Characterization of a toxic Pseudo-nitzschia spp. bloom in the Northern Gulf of Mexico associated with domoic acid accumulation in fish

• Published in: Harmful algae 2013-06, Vol.26, p.20-32
• Main Authors: Liefer, Justin D., Robertson, Alison, MacIntyre, Hugh L., Smith, William L., Dorsey, Carol P.
• Format: Article
• Language: English
• Subjects: Algae; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; body weight; coastal water; coasts; correlation; dissolved inorganic nitrogen; Domoic acid; Fish; Fundamental and applied biological sciences. Psychology; groundwater; Gulf of Mexico; light intensity; phosphorus; Plant cytology, morphology, systematics, chorology and evolution; Plants and fungi; Pseudo-nitzschia subfradulenta; salinity; silicon; species diversity; Submarine groundwater discharge; Thallophyta; toxicity; Trophic transfer; water quality
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2013.03.002

•A toxic Pseudo-nitzschia spp. bloom occurred in Alabama waters in summer 2009.•Toxin domoic acid (DA) possibly due to P. subfraudulenta, not known to produce DA.•Bloom likely triggered by a storm and subsequent groundwater discharge event.•Bloom density and DA quota highest in high salinity, nutrient-poor waters.•First known DA accumulation in Alabama, occurring in commercially important fish. A toxic bloom of Pseudo-nitzschia spp. was observed in the Alabama coastal waters of the northern Gulf of Mexico (NGOM) in June 2009 that resulted in the accumulation of domoic acid (DA) in fish. The bloom initiated following a large storm event that likely caused increased groundwater discharge 16–20 days prior to peak densities. Eleven sites, located in littoral shoreline waters and inshore embayments spanning the entire Alabama NGOM coastline, were sampled during peak densities to assess Pseudo-nitzschia species composition and toxicity, and associated water-quality parameters. Small fish (0.27–11.9g body weight) were collected at six of these sites for analysis of DA content. High Pseudo-nitzschia spp. densities (8.27×104–5.05×106celll−1) were detected at eight sites located in the littoral shoreline and particulate DA was detected at six of these littoral sites (48.0–540pgml−1). The bloom consisted primarily (>90%) of Pseudo-nitzschia subfraudulenta, a species previously characterized as forming only a minor component of Pseudo-nitzschia assemblages and not known to produce DA. Pseudo-nitzschia spp. were at low densities or not detected at the inshore sites and DA was detected at these sites. Pseudo-nitzschia spp. density varied along an estuarine gradient, with greater densities occurring in the most saline, clear, and nutrient-poor waters. Cell density was strongly and negatively correlated with silicate (Si) concentrations and the ratios of silicate to dissolved inorganic nitrogen and phosphate (Si:DIN and Si:PO4). Cell toxin quota was negatively correlated with phosphate, and strongly and positively correlated with the ratio of total nitrogen to total phosphorus (TN:TP). These relationships are consistent with previous observations that indicate Pseudo-nitzschia spp. density and toxicity are likely to be greater in high salinity, high irradiance, and nutrient-poor waters. DA was detected in 128 of 131 (98%) of the fish collected, which included seven primary and secondary consumer species. This is the first demonstration of trophic transfer of DA in this re