxins using a combination of solid phase extraction and liquid chromatography-tandem mass spectrometry. Phycotoxin concentrations and distribution varied spatially among sampling sites. Total okadaic acid (OA) and total dinophysistoxin-1(DTX-1) were present with the highest concentrations, followed by brevetoxin and microcystin. Cluster analysis revealed separation of phycotoxin patterns mostly between freshwater and brackish/marine sites. Correlation analysis revealed significantly positive correlations among total OA, total DTX-1, and pectenotoxin-2 concentrations, revealing their potential common source from the same HAB species. Temperature, dissolved oxygen, and pH were mostly correlated with multiple phycotoxins, suggesting their important role in shaping HABs and phycotoxin production. This study detects phycotoxins at low levels, which can help to provide early warnings of HABs to establish water quality baselines and maintain environmental health.