Climatic regulation of the neurotoxin domoic acid

Abstract

Domoic acid is a potent neurotoxin produced by certain marine microalgae that can accumulate in the foodweb, posing a health threat to human seafood consumers and wildlife in coastal regions worldwide. Evidence of climatic regulation of domoic acid in shellfish over the past 20 y in the Northern California Current regime is shown. The timing of elevated domoic acid is strongly related to warm phases of the Pacific Decadal Oscillation and the Oceanic Niño Index, an indicator of El Niño events. Ocean conditions in the northeast Pacific that are associated with warm phases of these indices, including changes in prevailing currents and advection of anomalously warm water masses onto the continental shelf, are hypothesized to contribute to increases in this toxin. We present an applied domoic acid risk assessment model for the US West Coast based on combined climatic and local variables. Evidence of regional-to basin-scale controls on domoic acid has not previously been presented. Our findings have implications in coastal zones worldwide that are affected by this toxin and are particularly relevant given the increased frequency of anomalously warm ocean conditions.T he Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) are recurring patterns of climate variability centered over the northeastern (NE) and equatorial Pacific, respectively, that fluctuate at scales of years (ENSO) to decades (PDO) (1, 2). Distinct, yet also related, these patterns can amplify or dampen each other through atmospheric teleconnection (1, 3). In the NE Pacific, they induce similar spatial patterns of sea surface temperature anomalies during positive (warm) and negative (cool) phases (4). Low-frequency physical variability attributed to the PDO and ENSO modulates large shifts in NE Pacific water temperature, ocean currents, and foodweb dynamics that can persist for months to years (2,5,6). Shifts in NE Pacific plankton communities occur as well (7-12); however, climate impacts on phytoplankton ecology in this region are relatively underexplored, largely due to a lack of phytoplankton data at sufficient scales.Decadal, regional-scale monitoring of domoic acid (DA) in shellfish can be used to investigate climate-scale impacts on phytoplankton ecology. The neurotoxin DA is produced by some species of the diatom genus Pseudo-nitzschia. It enters secondary trophic levels when suspension feeders such as shellfish and anchovies ingest toxic Pseudo-nitzschia cells. Consumption of these organisms by humans can lead to a serious neurological disorder named Domoic Acid Poisoning (DAP), also termed Amnesic Shellfish Poisoning. DAP symptoms range from gastrointestinal disturbance to seizures, memory loss, or, rarely, death (13,14).DA was first identified as a public health threat in 1987 (15). Toxin-producing Pseudo-nitzschia spp. and DA have since been identified worldwide with the greatest prevalence in, and most deleterious impacts on, productive eastern boundary upwelling systems (16). Laboratory experiments have found multiple ...

Mass mortality of marine birds in the Northeast Pacific caused by Akashiwo sanguinea

“…However, the etiology of foam-based marine bird mortality events was not identified until the A. sanguinea bloom in Monterey Bay in 2007 (Jessup et al 2009). Given the physiological flexibility of A. sanguinea ) the rapid response of this species to favourable environmental conditions (Cloern et al 2005) and the increase in coastal warming and climate variability, including marine heatwave events (Hobday et al 2016, Scannell et al 2016, McCabe et al 2016, McKibben et al 2017, we speculate that the frequency of foaminduced bird mortality events may continue to increase in the CCS and perhaps elsewhere.…”

Biosynthesis of the neurotoxin domoic acid in a bloom-forming diatom

“…S5). In vitro, DabA catalyzes the N -geranylation of L -Glu to form L -NGG (2) in a Mg +2 -dependent manner (Fig. 3A).…”

Harmful Algal Blooms in Eastern Boundary Upwelling Systems: A GEOHAB Core Research Project

“…Examination of a 15-year time series (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) (Barron et al, 2013). McKibben et al (2017) provide further evidence of climatic regulation of domoic acid in shellfish over the past 20 years in the northern California Current. They show the timing of elevated domoic acid to be strongly related to warm phases of the Pacific Decadal Oscillation and to Oceanic Niño Index events.…”

“…The seasonal transition to upwelling subsequently provided the nutrients necessary for development of a large-scale bloom, and a series of spring storms delivered the bloom to the coast. McKibben et al (2017) later provided evidence of climatic regulation of these events through assessment of domoic acid in shellfish in the northern California Current System over the past 20 years.…”

“…Ocean conditions in the Northeast Pacific associated with warm phases of these indices, including changes in prevailing currents and advection of anomalously warm water onto the continental shelf, are thought to contribute to increases in this toxin. In warm-phase years, the spring biological transitions date, indicative of the seasonal transition of the northern California Current to southward flow, occurs later; alongshore currents tend to be weaker in association with warm Pacific Decadal Oscillation values; estuarine and offshore water temperatures are elevated; the copepod species richness anomaly is positive and there is a shift in copepod composition to species of a predominantly offshore or southern origin; and domoic acid levels in Oregon coast razor clams exceed closure values (McKibben et al, 2017). If global warming causes these warm ocean regimes to become more persistent, as is hypothesized, domoic acid events on the US West Coast may increase in persistence and frequency (McKibben et al, 2017).…”