Seasonal and annual dynamics of harmful algae and algal toxins revealed through weekly monitoring at two coastal ocean sites off southern California, USA

Abstract

Reports of toxic harmful algal blooms (HABs) attributed to the diatom Pseudo-nitzschia spp. have been increasing in California during the last several decades. Whether this increase can be attributed to enhanced awareness and monitoring or to a dramatic upswing in the development of HAB events remains unresolved. Given these uncertainties, the ability to accurately and rapidly identify an emerging HAB event is of high importance. Monitoring of HAB species and other pertinent chemical/physical parameters at two piers in southern California, Newport and Redondo Beach, was used to investigate the development of a site-specific bloom definition for identifying emerging domoic acid (DA) events. Emphasis was given to abundances of the Pseudo-nitzschia seriata size category of Pseudo-nitzschia due to the prevalence of this size class in the region. P. seriata bloom thresholds were established for each location based on deviations from their respective long-term mean abundances, allowing the identification of major and minor blooms. Sixty-five percent of blooms identified at Newport Beach coincided with measurable DA concentrations, while 36 % of blooms at Redondo Beach coincided with measurable DA. Bloom definitions allowed for increased specificity in multiple regression analysis of environmental forcing factors significant to the presence of DA and P. seriata. The strongest relationship identified was between P. seriata abundances 2 weeks following upwelling events at Newport Beach.

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

“…Recent studies within the Southern California Bight (SCB) have documented chronic algal bloom hot spots that coincide with areas that have potentially significant anthropogenic nutrient inputs (Nezlin et al 2012). Before 2000, toxic outbreaks of Pseudo-nitzschia (an algal diatom that produces domoic acid) were considered rare (Lange et al 1994); however, in recent years, frequent occurrences (Seubert et al 2013) and high concentrations of this toxin have been documented in the SCB (Trainer et al 2000;Schnetzer et al 2007;Caron et al 2010) and have been attributed to upwelling (Lewitus et al 2012;Schnetzer et al 2013). Increased awareness of toxic HAB events served as the primary motivation for establishment of the Harmful Algae and Red Tide Regional Monitoring Program by the Southern California Coastal Ocean Observing System (SCCOOS).…”

Investigation of Algal Biotoxin Removal during SWRO Desalination through a Materials Flow Analysis

“…It is important to note that the Pseudo-nitzschia cell abundance data included in the SCCOOS database is not currently identified down to the species level [20]. Instead, cell abundance is classified into two different size fractions by light microscopy: the Pseudo-nitzschia delicatissima class (frustule widths >3 µm) and the Pseudo-nitzschia seriata class (frustule widths <3 µm) [20].…”

“…It is important to note that the Pseudo-nitzschia cell abundance data included in the SCCOOS database is not currently identified down to the species level [20]. Instead, cell abundance is classified into two different size fractions by light microscopy: the Pseudo-nitzschia delicatissima class (frustule widths >3 µm) and the Pseudo-nitzschia seriata class (frustule widths <3 µm) [20]. Of these genera listed, only some species of Alexandrium (producer of saxitoxin, STX), Dinophysis (producer of okadaic acid, OA), Lingolidinium polyedrum (producer of yessotoxin, YTX), and Pseudo-nitzschia (producer of domoic acid, DA) produce toxins [11].…”

“…SCCOOS data from a three-year period (2012)(2013)(2014)(2015) were first used to create an overview of the frequency and severity of blooms in the region, similar to the time-period specified by Seubert and co-workers [20] (Figure S1). To simplify the pMFA analysis, we did not separate bloom periods into either major or minor events as previously described [20][21][22].…”

“…To simplify the pMFA analysis, we did not separate bloom periods into either major or minor events as previously described [20][21][22]. Instead, a constant chlorophyll-a threshold using the overall mean of the 3-year data (~12 µg/L) was incorporated to identify significant events (comparable to the definition for minor blooms in [21]).…”