A cross-regional examination of patterns and environmental drivers of Pseudo-nitzschia harmful algal blooms along the California coast

Sandoval-Belmar, Marco; Smith, J. L.; Moreno, Allison R.; Anderson, Clarissa R.; Kudela, Raphael M.; Sutula, Martha; Kessouri, Fayçal; Caron, David A.; Chávez, Francisco P.; Bianchi, Daniele

doi:10.1016/j.hal.2023.102435

Cited by 11 publications

(4 citation statements)

References 108 publications

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“…Our results do not necessarily imply that domoic acid related marine mammal stranding events are solely driven by Pseudo-nitzschia blooms in the northernmost regions of Southern California. In fact, along with the Santa Barbara Channel, the San Pedro Channel (Santa Monica Pier and Newport Pier are within this area) are considered subregional domoic acid hotspots within Southern California (Sandoval-Belmar et al, 2023). However, in our time series, pDA observations at Stearns Wharf provide the best indication of when marine mammal strandings caused by domoic acid intoxication may occur.…”

Section: Discussionmentioning

confidence: 86%

Quantifying the linkages between California sea lion (Zalophus californianus) strandings and particulate domoic acid concentrations at piers across Southern California

Smith,

Cram,

Berndt

et al. 2023

Front. Mar. Sci.

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Domoic acid-producing blooms of the diatom genus Pseudo-nitzschia are pervasive in coastal environments globally. Domoic acid, a neurotoxin, accumulates via trophic transfer into marine food webs and is often associated with mass marine mammal mortality and stranding events. In Southern California, California sea lions (Zalophus californianus) are an indicator species for food web impacts of domoic acid because they are abundant secondary consumers, sensitive to domoic acid intoxication, and are actively monitored by stranding networks. However, domoic acid exposure may occur a distance from where a sea lion ultimately strands. This spatiotemporal variation complicates coupling domoic acid observations in water to strandings. Therefore, we sought to quantify whether monitoring data from four pier sites across the region, covering nearly 700 km of coastline from 2015-2019, could be used to predict adult and subadult sea lion strandings along the 68 km Orange County coastline surveyed by the Pacific Marine Mammal Center. We found that increased sea lion strandings were often observed just prior to an increase in particulate domoic acid at the piers, confirming that clusters of subadult and adult sea lion strandings with clinical signs of domoic acid intoxication serve as indicators of bloom events. In addition, domoic acid concentrations at Stearns Wharf, nearly 200 km from stranding locations, best predicted increased total sea lion strandings, and strandings of sea lions with domoic acid intoxication symptoms. Particulate domoic acid concentrations greater than 0.05 μg/L at Stearns Wharf were linked to stranding probabilities in Orange County ranging from 2.2% to 55% per week, and concentrations of 0.25 μg/L resulted in weekly stranding probabilities ranging from 16% to 81% depending on the stranding scenario modeled.

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Section: Discussionmentioning

confidence: 86%

Quantifying the linkages between California sea lion (Zalophus californianus) strandings and particulate domoic acid concentrations at piers across Southern California

Smith,

Cram,

Berndt

et al. 2023

Front. Mar. Sci.

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“…Our results show that UI plays a significant role as one of the most important predictors for cell abundance, contributing to the increase in cell density and explaining 11% of the deviance. Notably, in regions such as the West Coast of the USA, where Pseudo-nitzschia is a common harmful bloom former, prolonged blooms have been associated with the declining high-nutrient phase after upwelling events (Trainer et al, 2010;Sandoval-Belmar et al, 2023). In the southern estuaries of Galicia, higher abundances of Pseudo-nitzschia generally appear during the relaxation-upwelling conditions (Dıáz et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Potentially toxigenic phytoplankton patterns in the northwestern Iberian Peninsula

Detoni,

Navarro,

Padín

et al. 2024

Front. Mar. Sci.

