Apparent biogeographical trends in Alexandrium blooms for northern Europe: identifying links to climate change and effective adaptive actions

Probabilistic models for harmful algae: application to the Norwegian coast

“…Few machine learning techniques for modeling the probability of toxic algae have been explored, including GLM (Anderson et al, 2011), decision trees (Bouquet et al, 2022), and GBM (Klemm et al, 2022). We demonstrate that SVM is a highly reliable approach for estimating the presence and HA probability of toxic algae in Norwegian coastal waters.…”

“…and Dinophysis spp. are commonly associated with stratified waters (Klemm et al, 2022; Reguera et al, 2012). The simulated response supports these associations, as the presence probability of D. acuminata , Alexandrium spp., and A. tamarense increases in shallower MLD—commonly correlated with more stratified waters.…”

“…Assessing geographical regions and time periods with an elevated probability of toxic species detection can offer several advantages, such as optimizing monitoring programs by redistributing resources and efforts, enhancing the protection of public health, enabling early harvesting prior to toxin outbreaks, improving business planning and investment decisions, and fostering increased consumer confidence (Jin et al, 2020). Probabilistic models can serve this purpose and inform likelihood changes based on external factors that influence the growth of toxic algae, such as sea surface temperature (SST), mixed layer depth (MLD), photosynthetic active radiation (PAR), and sea surface salinity (SSS) (Anderson et al, 2011(Anderson et al, , 2012Bates et al, 2018;García-Portela et al, 2018;Jauffrais et al, 2013;Kim et al, 2008;Klemm et al, 2022;Paz et al, 2006;Reguera et al, 2012).…”

“…(Bouquet et al, 2022). In Irish coastal waters, gradient boosting models (GBMs) were applied to model the probability of the presence/absence of A. tamarense using inputs such as temperature, salinity, and a water stratification index (Klemm et al, 2022). Although these studies have made significant contributions, none have addressed a wide range of toxic algae taxa, nor have they been calibrated for the Norwegian coastal shelf.…”

“…These inputs are chosen for two reasons: (i) they have enough time span and spatial coverage matching the algae observations in the shellfish farms and (ii) algae growth is mostly driven by these factors. Algae show distinct temperature-related traits that cause them to grow or diminish in different temperature ranges (Basti et al, 2018; Fehling et al, 2004; Guerrini et al, 2007; Nagai et al, 2004; Rial et al, 2023; Röder et al, 2012; Thomas et al, 2012); PAR corresponds to the light available for photosynthesis and therefore strongly influences algae growth (Bill et al, 2012; García-Portela et al, 2018; Jauffrais et al, 2013); salinity variations affect algae by inducing osmotic stress, creating ion stress through the unavoidable absorption or loss of ions, and altering the cellular ionic ratios due to selective mechanisms (Jauffrais et al, 2013; Kirst, 1990; Klemm et al, 2022; Nagai et al, 2004; Rial et al, 2023; Weber et al, 2021); shallower MLD—a common proxy to well-stratified waters—is commonly associated with HABs (Klemm et al, 2022; Reguera et al, 2012). Note that other important variables, such as nutrients, are not included as no product available matches the farms in a long time series.…”