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The Galician estuaries are Europe’s foremost supplier of mussels, generating millions of euros annually and offering substantial employment opportunities for its population. One of the most critical threats to shellfish production is the occurrence of harmful algal blooms (HABs), contaminating bivalves with phytotoxins. To successfully tackle this problem, there needs to be a collaborative effort between the scientific community and decision-makers to establish a dynamic and effective monitoring system. This could enable early warnings and preventive actions to avert the loss of millions of tons of shellfish. Remote sensing, despite its limitations, requires commitment and effort by experts to devise effective methods for detecting target optical constituents mixed with other undesired target but that exhibit strong signals. Therefore, the essential necessity arises to identify approaches for mitigating the shortcomings of the undertaken efforts. The objective of this study is to assess the main environmental drivers of potential harmful genera (Pseudo-nitzschia, Dinophysis, Alexandrium, and Gymnodinium) in the Rías Baixas from 2015 to 2022, developing regression-based models and customizing Generalized Additive Models (GAMs) to investigate their spatial-temporal dynamics. Risk-susceptible bloom zones were identified in the river mouth of the Ría Pontevedra and from the center to offshore of the Ría Vigo. Early upwelling events triggered peaks in chlorophyll-a (Chl-a), driving Dinophysis grazing on phytoplankton communities mainly dominated by diatoms, flagellates, and ciliates. Subsequently, the upwelling intensity favoring Pseudo-nitzschia or Alexandrium minutum growth as larger diatoms declined. A. minutum exhibited elevated incidence over the past five years. Gymnodinium catenatum presented a rare occurrence across the three studied estuaries, which limited the assessment of its spatial dynamics in the region. This study emphasizes the need to integrate remote sensing evaluation of high-risk bloom areas (July to September), in-situ cell count collection, and enhanced efforts for forecasting future critical occurrences of HABs.

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“…For this reason, some outfalls may have a disproportionate role in coastal acidification, hypoxia and offshore habitat loss, and this aspect has not yet been explored. Other outcomes, such as the risk of toxic harmful algae blooms (HABs), should be considered as a third lines of evidence, as water recycling will modify not only the dispersion, but also the magnitude of DIN concentrations and phytoplankton biomass in the nearfield (Table 1 ), a factor linked to the risk of HABs 75 . Furthermore, other bioremediation solutions such as kelp and bivalve aquaculture may provide a partial solution that could be a more cost-effective means to treat localized discharges from outfalls and nearby non-point source discharges 76 , 77 .…”

Section: Discussionmentioning

confidence: 99%

Effect of ocean outfall discharge volume and dissolved inorganic nitrogen load on urban eutrophication outcomes in the Southern California Bight

Ho,

Kessouri,

Frieder

et al. 2023

Sci Rep

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Climate change is increasing drought severity worldwide. Ocean discharges of municipal wastewater are a target for potable water recycling. Potable water recycling would reduce wastewater volume; however, the effect on mass nitrogen loading is dependent on treatment. In cases where nitrogen mass loading is not altered or altered minimally, this practice has the potential to influence spatial patterns in coastal eutrophication. We apply a physical-biogeochemical numerical ocean model to understand the influence of nitrogen management and potable wastewater recycling on net primary productivity (NPP), pH, and oxygen. We model several theoretical management scenarios by combining dissolved inorganic nitrogen (DIN) reductions from 50 to 85% and recycling from 0 to 90%, applied to 19 generalized wastewater outfalls in the Southern California Bight. Under no recycling, NPP, acidification, and oxygen loss decline with DIN reductions, which simulated habitat volume expansion for pelagic calcifiers and aerobic taxa. Recycling scenarios under intermediate DIN reduction show patchier areas of pH and oxygen loss with steeper vertical declines relative to a “no recycling” scenario. These patches are diminished under 85% DIN reduction across all recycling levels, suggesting nitrogen management lowers eutrophication risk even with concentrated discharges. These findings represent a novel application of ocean numerical models to investigate the regional effects of idealized outfall management on eutrophication. Additional work is needed to investigate more realistic outfall-specific water recycling and nutrient management scenarios and to contextualize the benefit of these management actions, given accelerating acidification and hypoxia from climate change.

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A cross-regional examination of patterns and environmental drivers of Pseudo-nitzschia harmful algal blooms along the California coast

Cited by 11 publications

References 108 publications

Quantifying the linkages between California sea lion (Zalophus californianus) strandings and particulate domoic acid concentrations at piers across Southern California

Quantifying the linkages between California sea lion (Zalophus californianus) strandings and particulate domoic acid concentrations at piers across Southern California

Potentially toxigenic phytoplankton patterns in the northwestern Iberian Peninsula

Effect of ocean outfall discharge volume and dissolved inorganic nitrogen load on urban eutrophication outcomes in the Southern California Bight

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